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  • 1990-1994  (3,407)
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  • Chemical Engineering  (3,877)
  • transformation
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  • 1
    Electronic Resource
    Electronic Resource
    Agrobacterium-mediated transformation of white mustard (Sinapis alba L.) and regeneration of transgenic plants (1994)
    Springer
    Plant cell reports 13 (1994), S. 130-134 
    Details
    ISSN: 1432-203X
    Keywords: Sinapis alba L. ; Agrobacterium tumefaciens ; transformation ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A procedure for the regeneration of fertile transgenic white mustard (Sinapis alba L.) is presented. The protocol is based on infection of stem explants of 7–9 day old plants with an Agrobacterium tumefaciens strain harboring a disarmed binary vector with chimeric genes encoding neomycin phosphotransferase and β-glucuronidase. Shoots are regenerated from callus-forming explants within 3–4 weeks. Under selection, 10% of the explants with transgenic embryonic callus develop into fertile transgenic plants. Rooting shoots transferred to soil yield seeds within 14–16 weeks following transformation. Integration and expression of the T-DNA encoded marker genes was confirmed by histochemical β glucuronidase assays and Southern-DNA hybridization using primary transformants and S1-progeny. The analysis showed stable integration and Mendelian inheritance of trans-genes in transformed Sinapis lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239878
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  • 2
    Electronic Resource
    Electronic Resource
    Isolation and transformation of rice aleurone protoplasts (1994)
    Springer
    Plant cell reports 13 (1994), S. 394-396 
    Details
    ISSN: 1432-203X
    Keywords: Rice ; α-amylase ; protoplasts ; aleurone ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplasts isolated from the aleurone have been used extensively in molecular studies focusing on hormone-mediated regulation of gene expression in barley seed. To extend the use of aleurone protoplasts to other species, we have determined the conditions necessary for the isolation of protoplasts from rice aleurone layers of germinated seed. Many of the common cell wall degrading enzymes used in making protoplasts were tested for their ability to release protoplasts from rice aleurone layers. Cellulysin was found to be the most effective. Transformation of these aleurone protoplasts was accomplished using polyethylene glycol and DNA constructs containing the firefly luciferase reporter gene under the control of two different promoters were tested. Luciferase expression was 24-fold greater when the reporter gene was under the control of the CaMV 35S promoter than when the promoter from the alcohol dehydrogenase 1 gene was used. With the isolation and transformation of aleurone protoplasts from rice, it is now possible to investigate molecular events occurring in this tissue during germination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234145
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  • 3
    Electronic Resource
    Electronic Resource
    Hairy roots of Brassica napus: II. Glutamine synthetase overexpression alters ammonia assimilation and the response to phosphinothricin (1994)
    Springer
    Plant cell reports 14 (1994), S. 41-46 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium rhizogenes ; Brassica napus ; glutamine synthetase ; phosphinothricin ; rape ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hairy roots of Brassica napus (rape cv. Giant) have been produced that contain the cytosolic glutamine synthetase (GS) gene from Glycine max (soybean). Leaf explants were cocultivated with Agrobacterium rhizogenes strain A4T harbouring the binary vector pLN16. This vector was constructed by inserting a soybean cytosolic GS cDNA into the multiple cloning site of pGA643, placing it under the control of the CaMV promoter. In addition, the T-DNA region of pLN16 contained a NPTII gene for selection of transformed cells. Transgenic hairy roots grew prolifically on hormone-free media containing a selective level of kanamycin. Southern and northern analyses confirmed the presence of soybean GS DNA and transcripts, respectively. These transformed hairy roots also have a greater abundance of the GS polypeptide, approximately 3–6 fold greater GS activity and lower levels of endogenous ammonia. Hairy roots provide a useful system for studying responses to phosphinothricin (PPT). Hairy roots grown in media containing PPT had lower GS activity, greater ammonia accumulation and slower growth than controls. The presence of the soybean GS gene in the hairy roots reduced these PPT-induced effects and resulted in higher GS activity, lower ammonia levels and faster growth than in PPT-treated controls. Greater tolerance of PPT was also seen in shoots regenerated from the hairy roots displaying elevated levels of GS activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233296
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  • 4
    Electronic Resource
    Electronic Resource
    Genetic ecology: A new interdisciplinary science, fundamental for evolution, biodiversity and biosafety evaluations (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 429-437 
    Details
    ISSN: 1420-9071
    Keywords: Genetics ; ecology ; DNA-transfer ; conjugation ; transformation ; transduction ; transposons ; dormant cells ; epilithon ; microbial colonisation ; symbiosis ; virus resistance ; biosafety ; release of genes ; insults to humanity ; evolution ; biodiversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Genetic ecology is the extension of our modern knowledge in molecular genetics to studies of viability, gene expression and gene movements in natural environments like soils, aquifers and digestive tracts. In such milieux, the horizontal transfer of plasmid-borne genes between phylogenetically distant species has already been found to be much more frequent than had been expected from laboratory experience. For the study of exchanges involving chromosomally-located genes, more has to be learned about the behaviour of transposons in such environments. The results expected from studies in genetic ecology are relevant for considerations of evolution, biodiversity and biosafety. The role of this new field of research in restoring popular confidence in science and in its biotechnological applications is stressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01920741
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  • 5
    Electronic Resource
    Electronic Resource
    Stable expression of the GUS reporter gene in chrysanthemum depends on binary plasmid T-DNA (1994)
    Springer
    Plant cell reports 14 (1994), S. 59-64 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium ; transformation ; T-DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three chrysanthemum (Dendranthema grandiflora) cultivars were cocultivated with 2 Agrobacterium tumefaciens strains in combination with 4 pBIN19 derived binary plasmids, all carrying the Nosnptll selection gene and 35Sgus(intron) reporter gene. All binary plasmids transferred DNA to chrysanthemum explants but only pMOG410 gave good stable expression of GUS. This plasmid differs from the other plasmids in 2 aspects: 1) It carries a restored nptll gene and 2) the selection gene is positioned at the left border side of the reporter gene. Cocultivation with AGLO(pMOG410) yielded up to 13 GUS positive shoots per 100 explants. The presence of the gus and nptll gene in recovered shoots was confirmed by PCR and Southern blot analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233300
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  • 6
    Electronic Resource
    Electronic Resource
    Plasmid mediated silver resistance in Acinetobacter baumannii (1994)
    Springer
    BioMetals 7 (1994), S. 49-56 
    Details
    ISSN: 1572-8773
    Keywords: Acinetobacter ; conjugation ; curing ; plasmid ; silver uptake ; silver resistance ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Acinetobacter baumannii BL88, an environmental isolate, was resistant to 13 metals and 10 antibiotics. Plumbagin cured resistance to silver, cadmium, antimony, streptomycin and ampicillin at varying frequencies. However, only silver resistance transferred (1 × 10−6 recepient−1) to Escherichia coli K12 during conjugation. Correspondingly there was transfer of a 54 kb plasmid (pUPI199) from A. baumannii BL88. The plasmid transformed E. coli DH5α cells at a frequency of 1 × 10−8 recepient−1. The growth rate of E. coli DH5; (pUPI199) was slower as compared with E. coli DH5α. Plasmid pUPI199 was 76 and 9.6% stable in the host A. baumannii BL88 in the presence and absence of selection pressure, respectively. A. baumannii BL88 was found to accumulate and retain silver whereas E. coli DH5α (pUPI199) effluxed 63% of the accumulated silver ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00205194
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  • 7
    Electronic Resource
    Electronic Resource
    Transmission of injected DNA sequences to multiple eggs of Metaseiulus occidentalis and Amblyseius finlandicus (Acari: Phytoseiidae) following maternal microinjection (1994)
    Springer
    Experimental and applied acarology 18 (1994), S. 319-330 
    Details
    ISSN: 1572-9702
    Keywords: Maternal microinjection ; transformation ; genetic improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The persistence of DNA injected into two species of adult female phytoseiids and its transmission to serial eggs deposited by them was assessed by the polymerase chain reaction (PCR). The effect of DNA concentration on persistence and transmission was examined in Metaseiulus occidentalis. M. occidentalis females were microinjected with plasmid DNA at three different concentrations (250, 500, 750 ng μL−1) and allowed to deposit one to five eggs before the females and their last eggs were analyzed. Plasmid DNA was found in 82% of the females assayed and in 70% of all the eggs analyzed (including the fifth eggs produced after microinjection). Transmission of DNA to multiple eggs was also examined in Amblyseius finlandicus. Females of this species are less traumatized by microinjection allowing analysis of transmission over a more extended number of eggs. Females were microinjected and allowed to deposit eggs until their death. DNA from every fifth egg was analyzed by the PCR. PCR products were amplified from 51% of the eggs and from all egg classes except the 30th egg. The persistence and presence of plasmid DNA in both eggs and females suggests that (1) maternal microinjection is a more efficient method for DNA delivery than traditional egg microinjection, (2) it may be possible to isolate transformants from fewer maternally-microinjected females than originally expected, and (3) maternal microinjection could be useful as a DNA delivery system in other phytoseiids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00116313
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  • 8
    Electronic Resource
    Electronic Resource
    Canonical correlation and reduction of multiple time series (1994)
    Springer
    Annals of the Institute of Statistical Mathematics 46 (1994), S. 625-631 
    Details
    ISSN: 1572-9052
    Keywords: Rank of multiple time series ; transformation ; spectrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract It is shown that a degenerate rankd-variate stationary time series can be reduced to a full rank time series of lower dimension via an orthogonal transformationT provided that ρ, the canonical correlation between past and future of the time series is strictly less than one. Procedures for estimation of rank of the multiple time series,T and testing ρ=1 are outlined, the latter is related to testing the unit root hypothesis in ARMA models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00773471
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  • 9
    Electronic Resource
    Electronic Resource
    Genetics and gibberellin production inGibberella fujikuroi (1994)
    Springer
    Antonie van Leeuwenhoek 65 (1994), S. 217-225 
    Details
    ISSN: 1572-9699
    Keywords: Gibberella fujikuroi ; gibberellins ; mutants ; regulation by nitrogen ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gibberella fujikuroi (Fusarium moniliforme) is a complex group of plant pathogens. Some strains produce gibberellic acid and other gibberellins that promote growth and regulate various stages in plant development. The paper describes the research effort directed to development of genetic tools for this species. Furthermore the main features of the gibberellin biosynthetic pathway as established in Gibberella are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00871950
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  • 10
    Electronic Resource
    Electronic Resource
    Efficient plant regeneration through somatic embryogenesis from callus induced on mature rice embryos (Oryza sativa L.) (1994)
    Springer
    Plant cell, tissue and organ culture 36 (1994), S. 259-264 
    Details
    ISSN: 1573-5044
    Keywords: monocotyledons ; Oryza sativa L. ; plant regeneration ; rice ; somatic embryogenesis ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To obtain a reproducible efficient procedure for regeneration of rice plants through somatic embryogenesis from callus four published methods of callus induction and regeneration were compared. Callus was initiated from mature embryos of the Japonica cultivar Taipei 309 of rice (Oryza sativa L.). The number, mass and morphology of the callus formed on the scutellum were dependent on the medium used. A limited humidity and an optimal aeration of the culture vessels enhanced the frequency of embryogenesis and plant regeneration. A method described by Poonsapaya et al. (1989) was found to be the most efficient and was slightly modified. As a result 98% of the T309 embryos formed callus, of which 63% regenerated into plants. Each callus yielded an average of 6 plants. Plant morphology, fertility and seed set of the regenerants were found to be normal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037729
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  • 11
    Electronic Resource
    Electronic Resource
    Factors that effect leaf regeneration efficiency in apple, and effect of antibiotics in morphogenesis (1994)
    Springer
    Plant cell, tissue and organ culture 37 (1994), S. 257-269 
    Details
    ISSN: 1573-5044
