Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 121 (1984), S. 195-208 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden Proben von Nylon 6 Fasern, auf die Acrylmonomere wie Methylmethacrylat (MMA), Ethylmethacrylat (EMA) und n-Butylmethacrylat (n-BMA) mit unterschiedlichen Pfropfgraden aufgepfropft wurden, mit IR-Spektroskopie, Röntgenstreuung und Rasterelektronenmikroskopie untersucht. Dabei wurden die durch das Pfropfen entstandenen Änderungen im Vergleich zu den ungepfropften Nylon 6 Fasern ermittelt. Die IR-Spektren der rnit den verschiedenen Monomeren gepfropften Nylon 6 Fasern zeigen eine kleine Anderung in der Peakhohe. Die charakteristischen Peaks des ungepfropften Nylon 6 blieben bei den gepfropften Fasern mehr oder weni- ger erhalten. Ein Peak bei 1730 cm-' (Estergruppe) bestatigt, da13 das Polymere rnit dem Monomeren gepfropft worden ist.Die Daten der Rontgenstreuung an den gepfropften Proben zeigen einige bemer- kenswerte Veranderungen rnit dem Pfropfgrad, die von der Natur des gepfropften Monomeren abhangen. Der Kristallinitatsgrad variiert rnit dem Pfropfgrad. Zu Be- ginn des Pfropfens zeigt sich eine Abnahme beim Pfropfen rnit PMMA und eine Zu- nahme im Falle von PEMA und Pn-BMA.Bei hoheren Pfropfgraden (uber 50%) nimmt der Kristallinitatsgrad in allen drei Fallen ab. Der Orientierungsindex zeigte ein Ansteigen zu Beginn des Pfropfens bei rnit EMA und n-BMA gepfropftem Nylon 6 und fallt dann ab, wahrend er fur rnit MMA gepfropftes Nylon 6 kontinuierlich auch bei niedrigem Pfropfgrad abfallt.Die Untersuchungen der Oberflächencharakteristik bei den Ausgangs- und ge- pfropften Proben zeigen starke Änderungen der Oberfläche bei den verschiedenen Proben. Mit dem Ansteigen des Pfropfgrades nimmt der Durchmesser der Faser zu, und es erscheinen Poren und Risse an der Oberfläche.
    Notes: Samples of nylon 6 fibers grafted with the acrylic monomers methyl methacrylate (MMA), ethyl methacrylate (EMA), and n-butyl methacrylate (n-BMA) with various graft levels were investigated by infrared, X-ray and scanning electron microscopic studies and the changes due to grafting with respect to the parent nylon 6 fibers were studied.The IR spectra of grafted nylon 6 samples show that there is a little change in the peak heights by grafting of nylon 6 with various monomers. The characteristic peaks of parent nylon are, more or less, maintained in the case of grafted samples. A peak at 1730 cm-1 of the ester group was noted which confirms that the polymer has been grafted with the monomer.X-ray diffraction data on the grafted samples show some remarkable variations with the degree of grafting, depending upon the nature of the graft monomer. The percentage of crystallinity varies with the degree of grafting. In the initial stages of grafting it shows a decrease in the case of PMMA graft and an increase in the case of PEMA and Pn-BMA graft. At higher degrees of grafting (above 50% graft add-on) the percentage of crystallinity decreases in all the three cases. Orientation index has been found to increase in the initial stages of grafting in the case of EMA and n-BMA grafted nylon 6 and it decreases later on, whereas in the case of MMA graft it decreases continuously even at low graft level.The studies of surface characteristics for the parent and grafted samples show that spectacular changes on the surface of the various samples have taken place. With the increase in the graft level the diameter of the fiber increases and also the voids and cracks appear on the surface.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 173 (1989), S. 205-212 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Herkömmliches Vernetzen von Polyethylen niedriger Dichte (LDPE) wurde mit Dicumylperoxid (DCP) als Vernetzer durchgeführt. DCP wurde in verschiedenen Konzentrationen mit LDPE-Schnitzeln in einem Extruder bei 135 - 145°C gemischt. Monofilamentfäden wurden bei 110°C auf einer Laborziehmaschine gezogen. Die Zugdehnungseigenschaften, der prozentuale Schrumpf und die Dichte wurden mit Zunahme der DCP-Konzentration und der Heizdauer verbessert, während jedoch die prozentuale Quellung abnahm.
