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  • 1970-1974  (7,179)
  • 1965-1969  (7,819)
  • General Chemistry  (11,044)
  • Chemical Engineering  (3,242)
  • Engineering General  (521)
  • Bone
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Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 15 (1974), S. 111-123 
    ISSN: 1432-0827
    Keywords: Fluoride ; Calcium ; Phosphorus ; Bone ; Periosteum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une méthode d'estimation de la surface périostée de l'os en voie de minéralisation est mise au point et appliquée à des porcs recevant 2 mg de fluorure par Kg de poids et par jour pendant 10 mois. L'adjonction de fluor intervient significativement dans le cas d'une déficience en calcium et phosphore. La surface en voie de minéralisation est nettement réduite. Lorsque le calcium et phosphore sont normaux, l'addition de fluorure augmente nettement la surface en voie de minéralisation. Le microscope électronique à balayage permet de mettre en évidence au niveau de l'os une perte de l'orientation longitudinale des fibers et des surfaces poreuses irrégulières chez les animaux soumis au floor.
    Abstract: Zusammenfassung Zur Bestimmung der verkalkenden Oberfläche des Periosts wurde eine Methode entwickelt und bei Schweinen angewandt, welche während etwa 10 Monaten 2 mg Fluorid per kg Körpergewicht und per Tag erhalten hatten. Dieses zusätzliche Fluorid hatte eine signifikante Wirkung bei Calcium- und Phosphormangel. Die verkalkende Oberfläuche ging stark zurück, während jedoch, wenn kein Calcium- und Phosphormangel bestand, das zusätzliche Fluorid die verkalkende Oberfläche vergrößerte. Beobachtungen mit dem Raster-Elektronenmikroskop am Knochen zeigten, daß die Längsorientierung der Fasern fehlte und daß Knochen von mit Fluorid gefütterten Tieren unregelmäßige, poröse Oberflächen aufwiesen.
    Notes: Abstract A method for estimating periosteal bone-mineralizing surface was developed and applied to swine fed 2 mg of fluoride/kg of body weight/day for about 10 months. Added fluoride interacted significantly with calcium and phosphorus deficiency. Mineralizing surface was greatly reduced, whereas when calcium and phosphorus were adequate, added fluoride greatly increased mineralizing surface. Scanning electron microscope observations of bone disclosed loss of longitudinal orientation of fibers and irregular porous surfaces in bone from fluoride-fed animals.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 15 (1974), S. 125-132 
    ISSN: 1432-0827
    Keywords: Bone ; Collagen ; Formic Acid ; Crosslinkages ; Cyanogen Bromide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Bovine and chicken bone collagens have been solubilized and presumably denatured (gelatin) by treatment of demineralized, powdered tissue with 70% formic acid. Short periods of extraction such as four hours at 30°, conditions commonly used during cyanogen bromide cleavage of collagen, solubilized 50% and 15% of the chicken and bovine bone collagens respectively. Treatment of the tissues with sodium borohydride partially inhibited the extraction of collagen from chicken bone, but had little effect on the extraction of calf bone collagen. The heterogeneity of the bone gelatin from both species on disc electrophoretic analysis suggested that peptide bonds had been cleaved in some of the collagen chains during exposure to formic acid, thus facilitating the solubilization of the bone collagen as the gelatin. Analysis of the collagen extracted from chicken bone for reducible crosslinks indicated that a large proportion of these bonds had remained intact, in contrast to a previous finding that most of these crosslinks were destroyed in bone gelatin extracted by 4 M CaCl2, at pH 7.0. The stability of the major reducible crosslinks in bone collagen to severe acid conditions may explain in part some of its unique properties, such as its failure to swell or be solubilized in dilute acid, which distinguish it from soft tissue collagens.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 15 (1974), S. 173-179 
    ISSN: 1432-0827
    Keywords: Bone ; Strength ; Tension ; Compression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A simple method is described for visualising regions of bone that have yielded in tension. The appearance of such regions is quite different from that of regions that have yielded in compression. The significance of these findings is discussed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 15 (1974), S. 189-199 
    ISSN: 1432-0827
    Keywords: Bone ; Densitometry ; X-ray ; Radiation ; Specific gravity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract X-ray and γ-radiation techniques for evaluating bone density under field conditions in cattle and sheep were investigated. The best results were obtained from measurements of the density of radiographs of tibial tarsal bones of sheep and from the absorption of γ-radiation of the tibial tarsal bones of sheep and the fibular tarsal bones of cattle. The γ-radiation techniques may be carried out rapidly under field conditions (up to 30 animals an hour) and bone density can be estimated with a standard error of 0.042–0.046 SG units.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 169-182 
    ISSN: 1432-0827
    Keywords: Histochemistry ; Alkaline phosphatases ; Calcification ; Bone ; Teeth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Activity of alkaline phosphatases in unfixed cold microtome setions from the lower first molar area of newborn mice was recorded by histochemical methods. A substrate specificity test included the following phosphate compounds: ATP, CTP, GTP, UTP, ADP, AMP, GP, PPi, MDP and naphthol AS-TR phosphate. Intense staining was obtained in osteoblasts, stratum intermedium of the enamel organ and odontoblasts with all the substrates, except PPi and MDP. Staining of skeletal muscle fibres was obtained only with triphosphates as substrates. Addition of-SH groups decreased the hydrolysis of triphosphate compounds in cells involved in mineralization while the hydrolysis of monophosphate was inhibited. In contrast triphosphatase activity in striated muscle was enhanced when-SH compounds were added. Demineralization with EDTA diminished the cytoplasmic staining but induced a nuclear staining in hard tissue forming cells when triphosphates were used as substrates. No cytoplasmic and only slight nuclear staining was seen with GP or AMP as substrates. The triphosphate hydrolyzing capacity of tongue muscle fibres was, however, increased after the decalcification treatment. Addition of Mg2+ ions to the incubation media distinctly lowered the hydrolysis of triphosphates in the investigated tissues whereas the hydrolysis of ADP, AMP, GP and naphthol AS-TR phosphate remained unchanged. In view of the findings the triphosphatase activities at alkaline pH of muscle fibres and of cells related to hard tissue formation are considered to be due to activity of separate enzymes. The orthophosphate liberating enzyme activities at alkaline pH in osteoblasts, stratum intermedium and odontoblasts may be expressions of the catalytic functions of one common enzyme. Furthermore, the results indicate that CaATP might be the substrate used by the alkaline ATPase in mineralizing areas.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 239-250 
    ISSN: 1432-0827
    Keywords: EHDP ; Bone ; Collagen ; Histology ; Bone chemical analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The purpose of this study was to determine the short-term effects of various systemic doses of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone organic matrix and to relate these effects to the corresponding dose-related changes in bone mineral. EHDP was administered daily by subcutaneous injection at doses of 0.25, 2.5 and 40 mg/kg body weight for periods of one and two weeks. At both time intervals, rat tibiae were quantitatively analyzed for mineral content (ash, calcium and phosphorus) and for organic matrix content (matrix weight, nitrogen and certain amino acids). The latter data were correlated with semiquantitative histological analyses of the tibiae. Results of this study demonstrate that the short term effects of EHDP on bone chemistry and histology are variable and depend on the systemic dose and the duration of treatment. Systemic doses of 0.25 and 2.5 mg/kg EHDP following daily administration for one week resulted in transitory decreases in bone mineral content compared to controls. Following two weeks of treatment, both of these dose levels resulted in increased bone mineral content and, in addition, the 2.5 mg/kg dose resulted in tibiae which contained more organic matrix compared to control bones. In contrast to the low dose effects, a high systemic dose of EHDP—e.g. 40 mg/kg administered daily for 1 or 2 weeks—appears to act solely by inhibiting mineralization of newly-formed matrix.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 335-338 
    ISSN: 1432-0827
    Keywords: Fluoride ; Plasma ; Bone ; Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Fluoride analyses were carried out on blood samples from fasting subjects and on iliac crest biopsies obtained at autopsy, using an ion-selective electrode. Correlation coefficients of 0.53 and 0.67 respectively were determined between plasma fluoride and age, and bone fluoride and age. The proportionate rates of increase of fluoride levels in plasma and bone with age and the similarity of the correlation coefficients suggest that the fasting plasma fluoride concentration is in equilibrium with bone fluoride.