    Keywords: adventitious shoots ; Malus x domestica Borkh. ; tissue culture ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several factors that affect the frequency of organogenesis in apple leaf explants were examined for the scion cultivars ‘Empire’, ‘Freedom’, ‘Golden Delicious’, ‘Liberty’, ‘McIntosh’, and ‘Mutsu’ and for the rootstocks Malling 7A and Malling 26. The main factors affecting morphogenesis were BA concentration, basal medium, leaf explant origin and maturity, explant orientation, and photosynthetic photon flux. Depending on the genotype, optimal regeneration was obtained using either 22.2 or 31.1 μM BA and the N6 basal medium, with the exception of ‘Golden Delicious’ which regenerated better on MS medium. After 6 weeks, the average number of shoots per segment varied from 5 to 16, and the percentage of regeneration between 70 and 100%, depending on the genotype tested and the maturity of the explant. Regeneration capacity increased dramatically from the tip towards the base of the leaf, and was higher from the middle to the proximal end. Cefotaxime and carbenicillin, two antibiotics commonly used during transformation studies to eliminate Agrobacterium tumefaciens from plant tissue, were tested to determine their effect on morphogenesis. Cefotaxime at a dose of 250 mg 1-1 enhanced regeneration and shoot development, whereas carbenicillin at a dose of 500 mg l-1 induced abundant callus formation and inhibited regeneration. Kanamycin, a widely used selection agent for plant transformation, strongly inhibited regeneration even at very low doses. Schemes for selection and recovery of transgenic apple plants when kanamycin is used as the selection agent are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042339
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  • 12
    Electronic Resource
    Electronic Resource
    A robust protocol for site-directed mutagenesis of the D1 protein inChlamydomonas reinhardtii: A PCR-splicedpsbA gene in a plasmid conferring spectinomycin resistance was introduced into apsbA deletion strain (1994)
    Springer
    Photosynthesis research 42 (1994), S. 121-131 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast ; Photosystem II ; psbA ; site-directed mutagenesis ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper, we describe a protocol to obtain a site-directed mutants in thepsbA gene ofChlamydomonas reinhardtii, which overcomes several drawbacks of previous protocols, and makes it possible to generate a mutant within a month. Since the large size of the gene, and the presence of four large introns has made molecular genetics of thepsbA gene rather unwieldy, we have spliced all of the exons of thepsbA gene by PCR to facilitate genetic manipulation and sequencing of the gene. The resultant construct (plasmid pBA153, with several unique restriction sites introduced at exon boundaries) carried 1.2 and 1.8 kb intact sequences from the 5′- and 3′-flanking regions, respectively. The plasmid was used to transform a D1-deletion mutant and was found to complement the deletion and restore photosynthetic activity. In addition, a bacterialaadA gene conferring spectinomycin resistance (spe r) was inserted downstream of the intron-freepsbA gene, to give construct pBA155. This allowed selection of mutant strains deficient in photosynthesis by using spectinomycin resistance, and eliminated the possibility of selection for revertant strains which is a consequence of having to use photosynthetic activity as a selection pressure. Finally, pBA155 was used to construct pBA157, in which additional restriction sites were inserted to facilitate cassette mutagenesis for generation of mutations in spans thought to be involved in donor-side interactions. AllpsbA deletion strains transformed with intron-freepsbA-aadA constructs encoding the wild-type D1 sequence, and screened on spectinomycin plates for thespe r phenotype, were able to grow photosynthetically, and all showed identical kinetics for electron transfer from primary (QA) to secondary quinone (QB) in Photosystem II, as assayed by the decay of the high fluorescence yield on oxidation of the reduced primary acceptor (QA −).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02187123
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  • 13
    Electronic Resource
    Electronic Resource
    Micropropagation of thirteen Malus cultivars and rootstocks, and effect of antibiotics on proliferation (1994)
    Springer
    Plant growth regulation 15 (1994), S. 55-67 
    Details
    ISSN: 1573-5087
    Keywords: apple (Malus × domestica Borkh.) ; selection ; tissue culture ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Several factors that affect in vitro establishment, proliferation, and rooting of thirteen Malus cultivars and rootstocks were studied. Apple shoot tips (1.5±0.5 cm in length) were established using ascorbic and citric acids as antioxidants. Four proliferation media containing 1.0 mg 1−1 BA and different concentrations of IBA and GA3 were tested. Proliferation rates varied depending on the genotype and medium used. The highest proliferation rate was obtained for a rootstock that produced 11.6±2.5 shoots (1.5±0.8 cm in length) per tube per month. Rooting was induced with IBA for all the genotypes tested. The optimal IBA concentration was cultivar dependent (between 0.1 and 1.0 mg 1−1 IBA), and lower concentrations were necessary to induce rooting in liquid rather than in solid medium. The effects on shoot-tip proliferation of cefotaxime, carbenicillin and kanamycin, three antibiotics commonly used for transformation studies, were also evaluated. Cefotaxime at 200 mg 1−1 stimulated shoot growth and development, but at 500 mg 1−1 caused abnormal shoot morphology. Carbenicillin at 500 mg 1−1, alone or in combination with cefotaxime at 200 mg 1−1, inhibited proliferation and caused excessive enlargement of the basal leaves, inducing callus formation and release of phenolic compounds in the medium. Kanamycin at 50 mg 1−1 was phytotoxic and caused shoot chlorosis and necrosis. Consideration of the toxicity of these antibiotics is critical when designing transformation schemes for selection and recovery of transgenic apple plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024677
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  • 14
    Electronic Resource
    Electronic Resource
    Production of fertile transgenic maize by electroporation of suspension culture cells (1994)
    Springer
    Plant molecular biology 24 (1994), S. 51-61 
    Details
    ISSN: 1573-5028
    Keywords: Zea mays L. ; transformation ; electroporation ; bar ; phosphinothricin acetyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fertile, transgenic maize plants were generated by electroporation of suspension culture cells that were treated with a pectin-degrading enzyme. Electroporation of cells from two different suspension cultures, one derived from A188 X B73 and one derived from a B73-related inbred, with a plasmid containing the bar gene, resulted in high-frequency recovery of stably transformed callus lines. Plants were regenerated from thirteen transformed callus lines and transmission of bar to progeny was demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040573
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  • 15
    Electronic Resource
    Electronic Resource
    Stable transformation and long-term expression of the gusA reporter gene in callus lines of perennial ryegrass (Lolium perenne L.) (1994)
    Springer
    Plant molecular biology 24 (1994), S. 401-405 
    Details
    ISSN: 1573-5028
    Keywords: Lolium perenne L. ; transformation ; rice gene GOS2 ; long-term GUS expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable transformation of perennial ryegrass (Lolium perenne L.) was achieved by biolistic bombardment of a non embryogenic cell suspension culture, using the hpt and gusA gene. The transformation yielded on the average 5 callus lines per bombardment (1.4×106 cells). Stable integration of the genes into the plant genome was demonstrated by Southern analysis of DNA, isolated from hygromycin-resistant callus lines. The gusA reporter gene, which was regulated by the constitutive promoter of the rice gene GOS2, was expressed in both transient and stable transformation assays, indicating that this promoter is suitable for expression of a transferred gene in perennial ryegrass. Long-term GUS expression was observed in ca. 40% of the callus lines, whereas the other callus lines showed instability after 6 months and 1 year of culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020178
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  • 16
    Electronic Resource
    Electronic Resource
    Molecular improvement of cereals (1994)
    Springer
    Plant molecular biology 25 (1994), S. 925-937 
    Details
    ISSN: 1573-5028
    Keywords: cereals ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014667
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  • 17
    Electronic Resource
    Electronic Resource
    Structure and function of selectable and non-selectable transgenes in maize after introduction by particle bombardment (1994)
    Springer
    Plant molecular biology 25 (1994), S. 951-961 
    Details
    ISSN: 1573-5028
    Keywords: Cell biology ; epigenetics ; maize ; transformation ; transgenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zea mays transformants produced by particle bombardment of embryogenic suspension culture cells of the genotype A188 × B73 and selected on kanamycin or bialaphos were characterized with respect to transgene integration, expression, and inheritance. Selection on bialaphos, mediated by thebar orpat genes, was more efficient than selection on kanamycin, mediated by thenptII gene. Most transformants contained multicopy, single locus, transgene insertion events. A transgene expression cassette was more likely to be rearranged if expression of that gene was not selected for during callus growth. Not all plants regenerated from calli representing single transformation events expressed the transgenes, and a non-selectable gene (uidA) was expressed in fewer plants than was the selectable transgene. Mendelian inheritance of transgenes consistent with transgene insertion at a single locus was observed for approximately two thirds of the transformants assessed. Transgene expression was typically, but not always, predictable in progeny plants-transgene silencing, as well as poor transgene transmission to progeny, was observed in some plant lines in which the parent plants had expressed the transgene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014669
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  • 18
    Electronic Resource
    Electronic Resource
    Stably transformed cell lines from protoplasts of maize endosperm suspension cultures (1994)
    Springer
    Plant cell, tissue and organ culture 37 (1994), S. 39-46 
    Details
    ISSN: 1573-5044
    Keywords: endosperm cell culture ; maize ; protoplast ; transformation ; zeins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts were isolated from Zea mays (L.) A69Y endosperm suspension cultures and transformed by polyethylene glycol mediated DNA uptake with chimaeric gene constructs containing β-glucuronidase (GUS) or neomycin phosphotransferase II (NPTII); GUS-expressing and Kanamycin-resistant cultures were recovered. The transformed cells showed integration of the introduced foreign genes into genomic DNA and maintained their ability to synthesize endosperm-specific reserve proteins (zeins). No deletion or rearrangement of zein genes were observed in transformed cultures. Stable transformation of cultured maize endosperm cells may therefore represent a new methodological approach for the study of the transcriptional regulation of endosperm-expressed genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048115
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  • 19
    Electronic Resource
    Electronic Resource
    A simple technique for producing 13C or 14C-labelled fronds of Lemna gibba and their use in soil incubation investigations (1994)
    Springer
    Plant and soil 160 (1994), S. 185-191 
    Details
    ISSN: 1573-5036
    Keywords: carbon-labelling ; carbon dioxide production ; decomposition ; 14C-glucose ; Lemna ; soil organic matter ; sugars ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The duckweed Lemna gibba required light and a suitable energy source such as sucrose, glucose or fructose, for maximum growth in culture. The requirement for light was relatively unimportant and the plants grew well in a photon flux density of only 52 μmol m-2s-1 PAR. The uptake and incorporation of uniformly labelled 14C-glucose into fronds was related only to the concentration of the sugar. When incubated with soil, labelled L. gibba behaved in a manner similar to that of labelled ryegrass roots which had been produced by a more elaborate technique using a 14CO2 labelled atmosphere. During incubation with soil for 224 days the L. gibba material (specific activity 6133 Bq mg-1 d. wt) lost 64% of its radioactivity as 14CO2 and ryegrass (specific activity 6634 Bq mg-1 d. wt) lost 49%. Alkaline extracted humic and fulvic acids from soil had specific activities for the L. gibba incubation of 3409 and 407 Bq mg-1 solid and for ryegrass roots of 4609 and 546 Bq mg-1 solid respectively. The production of 13C or 14C-labelled L. gibba can be undertaken using only simple equipment producing material the specific radioactivity of which can be controlled by adjusting the activity of the sugar energy source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010144
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  • 20
    Electronic Resource
    Electronic Resource
    Cloning of ω3 desaturase from cyanobacteria and its use in altering the degree of membrane-lipid unsaturation (1994)
    Springer
    Plant molecular biology 26 (1994), S. 249-263 
    Details
    ISSN: 1573-5028
    Keywords: desB gene ; desaturase ; fatty acid ; Synechococcus sp. PCC 7942 ; Synechocystis sp. PCC 6803 ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacteria respond to a decrease in temperature by desaturating fatty acids of membrane lipids to compensate for the decrease in membrane fluidity. Among various desaturation reactions in cyanobacteria, the desaturation of the ω3 position of fatty acids is the most sensitive to the change in temperature. In the present study, we isolated a gene, designated desB, for the ω3 desaturase from the cyanobacterium, Synechocystis sp. PCC 6803. The desB gene encodes a protein a 359 amino-acid residues with molecular mass of 41.9 kDa. The desB gene is transcribed as a monocistronic operon that produced a single transcript of 1.4 kb. The level of the desB transcript in cells grown at 22°C was 10 times higher than that in cells grown at 34°C. In order to manipulate the fatty-acid unsaturation of membrane lipids, the desB gene in Synechocystis sp. PCC 6803 was mutated by insertion of a kanamycin-resistance gene cartridge. The resultant mutant was unable to desaturate fatty acids at the ω3 position. The desA gene, which encodes the Δ12 desaturase of Synechocystis sp. PCC 6803, and the desB gene were introduced into Synechococcus sp. PCC 7942. Whilst the parent cyanobacterium can only desaturate membrane lipids at the Δ9 position of fatty acids, the resultant transformant was able to desaturate fatty acids of membrane lipids at the Δ9, Δ12 and ω3 positions. These results confirm the function of the desB gene and demonstrate that it is possible to genetically manipulate the fatty-acid unsaturation of membrane lipids in cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039536
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  • 21
    Electronic Resource
    Electronic Resource
    Identification of conserved domains in the Δ12 desaturases of cyanobacteria (1994)
    Springer
    Plant molecular biology 24 (1994), S. 643-650 
    Details
    ISSN: 1573-5028