    Notes: Conventional crosslinking of low density polyethylene (LDPE) was carried out using dicumyl peroxide (DCP) as crosslinking agent. DCP in various concentrations was mixed with LDPE chips in an extruder at 135 - 145°C. Monofilaments were drawn on a laboratory drawing machine at 110°C. It was found that tensile properties, percent shrinkage and density were improved with the increase in the concentration of DCP and in the heating period, whereas, however, the percent swelling decreased.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 171 (1989), S. 131-139 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden Molekulargewichtsuntersuchungen an chloriertem, ataktischem Polypropylen, das durch Chlorierung von ataktischem Polypropylen hergestellt wurde, mit Hilfe von Viskositätsmessungen und Gelpermeationgschromatographie durchgeführt. Die Grenzviskositätszahl, das zahlenmittlere Molekulargewicht (Mn) und das gewichtsmittlere Molekulargewicht (Mw) hängen sowohl vom Chlorierungsgrad als auch von den Synthesebedingungen ab. Die beobachteten Phänomene werden diskutiert.
    Notes: Molecular weight studies of chlorinated atactic polypropylene (CAPP), prepared by thermal chlorination of atactic polypropylene (APP), have been carried out by viscosity measurements and gel permeation chromatography. In general, the intrinsic viscosity [η], number average molecular weight (Mn) and weight average molecular weight (Mw) are dependent on degree of chlorination as well as synthesis conditions. The phenomena observed are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 163 (1988), S. 23-35 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Chlorierung von ataktischem Polypropylen (APP) wurde thermisch gestartet und in Tetrachlorkohlenstoff durchgeführt. Es wurde gefunden, daß mit zunehmender Verdünnung der Chlorierungsgrad steigt, was in % Gewichtszunahme gemessen wurde. Grund für dieses Verhalten ist eine größere Aufweitung und Beweglichkeit der APP-Ketten, wodurch die durch Chlor zu ersetzenden Stellen besser zugänglich werden. Die Reaktionsordnung in Abhängigkeit von der APP-Konzentration beträgt 0,84 und die Aktivierungsenergie (Er) 5,29 kcal/mol. Die Erhöhung der Strömungsrate führt zu einem höheren Chlorierungsgrad. Dieser steigt bis zu einer Strömungsrate von 1 l/h linear an, um dann ein konstantes Nivoau anzustreben. IR-Spektroskopie und 13C-NMR-Untersuchungen weisen darauf hin, daß die Chlorierung an allen drei ersetzbaren H-Atomtypen vorkommt. Der Startschritt des Mechanismus ist wahrscheinlich die Substitution des tertiären H-Atoms durch freie Chlorradikale und nachfolgendem Austausch der sekundären und primären H-Atome durch entweder fortschreitende Substitution oder den Eliminierungs-Additions-Mechanismus.