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  • 8
    ISSN: 1432-0827
    Keywords: Osteogenesis ; Osteoinduction ; Bone ; Matrix ; Cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Bone matrix demineralized in 0.6 N HCl at 2° for 24 h and implanted in muscle in allogeneic rats possesses consistently reproducible bone morphogenetic activity. Experiments on implants of matrix, obtained from donors injected with3H-tyrosine or3H-tryptophan, or Na35SO4, suggest that bone morphogenetic property is a protein or apart of a protein that is (1) insoluble in buffer solutions, pH 3.6 and 5.0; (2) degraded in buffer solutions at pH 7.4 by an endogenous sulfhydryl-group neutral proteinase; (3) digested by trypsin at 15° within 8 h without solubilization of the helical regions, possibly even without degradation of the nonhelical ends of the bone collagen molecule, and without any loss of the periodic ultrastructure of the collagen fibrils; (4) degraded or removed by 0.1 N NaOH at 2° within 24 h without solubilization of collagen; (5) biologically active even after nitration of tyrosyl groups with tetranitromethane. The release of only one-third of the radioactivity with loss of nearly all yield of new bone by limited tryptic digestion of3H-borohydride-reduced matrix indicates that the bone morphogenetic response is the function of a non-collagenous component. Autoradiographs of implants of matrix with non-collagenous proteins labelled with3H-tryptophan,3H-tyrosine, or both3H-tyrosine and3H-phenyl-alanine demonstrate random dissemination of the radioactive constituents and no evidence of local transfer of labelled proteins or soluble protein derivatives. Hypothetically, the bone morphogenetic response is controlled by an insoluble acidic bone morphogenetic protein or polypeptide (BMP) and a soluble neutral proteinase (BMP-ase) resembling trypsin in activity except functionally more specific for BMP. Firmly bound but separable from bone collagen, BMP is one of many short-lived morphogenetic substances appearing and disappearing throughout embryonic development and persisting in postfetal life. Where the BMP receptor resides and how it activates cell mechanisms of differential repression and derepression of such genes as code for osteogenesis is unknown.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 153-160 
    ISSN: 1432-0827
    Keywords: Lysosomes ; Bone ; Resorption ; Osteoclast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des techniques histochimiques de microscope photonique et électronique montrent que les ostéoclastes métaphysaires chez des rats “sans incisive” présentent des quantités plus importantes de phosphatase acide, d'acryl sulfatase et de trimétaphosphatase acide lysosomiales. L'activité en phosphatase lysosomiale à pH neutre est aussi plus élevée dans les ostéoclastes métaphysaires, sauf dans les cellules situées sous la métaphyse, où l'enzyme est absente. L'absence de résorption de la matrice organique semble en rapport avec l'absence de bordures en brosse et une absence d'enzyme lysosomiale extracellulaire. Malgré cette absence, une dissolution de cristaux inorganiques a été mise en évidence au microscope électronique, suggérant que la dissolution minérale est un processus distinct de la désintégration enzymatique de la matrice organique.
    Abstract: Zusammenfassung Histochemische Techniken für Licht- und Elektronenmikroskopie zeigten, daß metaphysäre Osteoklasten “Schneidezahl-loser” (SL) Ratten erhöhte Mengen von lysosomaler saurer Phosphatase, von Arylsulfatase und von saurer Trimetaphosphatase enthielten. Die Aktivität der lysosomalen Phosphatase bei neutralem pH war in den metaphysären Osteoklasten ebenfalls erhöht, außer in den Zellen direkt unterhalb der Wachstumsplatte, wo dieses Enzym nicht vorkam. Es konnte überhaupt keine Resorption der organischen Matrix festgestellt werden, was übereinzustimmen schien mit der Abwesenheit eines gekräuselten Saumes und einer gleichzeitigen Abwesenheit des extrazellulären lysosomalen Enzyms. Trotzdem wurde im Elektronenmikroskop das Verschwinden anorganischer Kristalle festgestellt, was darauf schließen läßt, daß die Auflösung des Minerals nicht derselbe Vorgang ist wie die enzymatische Auflösung der organischen Matrix.
    Notes: Abstract Histochemical techniques for light and electron microscopy showed that metaphyseal osteoclasts in “incisors absent” rats contained greater than normal amounts of lysosomal acid phosphatase, aryl sulfatase and acid trimetaphosphatase. Lysosomal phosphatase activity at neutral pH was also elevated in the metaphyseal osteoclasts except in those cells immediately beneath the growth plate, where this enzyme was absent. The failure of any discernable resorption of organic matrix appeared to correlate with the absence of a ruffled border and a concomittant absence of extracellular lysosomal enzyme. Despite this failure, electron microscopic evidence of inorganic crystal removal was noted, suggesting that mineral dissolution represents a separate process from the enzymatic breakdown of organic matrix.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 13-36 
    ISSN: 1432-0827
    Keywords: Osteoclast ; Bone ; Resorption ; Crystals ; Organic-inorganic relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The organic-inorganic relationships in bone matrix undergoing osteoclastic resorption have been studied in rat tibial diaphyses using electron microscope techniques in an attempt to identify the steps of the resorption process. Results suggest that bone resorption occurs in two phases: the first, an extracellular phase, leads to bone matrix fragmentation and partial dissolution, and the second, an intracellular phase, to complete digestion of the breakdown products of the bone matrix. The first component of the bone matrix to be attacked by the osteoclast is the ground substance. This induces the release of the crystals lying between, and on, the collagen fibrils; any crystals lying within fibrils are released later, when the fibrils break up. As this stage proceeds, the collagen fibrils retain their normal intrinsic texture, but gradually loose their lateral aggregation, appearing as individual fibrils (some of them uncovered by crystals), mixed with fragments of fibrils and many free crystals. The loosened but otherwise structurally normal collagen fibrils, and their fragments, are strongly argyrophilic. Complete dissolution of the disaggregated fibrils occurs outside the cell, both in the resorption zone and in the initial portion of the channels of the ruffled border. The free crystals present in the resorption zone and those phagocytosed in cytoplasmic vacuoles are organic-inorganic structures, whose organic component (the crystal ghost) is, at least in part, of proteoglycan nature. Dissolution of inorganic material occurs within the cytoplasmic vacuoles of the osteoclasts. Results are viewed in relation to the process of bone resorption and, as far as crystal ghosts are concerned, to that of bone calcification. A tentative summary of the various steps involved in the mechanism of bone resorption is given.
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  • 11
    ISSN: 1432-0827
    Keywords: Bone ; Parathyroid ; 25-Hydroxycholecalciferol ; Adenosine 3′, 5′ cyclic monophosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Phenytoin, at a concentration which is known to inhibit parathyroid extract-induced bone resorptionin vitro, has been shown to have no significant effect on either the cyclic AMP content of four-day-old mouse calvaria which had been in tissue culture for 48 h or on the increase in cyclic AMP content occurring after the addition of parathyroid extract to the medium. Phenytoin has also been shown to be an effective inhibitor of bone resorptionin vitro induced by 25-hydroxycholecalciferol. These observations suggest that the inhibitory effect of phenytoin on parathyroid extract and hormone-induced bone resorption takes place beyond the cyclic AMP stage.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 219-226 
    ISSN: 1432-0827
    Keywords: Bone ; Phosphate ; ATP ; Calcium ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract An active constituent of the leaves ofSolanum malacoxylon (SM) is shown to promote calcium resorption and citrate production in embryonic chick frontal bone culturedin vitro. When injected into rats, SM reduces the ATP content of liver and kidneys. This phenomenon may be related to the ability of SM to stimulate mitochondrial ATPase activity at pH 9.4. SM significantly reduces the concentration of phosphate necessary to alter the uptake of calcium and respiration of siolated mitochondria. The data suggest that SM influences calcium and phosphate metabolism by affecting ion movements into and out of mitochondria.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 283-289 
    ISSN: 1432-0827
    Keywords: Sodium fluoride ; Osteoporosis ; Bone ; Strength ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'utilisation thérapeutique de fluorure de sodium a été recommandée dans le traitement de diverses maladies osseuses ostéopéniques. Cet emploi est basé principalement sur les effects ostéosclérotiques bien connus du fluorure de sodium, mais on connait mal son effet sur la force de résistance osseuse. L'influence de diverses concentrations de fluorure de sodium sur la force de résistance osseuse de jeunes rats soumis à des régimes riches et pauvres en calcium a été étudiée. L'administration de fluorure de sodium augmente le diamètre osseux, indiquant une stimulation de la formation de l'os périosté, mais la force de résistance osseuse est réduite ou non modifiée par l'ingestion de fluor.
    Abstract: Zusammenfassung Die therapeutische Verwendung von Natriumfluorid ist für eine Anzahl von Knochenmangel-Krankheiten empfohlen worden. Die Empfehlungen basieren hauptsächlich auf den bekannten osteosklerotischen Wirkungen von Natriumfluorid; über dessen Effekt auf die Knochenstärke ist wenig bekannt. In dieser Arbeit wurde der Einfluß verschiedener Konzentrationen von Natriumfluorid auf die Knochenstärken von wachsenden Ratten mit hoher und niederer Calciumeinnahme untersucht. Die Verabreichung von Natriumfluorid erhöhte den Knochendurchmesser, was auf eine Stimulierung der Periostbildung hinwies, die Knochenstärke wurde jedoch durch Fluorideinnahme herabgesetzt oder nicht beeinflußt.