    Keywords: Anabaena variabilis ; fatty-acid desaturation ; Synechococcus PCC7002 ; Synechococcus PCC7942 ; Synechocystis PCC6714 ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacterial genes for enzymes that desaturate fatty acids at the Δ12 position, designated desA, were isolated from Synechocystis PCC6714, Synechococcus PCC7002 and Anabaena variabilis by crosshybridization with a DNA probe derived from the desA gene of Synechocystis PCC6803. The genes of Synechocystis PCC6714, Synechococcus PCC7002 and A. variabilis encode proteins of 349, 347 and 350 amino acid residues, respectively. The transformation of Synechococcus PCC7942 with the desA genes from Synechocystis PCC6714, Synechococcus PCC7002 and A. variabilis was associated with the ability to introduce a second double bond at the Δ12 position of fatty acids. The amino acid sequence of the products of the desA genes revealed the presence of four conserved domains. Since one of the conserved domains was also found in the amino acid sequences of ω3 desaturases of Brassica napus and mung bean, this domain may play an essential role in the introduction of a double bond into fatty acids bound to membrane lipids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023560
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  • 22
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    Directed disruption of the Chlamydomonas chloroplast psbK gene destabilizes the photosystem II reaction center complex (1994)
    Springer
    Plant molecular biology 24 (1994), S. 779-788 
    Details
    ISSN: 1573-5028
    Keywords: Chlamydomonas reinhardtii ; chloroplast ; transformation ; photosystem II ; psbK
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using particle gun-mediated chloroplast transformation we have disrupted the psbK gene of Chlamydomonas reihardtii with an aadA expression cassette that confers resistance to spectinomycin. The transformants are unable to grow photoautotrophically, but they grow normally in acetate-containing medium. They are deficient in photosystem II activity as measured by fluorescence transients and O2 evolution and they accumulate less than 10% of wild-type levels of photosystem II as measured by immunochemical means. Pulse-labeling experiments indicate that the photosystem II complex is synthesized normally in the transformants. These results differ from those obtained previously with similar cyanobacterial psbK mutants that were still capable of photoautotrophic growth (Ikeuchi et al., J. Biol. Chem. 266 (1991) 1111–1115). In C. reinhardtii the psbK product is required for the stable assembly and/or stability of the photosystem II complex and essential for photoautotrophic growth. The data also suggest that the stability requirements of the photosynthetic complexes differ considerably between C. reinhardtii and cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029859
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  • 23
    Electronic Resource
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    Cotton (Gossypium hirsutum L.) pollen-specific polygalacturonase mRNA: tissue and temporal specificity of its promoter in transgenic tobacco (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1989-1993 
    Details
    ISSN: 1573-5028
    Keywords: polygalacturonase ; pollen-specific promoter ; cotton ; transgenics ; transformation ; β-glucuronidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A gene (G9) expressed during late microsporogenesis in cotton (Gossypium hirsutum L.) was isolated. Sequence analysis of the cDNA (1.3 kb) as well as the gene (2.6 kb) revealed an open reading frame of 1233 bases encoding a protein of 43.9 kDa. The coding region of the gene is interrupted by three introns. Northern analysis of the RNA from developing anthers showed that the transcripts appear 12 days before anthesis and that the maximal concentration of RNA occurs in pollen on the day of anthesis. This pattern of gene expression suggests functions in post-anthesis events. Sequence comparisons with other known plant genes indicated that G9 is homologous to polygalacturonases. The G9 promoter conferred tissue and temporal specificity of β-glucuronidase (GUS) expression in transgenic tobacco plants. Thus, the G9 promoter can be used to drive gene expression in homologous as well as heterologous plants in a tissue-specific manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019509
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  • 24
    Electronic Resource
    Electronic Resource
    Influence of a compatibilizing agent on the phase morphology of a polyethylene-polyamide 6 blend in a modular intermeshing co-rotating twin screw extruder (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 221-228 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A study of the influence of a compatibilizing agent on phase morphology development in a 75/25 polyethylene/polyamide-6 blend in a modular co-rotating twin screw extruder is presented. The development of phase morphology along the axis of the modular screw was observed by cooling the extruder and removing the polymer from the screw channels. Changes in phase morphology due to the addition of a compatibilizer have been investigated using scanning electron microscopy. Sufficient quantities of compatibilizing agent produce significant increases in the rate of mixing and also reduce the scale of the phase morphology. Much larger quantities (5%) than actually required for interface coverage are needed for rapid mixing. This seems to be due to the high viscosity of the matrix.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340308
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  • 25
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    Thermoplastic polyheterocycles. II: Polyalkylene-imidesPresented in part at the 25th anniversary meeting of the ACS Polymer Group of the North Carolina Section of the American Chemical Society, Chapel Hill, N.C., Nov. 12, 1992. (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 305-307 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyalkylene-imides (i.e., aliphatic-aromatic polyimides) were prepared smoothly in N-methyl pyrollidone from straight chain aliphatic diamines and pyrromellitic dianhydride. Melting points of the polymers ranged from about 300 to 450°C, depending of the length of the alkylene chains. An odd/even effect related to the alkylene chain was noted for melting points and glass transition temperatures (Tg) of the polymers. The Tgs were relatively high, especially when compared to similarly structured polyalkylene-heterocycles, e.g., polyakylenebenzoxazoles.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340412
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  • 26
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    Electronic Resource
    Mechanical properties and deformation mechanism of polyoxymethylene chain in the crystalline state (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 308-317 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The true crystallite modulus of polyoxymethylene (POM) was evaluated experimentally and thoeretically as a function of temperature. The mechanical deformation mechanism of POM was lattice-dynamically predicted and confirmed by measuring the stress-induced vibrational frequency shifts of the infrared and Raman spectra, which were interpreted on the basis of anharmonic potential field.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340413
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  • 27
    Electronic Resource
    Electronic Resource
    Deformation and entanglement in semicrystalline polymers (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 318-329 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Transmission electron microscopy and optical studies of thin films of isotactic polystyrene (iPS) and polyoxymethylene (POM) provide evidence for a distinction between crazing mechanisms in semicrystalline polymers above and below Tg. In the latter temperature regime, deformation in iPS and POM crystallized at high supercooling has been discussed in terms of existing models for crazing in amorphous glassy polymers, based on entanglement ideas. Above Tg, where the difference in mechanical behavior of the amorphous and crystalline regions becomes marked, the fibrillar nature of local deformation appears to be a consequence of the inhomogeneity of the undeformed polymer.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340414
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  • 28
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    Electronic Resource
    The influence of inclusion geometry on the elastic properties of discontinuous fiber composites (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 352-360 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Simplifying assumptions are used to reduce micromechanical treatments to compact expressions which directly reveal the role of the inclusion shape and aspect ratio in establishing the elastic behavior of heterogeneous materials. Attention is directed to the comparison of aligned ellipsoidal and cylindrical inclusions that exhibit transversely isotropic behavior characterized by five independent elastic constants. These comparisons show that the effective transverse in-plane moduli (ET*, k* and GTT*) are essentially independent of inclusion shape for aspect ratio greater than ∼ 20; ellipsoidal inclusions provide higher longitudinal reinforcement than cylindrical inclusions of equivalent aspect ratio. Comparison of predictions with measured elastic moduli shows that both the cylindrical and ellipsoidal shape models for isolated inclusions overpredict longitudinal elastic constants for systems which exhibit evidence of inclusion agglomeration. The notion of an effective aspect ratio based on clusters of filaments responding as a coherent unit appears to provide a means for reconciling a wide range of experimental observations.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340417
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  • 29
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    Properties of electropolymerized polycarboxyphenylmethacrylamide matrices/graphite fiber composites: Crosslinking effect (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 341-351 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Imide formation from -CONH and -COOH functional groups of 2-carboxyphenylmethacrylamide (2-CPM), 4-carboxyphenylmethacrylamide (4-CPM), 4-carboxyphenyl methacrylamide/methylmethacrylate (4-CPM/MMA) and 4-carboxyphenylmethacrylamide/N-phenylmalemide (4-CPM/NPMI) electropolymerized matrices was investigated. It was found that 2-CPM polymers undergo intramolecular imidization and anhydride formation, which result in a small amount of crosslinked network. On the other hand, the thermally cured 4-CPM polymer demonstrates a significant increase in gel fraction. Tg and dynamic storage modulus, owing to crosslinked network formation. Tgs of 4-CPM/MMA and 4-CPM/NPMI composites measured by thermomechanical analysis after thermal heating were increased and were correlated very well with the preheating time. The 4-CPM/MMA composites with a particle crosslinking (Tg increased to 245°C) maintained a higher Izod impact strength than a typical epoxy composite (200 kJ/m2 vs. 100 kJ/m2). Upon heating to promote crosslinking, a lower shear strength (65 MPa) of a 4-CPM/MMA composite increased to a strength of 78 MPa, close to the 80 MPa of an epoxy composite at 67% fiber volume fraction. A lower water absorption of around 1% was associated with the increased crosslinking. The mechanical properties of the 4-CPM/NPMI composites showed a similar trend upon preheating.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340416
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    Electronic Resource
    Diffusion of low molecular weight substances into a fiber with skin-core structure - rigorous solution of the diffusion in a coaxial cylinder of multiple components (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 330-340 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The diffusion equation of low molecular weight substances (penetrant) into a coaxial cylinder of multiple components (m) was formulated in general and solved rigorously. As the simplest but a practical case of m = 2, which corresponds to the diffusion of penetrant into fibrous material with skin and core structure, the diffusion of penetrant was analyzed in detail. That is, changes in the penetrant concentration distribution within the coaxial dual cylinder of skin and core components and the total amount of penetrant sorbed within the cylinder both with time after exposing the cylinder to atmosphere of fixed penetrant concentration of Cout were calculated with variation of the diffusion coefficient ratio (D1/D2) and the radius ratio (R2/R1), where D1 and D2 are the diffusion coefficients of penetrant in the core and the skin, and R2 and R1 are the radii of the fibrous material and the core, respectively. Keeping (R2/R1) at a constant value of 1.2 but varying (D1/D2) from 104 to 10-2, the penetrant concentration distribution was calculated and found to be much different particularly within the core between (D1/D2) 〉 1 and (D1/D2) 〈 1. The sorption curves were also found to deviate in their respective ways from that of Fickian curve of a homogeneous cylinder with (D1/D2) = 1 except at initial stage of sorption. Further, by keeping (D1/D2) constant but varying (R2/R1) from 1.1 to 1.5, the effects of relative skin thickness upon the sorption curve were studied.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340415
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    Electronic Resource
    Orientation parameters for the specification of effective properties of heterogeneous materials (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 361-370 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A general formulation is presented for the orientation averaging of the properties of representative volume elements of heterogeneous materials. Approximations are introduced that result in the identification of four independent orientation parameters that are required to specify a general state of three-dimensional orientation. The general relationships are reduced further for the special case of “planar” and “axial” distribution and applied to an aggregate averaging scheme for short-fiber composites.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340418
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  • 32
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    On molecular composites and the compatibility issue (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 377-378 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340420
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  • 33
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    Thermodynamics of processing synthetic fibers (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 371-376 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper deals with a new approach to nonlinear and nonequilibrium thermodynamics. The new concept, developed by P. H. Lindenmeyer, states that in a heat-setting process, with the same average processing temperature, the addition of a sinusoidal fluctuation (approximately) can produce two opposite changes depending upon the frequency and amplitude of the temperature fluctuation. Preliminary experimental results obtained on nylon 6 monofilaments using a flexible thermomechanical analyzer have clearly shown that the physical properties (in this case torque-twist modulus) depend not only upon the average temperature but also upon its time rate of change.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340419