    Notes: Chlorination of atactic polypropylene (APP) was thermally initiated and carried out in carbon tetrachloride (CCl4) solution. It was found that with the increase in dilution, there is an increase in the extent of chlorination, as measured in terms of % weight-gain. The reason for this behaviour has been ascribed to a greater degree of opening up and mobility of APP chains thus increasing the accessibility of the replaceable sites to chlorine. The order of the reaction with respect to APP concentration was found to be 0.84, the overall activation energy (Er) being 5.29 kcal/mol. Increase in flow rate leads to an increase in the extent of chlorination and was found to be increasing linearly with a flow rate up to 1 l/h beyond which it levels off. IR spectroscopy and 13C-NMR studies indicate the chlorination occurring in all the three types of replaceable H-atoms in APP. The mechanism appears to be initial substitution of tertiary H-atom by free chlorine radical followed subsequently by replacement of secondary and primary H-atoms via either progressive substitution or elimination-addition mechanism.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 161 (1988), S. 77-87 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Monfilamente von Polyethylen niederer Dichte mit unterschiedlichem Verstreckungsgrad wurden der Strahlung einer Co60-Gammastrahlenquelle unterworfen. Es zeigte sich, daß die Zugfestigkeit mit ansteigender Strahlungsdosis bis 20 Mrd stark verbessert wird, oberhalb dieser Dosis wird eine scharfe Abnahme der Reißfestigkeit und des Anfangsmoduls beobachtet. Die Quellung nahm ebenfalls mit zunehmender Strahlungsdosis ab. Jedoch zeigte die Dichte einen ansteigenden Trend. Der Schrumpf nahm bei allen Filamenten mit steigender Strahlungsdosis und Verstreckungsgrad zu. Die Ergebnisse wurden als Zunahme der Vernetzungsdichte mit zunehmender Strahlungsdosis erklärt, bei gleichzeitiger Abnahme der Kristallinität, die in fortgeschritteneren Bestrahlungsstadien stärker wird. Die Proben zeigten einen Memory-Effekt nach Verstreckung bie 110°C, Abkühlen unter Spannung, gefolgt von abermaligem Aufheize auf 110°C in entspannter Form. Der Schrumpf war noch immer viel größer, aber unabhängig vom Verstreckungsgard.
    Notes: Low density monofilaments of polyethylene with varying draw ratios were subjected to high energy radiation using Co60 gamma radiation source. It was found that the tensile strength is sharply improved with the increasing dose up to 20 Mrd beyond which a sharp decrease in tenacity and initial modulus was observed. The swelling behaviour also decreased with the increased in dose of irradiation. However, density showed an increasing trend. The shrinkage behaviour of all the filaments was found to increase with increasing dose and draw ratios. The results have been explained in terms of continuous increase in crosslink density with the increasing dose of irradiation along with loss of crystallinity, which appears to be more severe in the latter stages of exposure. The samples exhibited memory effect after redrawing at 100°C and cooling under tension followed by further heating at 110°C under relaxed condition. The shrinkage was still much higher but independent of draw ratio.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 112 (1983), S. 95-106 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die thermischen Eigenschaften von Methylmethacrylat (MMA), Ethylmethacrylat (EMA) und n-Butylmethacrylat (n-BMA), gepfropft auf Nylon 6 Fasern mit verschiedenen Pfropfgraden wurden durch Thermogravimetrie (TGA) und Differentialthermoanalyse (DTA) untersucht und die Ergebnisse mit denen von Nylon 6 Fasern verglichen. Es wurde gefunden, daß die Anfangsabbautemperatur (IDT) der gepfropften Proben geringer war als die von Nylon 6. Andererseits wurde die gesamte thermische Stabilität mit allen drei Monomeren größer, gefolgt von einer späteren Abnahme mit zunehmendem Pfropfgrad. Für die gepfropften Proben folgen IDT und IPDT (initial procedural decomposition temperature) der Reihe MMA-g-Nylon 〈 EMA-g-Nylon 〈 n-BMA-g-NylonDie Differentialthermoanalyse zeigt ein Absinken der Glastemperatur (Tg) sowie der Schmelztemperatur (Tm). Bei mit MMA und EMA gepfropften Proben ist das Absinken klein über einen weiten Bereich des Pfropfgrades. Bei n-BMA ist das Absinken stärker. Ein breiter Schmelzbereich wurde bei den gepfropften Proben gefunden. Untersuchungen über die Entflammbarkeit zeigten ebenfalls, daß mit zunehmendem Pfropfgrad und zunehmender Länge der Alkylkette die Leichtigkeit der Entflammbarkeit zunimmt, ausgedrückt durch den Sauerstoffindex. Die möglichen Gründe für diese Phänomene werden diskutiert.