    Notes: Abstract The therapeutic use of sodium fluoride has been recommended in a variety of osteopenic bone diseases. The recommendations are based mainly on the known osteosclerotic effects of sodium fluoride and little information is available as to its effect on bone strength. The influence of various concentrations of sodium fluoride on bone strength in growing rats on high and low calcium diets was studied. The administration of sodium fluoride increased bone diameter, indicating stimulation of periosteal bone formation, but bone strength was reduced or not affected by fluoride ingestion.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 291-299 
    ISSN: 1432-0827
    Keywords: Bone ; Collagenase ; Lysozyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Du lysozyme de blanc d'œuf, ainsi que des protéines basiques, telles que de l'histone et une base dépourvue de protamine, semblent inhiber la collagénase osseuse de souris. L'inhibition de collagénase osseuse de souris par le lysozyme est mise en évidence lorsque l'activité de la collagénase est étudiée en utilisant du collagène comme substrat à l'état solide, mais non lorsque le collagène est utilisé en solution. D'autre part, l'inhibition de l'activité en collagénase par l'histone et une base dépourvue de protamine est observée dans les deux systèmes. L'inhibition de collagénase ossuese de souris par des molécules polyanioniques est intéressante, étant donné que des travaux antérieurs ont montré que plusieurs molécules polyanioniques telles que l'héparine, le sulfate de dextrane et l'acide polyethylenesulfonique augmentent l'activité de collagénase osseuse de souris dans les mêmes conditions expérimentales. Comme le lysozyme est largement présent dans les tissus conjonctifs et que sa concentration carie avec l'ampleur du remaniement tissulaire, l'inhibition de la collagénase osseuse de souris suggère un role éventuel dans la régulation de la dégradation du collagène, pendant le remaniement des tissus collagéniquesin vivo au cours d'états normaux et pathologiques.
    Abstract: Zusammenfassung Lysozyme aus Hühnereiweiß sowie Basis-Proteine, wie z. B. Histon und Protamin-freie Basen, erwiesen sich als Hemmer der Mäuseknochen-Kollagenase. Diese Hemmung durch Lysozym wurde festgestellt, wenn für die Messung der Kollagenase-Aktivität Kollagen in Substanz als Substrat verwendet wurde, nicht aber, wenn das Substrat aus gelöstem Kollagen bestand. Andererseits wurde die Hemmung der Kollagenase-Aktivität durch Histon und Protamin-freie Basen in beiden Versuchssystemen festgestellt. Die Hemmung von Mäuseknochen-Kollagenase durch polykationische Moleküle ist interessant, vor allem im Hinblick auf frühere Feststellungen, daß mehrere polyanionische Moleküle, wie Heparin, Dextransulfat und Polyaethylensulfonsäure, die Aktivität der Mäuseknochen-Kollagenase unter denselben experimentellen Bedingungen erhöhen. Da Lysozym in Bindegeweben überall verteilt ist und da dessen Konzentration mit der Neubildungsrate des Gewebes variiert, läßt die Hemmung der Mäuseknochen-Kollagenase durch Lysozym dessen mögliche Rolle in der Regulierung des Kollagenabbaues vermuten, und zwar während der Neubildung von Kollagengeweben in vivo in normalen und pathologischen Zuständen.
    Notes: Abstract Egg white lysozyme, as well as basic proteins such as histone and protamine-free base, were found to inhibit mouse bone collagenase. The inhibition of mouse bone collagenase by lysozyme was detected when the activity of the collagenase was assayed using collagen as the substrate in the solid state, but not when the collagenase activity was assayed using collagen in solution as the substrate. On the other hand, the inhibition of collagenase activity by histone and protamine-free base was observed in both assay systems. The inhibition of mouse bone collagenase by polycationic molecules is interesting in light of previous findings that several polyanionic molecules, such as heparin, dextran sulfate and polyethylenesulphonic acid, enhance the activity of mouse bone collagenase under the same experimental conditions. Since lysozyme is widely distributed in connective tissues and its concentration varies with the rate of tissue remodeling, the inhibition of mouse bone collagenase by lysozyme suggests its possible role in the regulation of collagen degradation during the remodeling of collagenous tissuesin vivo during normal and pathological states.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 309-315 
    ISSN: 1432-0827
    Keywords: Osteoblast ; Matrix ; Bone ; Scanning electron microscope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les territoires sécrétoires des ostéoblastes d'os pariétal de rats sont déterminées en utilisant la microscopie électronique à balayage. Le territoire moyen de 4.620 cellules, dans 19 territoires, est de 154 μm2 par ostéoblaste. Les valeurs extrêmes par champ varient de 136 à 177 μm2 par ostéoblaste. Quatre cent cellules sont mesurées individuellement; la valeur moyenne par ostéoblaste est de 143 μm3 avec une déviation standard de 33. Le taux d'apposition journalier, mesuré par la tétracycline pendant 8 jours, est de 3.12 μm (déviation standard 0.22). Ce qui correspond à une production matricielle journalière d'environ 470 μm3 par ostéoblaste.
    Abstract: Zusammenfassung Die Ausscheidungsbereiche von Ratten-Osteoblasten des Scheitelbeines wurden mit dem Raster-Elektronenmikroskop direkt gemessen. Der durchschnittliche Bereich von 4620 Zellen in 19 Gesichtsfeldern war 154 μm2 per osteoblast. Der Streubereich lag in den verschiedenen Gesichtsfeldern zwischen 136 und 177 μm2 per Osteoblast. 400 Zellen wurden einzeln gemessen. Bei diesen war der Durchschnittswert per Osteoblast 143 μm2, mit einer Standard-Abweichung von 33. Die tägliche Anlagerungsrate während einer Periode von 8 Tagen war 3,12 μm (Standard-Abweichung 0,22); sie wurde mittels Tetracyclinmarkierung der Mineralisierungsfront gemessen. Dies ergab eine tägliche Produktionsrate der Matrix von etwa 470 μm3 per Osteoblast.
    Notes: Abstract The secretory territories of rat osteoblasts on the parietal bone were measured directly using scanning electron microscopy. The mean territory of 4620 cells in 19 fields was 154 μm2 per osteoblast. The range for the fields was 136 to 177 μm2 per osteoblast. Four hundred cells were measured individually—for these the mean value per osteoblast was 143 μm2 with a standard deviation of 33. The daily rate of apposition over an 8 day period was 3.12 μm (standard deviation 0.22) measured by tetracycline marking of the mineral front. This gave a daily matrix production rate of approximately 470 μm3 per osteoblast.
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  • 16
    Electronic Resource
    Electronic Resource
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    Calcified tissue international 14 (1974), S. 327-331 
    ISSN: 1432-0827
    Keywords: Bone ; Piezoelectricity ; Collagen ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The piezoelectric constant of mature and immature bone (defined herein) has been measured in an effort to determine whether it varies with age. It was found that the average value of the piezoelectric constantd 14 of femur from three week old calves was 58% of the value of femur from three year old bulls. The results were interpreted to indicate qualitative differences in the corresponding collagen matrices. Mature human tibia from males ranging in age from 21 to 53 years of age showed a small but significant increase ind 14 with age. Some data concerning diseased human bone, and well-preserved human bone excavated in Peru are also presented.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 333-337 
    ISSN: 1432-0827
    Keywords: Bone ; Materials ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des métaux poreux et des céramiques sont implantés dans l'osin vivo et sont prélevés, après différents intervalles, pour étudier histologiquement la colonisation tissulaire. Les implants prélevés sont fixés avec les tissus environnants et inclus dans des epoxy-résines, de faible viscosité. Les échantillons sont coupés à l'aide d'une scie diamantée et fixés sur des lames pétrographiques, pour être ensuite amincis à environ 75 μm. Ils sont légèrement colorés au bleu de méthylène et à l'alizarine rouge S, qui donne un bon contraste entre tissus durs et mous et démontrent la présence d'os calcifié dans les implants poreux métalliques et céramiques.
    Abstract: Zusammenfassung Poröse Metall- und Keramikstücke wurden in vivo in Knochen implantiert und nach verschiedenen Intervallen entnommen, um histologisch zu untersuchen, wie weit sie ins Gewebe eingewachsen waren. Die entnommenen Implantate mit dem sie umgebenden Gewebe wurden fixiert, dehydriert und in ein niedrigvisköses Epoxy-Harz eingebettet. Die Proben wurden mit einer Diamantsäge in dicke Schnitte zerteilt, auf Steinscheiben zementiert und von Hand auf etwa 75 μm geschliffen. Sie wurden mit Methylenblau und Alizarin-Rot S schwach gefärbt; dies ergibt einen großen Kontrast zwischen Knochen und Weichgewebe und zeigt die Bildung von verkalktem Knochen innerhalb poröser Metall- und Keramik-Implantate deutlich.
    Notes: Abstract Porous metals and ceramics were implanted in bonein vivo and retrieved at intervals for histological evaluation of tissue ingrowth. Recovered implants with surrounding tissues were fixed, dehydrated and embedded in a low-viscosity epoxy resin embedding medium. The embedded samples were cut into thick sections with a diamond saw, cemented to petrographic slides, and hand-ground to approximately 75 μm. They were lightly stained with methylene blue and Alizarin Red S, which provided great contrast between the bone and soft tissues, and clearly demonstrated the formation of calcified bone within porous metal and ceramic implants.