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    Masthead (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340501
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  • 35
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    A review on the tensile strength of polyethylene fibers (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 266-268 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340406
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    Crack propagation in biaxially oriented polypropylene at low temperature (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 269-278 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The crack growth behavior of polypropylene biaxially oriented by cross-rolling was studied at low temperature. Single edge notch testing produced a stable tearing type of crack growth in both 50% and 80% biaxially oriented polypropylene at -40°C, in contrast to the brittle fracture of unoriented polypropylene. The crack growth in the two oriented materials began slowly and accelerated to a constant rate that was higher in the 80% oriented material than in the 50% oriented material. The main difference between the crack growth behavior of the two was the longer period of initial slow growth in the case of 80% orientation. This period of slow growth corresponded to crack growth through the notch tip damage zone. Residual strength diagrams were used to present the crack growth data obtained when the stress state was intermediate between plane stress and plane strain. Fractography revealed large differences among the fracture surfaces of the three materials with the unoriented polypropylene showing a grainy appearance from the brittle fracture. The two oriented materials showed considerable ductility. The 50% oriented material showed many voids in the fracture surface, indicating that voiding during the fracture process contributed significantly to the toughness improvement. The 80% oriented polypropylene showed delamination crazing on the fracture surface with layered material and fibrils bridging the crazes.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340407
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    The oxidative degradation of imide polymers. I: Ozonolysis of a model compound, N-phenylphthalimide (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 279-284 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The reactions of N-phenylphthalimide films with ozone have been studied under a variety of conditions: dry ozone, moist ozone, ozone plus ultraviolet light, as well as ozone plus water vapor plus ultraviolet light. This compound is a conveniently available model for imide polymers. These reaction conditions represent simulation of certain aspects of the space environment. For each set of reaction conditions the reaction products were determined by combined gas chromatography/mass spectrometry. Semiempirical molecular orbital computations were made of the relative energetics of possible reaction pathways consistent with the generation of the observed products. The reaction products found indicate fragmentation of the imidic moiety for which the energetics are favorable.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340408
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  • 38
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    Double coated optical fibers undergoing temperature variations: The influence of the mechanical behavior on the added transmission losses (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 414-419 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A model to predict the temperature-induced added loss in dual-coated optical fibers is presented. Longitudinal and lateral temperature-induced forces, originating from fiber irregularities and from the mismatch among the expansion coefficients of the glass fiber and of the coatings, are consistently included in the model. Both the bendings of the glass fiber and of the coating are considered. Transmission losses are explicity computed according to Petermann's theory on the microbending of single-mode fibers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340506
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  • 39
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    Semianalytical solution for epoxy-amine curing in the presence of nonisothermal effects (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 405-413 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The curing of epoxy-amine polymer has been modeled by the reaction of functional groups, and the mole balance of these is governed by a set of six nonlinear differential equations. In this work, we have first developed a complete analytical solution for isothermal curing. For nonisothermal curing, we have divided the domain of hydroxyl group concentration β into small increments Δβ and adopted our analytical results for this domain. In addition, we solved the energy balance equation analytically and obtained the temperature rise for Δβ. We have compared our results with those obtained from the Runge Kutta numerical solutions. We have shown that our semianalytical technique is about a thousand times more efficient and faster.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340505
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  • 40
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    Influence of a core/shell rubber phase on the morphology and the impact resistance of a PC/SAN blend (75/25) (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 613-624 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: At 75/25 concentration ratio, bisphenol a polycarbonate (PC)/styreneacry-lonitrile copolymer (SAN) blend has poor impact resistance compared to PC/ABS. A rubber phase methacrylate-butadiene-styrene (MBS) of core/shell type was dispersed in PC/SAN blend. The morphology of the unmodified and modified blend was investigated. The influence of the acrylonitrile ratio in the SAN on the microstructure was studied. It clearly shows that core/shell resides at the interface between PC and SAN. It seems that core/shell particles enhance the adhesion between the different phases. Their presence influences the interface mobility; i.e., the coalescence of the dispersed phase observed in pure PC/SAN is considerably reduced when the MBS particles are added. The impact resistance of the samples was correlated with the morphology.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340802
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  • 41
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    Electronic Resource
    Modeling of polypropylene degradation during reactive extrusion with implications for process control (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 598-612 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper presents the development of a model for free radical initiated polypropylene degradation during reactive extrusion that combines a kinetic model of the polypropylene degradation reaction with a simplified model of the melting mechanism in the extruder. The free radical initiated degradation of polypropylene is characterized by a narrowing of the molecular weight distribution (MWD) and a decrease in the molecular weight averages. A high temperature SEC is used to determine MWD's for three different commercially available polypropylenes degraded at various initiator concentrations in a 1.5 inch single screw extruder (L/D = 24:1). The predictions of the kinetic model alone and the combined kinetic-melting model are compared with the experimentally determined MWD's and molecular weight averages for the degraded polypropylenes. The predictions of a modified kinetic model that includes the possibility of termination by combination are also examined. The kinetic-melting model is found to provide significantly improved predictions of the experimentally determined MWD's and molecular weight averages in comparison to the original kinetic model. A viscosity-molecular weight relationship is also developed, which is then used to determine the gain of the degradation process as a function of the initiator concentration from the molecular weight averages predicted by the kinetic-melting model. Earlier work has shown such prior knowledge of the process gain can be used to significantly improve the performance of process control schemes for the degradation process.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340708
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  • 42
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    Electronic Resource
    Rubber modified epoxy resin. I: Cure kinetics and chemorheology (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 625-631 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The curing and vitrification effect during the reaction of ATBN modified epoxy resin was studied through the dynamic differential scanning calorimetry method and a new reaction kinetic equation containing generalized WLF equation was developed to describe the reaction rate at both glassy and rubbery state. An autocatalytic mechanism was found to describe adequately the cure kinetics of the rubber modified epoxy resin and the overall order of reaction was assumed to be 2. The kinetic parameters were determined from the DSC data through the Marquardt's multivariable nonlinear regression method and Runge-Kutta integration technique. The presence of rubber indicated minor effect on the cure kinetics of epoxy resin. The Arrhenius type viscosity function was employed to establish a relationship between viscosity data measured by RMS and chemical conversion calculated from the reaction kinetic equation.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340803
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  • 43
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    Electronic Resource
    Modeling of the Dynamics of Water and R-11 blown polyurethane foam formation (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 642-649 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyurethane foam formation involves both polymerization and expansion processes. The dynamics of the water and R-11 blown foams depend on the rates of chemical and physical blowing processes, along with the rate of viscosity increase of the reacting mixture. Experiments were carried out to study the dynamics of free rising, water and R-11 blown rigid polyurethane foams. The density and temperature change during the foam formation were monitored. A theoretical model was developed to predict the density and temperature variation with time. In the model, the physical blowing agent (R-11) evaporation process is assumed to be heat generation-controlled and the carbon dioxide generation process to be controlled by the rate of the water-isocyanate reaction. The kinetic parameters of the reactions of isocyanate with polyol and water were obtained separately and were asssumed to be independent of each other. The water-isocyanate reaction appears to follow first-order kinetics with respect to concentration of water. The theoretical predictions of the model show good agreement with the experimental data for density variation with time. The model predictions for temperature rise also match experimental data, except at the later stages of foaming when it is found to be slower than the experimental measurements. However, this deviation does not affect the dynamics of density change since it occurs after the completion of the expansion process.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340805
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  • 44
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    In-situ cure monitoring of diamine cured epoxy by fiberoptic fluorimetry using extrinsic reactive fluorophore (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 707-715 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper describes the application of a molecular sensor for in-situ monitoring of epoxy-diamine cure via remote sensing fiberoptic probes. A custom-built, fiberoptic fluorimeter allows on-line recording of fluorescence spectra directly from the cure environment. Cure reactions in epoxy-diamine network, such as diglycidyl ether of bisphenol A-diaminodiphenyl sulfone (DGEBA-DDS) or diglycidyl ether of butanediol-diaminodiphenyl sulfone (DGEB-DDS), have been monitored by a reactive molecular sensor, diamino azobenzene (DAA). DAA exhibits sensitive changes in UV-visible and fluorescence spectra due to the conversion of its primary amine groups to secondary and tertiary amine groups. Fluorescence intensities are correlated with extent of reaction in epoxy network and processing parameters, such as cure temperatures and time. The use of an internal reference dye for normalization of fluorescence intensities is necessary for the quantitative correlation of spectral signals with the network structure. Variables affecting the fluorescence intensity such as excitation volume, probe location, excitation intensity fluctuation, temperature, and background intensities from optical fiber can be calibrated by normalizing the signal intensities against the internal reference. Sulforhodamine 101 was found to be a satisfactory reference dye which provides stable, readable signals over temperatures up to 200°C.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340903
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  • 45
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    Electronic Resource
    Kinetic parameters estimation for cure reaction of epoxy based vinyl ester resin (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 742-749 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new graphical estimation technique is proposed for the determination of the kinetic parameters describing an autocatalytic reaction. A differential scanning calorimeter was used to monitor the reaction kinetics of an epoxy-based vinyl ester resin. The method utilizes information from a zero initial reaction rate, conversation at vitrification, the ratio of reaction rate constants under different isothermal conditions, and characteristics of the phenomenological kinetic model with assumptions being made about the overall reaction order. By fitting data to the integrated reaction rate equation with adjustments for the isothermal conditions, the kinetic parameters are estimated without using a linear or nonlinear regression method. Different kinetic parameters can be estimated from data before and after the gel point which was obtained from the relationship between the glass transition temperature and the degree of cure.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340907
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  • 46
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    Kinetic model and thermal properties of a thermally cured thermosetting polycarbonate (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 734-741 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Diethylene gycol bis(allyl carbonate) is widely used for the production of optical plastic for lenses, safety glasses and guards, watch crystal, and instrument windows. The monomer polymerizes via a free radical mechanism using benzoyl peroxide as an initiator to form a thermosetting polycarbonate. This polymerization process involves a long cure cycle at temperature below 100°C. Differential scanning calorimetry (DSC) and rheometric dynamic testing are used to characterize the thermal and kinetic properties. These properties include the heat of reaction, activation energy, rate constants of polymerization, and time and extent of cure at gelation.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340906