    Notes: Thermal Properties of methyl methacrylate (MMA), ethyl methacrylate (EMA) and n-butyl methacrylate (n-BMA) grafted onto nylon 6 fibre with various graft levels were investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) and the results compared with that of parent nylon 6 fibre. It was found that the initial decomposition temperatures (IDT) of the grafted samples were lower than that of the parent nylon 6 fibre. On the other hand with all the three monomers, there was an increase in overall thermal stability followed by subsequent decrease with increase in the graft level. Among the grafted samples both the IDT and IPDT (initial procedural decomposition temperature) followed the order MMA-g nylon 〉 EMA-g nylon 〈 n-BMA-g nylonDifferential thermal analysis shows a depression in glass transition temperature (Tg) as well as in melting temperature (Tm). In the case of the MMA and EMA grafted samples, the depression is small over a wide range of graft level. In the case of the n-BMA grafted samples, the depression is higher. A wide melting range was obtained in the grafted samples. Flammability studies also showed that with an increase in the graft level as well as an increase in the alkyl chain the ease of flammability increased as expressed by limiting oxygen index (LOI) values. The possible reasons for the phenomena occurred have been discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 422-429 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Affinity chromatography (biospecific adsorption) relies on specific interactions of biological molecules such as enzymes, antigens, antibodies, and proteins. The process consists of three steps: adsorption, washing, and elution. A mathematical model including convection, diffusion, and reversible reaction is formulated to analyse the breakthrough behaviour of the solute. A moving finite element orthogonal collocation method is applied with respect to the space variables of the governing partial differential equations of the model to evaluate the breakthrough of the solute. Danckwerts' boundary conditions are considered for the column. The validity of the numerical scheme is checked by comparison with an analytical solution for a simplified model. The results obtained from model simulation show that the breakthrough time of the solute is significantly influenced by the axial dispersion coefficient, solute concentration, ligand content, reaction kinetics, particle porosity, particle size, and flow rate. Solute recovery and bed utilisation efficiencies are evaluated for different values of the above parameters.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 361-368 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Depolymerization of poly-∊-caprolactam chips was carried out at low pressures (3-15 mm Hg) and elevated temperature (225°-270°C) in the presence of sodium hydroxide as catalyst. The effects of variation of amount of sodium hydroxide, time, temperature, and pressure on ∊-caprolactam yield were studied. With increase in alkali content the yield increases linearly, reaching a maximum at 1% (w/w) NaOH and then falls. The yield increases with time of depolymerization up to 4 1/2 hr and then becomes practically constant. Between 240° and 250°C there is a sudden increase in depolymerization rate. Further increase in temperature has very little effect. Decrease in pressure from 15 to 3 mm Hg shows a nine-fold increase in yield. The optimum conditions for the depolymerization were a temperature of 250°C, a pressure of 3 mm Hg, and a time 4 1/2 hr in the presence of 1% NaOH (w/w), which gave a 90.5% yield of ∊-caprolactam. Physical properties, IR spectra, and behavior toward polymerization of the recovered monomer indicated the presence of some impurities.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 2253-2262 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Polypropylene-g-polymethacrylic acid graft copolymer, prepared by simultaneous-irradiation technique, was characterized to determine the structural changes, occurring in the copolymer. The presence of polymethacrylic acid graft in the copolymer was ascertained by infrared spectroscopy. Crystallinity of the grafted fibers, as deduced from X-ray diffraction pattern, showed a decrease with the increase in graft level in the fiber. Such a behavior has been attributed to the dilution of crystalline fraction of polypropylene by the incorporation of amorphous polymethacrylic acid chains in the fiber matrix, without disrupting the original crystallites of the backbone polymer. The density of the grafted samples showed a continuous increase with the increase in percent graft. However, the diameter did not change up to 16% graft content, beyond which an increase in the diameter was observed. This increase in diameter has been related with the sharp increase in disperse dye uptake of the grafted fiber at higher levels of grafting.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 3365-3368 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Mechanical properties of polypropylene-g-poly(methacrylic acid) fibers, prepared by graft copolymerization of methacrylic acid onto polypropylene fiber using simultaneous gamma ray irradiation technique, were evaluated. In general, an improvement in the mechanical behavior of the polypropylene fiber by grafting was observed. Denier and initial modulus of the fiber showed a linear increase with the percent graft, and elongation showed an opposite trend. The results have been explained in terms of reinforcing effect of poly(methacrylic acid) grafts and reduction in the segmental mobility of the polymeric chains. Tenacity also increases up to certain graft level, beyond which a sharp decrease occurs, probably due to the influence on the compactness of the macromolecular chains with the further grafting.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...