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  • 18
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    Calcified tissue international 15 (1974), S. 11-20 
    ISSN: 1432-0827
    Keywords: Bone ; Growth ; Resorption ; Caudal ; Vertebra ; Fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une méthode de mesure de l'apposition et de la résorption osseuse est mise au point au niveau de la septième vertèbre caudale de jeunes rats, pesant 25–90 g, pendant la période de croissance. Cette pièce osseuse a des avantages certains par rapport à d'autres localisations, car elle est symétrique en coupe transversale et non affectée par des forces corticales. En utilisant trois marqueurs d'os différents, fluorescents en lumière ultra-violette, administrés à des intervalles de 3, 5 ou 7 jours, les modifications de croissance sont observées sur des coupes transversales centrales, non décalcifiées, de la septième vertèbre caudale. Une formation osseuse linéaire se développe à une vitesse moyenne de 10.0 μ/jour et une résorption linéaire de 6.1μ/jour est notée. Pendant la période de croissance observée, la formation osseuse s'observe exclusivement à la surface du périoste et la résorption se fait le long de la surface de l'endoste. A ce niveau l'os est totalement résorbé, chez des animaux de 25 g en 22–26 jours. Il semble que chez des animaux plus âgés, une formation osseuse endostée se développe rendant alors impossible toute étude prolongée dans cette région.
    Abstract: Zusammenfassung Es wird eine Methode zur Messung der Knochenbildungs- und Resorptionsgeschwindigkeiten im siebten Caudalwirbel junger Ratten während ihrer Wachstumsperiode von 25–90 g beschrieben. Dieser Knochen hat gegenüber jenen, die vorgängig untersucht wurden, den großen Vorteil, in transversalen Schnitten symmetrisch und unbeeinflußt von kortikalen Unregelmäßigkeiten zu sein. Die Art der Wachstumsveränderungen wurden an nichtentkalkten zentralen Transversalschnitten der siebten Caudalwirbeln bestimmt; dazu wurden drei verschiedene, farbige, im UVbereich fluoreszierende Knochenmarkierungssubstanzen verabreicht und zwar in 3-, 5- oder 7tägigen Intervallen. Die lineare Knochenbildung fand mit einer mittleren Geschwindigkeit von 10,0 μ pro Tag statt, die lineare Knochenresorption mit einer solchen von 6,1 μ pro Tag. Während der untersuchten Wachstumsperiode fand die Knochenbildung ausschließlich an der Periostoberfläche und die Knochenresportion an der endostalen Oberfläche statt. Der Knochen, der beim 25 g schweren Tier an diesem Ort vorlag, verschwand durch die endostale Resorption innerhalb von 22–26 Tagen
    Notes: Abstract A method for measuring bone formation and resorption rates in the seventh caudal vertebra of young rats during the growth period from 25–90 g is reported. This bone site has unique advantages over those previously studied, being symmetrical in transverse section and uncomplicated by cortical drift. Utilising three different coloured ultraviolet fluorescent bone labelling substances administered at either 3, 5 or 7 day intervals, the nature of growth changes was determined from undecalcified central transverse sections of the seventh caudal vertebrae. Linear bone formation occurred at a mean rate of 10.0 μ/day and linear bone resorption at 6.1 μ/day. During the growth period studied, bone formation occurred exclusively on the periosteal surface and bone resorption on the endosteal surface. Bone existing in this site in 25 g animals was completely removed by endosteal resorption within 22–26 days. Evidence exists that in older rats endosteal bone formation occurs and renders the site unsuitable for long term studies.
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  • 19
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    Calcified tissue international 15 (1974), S. 45-54 
    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Microhardness ; Mineralization ; Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Microhardness was measured in sampling sites in the tibial diaphysis of control rats that received less than 1 ppm fluoride in the drinking water, and experimental rats that received 30, 90 and 120 ppm fluoride in the drinking water for 17 days. The latter dose was toxic, as evidenced by a decreased final body weight in this group. By means of tetracycline labelling, it was possible to measure bone hardness in four zones of increasing bone age: I) 3 days, II) 8 days, III) 13 days and IV) 22 days. Zones I through III represented bone formed during fluoride treatment, and Zone IV bone formed before fluoride treatment. In the control group, microhardness increased from Zone I to II, probably because mineral concentration was relatively low in Zone I, and remained constant thereafter. In the 90 and 120 ppm fluoride-treated groups, maximum microhardness was not achieved until Zone III. This delay was probably due to the fact that fluoride in large doses inhibits the rate of mineralization. In the 30 ppm fluoride-treated group, there was no delay in achievement of maximum microhardness; microhardness values in Zones I and III were greater than those in control animals, and microhardness in Zone III was higher than that in Zone IV. These results show that: 1) bone microhardness is increased in bone formed during fluoride treatment in rats given 30 ppm fluoride in the drinking water, 2) toxic doses of fluoride delay, but do not prevent achievement of normal maximum microhardness, and 3) changes in microhardness are seen only in bone formed during fluoride treatment.
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  • 20
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    Calcified tissue international 15 (1974), S. 71-76 
    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Deficiency ; Osteoporosis ; Species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract 21-day-old rats and mice were fed a low-calcium diet (0.02% Ca) or a normal diet (0.5% Ca) for two weeks. Administration of the low-calcium diet resulted in greater decreases in femur ash content and serum calcium in rats than in mice. Microscopic examination revealed that metatarsal bones from a majority of the rats fed a low-calcium diet displayed moderate or severe osteoporotic changes whereas bones from mice were either normal or displayed only slight osteoporotic changes under the same experimental conditions. These results indicate that mice are better able to adapt to a low-calcium diet than are rats of the same age.
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  • 21
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    Calcified tissue international 15 (1974), S. 315-324 
    ISSN: 1432-0827
    Keywords: Bone ; Mineral ; Osteogenesis ; Interference microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A method based on tetracycline labeling was developed for selecting, in frozen sections of fetal mouse femur, bone foci approximately 6, 24, 48 and 72 h of age. Microinterferometric measurements of these foci permitted a calculation of the effective thickness (t) and refractive index (n) of each focus. After demineralizing the sections by a method which left the organic portion of the bone intact, the foci were re-measured andt andn of the organic compartment of each focus were determined;t andn of the mineral compartment were calculated by difference. A sharp decrease and subsequent rise in then of whole bone occurred between 6 and 48 h. These changes derived from the mineral compartment, and were thought to have resulted from the formation of amorphous calcium phosphate and hydroxyapatite, respectively. The mineral present in 6 h foci, however, was believed to be some precursor of amorphous calcium phosphate.
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  • 22
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    Calcified tissue international 15 (1974), S. 329-332 
    ISSN: 1432-0827
    Keywords: Microradiography ; Bone ; X-ray
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A low cost, self-contained, commercially available, X-ray apparatus which possesses the essential qualifications necessary to produce high resolution microradiographs of undecalcified bone is described. The widespread current use of this machine in pathology laboratories may make purchase of such a unit optional.
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  • 23
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    Calcified tissue international 16 (1974), S. 73-88 
    ISSN: 1432-0827
    Keywords: Dentine ; Bone ; Histocytochemistry ; Physiological Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Histochemical methods were used to detect differences in amino acid reactive groups between bone and osteoid, dentine and predentine. Three major differences were found: Predentine and osteoid contained more reactive sulphydryls than their mineralized counterparts. The greatest reaction for this reactive group was obtained at the mineralizing front. Dentine and bone contained a complex between amino and carboxylic acid groups; predentine and osteoid did not have this complex and carboxylic acid residues were less in these tissues. Dentine and bone contained much greater amounts of histidine or a histidine-like component than did predentine and osteoid. It is proposed that these differences are involved in initiation of mineralization.
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  • 24
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    Calcified tissue international 16 (1974), S. 261-275 
    ISSN: 1432-0827
    Keywords: Dentine ; Bone ; Mineralization ; Density gradient fractionation ; Proteoglycans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract In order to obtain enough material to analyse the organic matrix of mineralizing tissue a technique for preparative separation according to the degree of mineralization was developed. The method employs ultracentrifugation of powdered material in density gradients made from acetone and bromoform. The density range of the fractions is checked by refractive index measurements of the gradient medium. The amount of the material in the fractions is checked by weighing and their degree of mineralization is estimated by determining the Ca/N and P/N ratios. The homogeneity of the fractions is determined by soft X-ray microscopy. Isolated dissected microscopic bone structure (osteones and lamellar bone fragments) with different degrees of mineralization were fractionated in this way. Chromatography on Sepharose 2B of proteoglycans from costal cartilage exposed to an acetone-bromoform gradient revealed no effect of the gradient medium on the molecular size of the proteoglycans.