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  • 47
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    Strength development in powder processing of poly(tetrafluoroethylene)NCL communication no. 5630. (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1065-1069 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(tetrafluoroethylene) (PTFE) is a versatile engineering plastic with excellent chemical and electrical resistance, a wide working temperature range, and a low coefficient of friction. PTFE is processed by the powder processing technique because of its high melt viscosity. The powder processing of polymers involves cold compaction of the polymeric powders, followed by sintering of the preforms at elevated temperatures. Sintering is a critical operation since the mechanical properties of the products are determined by the interparticle coalescence and diffusion of polymer chains across the interface. The results of the studies of the strength development during sintering of PTFE are reported here. The strength was measured in terms of the tensile strength at break, and the dependence of the tensile strength on compaction pressure, particle size, and processing time is discussed. The time dependence of strength development could be described by a diffusion controlled process in which the strength is proportional to the 1/4th power of the processing time.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341305
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  • 48
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    Electronic Resource
    Multiobjective dynamic optimization of a nonvaporizing nylon 6 batch reactor (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1161-1172 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Multiobjective dynamic optimization has been carried out on a nonvaporizing nylon 6 batch reactor. Three objective functions have been identified, viz., minimization of the concentration of unreacted monomer in the product, minimization of the dimer concentration, and minimization of the reaction time, for producing polymer having a specified value, μn, d, of the number average chain length. Two problems have been studied in this paper, each consisting of two objective functions taken from the above set. Pareto solutions have been generated using an algorithm based on Pontryagin's minimum principle and the method of Lagrangian multipliers. The effects of various physical and computational parameters have been studied, and methods have been developed to overcome the numerical difficulties that arise during the solution. The Pareto sets so generated can be coupled with the surrogate worth trade-off (SWT) method, which facilitates interaction with a decision maker (DM). The optimal temperature histories obtained for the two problems studied are quite different and suggest that one must solve the three-dimensional problem in which the vector objective function incorporates all three objective functions. Results from the present study could be used as starting guesses to converge rapidly on the solution of the three-dimensional problem.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341502
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  • 49
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    Entrance pressure drop studies of corn meal dough during extrusion cooking (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1187-1195 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The entrance pressure drop during extrusion cooking of corn grits was measured using a cylindrical die viscometer attached to a single screw extruder and compared with results obtained using low-density polyethylene (LDPE). The cylindrical die viscometer had a length to diameter ratio of 40 with half-entry angles of 30, 37.5, 45 and 90° with the horizontal. The entrance pressure drop at the die was measured as a function of extrusion temperature, product moisture content and the die entry angle. Results indicate that the flow behavior of corn grits and the entrance pressure drop were affected by product moisture content, process temperature and the shear history in the extruder. Entrance pressure drop also increased with wall shear stress for plastic melt, but for food biopolymer, the increase was observed provided shear history effects were minimized. Entrance correction increased with apparent shear rate for LDPE, but the reverse was true for corn meal. Using Cogswell's analysis, corn grits exhibit severe extension thinning behavior in entry flow.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341504
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  • 50
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    Electronic Resource
    Isocyanate trimerization kinetics and heat transfer in structural reaction injection moldingBased on work presented at the Advanced Composites Conference, Detroit, October 1991. (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1173-1186 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Guidelines are developed for molding large composite parts via structural reaction injection molding using glass preforms and polyisocyanurate resins. These are based on numerical simulations of the simultaneous heat transfer and reaction kinetics of a commercial system during and after mold filling. Premised requirements are that resin does not gel before the mold is filled, yet, reactions are sufficiently vigorous to approach completion. An existing mechanistic kinetic model is used and material parameters found from a chemical kinetics study employing an insulated cup. It is found desirable to use a high mold temperature and a low preform temperature in molding. Nondimensionalization of the governing equations reveals the existence of a Nusselt number (Nu), which describes the relative importance of heat transfer between resin and glass relative to thermal diffusion to the mold wall. With a Nusselt number of about 50 or higher it is possible to use the cooling capacity of the preform to extend gel time. The magnitude of Nu is influenced by part thickness, glass fraction, strand diameter, and flow velocity. Thus, the effect of the preform on extending resin gel time is within control of the molder.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341503
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  • 51
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    A study of the effect of the extrusion variables and screw design on the thermal and rheological characteristics of acetal and nylon 66 (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1196-1201 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A detailed study of the effect of several extrusion variables was made on the rheological and thermal properties of Delrin II acetal homopolymer and Zytel 42 polyamide 66 materials. A 63.5 mm Davis Standard extruder was used to measure the effect of screw design, screw rpm, die and head pressure, and melt temperature on the rheology of acetal and nylon 66 resins. A single stage metering screw was used to determine the effect of screw geometry and viscous heating on the melt viscosity breakdown and the rate of degradation of each polymer. The melt temperature was measured in the melt stream in the channel and correlations are shown between ideal melt temperature predicted from the rheology data and the actual loss of properties of each polymer due to viscous heating. The paper also discusses how to measure the melt temperature accurately in extrusion, and to use it as a key indicator to optimize the extrusion process, and to control the rheology, thermal stability, and the molecular weight of a polymer during processing.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341505
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  • 52
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    Weld lines and mechanical properties of injection molded polyethylene/polystyrene/copolymer blends (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1202-1210 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this article, we investigate the effect of weld lines on the tensile mechanical properties of unmodified and copolymer modified high density polyethylene (HDPE) and polystyrene (PS) blends. The homopolymers were melt blended in the proportion of 20 wt% HDPE and 80 wt% PS using a twin screw extruder at a temperature of 200°C. The results show that the mechanical properties are generally lower when weld lines are present. The decrease of the mechanical properties is much more pronounced for the blends. The addition of small amounts of a commercial styrene/butadiene copolymer significantly improves the strength and the elongation at break of this blend. An optimum copolymer concentration was observed at 3 wt%. This value coincides with the interphase saturation concentration of the copolymer obtained from the analysis of the DMTA (dynamic mechanical and thermal) properties of the blends. The copolymer was also found to induce important changes in the morphology of the blend. The interdiffusion of the polymer fronts in the weld region was also improved by the presence of the copolymer. It is believed that these two aspects contribute to the enhanced properties obtained with copolymer modified blends in presence of weld lines. An important effect of the injection temperature on the tensile strength and the elongation at break of welded samples with copolymer modified blends was observed. The effect of mold temperature on these properties was less important mainly at low injection temperatures. Only a slight effect of these two parameters was observed for the tensile modulus in the range of mold and injection temperatures considered in this study.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341506
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  • 53
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    Experimental study of transcription of minute width grooves in injection molding (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1211-1218 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In injection molding of substrates for optical discs, precise transcription of pits and grooves is very important. For high-density optical discs, molding transcription for minute grooves with widths on the sub-micron level is required. In this paper, in order to clarify the relationship between molding conditions and transcription quantitatively, transcription of minute rectangular grooves (width 0.55 μm, depth 70 nm) in injection molding of polycarbonate resin was studied. The relationship between molding conditions and the transcription heights was verified. And, by introducing the equivalent thickness of the vitrified layer concept, a transcription model related to the minute groove width is proposed. This equivalent thickness of the vitrified layer is estimated to be 100 to 150 nm at the point of filling completion under a certain molding condition. Also, using the above description of the equivalent thickness of the vitrified layer, it is possible to estimate the extent of transcription under the various molding conditions.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341507
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  • 54
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    Masthead (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341601
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  • 55
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    Moldability studies for the reaction injection molding of polydicyclopentadiene (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 929-936 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Moldability diagrams for the filling and curing stages of a dicyclopentadiene (DCPD) based reaction injection molding (RIM) system were established based on a simplified engineering approach. Initial monomer temperature and filling time are the critical parameters for the filling stage whereas in the curing stage, mold wall temperature and demold time proved to be the main processing variables. The physical and thermal properties of the molded samples were examined and the results indicate that such simplified moldability diagrams are sufficiently accurate to establish the processing conditions for the system under investigation.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341110
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  • 56
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    Anisotropy in injection-molded ethylene-propylene-diene rubbers. Part II: Disks delaminated by a water-jet cutting technique (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 913-920 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Anisotropy and molecular orientation are well known phenomena in the field of thermoplastics, but only a few studies have described anisotropy in rubber materials. It has been shown that injection molding gives rise to a higher degree of anisotropy than compression molding. The anisotropy in the rubber material was strengthened by carbon black and is presumably due to molecular orientation. This paper describes the anisotropy of injection-molded ethylene-propylene-diene rubbers. The two polymers had different molecular weight distributions and thus different rheological properties. The compounds were injected into center-gated 4mm thick disks. The disks were subsequently split into three layers using a water-jet cutting technique. Measurement of mechanical and swelling properties in the different layers and directions showed that the anisotropy varied through the thickness of the disk. By X-ray scattering it was shown that rubber molecules had a preferred direction and thus, that the anisotropy was probably predominantly due to molecular orientation created during the mold filling.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341108
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  • 57
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    Design and processing optimization of extruder screws (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 937-945 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Only recently has increasing use been made of computer simulation in the field of extruder engineering. This simulation is based on physico-mathematical process models. In order to achieve a closed, process engineering-based extruder layout and operating behavior simulation it is necessary to have models describing the throughput behavior, the melting process, the temperature development, the pressure profile over the screw length, the residence time distribution, the mixing and dispersion processes, and also the torque and power requirements. In the Plastics Technology Section of the University of Paderborn (KTP) a program for the computer-aided design of extruders (REX), financed by 17 companies, was developed which will permit rapid application of the models developed there and will fulfill the requirements set out above. Since no computation-intensive numerical methods like Finite Element or Finite Difference Methods (FEM, FDM) are required, the algorithms are very rapid, which means that short computing times are achieved (just a few seconds on an IBM AT).