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  • 25
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    Calcified tissue international 14 (1974), S. 161-168 
    ISSN: 1432-0827
    Keywords: Diphosphonates ; Osteoid Synthesis ; Hydroxyproline ; Bone ; Formation-Resorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Deux diphosphonates, à savoir l'éthane-1-hydroxy-1,1-diphosphonate (EHDP) et le dichlorométhane diphosphonate (Cl2MDP), inhibentin vitro la résorption osseuse qui est stimulée soit par la parathormone ou par voie intrinsèque dans un système de culture d'os en remaniement. Alors que le Cl2MDP est plus efficace que l'EHDP dans l'inhibition de la résorption, ce fait semble en rapport avec une diminution de le formation de tissu ostéoide. Il s'en suit une diminution biochimique et morphologique marquée du remaniement osseux avec le Cl2MDP à une concentration équivalent à 10 μg de phosphore/ml de milieu de culture. La différence d'activité entre l'EHDP et le Cl2MDP peu être liée à leur affinité relative pour les surfaces du minéral osseux et, par suite, à leur concentration effective dans la fluide extracellulaire osseux. Les diphosphonates pourraient aussi affecter l'os indirectement si l'on admet que le degré de minéralisation de la matrice est important pour l'induction et la régulation de l'activité ostéoblastique dans l'os en voie de remaniement.
    Abstract: Zusammenfassung Zwei Diphosphonate, Aethan-1-hydroxy-1,1-diphosphonat (EHDP) und Dichloromethylen-Diphosphonat (Cl2MDP) hemmen in vitro die Knochenresorption. Diese wird verfolgt entweder mittels Stimulierung durch PH oder in einem Kultursystem, in welchem normale Knochenneubildung stattfindet. Während Cl2MDP die Resorption wirksamer hemmt als EHDP, scheint es ebenfalls eine Verminderung der Osteoidbildung zu verursachen. Dies bewirkt eine deutliche biochemische und morphologische Herabsetzung der Knochenneubildung, bei einer Cl2MDP-Konzentration von 10 μg Phosphor/ml Kulturmedium. Die unterschiedliche Wirksamkeit von EHDP und Cl2MDP läßt sich wahrscheinlich auf ihre verschiedenen Affinitäten zu der Oberfläche des Knochenminerals und somit auf ihre tatsächliche freie Konzentration in der extracellulären Flüssigkeit des Knochens zurückführen. Ausgehend von der Annahme, daß die Anregung und Regulierung der Osteoblasten-Aktivität bei der Knochenneubildung vom Ausmaß der Matrix-Mineralisation bestimmt wird, läßt sich die Vermutung aufstellen, daß die Diphosphonate die Knochenbildung auch indirekt beeinflussen können.
    Notes: Abstract Two Diphosphonates, ethane-1-hydroxy-1,1-diphosphonate (EHDP) and dichloromethylene diphosphonate (Cl2MDP) inhibitin vitro bone resorption, which is either stimulated by parathyroid hormone or intrinsic in a bone remodeling culture system. While Cl2MDP is more effective than EHDP in inhibiting resorption, it also appears to result in a related diminution in osteoid formation. This effect causes a marked biochemical and morphological depression of bone remodelling with Cl2MDP at a concentration equivalent to 10-μg-phosphorus/ml of culture medium. The difference in activity between EHDP and Cl2MDP may be related to their relative affinities for the bone mineral surfaces and hence their effective free concentration in the bone extracellular fluid. It is hypothesized that diphosphonates may also affect bone formation indirectly if one assumes that the degree of mineralization of the matrix is important in the induction and regulation of osteoblastic activity in remodelling bone.
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  • 26
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    Calcified tissue international 14 (1974), S. 195-210 
    ISSN: 1432-0827
    Keywords: Bone ; Fossil bone ; Bone resorption ; Boring channels ; Fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'action ostéoclasique exercée par un champignon appartenant au genreMucor sur des os inhumés a été étudiée au point de vue morphologique. L'érosion ossuse donne lieu à des cavités et à des canalicules de percement, dont les parois apparaissent régulièrement calcifiées jusqu'a l'interface avec le champignon, ce qui veut dire que la réabsorption intéresse en même temps la matrice organique et les cristallites. Au contraire des ostéoclastes, la membrane du champignon ne montre jamais un bord en brosse au niveau des points où elle se met en contact avec le tissu osseux. De même l'examen au microscope électronique ne décele apparemment aucun passage de matériel dans l'épaisseur de la membrane ainsi que dans le protoplasme du champignon, ce qui porte à admettre qu'un processus de solubilisation a lieu au préalable. Seulement dans le cas où le champignon présente des phénomènes de vieillissement, des données font prévoir la libération d'une substance capable de décalcifier la matrice organique. Tous les résultats ci-dessu sont discutés de façon analytique et comparés à ceux fournis par les canalicules de percement des os fossiles.
    Abstract: Zusammenfassung Die osteoklastische Aktivität eines der Mucor-Gattung angehörenden Pilzes auf begrabene Knochen wurde morphologisch untersucht. Die Wirkung dieses Pilzes in der Knochenerosion führt zu Resorptionshöhlen und Bohrkanälen, deren Wände scharf und bis zur Oberfläche gut verkalkt sind; das bedeutet, daß die Knochenresorption gleichzeitig die Kristalliten und die organische Matrix in Mitleidenschaft zieht. Im Gegensatz zu den normalen Osteoklasten zeigt die Membran des Pilzes an den Berührungsstellen mit dem Knochengewebe keinen Bürstensaum. Ebenfalls läßt eine elektronenmikroskopische Untersuchung keinen Durchgang von Substanzen durch die Membran und das Protoplasma des Pilzes erkennen, so daß man annehmen muß, daß vorher ein Auflösungsprozeß stattgefunden hat. Die Vermutung liegt nahe, daß eine Substanz, welche den anorganischen Knochenanteil aufzulösen vermag, sich
    Notes: Abstract A morphological investigation has been carried out on the osteoclastic activity revealed by a fungus of theMucor genus on buried bone. The hallmark of its activity in eroding bone is the finding of resorption pits and boring channels whose walls are sharp and well calcified up to the free edge, suggesting that bone resorption affects crystallites and the organic matrix simultaneously. Unlike normal osteoclastic cells, the fungal membrane in contact with the bone shows no brush border. As the electron microscope reveals no migration of material to the fungal membrane and its protoplasm, the view is expressed that the material which reaches the fungus has been previously solubilized. There is good reason for supposing that a substance capable of solubilizing the inorganic bone fraction spreads freely through bone tissue, decalcifying the matrix, where, but only where, hyphae show the effects of ageing. All the findings are thoroughly discussed and compared with those furnished by the boring channels in fossil bone.
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  • 27
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    Calcified tissue international 14 (1974), S. 245-249 
    ISSN: 1432-0827
    Keywords: Bone ; Repair ; Histology ; Implant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Um modèle expérimental, destiné à l'étude de la cicatrisation osseuse, est mis au point. Il permet d'obtenir du tissu osseux pour des études qualitatives et quantitatives. Des tubes de nylon sont implantés dans l'alvéole d'incisives extraites de cobayes. Une étude histologique de coupes longitudinales montrent que les implants de nylon ne retardent pas la cicatrisation des lésions osseuses et contiennent suffisamment de tissus pour des études biochimiques.
    Abstract: Zusammenfassung Es wurde ein Modellsystem zum Studium der Knochenwiederherstellung entwickelt, mit Hilfe dessen man von dem sich wiederbildenden Knochengewebe Proben für die qualitative und quantitative Bestimmung entnehmen kann. Dazu wurden in die Alveolen extrahierter Schneidezähne von Meerschweinchen Nylonschläuchlein eingelegt. Die histologische Untersuchung von Längsschnitten zeigte, daß die Nylonimplantate den Wiederherstellungsprozeß des Knochendefektes nicht verzögerten, daß sie herauspräpariert werden konnten und genügend Gewebe enthielten, um für biochemische Untersuchungen verwendet zu werden.
    Notes: Abstract A model system for the study of bone repair has been developed which allows the recovery of repairing osseous tissue for qualitative and quantitative evaluation. Nylon tubes were implanted in the alveoli of extracted incisors in guinea pigs. A histological study of longitudinal sections showed that the nylon implants did not delay the reparative processes of the bony defect, could be dissected out and contained sufficient tissue to be used in biochemical studies.
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  • 28
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    Calcified tissue international 14 (1974), S. 251-255 
    ISSN: 1432-0827
    Keywords: Cartilage ; Bone ; Vitamin A ; Phosphatases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Au cours d'une étude du cartilage épiphysaire de poulets normaux et déficients en vitamine A, la composition organique et l'activité phosphatasique du cartilage au repos, du cartilage en voie d'ossification et de l'os nouvellement formé ont été mesurées. Le cartilage en voie d'ossification et l'os nouvellement formé ont un contenu plus élevé en matériel inorganique, phosphate et collagène que le cartilage au repos. Une déficience en vitamine A provoque une augmentation du contenu en phospholipide de tous les trois tissus. Le cartilage au repos, en cas de déficience en vitamine A, présente, après homogénéisation et centrifugation, un surnageant dont l'activité en phosphatase alcaline et en glycérophosphatase est plus élevée que celle des témoins. Il semble que les effets enzymatiques de l'avitaminose A soient liés à des altérations de la membrane lysosomiale avec décharge de phosphatases. La minéralisation normale semble aussi faire intervenir une activité phosphatasique.
    Abstract: Zusammenfassung Diese Arbeit beschreibt Untersuchungen des Epiphysenknorpels bei normalen Küken und solchen mit Vitamin-A-Mangel. Die organische Zusammensetzung und die Phosphatase-Aktivität in ruhendem Knorpel, ossifizierendem Knorpel und neugebildetem Knochen wurden gemessen. Der ossifizierende Knorpel und der neugebildete Knochen hatten einen höheren Gehalt an anorganischem Material, an Phosphat und Kollagen als der ruhende Knorpel. Vitamin-A-Mangel führte zu einem erhöhten Phospholipidgehalt in allen drei Geweben. Nach Homogenisierung und Zentrifugierung fand sich im Überstand des ruhenden Knorpels von Vitamin-A-Mangelgewebe eine höhere alkalische Phosphatase- und Glycero-phosphatase-Aktivität als bei den Kontrollen. Es wird angenommen, daß die Wirkung des Vitamin A-Mangels auf die Enzyme im Zusammenhang steht mit der Schädigung der lysosomalen Membran, wobei Phosphatasen freigesetzt werden, und daß die normale Mineralisierung die Phosphatasen-Aktivität ebenfalls anregt.
    Notes: Abstract This paper reports studies of the epiphyseal cartilage in normal and vitamin A deficient chicks. The organic composition and the phosphatase activity in the resting cartilage, ossifying cartilage and new bone were measured. The ossifying cartilage and new bone had a higher content of inorganic material, phosphate and collagen than the resting cartilage. Vitamin A deficiency caused increase in the phospholipid content of all three tissues. The resting cartilage from vitamin A deficient tissue had, after homogenisation and centrifugation, a supernatant with an activity of alkaline phosphatase and glycerophosphatase higher than that in control samples. It is considered that effects of vitamin A deficiency on enzymes are related to defects of the lysosomal membrane with release of phosphatases, and that normal mineralisation also involves phosphatases activity.
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  • 29
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    Calcified tissue international 15 (1974), S. 181-188 
    ISSN: 1432-0827
    Keywords: Biopsy ; Bone ; Calcium ; Phosphorus ; Specific gravity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The specific gravities (SG) of bone samples taken from various parts of the skeleton of cattle and sheep were determined gravimetrically in an effort to establish which sites give the most reproducible and uniform results, so that between animals, or sequential within animals, comparisons may be made with maximum sensitivity. Samples obtained from the mandible of sheep and the rib of cattle and sheep were found to be too variable to be useful for most purposes. Best results were obtained using whole bones which are easily prepared, such as the tibial tarsal bones of cattle and sheep and the fibular tarsal bone of cattle. These bones gave within animal deviations of 0.012–0.024 SG units, when comparing left bone with right bone. Slightly higher values were obtained for coccygeal vertebrae from cattle and distal metacarpal condyles from sheep. SG was related to ash, calcium and phosphorus contents of coccygeal vertebrae of cattle and it is considered that, for survey work on the mineral status of the bones of cattle and sheep, the correlations are sufficiently high to make their determination unnecessary. This will enable radiation determined SG techniques to be applied to this type of work.
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  • 30
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    Calcified tissue international 14 (1974), S. 31-48 
    ISSN: 1432-0827
    Keywords: Bone ; Cartilage ; Calcification ; Collagen ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une méthode pour l'étude de la croissance des os longs de foetus de rat, en culture d'organe, dans un milieu chimiquement défini, a été mise au point. Les extrémités cartilagineuses et les parties centrales de l'os sont analysées séparément pour leur croissance et minéralisation en étudiant leur contenu en collagène, calcium et phosphate, poids sec, et incorporation de proline marquée en hydroxyproline. La croissance et la minéralisation des parties centrales osseuses sont plus lentes dans un milieu chimiquement défini qu'in vivo. La croissance peut être accélérée en ajoutant au milieu des acides aminés non essentiels, de l'albumine ou du sérum. Les extrémités cartilagineuses présentent une augmentation plus importante en poids et contenu en collagène que les parties centrales et l'adjonction de diverses substances a moins d'effet sur la croissance. La croissance et la minéralisation des parties centrales sont augmentées en élevant la concentration du milieu en phosphate de 1.5 à 4.5 mM, avec ou sans adjonction de sérum ou d'albumine. A une concentration faible de calcium (0.5 mM), la croissance et la minéralisation des parties centrales sont arrêtées. A une concentration faible en magnésium (0.5 mM), la minéralisation est augmentée, mais la croissance est arrêtée.
    Abstract: Zusammenfassung Es wird eine Methode beschrieben, mit welcher das Wachstum der Röhrenknochen von Rattenembryos in einem chemisch bestimmten Medium in Organkultur untersucht werden kann. Die Knorpelenden und Knochenschäfte wurden gesondert auf Wachstum und Mineralisation geprüft, indem Collagen-, Calcium- und Phosphatgehalt, das Trockengewicht und der Einbau von markiertem Prolin in Hydroxyprolin gemessen wurden. Wachstum und Mineralisation des Knochenschaftes waren langsamer in einem chemisch bestimmten Medium als in vivo. Das Wachstum konnte beschleunigt werden, indem dem Medium nicht-essentielle Aminosäuren, Albumin oder Serum beigegeben wurden. Die Knorpelenden zeigten eine viel stärkere Zunahme an Gewicht und Collagengehalt als die Schäfte, und Anreicherung des Mediums hatte weniger Wirkung auf ihr Wachstum. Das Wachstum und die Mineralisation der Knochenschäfte nahmen zu, wenn die Phosphatkonzentration im Medium zwischen 1,5 und 4,5 mM erhöht wurde, und zwar unabhängig davon, ob dem Medium Serum oder Albumin beigegeben wurde oder nicht. Bei niederer Calciumkonzentration (0,5 mM) im Medium wurden Wachstum und Mineralisation der Knochenschäfte beeinträchtigt. Bei niedriger Magnesiumkonzentration (0,5 mM) wurden die Mineralisation erhöht, das Wachstum hingegen gehemmt.
    Notes: Abstract A method for studying the growth of fetal rat long bones in a chemically defined medium in organ culture is described. Cartilage ends and bone shafts were analyzed separately for growth and mineralization by measuring the collagen, calcium, and phosphate content, dry weight, and incorporation of labeled proline into hydroxyproline. Growth and mineralization of the bone shaft were slower in a chemically defined medium thanin vivo. Growth could be enhanced by supplementation of the medium with non-essential amino acids, albumin or serum. Cartilage ends showed a greater increase in weight and collagen content than the shafts, and medium supplements had less effect on their growth. Bone shaft growth and mineralization were enhanced by increasing medium phosphate concentration over a range of 1.5 to 4.5 mM whether or not the medium was supplemented with serum or albumin. At a low medium calcium concentration (0.5 mM) bone shaft growth and mineralization were impaired. At a low magnesium concentration (0.5 mM) mineralization was enhanced, but growth was impaired.
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  • 31
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    Calcified tissue international 14 (1974), S. 83-86 
    ISSN: 1432-0827
    Keywords: Bone ; Reproductive cycle ; Pigeons ; Amorphous ; Crystalline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une étude de diffraction aux rayons X, au cours du cycle de ponte d'oeufs de pigeon, a été entreprise pour évaluer les modifications de la proportion entre les phases de phosphate de calcium amorphe et apatitique. La partie médullaire du fémur de pigeon est totalement résorbée au cours du cycle de reproduction. Au cours de ce processus, l'os contenant plus de phosphate de calcium amorphe est résorbé avant celui qui est riche en cristaux. Ainsi l'os à contenu amorphe plus élevé est métaboliquement plus actif que l'os riche en cristaux. L'os médullaire qui peut être induit chez le pigeon mâle par traitement aux oestrogènes, ressemble, au point de vue diffraction aux rayons X, à l'os médullaire des femelles au début du cycle de reproduction.
    Abstract: Zusammenfassung Mittels Röntgen-Diffraktion wurden die Veränderungen in den prozentualen Mengen der amorphen und der kristallinen Calciumphosphat-Phasen im Femur der Taube während des Eierlegens untersucht. Der medulläre Teil des Taubenfemur wird während des Fortpflanzungscyclus vollständig resorbiert. Dabei wird der Teil des Knochens, der mehr amorphes Calciumphosphat enthält, vor dem kristallreichen Teil resorbiert. Daraus folgt, daß der Stoffwechsel des Knochens mit höherem amorphem Gehalt aktiver ist als derjenige des Knochens mit höherem kristallinem Gehalt. Weiter konnte mittels Röntgendiffraktion festgestellt werden, daß der medulläre Knochen, welcher in männlichen Tauben durch Oestrogenbehandlung erzeugt werden kann, dem weiblichen medullären Knochen am Anfang des Fortpflanzungscyclus gleicht.
    Notes: Abstract This is an X-ray diffraction study of the changes in the proportional amounts of the amorphous and apatitic calcium phosphate phases in pigeon femur during the egg-laying cycle. The medullary portion of pigeon femur is completely resorbed in the reproductive cycle. In this process the portion of bone which is higher in amorphous calcium phosphate is resorbed before the crystal-rich portion. Thus, bone with a higher amorphous content is more metabolically active than more crystalline bone. Finally, medullary bone which can be produced in male pigeons by estrogen treatment was found by X-ray diffraction to resemble female medullary bone at the beginning of the reproductive cycle.