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341111
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  • 58
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    Masthead (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341201
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  • 59
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    Rheological and mechanical properties of thermotropic polyesters with long flexible spacers in the main chain (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 949-957 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Linear thermotropic liquid crystalline polymers based on two bisphenol monomers and terephthaloyldichloride were prepared via melt polymerization. Fibers from liquid crystalline polymers were spun above the mesophase transition temperature. In this work, the mechanical and morphological properties of fibers based on such polymers were studied. High values of tensile strength and tensile modulus were obtained, and we tried to prove these high mechanical properties quantitavely by using rheological properties of these polymers and morphology of their fibers. These values were varied by the take-up speed.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341202
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  • 60
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    The morphology of rigid-rod polymers and molecular composites resulting from coagulation processing (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 965-974 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of processing conditions on the morphology of molecular composite films are examined by optical and electron microscopy. During coagulation processing from solutions in methanesulfonic acid (MSA), rigid-rod polymer, such as poly(p-phenylenebenzobisoxazole) (PBO), phase separates into undesirable aggregates. The coagulant and the method of its introduction have been found to exert a strong impact on the final film morphology. A quench of a PBO solution in MSA into a water bath results in a three dimensional interconnected network of PBO, while a slower introduction of water results in a more amorphous material. A computer simulation program of the coagulation process has been developed to better understand the different structures emerging from coagulation processing of molecular composites. The simulation results are in qualitative agreement with the experimental observations.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760341204
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    Air drag on fine filaments at oblique and normal angles to the air stream (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 958-964 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Measurements are reported for air drag on fine filaments whose axes are oriented at oblique and normal angles to the air velocity. In terms of the drag coefficient CDN the data are fit well by the following relation: CDN = 6.96(ReDN)-0.440(d/d0)0.404, where ReDN is the Reynolds number based on flow normal to the fiber axis, and d/d0 is a dimensionless fiber diameter. A wide range of conditions were tested: filament diameters ranged from 13 to 390 microns, gas velocities ranged from 22 to 83 m/s, and fiber Reynolds numbers ranged from 29 to 2120.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341203
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  • 62
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    Some effects of irradiation on properties of filled PVC compounds (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 981-985 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Compounds based on poly(vinyl chloride) (PVC), and containing CaCO3 filler and trifunctional acrylic crosslinking agent have been crosslinked by exposure to γ-rays at dosages to 70 kGy. The crosslinking agent was found to be essential for crosslinking to proceed, only minor sensitivity to the irradiation having been found in compounds omitting the chemical. The presence of filler somewhat inhibits crosslink effectiveness, as measured by solvent uptake data. Elastic moduli and elongations at rupture respond to crosslinking processes, the latter being particularly sensitive to the effects of irradiation. The presence of filler was found to raise modulus, while ductilities of compounds were greater than expected, owing to adhesion at polymer/filler interfaces. Favorable acid/base interaction forces appear responsible for the effect. The reduced sensitivity of filled PVC compounds to γ-ray exposure is attributed to polymer immobilization, the consequence of strong interfacial bonding with the filler.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341206
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  • 63
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    Spinnability of ultrasonically synthesized poly(vinyl alcohol-b-acrylonitrile) emulsions (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 975-980 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The relationship between spinnability and composition of poly(vinyl alcohol)/polyacrylonitrile block copolymer emulsions prepared by an ultrasonic technique is presented. Theoretical analysis and experimental investigation by multiple techniques show that the micellar structure characteristics of the block copolymer emulsions and the behavior of emulsion in shear flowing and coagulating in spinning process are the key factors affecting the spinnability. The mechanical properties of the final fibers are related to the composition, molecular weight, spinnability of the copolymers, and the processability of the as-spun fibers.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760341205
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    Non-Newtonian and isothermal analysis of flow of poly(methyl methacrylate) in a model twin screw extruder. Part I (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 986-994 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The flow analysis network (FAN) method was modified to analyze the flow of poly(methyl methacrylate) (PMMA) in a model counter-rotating nonintermeshing screw extruder. The numerical prediction of the pressure profiles was compared with the experimental results. Flow patterns in the screw elements of the model counter-rotating nonintermeshing twin screw extruder were also predicted. A new flow path method was developed to calculate the residence time distribution. This result will be applied to analyze the flow during the reaction in the model twin screw extruder.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341207
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    The production and properties of oriented polypropylene laminates (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1016-1024 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanical properties of isotactic polypropylene can be enhanced in one direction by a combination of rolling and drawing in a rolling mill. The longitudinal strength and modulus of the oriented polypropylene (OPP) increases with an increase in draw ratio; however, the transverse properties remain relatively unchanged. In this study, multidirectional OPP laminates [with (0)2, (0/90)s and (0/±45)s lay-ups] were made to obtain sheet materials with improved properties in more than one direction in the plane. A hot-plate welding technique was used to produce these translucent and recyclable laminates. The in-plane properties of the laminates were successfully predicted with classical laminate theory (CLT), which is commonly used to predict the properties of fiber reinforced materials. These laminates can be quasi-isotropic and were found to have improved modulus [up to 6 GPa for (0/90)s laminates] and strength [up to 150 MPa for (0/90)s laminates] as well as exceptionally good impact toughness.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341211
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  • 66
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    Continuous crosslinking of ethylene vinyl acetate and ethylene methyl acrylate copolymer blends by on-line microwave heating (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1011-1015 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The transesterification reaction catalyzed by dibutyltin oxide has been used to crosslink miscible blends (at about 200°C) of ethylene vinyl acetate (EVA) and ethylene methyl acrylate (EMA) copolymers. Then, microwave heating at 2.45 GHz with the fundamental TE01 mode was used for activation of this crosslinking reaction. The microwave treatment was carried out in a continuous process through a resonant cavity on line with a twin screw extruder equipped with a strip die or a circular die, which imposed the shape of the samples in the waveguide. Therefore, a shape factor due to the geometry of the samples and their orientation with respect to the electromagnetic field was defined. Last, this technique was applied to the microwave crosslinking of an EVA/EMA blend dispersed in a polypropylene matrix and consequently offers a new route to control the morphology of the polymer blends.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760341210
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    Fiberoptic intrinsic fluorescence for in-situ cure monitoring of amine cured epoxy and composites (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1025-1032 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The cure reactions of epoxy-diamine and its composites are monitored in-situ using the intrinsic fluorescence of the aromatic diamine, diaminodiphenyl sulfone (DDS). With a fiberoptic fluorimeter, in-situ cure monitoring was performed via a single fiber, distal-end probe, in neat epoxy as well as in commercial grade prepregs containing graphite fibers and DDS curing agent. The prepregs were investigated during multiply lamination in an oven. The fluorescence excitation spectra were obtained by emitting at 420 nm with a scan range of 320 to 400 nm, and the DDS peak position was determined as a function of cure time and temperature. The DDS spectra show a progressive red shift up to 24 nm when the primary amine is reacted with epoxide to become the secondary and the tertiary amines. The spectral shift of the DDS is also correlated with the extent of epoxide reaction determined by the Fourier transform infrared (FTIR) spectroscopy. Both data exhibit a linear relation, consistent with the behavior of the DDS peak shift, which increases linearly with the amine reaction. The excitation spectra also show a temperature dependency such that the amount of red shift increases with the measurement temperature in a manner that can be described by an exponential function. The temperature effects also depend on the state of cure in the sample. The temperature correction can be made by the application of an empirically developed equation. Thus, a direct comparison can be made among the on-line data obtained under varying conditions of cure, by reducing the spectral data to any reference temperature. This intrinsic fluorescence technique is much simpler than the previously reported extrinsic fluorophore technique, which requires the addition of an extrinsic fluorophore and an internal dye, and can be applied to any commercial prepregs containing DDS, thus making it a very powerful and widely applicable monitoring tool for composite processing.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760341212
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    Masthead (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341301
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    Processing/morphology correlations in poly(benzoate-co-naphthoate) liquid crystalline polymers (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1327-1335 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The molecular orientation and disclination defects in injection molded bulk samples of liquid crystal polymers have been revealed by transmission electron microscopy (TEM). Using a recently optimized lamellar decoration and etch technique for use with poly(benzoate-co-naphthoate), we have studied in detail the skin-core morphology produced by realistic injection molding processing. In the skin, the director is observed to be highly aligned along the flow direction, and the defect density is very low (10 cm-2). In the core, however, the defect density is six orders of magnitude greater, and the director lies predominantly in the plane defined by the flow and neutral directions. The flow during processing is turbulent, giving rise to distinct morphological features and disclination clusters. When the material is filled at 20% volume fraction with long glass fibers, the molecular and filler orientations are nearly parallel. Dimensional precision also correlates with the morphology and improves with increasing core fraction.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760341705
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    Extrudate roughness of high-density polyethylene and linear low-density polyethylene: Determination of key parameters using screening design (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1047-1055 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A screening design is used to establish the contribution of various parameters to the roughness of cylindrical extrudates. A dimensionless response variable is proposed to characterize the extrudate roughness, and the effects of ten parameters on this roughness response were examined. Two polyethylenes (one high density and one linear low density) were investigated using a 45 mm single screw extruder. The results show that the main parameters affecting the extrudate roughness are, in order of importance, apparent shear stress at the die wall, die diameter, ratio of die length to diameter, and type of polymer. The other six parameters (the use of an additive, recycling, type of entrance adapter, die material, die temperature, melt temperature) were found to have a non-significant contribution to roughness.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760341303
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    Molecular dynamics of polybenzimidazole and contributions from chaosThis topic was previously presented at the 1992 U.S. Army Edgewood Research, Development and Engineering Center, Scientific Conference on Chemical Defense Research, November 17-20, 1992, Aberdeen Proving Ground, Md. (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1070-1079 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Molecular dynamics has been used to study possible dynamic mechanisms that may contribute to the property degradation known to exist for polybenzimidazole (PBI) upon hydration. During this study, chaotic movements of a chain pair were observed. Changes in onset and duration of this movement were also observed, which depended upon both hydration state and stress direction involved. Such trends suggested that specific mechanistic pathways may exist that could directly lead to property (such as modulus) loss.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341306
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    Rheological properties of blends of lithium- or sodium-sulfonated polystyrene ionomers with polyamide 6 (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1056-1064 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dynamic viscoelastic properties of blends of alkali metal salts of sulfonated polystyrene ionomers with polyamide 6 were investigated in the melt. The blends of lithium-sulfonated polystyrene (10 mol% sulfonation) with polyamide 6 (LiSPS/PA-6) behaved as a homogeneous viscoelastic fluid over most of the blend composition range, since blending with PA-6 disrupted the ionic network of the LiSPS. Specific interactions between the lithium sulfonate group and the amide group are believed to be responsible for the behavior. By contrast, blends of sodium-sulfonated polystyrene with PA-6 (NaSPS/PA-6) showed typical behavior of immiscible systems in that they exhibited large positive deviations from the log-additivity rule for complex viscosity. This implied that sodium sulfonate groups did not interact strongly with amide groups, in contrast to the behavior of lithium sulfonates. Oldroyd's emulsion model was applied to the results of dynamic viscoelasticity studies of both the immiscible ionomer/PA-6 blends and the polystyrene/PA-6 blends. For the latter, the fit was much better than for the former. This difference in behavior might be due to partial miscibility or to the presence of an indistinct phase boundary in the “immiscible” ionomer-based systems.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341304
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    On the pressure dependency of the viscosity of molten polymers (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1535-1546 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A slit viscometer to measure the viscosity of polymer melts under processing conditions is described. Along the slit a pressure drop is generated by applying a pressure at both the entrance and the exit. In this way the pressure in the center can be controlled independently of the shear rate. The pressure gradient in the slit is measured by means of three pressure transducers which are mounted in the region of fully developed flow. Results of pressure-dependent viscosity measurements on polystyrene, polyacrylonitrile-butadiene-styrene, and polypropylene are presented in a shear rate range of five decades. The flow curves obtained at different pressures and temperatures can be shifted onto a master curve. The shear thinning behavior of the three materials is adequately described with the generalized Cross-Carreau equation, while the zero shear viscosity is modeled with a generalized Arrhenius-W.L.F. relationship, incorporating a pressure dependency. Alternatively, it is possible to describe the zero shear viscosity in terms of the free volume fraction and the temperature.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760342004
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    Three-dimensional modeling of reaction injection molding. II: Application (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1401-1405 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The objective of this research is to demonstrate the application of a general model of reaction injection molding (RIM) to a complex shaped mold part. Using the fundamental physical and chemical properties of the RIM system, prediction of RIM moldability can be made. The numerical techniques used in this research are presented in a previous paper (1). The rigorous modeling of the transport processes and the dynamics of the filling front for a particular application are described in this work.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341806