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  • 32
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    Calcified tissue international 14 (1974), S. 49-58 
    ISSN: 1432-0827
    Keywords: Glycosaminoglycans ; Intracellular ; Chondrocytes ; Cartilage ; Embryonal ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les glycosaminoglycanes acides de chondrocytes isolés, en suspension, sont étudiés. La matrice extracellulaire est isolée par traitement successif à la trypsine et à la collagénase d'os d'embryons de poulet, âges de 15 à 17 jours. Après digestion à la papaïne et élimination des acides nucléïques par traitement à la DNAse et à la RNAse, les glycosaminoglycanes sont précipités par le CPC et isolés sous la forme de leur sel sodique. Les analyses des propriétés de solubilité du CP glycosaminoglycane par le microfractionnement d'Antonopoulos et coll. (1964) révèlent la présence de glycosaminoglycanes intracellulaires de poids moléculaire et/ou de densité de charge nettement plus faibles que ceux de la matrice extracellulaire. Sur des électrophorèses de microzones, une petite partie des glycosaminoglycanes intracellulaires isolées présente une mobilité similaire à celle des solutions témoins de sulfate de chondroitine, alors que la portion la plus importante ne se déplace qu'à mi-distance de l'acide hyaluronique et montre une large trainée, indiquant une faible charge négative. Ce fait semble dû à une perte de l'influence de régulation des composants matriciels éliminées, sur la synthèse des glycosaminoglycanes et au rejet dans le milieu de glycosaminoglycanes initialement synthétisé. Pour la première fois, une faible quantité d'acide hyaluronique intracellulaire est mise en évidence par une mobilité électrophorétique typique.
    Abstract: Zusammenfassung Saure Glykosaminoglycane von isolierten Chondrocyten in Suspension wurden untersucht, und die extracelluläre Matrix von 15–17 Tage alten Knochen von Kükenembryos wurde durch die aneinanderfolgende Behandlung mit Trypsin und Collagenase erhalten. Nach der Papain-Verdauung und Beseitigung der Nucleinsäuren mittels DNS- und RNSase-Behandlung wurden die Glykosaminoglycane mit CPC gefällt und als Natriumsalz isoliert. Untersuchungen der Löslichkeit der CP-Glykosaminoglycane mittels des Mikrofraktionierungsverfahrens von Antonopouloset al. (1964) zeigten intracelluläre Glykosaminoglycane mit meist niedrigerem Molekulargewicht und/oder niedrigerer Ladungsdichte als diejenigen der extracellulären Matrix. In der Mikro-Zonen-Elektrophorese zeigte nur ein kleiner Teil der isolierten intracellulären Glykosaminoglycane eine Mobilität, die dem Standard des Chondroitinsulfats entsprach. Der größte Teil legte nur die halbe Distanz der Hyaluronsäure zurück und zeigte breites “Tailing”, was auf eine niedrigere negative Ladung hindeutet. Die Ursache dafür wurde interpretiert als Verlust eines regulierenden Einflusses der entfernten Matrixkomponenten auf die Glykosaminoglycan-Synthese und als Abgabe ursprünglich synthetisierter Glykosaminoglycane in das Medium. Es wurde erstmals, anhand der typischen elektrophoretischen Beweglichkeit, eine kleine Menge von intracellulärer Hyaluronsäure nachgewiesen.
    Notes: Abstract Acid glycosaminoglycans were studied from isolated chondrocytes in suspension and the extracellular matrix obtained by sequential trypsin and collagenase treatment of 15- to 17-day-old embryonic chick bone. After papain digestion and removal of the nucleic acids by treatment with DNAse and RNAse, the glycosaminoglycans were precipitated by CPC and isolated as their sodium salt. Analyses of the CP-glycosaminoglycan solubility properties with the microfractionation procedure of Antonopouloset al. (1964) showed intracellular glycosaminoglycans of predominantly lower molecular weight and/or charge density than those of extracellular matrix. On micro-zone electrophoresis, only a minor part of the isolated intracellular glycosaminoglycans showed a mobility similar to that of the chondroitin sulphate standards while the major part moved only half the distance of hyaluronic acid and showed broad tailing, indicating a low negative charge. This was considered to be due to loss of a regulatory influence of the removed matrix components upon glycosaminoglycan synthesis and to release of originally synthesized glycosaminoglycans into the medium. For the first time, a small amount of intracellular hyaluronic acid was shown by typical electrophoretic mobility.
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  • 33
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    Calcified tissue international 15 (1974), S. 333-339 
    ISSN: 1432-0827
    Keywords: Vitamin D ; Bone ; Resorption ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A series of analogues of vitamin D have been tested for their ability to stimulate bone resorption in two test systems used previously to investigate the metabolites of vitamine D. These analogues were tested (a) by directly comparing their action on bone explants of mouse half-calvariain vitro, and (b) by injecting them into young mice and measuring the degree of resorptionin vitro when explants were prepared 18 hours after the injection. It is concluded that the key functional groups concerned with enhancing the activity of vitamin D3 are the 1α- and the 25-hydroxyl,both together; the cis ring structure for ring A appears necessary. 1α-Hydroxycholecalciferol (1α-OHD3) is about as active as 25-OHD3 in the direct test, but its potency is much nearer to that of 1,25-(OH)2D3 when tested by the second (indirect) method; it seems likely that 1α-OHD3 is converted into 1,25-(OH)2D3 in vivo. The results are discussed in relation to the designing of analogues for clinical and experimental use.
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  • 34
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    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Keywords: EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone and serum chemistry were investigated in adult rabbits. EHDP was administered by subcutaneous injection at doses of 0.25, 2.5 and 10 mg/kg body weight/day for of 28 days. Blood samples were obtained weekly from each rabbit and serum levels of total calcium, ionized calcium, inorganic phosphate and alkaline phosphatase were determined. At the end of the treatment period all rabbits were sacrificed and the tibiae removed for chemical analysis and histological evaluation. The effect of EHDP administration on serum chemistry was both dose- and time-related. The highest of the three doses, 10 mg/kg/day, resulted in a time-related decrease in total serum calcium. This dose also caused a rapid but transient reduction in serum ionized calcium. The effect of EHDP on serum inorganic phosphate was biphasic. Administration of 2.5 mg/kg/day resulted in a time-related elevation in this parameter, whereas the 10 mg/kg/day dose resulted in a time-related hypophosphatemic response. There were no significant drug-related changes in tibial fat-free dry weight, ash weight, total calcium or total phosphorus values. However, administration of 2.5 and 10 mg/kg/day EHDP resulted in increased osteoid tissue as measured histologically. These results are compared with data from other EHDP studies, and discussed in relation to the maturity and growth-state of the experimental animals.
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  • 35
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    Calcified tissue international 16 (1974), S. 305-313 
    ISSN: 1432-0827
    Keywords: Osteosarcoma ; Lyophilization ; Induction ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Bone formation was induced by iso- and home-implantation of lyophilized mouse osteosarcoma, in which an osteogenic activity is observed. The inducing factor is present exclusively in osteosarcoma, such as BF and Gardner, while not in non-osteogenic tumors, such as Ehrlich ascites tumor (2N & 4N) or mouse mammary carcinoma. The production of bone was rapid and extensive. It usually occurred within 21 days, and the time required for osteogenesis was almost the same as that reported in previous studies.
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  • 36
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    Anatomy and embryology 143 (1974), S. 159-183 
    ISSN: 1432-0568
    Keywords: Bone ; Femur ; Development ; Gravity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The significance of similitude principles for the postnatal development of the cross-sectional area at midlength of the human and rat femur has been subjected to an investigation based both on theory and on observation. Cross sections were taken from 69 femora of female Sprague-Dawley rats 34, 72, 102, and 840 days old and from the right human femora of 94 males and 58 females ranging from 1 day to 89 years of age. The regression of the square-root of the cross-sectional area divided by π on femur length is linear in the rats. The empirical regression line estimated by the method of least squares from the measurements and the theoretical curve calculated on the assumption of adaptive allometric growth and centrically applied loads are more or less alike in slope and elevation. The corresponding empirical relationship in the human femora turned out statistically nonlinear in the males and linear in the females. Comparing the empirical regression functions with five theoretical curves, it has been revealed that the observations are best approximated by two curves calculated on the assumption of centrically or eccentrically applied loads and adaptive allometric growth of the cross-sectional diameter. It was further uncovered that the cross-sectional diameters at midlength of the femur are not changed isometrically with femur length both in rats and in man. Considering a simple model of the human body in the stance phase of slow walking gait on the scale of a neonate and an adult male, the hypothesis was advanced that the stresses at midlength of the femur are not altered much while the femur grows from neonate to adult size, because the outer and inner radii of the femur actually change during growth in such a way that the effects due to scale are appropriately compensated.