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    Three-dimensional modeling of reaction injection molding. IPortions of this work were originally presented as “3-D Transient Computer Simulation of Flow, Reaction and Heat Transfer in Reaction Injection Molding” at the annual meeting of the AICHE in Los Angeles, November 1991. (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1393-1400 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this research a model to simulate both the filling the curing stages of a reaction injection molding (RIM) process in complex three-dimensional molds is developed. This model can be used to predict not only the temperature and conversion changes with time but also the front position during filling. Using given physical and chemical properties of the RIM system, moldability can be determined in advance. The numerical techniques used in this research include adaptation of the SIMPLE algorithm developed by Patankar for a moving-front, two-phase system with non-negligible inertial effects, and exothermic chemical reaction. The model predictions of temperature and conversion compare favorably with available data on simple two-dimensional molds. The ability of the model to predict the dynamics of filling in more complicated molds was verified by comparison to mold filling experiments with water and a polyurethane foam.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760341805
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    Water soluble copolymers. 55: N-isopropylacrylamide-co-acrylamide copolymers in drag reduction: Effect of molecular structure, hydration, and flow geometry on drag reduction performance (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1429-1439 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Non-ionic, hydrophobically associating, water soluble N-isopropylacrylamide-co-acrylamide (IPAM) copolymers have been synthesized and characterized specifically for the study of drag reduction. The drag reduction (DR) performance has been measured with a rotating disk rheometer and a capillary flow apparatus. The DR studies were performed in deionized water, 0.514 M NaCl and 1 M urea. DR efficiency is dependent on copolymer structure, composition, and solvation. Copolymers showing intermediate values of hydrophobic character are found to be the most effective drag reducers. For this copolymer series, IPAM-70 (the copolymer synthesized with 70 mole% N-isopropylacrylamide in the feed) is the most efficient drag reducer. The DR properties of the IPAM copolymers are influenced by hydrophobic associations as well as hydrogen bonding. The effects of salts from the Hofmeister series, cosolvents such as dioxane, and temperature are also examined. Drag reduction performance of the various copolymers is correlated to empirical relationships involving degree of polymerization, second virial coefficient or other solvation parameters, and concentration.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760341810
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    Masthead (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342101
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    Enhancement of electrical conductivity of uniaxially and biaxially processed poly(p-phenylene sulfide) films (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1564-1579 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A fundamental study of electrical conductivity of uniaxially and biaxially stretched poly-p-phenylene sulfide (PPS) film was conducted. In this paper, we paid special attention to understand the effect of processing conditions on the electrical conductivity as well as the conduction mechanism of tantalum pentafluoride (TaF5) doped PPS. The electrical conductivity of PPS film was measured by a four-point probe method in the parallel and perpendicular directions to the stretching direction. The infrared spectra of doped and undoped stretched PPS films demonstrate that the TaF5 doping causes distortion (polaron) in PPS chain and conduction. A similar discussion was reported by Tsukamoto, et al. (1, 2). They found the delocalization of π-electrons in doped PPS by X-ray spectoscopy (XPS), infrared spectroscopy (IR), and C13-NMR. The conductivity of doped PPS films increased with increasing stretching ratio. The crystallinity effect on the electrical conductivity was investigated by changing crystallinity of PPS films in terms of annealing and multi-axially stretching. Orientation development was investigated by wide angle X-ray scattering and birefringence techniques. The relationship between conductivity and orientation of stretched PPS films was investigated by introducing electrical anisotropy.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760342008
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    Rubber modified epoxy resin. II: Phase separation behavior (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1598-1604 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: DGEBA (diglycidyl ether of bisphenol A)-ATBN (amine terminated butadiene acrylonitrile copolymer) blends exhibited upper critical solution temperature (UCST) behavior. Triethylene tetramine (TETA) was introduced as an amine curing agent of epoxy. The real-time phase separation behavior of ATBN-added epoxy system during cure was investigated using laser light scattering. SEM (scanning electron microscopy) and optical microscopy were also employed to observe the morphology of the epoxy blends. Since the DGEBA-ATBN blends showed UCST behavior, the degree of phase separation when cured at low temperature was higher than that when cured at high temperature. The domain correlation length increased as the curing temperature was lowered. Dynamic mechanical analysis (DMA) results indicated that the phase inversion occurred above 20 wt% of ATBN composition.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760342104
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    Rheology and physical properties of ternary blends containing a thermotropic liquid crystalline copolyester (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1605-1612 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ternary blends of polyarylate (PAR) U-Polymer 100, thermotropic liquid crystalline copolyester (LCP) Vectra A950, and a block copolyesterether Hytrel 7246 were investigated in terms of rheological properties, morphology, and mechanical properties. The PAR/Hytrel blend exhibited melting point depression and gave a unique single Tg over the entire range of blend compositions. Addition of Hytrel to the PAR/LCP blend decreased both dynamic viscosity and storage modulus over the normal processing temperature range. Further, it notably reduced the voids between the LCP domains and the matrix, and improved the mechanical properties. The optimum usage level of Hytrel proved to be 2 phr.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342105
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    Molecular and lamellar structure of an extrusion-grade medium-density polyethylene for gas distribution (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1581-1588 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An extrusion-grade medium-density polyethylene was fractionated by size exclusion chromatography and selective solvent extraction. The fractions were studied by infrared spectroscopy, differential scanning calorimetry, and transmission electron microscopy. Infrared spectroscopy showed that chain branching was concentrated to the low molar mass material. Transmission electron microscopy showed the presence of roof-shaped crystals in the low molar mass samples and curved S-or C-shaped lamellae in the high molar mass samples. These features could be used for identification of different molar mass species in the unfractionated sample.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342102
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  • 82
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    A polarized light scattering approach for dispersed phase morphology characterization in simulated polymer blends (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1589-1597 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A light scattering technique using a normal-incidence polarized light beam for the characterization of skin/core simulated polymer blend samples is described. The patterns of reflected, polarized scattered light from an inhomogeneous blend were captured using a video camera. The blend was illuminated from a focused laser source. The simulated samples were constructed by incorporating glass fibers (skin) and glass microspheres (core) in a polymer matrix. Asymmetrical patterns were obtained. They reflect the anisotropic nature of the near-surface morphology. Moreover, the change of the anisotropy ratio of the iso-intensity curves plotted, as a function of distance from the position of the incident laser beam on the sample, gives information about the skin and the core content as well as the skin thickness.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342103
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  • 83
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    Polymeric antiplasticization of polycarbonate with polycaprolactone (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1613-1618 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Physical blends of polycarbonate (PC) with polycarprolactone (PCL), containing 0 to 30% PCL were prepared by melt mixing. The compatible blends were studied using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), mechanical testing, rheological and density measurements. Yield strength, elastic modulus, and density of the blends were found to attain maximum values, depending on PCL content, while Tg continuously decreased. PCL presence resulted in the embrittlement of PC as detected by impact and tensile tests. These combined data lead to propose a mechanism of polymeric antiplasticization in the PC/PCL system; a phenomenon uncommon in polymer-polymer blends. Simultaneously, the PC's β-transition intensity was depressed, as detected by DMA. Activation energy of PC secondary relaxation process was found to be higher for PC/PCL blends than for PC. Thus, local, intermolecularly non-cooperative motions, usually associated with β-relaxation, are restricted in the presence of PCL. The addition of PCL to PC results in increased shear sensitivity and lower high shear rates viscosity, improving processability.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342106
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  • 84
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    Electronic Resource
    Analytical approximation of degradation profiles in polymer products (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1619-1627 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A general, but simple, analytical technique is proposed for the solution of diffusion-controlled reaction problems (as, for example, occur during the photooxidation of polymers). With this technique the stationary concentration and reaction rate profiles can be calculated for arbitrary reaction kinetics and concentration dependent diffusion coefficients. As an example, the photo-oxidation of polyolefins is considered, which involves complex, concentration dependent, reaction kinetics. Excellent agreement between the analytical approximation and the numerical solution is obtained. Further, an analytical expression for the degradation profile (extend of reaction) is derived, which includes the starting-up effect. It is shown that owing to instationary effects, the degradation profiles obtained with artificial weathering tests may differ considerably from those obtained with outdoor weathering experiments. It is therefore suggested that artificial weathering tests be used to measure the reaction rate parameter and calculate the degradation profile rather than measuring the degradation profile directly.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342107
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  • 85
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    Electronic Resource
    Masthead (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342201
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  • 86
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    Quantitative model relating electrical resistance, strain, and time for carbon black loaded silicone rubber (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1628-1634 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A quantitative model has been developed relating electrical resistance with strain and time for carbon black filled silicone rubber compounds. The model is based on concepts and methods used in the field of viscoelasticity. Relaxation experiments are performed in order to evaluate material parameters. With these, resistance-strain-history relations, under other loading conditions may be predicted.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342108
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  • 87
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    Tension of carbonization for carbon fiber (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1480-1484 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanical properties of carbon fiber, especially tensile modulus, are closely related to the orientation of crystals. Hence, the stretching of carbon fiber during carbonization is of importance. In this study, the tension arm between the carbonization furnaces was used to stretch carbon fiber. The relationships among the stretching tensions of the first stage carbonization (〈 800°C) and the second stage carbonization (〉 1200°C), the aromatization index for oxidized polyacrylonitrile fiber, and the properties of carbon fiber are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341907
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  • 88
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    Dynamic rheological properties of polyetherimide/polyetheretherketone/liquid crystalline polymer ternary blends (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1492-1496 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dynamic rheological properties of poly(etherimide)/poly(etheretherketone)/liquid crystalline polymer (LCP) ternary blends were measured in order to correlate these properties with the morphology obtained after extrusion. The viscosity radio, ηd/ηm, where ηd = disperse phase viscosity and ηm = matrix viscosity, had to be redefined. Below 50 wt% LCP, ηd = ηLCP, ηm = ηPEEK+PEI and ηd/ηm 〈 1. Above 50 wt% LCP, ηd = ηPEEK+PEI, ηm = ηLCP and ηd/ηm 〉 1. Fibrillar morphologies were obtained in both cases, except below a concentration of 20 wt% LCP. At low concentrations of LCP the ternary blends had lower viscosities than the component polymers, showing a flow promotion effect of the LCP on the PEI- and PEEK-rich phases.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341909
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  • 89
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    Electronic Resource
    Masthead (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342001
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  • 90
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    Investigation of processing-structure-properties relationships in polyethylene blown films (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1506-1514 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Molecular orientation imparted during film fabrication is known to have a major effect on mechanical and thermal properties of both glassy and semicrystalline polymers. A three-variable Box-Behnken designed experiment was used to study the effects of die gap, die land length, and blowup ratio (BUR) on key linear low density polyethylene (LLDPE) blown film properties at constant final film thickness. In addition, differences in molecular orientation in the films were studied using optical birefringence and shrinkage methods. Measured key film properties were correlated to processing conditions and to measured molecular orientation. Die land length had no significant effect on film structure and properties. All LLDPE films exhibited about 70 to 80% shrinkage in the machine direction (MD) but expanded in the cross direction (CD). Most films exhibited negative in-plane birefringence. MD Elmendorf tear was found to be inversely related to drawdown ratio and MD shrinkage, suggesting that MD tear is dependent primarily on amorphous chain extension and hence, amorphous segments orientation for LLDPE blown films. Dart impact strength of the films was shown to be related to MD shrinkage and to the induced surface roughness due to varying die gap. In a separate study, blown films of three high pressure LDPEs were fabricated under nearly identical conditions. No correlation was found between birefringence and shrinkage data on the LDPE blown films.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341911
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  • 91
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    Modeling the dielectric behavior of epoxy resin blends during curing (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1517-1528 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A model is developed to describe the evolution of dielectric behavior during the cure of epoxy resins and of blends containing soluble polymeric additives. Data on cure kinetics are used to predict: (a) changes in viscosity and hence in ion mobility; (b) gelation times; (c) vitrification times; and (d) dipolar relaxation times, for both resin and blends. These predictions are then used in conjunction with the Maxwell-Wagner-Sillars (MWS) theory to calculate dielectric permittivity ∊′ and loss ∊″ as functions of cure time and test frequency in both resin and blends. The predictions are compared with experimental data on dielectric behavior obtained during cure of both neat epoxy resin and of blends containing 15 wt% CTBN (carboxyl-terminated poly(butadiene-co-acrylonitrile)).
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342002
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  • 92
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    Interrelationship of strength and flow characteristics of polystyrene (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1497-1505 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This study investigated the interrelationship between strength and flow characteristics of general-purpose polystyrene (GPPS) used in injection molding applications. The ease of flow was chosen as a measure of processability and was evaluated using the melt flow rate and capillary rheometer techniques. Of the different strength tests that were examined, flexural and notched tensile strength tests were most effective in differentiating between commercial grades of high and low molecular weight GPPS. While characterizing strength of injection molded specimens, the degree of molecular orientation was taken into consideration. For unplasticized resins, increasing the weight average molecular weight by about 100,000 enhanced the flexural strength by 10%, but also increased the viscosity at low shear rates (10 to 100 s-1). The increase in molecular weight had virtually no effect on viscosity at the highest shear rates (up to 10,000 s-1). Plasticized resins displayed a 6% loss in flexural strength as well as a significant reduction in viscosity (throughout the shear rate range) as compared with the unplasticized resins. As expected, the improvement in strength achieved by increasing molecular weight leads to a simultaneous increase in the viscosity, i.e., a deterioration of processability. In addition, our study indicates that for samples without preferential molecular orientation, narrowing the molecular weight distribution significantly improves the balance of strength and melt flow rate properties.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341910
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  • 93
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    Effects of component addition protocol on the reactive compatibilization of HDPE/PET blendsBased on a presentation given at SPE's ANTEC 1993 and 8th International Congress on Compatibilizers and Reactive Polymer Alloying, “Compalloy '93.” (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1709-1719 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyethylene terephtyalate (PET) and high-density polyethylene (HDPE) constitute a major portion of the thermoplastic materials currently being used in the packaging industry. Blends of HDPE/PET can be compatibilized by utilizing ester groups or terminal carboxyl and hydroxyl groups present in PET. An ethyleneglycidyl methacrylate copolymer (EGMA) was found to be very effective in compatibilizing this blend by forming a compatibilizer in-situ. The in-situ formation of the compatibilizer and its distribution could be affected by different sequences and modes of component addition. To determine the best protocol of component addition for such a reactive compatibilization process, different sequences and modes of component addition were tried out in an intensive batch mixer and in a twin-screw extruder. All these experiments resulted in blends with vastly different dispersion of the minor phase and mechanical properties. In general, sequences where the reactive polymer was grouped with the nonpolar component of the blend initially resulted in the best compatibilization.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342302
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  • 94
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    In-line monitoring of molten polymers: Near infrared spectroscopy, robust probes, and rapid data analysis (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1758-1766 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The concept of improved product quality and reduced costs has revolutionized analytical techniques in the polymer industry. It has brought in-line analysis to the forefront, with near infrared (NIR) spectroscopy proving to be a very viable technique for such operations. A system for continuous in-line near infrared monitoring of molten polymer blends, copolymers, and polymer reactions is being developed. The ultimate objective is to use this monitoring system to develop feedback control for polymeric processes. Experiments on blends of polystyrene and poly(phenylene oxide) have been performed by using a flow cell, located at the exit port of a single-screw extruder. Qualitative analysis of spectral data has been substantiated by a variety of quantitative (multivariate) techniques. Robust calibration models, suitable for on-line predictions, have been developed. The success of in-line process analysis depends on the performance of fiber-optic probes that are inserted into the process stream. These probes normally succumb to the demands of the rigorous process environment, typical of polymeric processes, i.e., high temperatures, high pressures, and adverse chemical conditions. Design and development of fiber-optic probes that are capable of withstanding such harsh conditions have also been undertaken. Results will be reported on the polymeric systems and optical probes.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342307
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  • 95
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    Long-term properties of hot-water polyolefin pipes - a review (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1773-1787 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This is a review on the long-term behavior of polyolefin pipes used in hot-water environments. Included in the review is work done on pipes of crosslinked polyethylene, isotactic poly(butene-1), isotactic polypropylene and medium-density polyethylene, and in particular the extensive work performed at Studsvik, Sweden. A collective view of the changes in antioxidant concentration profiles and molecular/physical structure accompanying hot-water exposure is presented. Failure at high stress levels is preceded by gross deformation (Stage I failure), whereas at lower stresses fracture is brittle either without any signs of thermal oxidation (Stage II) or induced by a strong and spatially concentrated thermal oxidation (Stage III). It is shown that the Stage III lifetime can be divided into three phases, denoted Regimes A, B, and C. They involve internal precipitation of antioxidant from a supersaturated solution (Regime A), diffusion-controlled migration of antioxidant to the surrounding media (Regime B), and degradation of the polymer by thermal oxidation (Regime C). For hitherto reported cases the Regime B life constitutes 80% to 90% of the entire life. A presentation is also made of current lifetime extrapolation methods.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342402
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  • 96
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    On the significance of the standardized notched impact strength for materials selection and design (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1799-1807 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Experimental data on the standard Charpy notched impact strength (CNIS) for a large sampling of particulate-filled and rubber-modified polypropylenes were analyzed. To determine the significance of the CNIS for material selection and design, CNIS data were compared with fracture toughness measurements expressed as the critical strain energy release rate G′c, measured under impact loading. A scale factor representing the state of stress at the crack tip was calculated, assuming small scale yielding, Class I linear elastic fracture mechanics (LEFM). Based on the data, three principal groups of materials were identified. In the smallest of the three, CNIS and G′c measurements showed the same functional dependence on the material variables studied and were characterized by a scale factor independent of the composition. In these cases, one can justify comparisons of toughness of different compositions using single values of the CNIS, since the materials are probably being compared in equivalent states of stress. In a second group, CNIS and G′c also show the same functional dependence on material variables, but exhibit large variations in the scale factor with composition. One should not compare the toughness of different materials from this group based on single values of CNIS, since it is likely that the comparisons would not be made relative to equivalent states of stress. In these cases, only measurements of G′c can separate the effect of specimen geometry from those of the intrinsic properties of the material. The majority of materials studied fell into a third group, in which the CNIS and G′c exhibited substantially different functional dependencies on the material properties, and the scale factors depended also on composition. In these latter cases, a comparison of CNIS values for different compositions is not a reliable indication of the relative toughness and is of little value as a parameter for material selection and design.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342404
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  • 97
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    Interfacial tension in polymer melts. Part II: Effects of temperature and molecular weight on interfacial tension (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1834-1839 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Interfacial tension is one of the most important parameters that govern the morphology of polymer blends and the quality of adhesion between polymers. However, few data are available on interfacial tension due to experimental difficulties. A pendant drop apparatus was used for the determination of the interfacial tension for the polymer pair polypropylene/polystyrene (PP/PS). The effects of temperature and molecular weight were evaluated. The range of temperatures used was from 178° to 250°C, and the range of molecular weights used was from 1590 to 400,000. The interfacial tension decreased linearly with increasing temperature. With only one exception, higher molecular weight systems showed weaker dependence of interfacial tension on temperature than lower molecular weight systems. Also, polydisperse systems showed a stronger dependency on temperature than the monodisperse systems. The value of the interfacial tension, which increases with molecular weight, appears to level off at molecular weights above the entanglement chain length. For the polymer pair PP/PS, the dependency of the interfacial tension on the number average molecular weight appears to follow the well-known semi-empirical (-2/3) power rule over most of the range of molecular weights. Comparable correlations were obtained with values of the power between -1/2 and -1.0.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760342408
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    Publications by P. H. Lindenmeyer (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 251-251 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340403
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  • 99
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    Masthead (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340401
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  • 100
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    Does quantum magic impinge on polymer physics? (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 260-265 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Penrose states that quantum effects can occur even in relatively large systems when energy differences remain small. This is just the situation with polymer materials. A quantum description by Penrose of the formation of quasi-crystals can be rewritten to apply to polymer crystallization. The implications of the need to take account of quantum effects are discussed. Another approach based on the quantization of energy levels in clusters of atoms offers a possible explanation of heat setting in nylon and polyester fibers. Finally some problems of the interpretation of quantum theory are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340405
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