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  • 37
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    Polymer Engineering and Science 14 (1974), S. 72-75 
    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 series of rigid polyurethane foams of densities varying from 65 kg/m-3 to 400 kg/m-3 have been tested in compression as a function of rate and temperature. Two yield points are observed, the lower one being associated with the surface layers, the higher with the bulk of the material. The yield points may be predicted to a first approximation for the higher density foam using a model based on the buckling of a thinwalled cylinder.
    Additional Material: 7 Ill.
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  • 38
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    Polymer Engineering and Science 14 (1974), S. 362-365 
    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 effect of changes in crystallinity on the β-transition in poly(vinyl chloride) was studied by dynamic mechanical measurements of loss tangent (tan δ) and storage modulus (E′) over the temperature range -160° to 85°C. Four frequencies were covered, 3.5, 11, 35, and 110 Hz. The data presented demonstrate that crystallinity has a significant influence on the relaxation processes involved in the β-transition. The restrictions on segmental mobility imposed by crystallinity are most pronounced in the region between Tβ and Tg, with Tβ tending to shift to lower temperatures, Tg shifting to slightly higher temperatures, the magnitude of tan δ decreasing, and engineering tensile strength increasing. Our data also show that individual PVC resins have mechanical and physical properties which differ enough so that comparisons which are often made between them may be inconclusive. Moreover, the properties of one resin may be more sensitive to thermal treatment than those of another. We are continuing this study to establish correlations between the observed trends and other important mechanical properties such as impact strength, toughness, tensile, and compressive strength.
    Additional Material: 4 Ill.
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  • 39
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    Polymer Engineering and Science 14 (1974), S. 155-158 
    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 equations of stress-strain of gel-filled polymer under large deformation were derived by using a simple model i.e. a sphere in a cubic matrix. The author finds for no adhesion between the phases: In case of perfect adhesion between the phases: where σ(α) is the stress of a blend at an elongation ratio of α, σR(α) the stress of a rubber matrix at α, σG(αG) the stress of a gel component at αG, σR (αR) the stress of a rubber matrix at αR, φ the volume fraction of gel. The validity of Eq 1 was shown for the polychloroprene vulcanizates containing polystyrene-gel which exhibits no adhesion with the polychloroprene matrix. This result shows the value of the model proposed here. The tensile strength of polychloroprene vulcanizates filled with polychloroprene-gel at break is discussed by the use of Eqs 2-4.
    Additional Material: 4 Ill.
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  • 40
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    Polymer Engineering and Science 14 (1974), S. 177-188 
    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: Two overriding characteristics for major applications of plastics in consumer products are: - the need for high volume production and - their exposure to hostile environments.Successful application and continued growth for plastics in these products requires knowledgeable prediction of performance in the process to produce the plastic part and in the environments to which it will be exposed during the product's lifetime. Progress on establishing relationships between material properties and structure are described with emphasis on response to melt process conditions and behavior when exposed to hostile environments.Commercial plastics and the processes by which they are converted into useful applications are complex systems. A multitude of interacting variables must be dealt with in order to achieve successful implementation in commercial products. Specific examples are discussed in the area of processing for non-Newtonian flow characteristics and overt effects in injection molding and extrusion, tailoring of polymers within established rheological limits and the influence of melt processing on physical and mechanical properties. The influence of application environments is discussed and specific examples are given for environmental stress cracking, stress-environment embrittlement and the effects of hot water solutions on polymer systems.
    Additional Material: 27 Ill.
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  • 41
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    Polymer Engineering and Science 14 (1974), S. 212-222 
    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: Flow patterns have been observed during the injection molding of rheologically characterized low-density polyethylene and polystyrene melts under various molding conditions. Some studies of high-density polyethylene were also carried out. Various mold designs were included in the study and the flow patterns investigated under both isothermal and cold cavity wall conditions. In addition to investigating injection molding of single polymer melts, flow patterns in the sandwich molding of polyethylene and polystyrene were studied.
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  • 42
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    Polymer Engineering and Science 14 (1974), S. 50-57 
    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 chemo-rheological behavior has been elucidated for three high temperature epoxy resins. Constant temperature and shear stress measurements were made on a modified Weissenberg Rheogoniometer. Curing behavior of various temperatures is unified by a time-temperature superposition method. The curing rate of one resin, Ferro E-293, is limited by the chemical reaction. The other resins, 3M PR-286 and PR-288, each have consecutively occurring reactions, both of which are diffusion limited. The chemo-rheological information obtained for these materials is used to model viscosity for compression molding of hand-laidup composites.
    Additional Material: 15 Ill.
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  • 43
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974) 
    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
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  • 44
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    Polymer Engineering and Science 14 (1974), S. 98-100 
    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 melt flow of a plastic as measured by the standard method (ASTM D-1238) is at a high enough stress so that the flow is non-Newtonian. If the die in the plastometer is replaced by a nonstandard, tapered die of large orifice, a lower stress can be used and the flows are shown to be comparable to Newtonian viscosities measured in a cone and plate rheometer. Under these conditions the plastometer can be used as a sensitive measure of the melt stability of a plastic.
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  • 45
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    Polymer Engineering and Science 14 (1974), S. 120-123 
    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 porosity of poly (vinyl chloride) (PVC) resin particles produced in bulk polymerization is sensitive to polymerization conditions. Using scanning electron microscopy, 60μ spherical beads of PVC are shown to be composed of loosely packed 1μ spherical subparticles. This complex morphology is characterized by a variability in surface area. The surface area of bulk PVC materials can be measured by a chromatographic technique. The elution time of n-octane as a probe molecule on PVC packed columns is simply related to PVC surface area. At approximately constant particle size (measured by Coulter counter and optical microscopy), surface areas measured by argon adsorption are correlated to chromatographic elution times. The bulk density, plastisol viscosity and pore volume (from mercury penetration porosimetry) are determined and related to specific surface area.
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  • 46
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    Polymer Engineering and Science 14 (1974), S. 249-259 
    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 effect of cold rolling on the Izod impact strength of amorphous polycarbonates has been studied. The impact strength is a function of the roll reduction as well as the original sheet thickness. Sheets varying from 0.125 to 0.645 inches in thickness have been studied and roll reductions up to 50 percent have been utilized. It is shown that enhancement in impact strength occurs at very small percent roll reductions. The orientation release stress has been measured as a function of roll reduction and the internal stresses through the thickness of the sheets have been studied by birefringence methods. It is suggested that the residual stresses are responsible for impact enhancement rather than the molecular orientation.
    Additional Material: 22 Ill.
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  • 47
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    Polymer Engineering and Science 14 (1974), S. 702-705 
    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: Plasticized poly(methyl methacrylate) and methyl methacrylate/acrylate copolymer films were examined by isothermal creep at low loads measured at several temperatures from ∼Tg to Tg + 15°C. Viscosity calculated using η = σ/3\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document} was plotted vs temperature giving precise values for Tg based on a viscosity criterion of η = 1013 poises. Creep fracture data at various temperatures below Tg were interpreted using the maximum apparent viscosity measured at the minima of strain rate vs strain curves. Plots of ηmax VS stress at several temperatures gave values of ΔTg/Δσ of -1° to 2°C/106 N/m2 in agreement with treatment of ΔTg/Δσ based on free volume. Fracture occurred at low elongations when ηmax was ≥1013 poises, and at higher elongations when ηmax was 〈1013 poises supporting the concept that fracture is related to the lowering of Tg under stress. Plots of log σ VS log εb (the elongation at fracture) had the same form as that for crosslinked elastomers above Tg reported by T. L. Smith. Plots of log \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document}b VS log εb also had the same form supporting proposals on the rate sensitivity of fracture.
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  • 48
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    Polymer Engineering and Science 14 (1974), S. 538-541 
    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 the manufacture of electronic devices for integrated circuits, reducing the number of resist steps is desirable for a variety of reasons. We describe some experiments on a process aimed at reducing the number of resist and registration steps in electron beam lithography. The process involves locally varying the electron dose in an electron sensitive resist (in this case poly[methyl methacrylate]) so that the different levels of exposure can be distinguished by subsequent developing. Reliable results have been achieved with three levels: (i)Strongly exposed (resist removed after short immersion in developer).(ii)Partially exposed or “metastable” (resist removed only after prolonged immersion in developer).(iii)Unexposed.In strongly exposed regions, operations such as etching may take place while using the metastable and unexposed regions to protect the workpiece. Subsequently, the metastable region may be developed for further processing.
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  • 49
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    Polymer Engineering and Science 14 (1974), S. 567-572 
    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: Aspects of the present status of structure-property correlations for linear polycarboranesiloxanes which contain rigid carborane cages and flexible siloxane in-chain linkages are discussed. Low temperature secondary transitions, glass transitions, crystallization and melting transitions, and high temperature chemical transformations in inert and air atmospheres are emphasized. The linear polymers serve as the basis for new high-temperature elastomers.
    Additional Material: 8 Ill.
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  • 50
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 810-816 
    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: Processors have encountered processing problems in dealing with thermoforming co-extruded sheet where one layer is semitransparent to incident radiant energy of the heater banks and the other is opaque. An analysis of the radiant heating process shows that significant volumetric absorption of radiant energy takes place within the semitransparent sheet. From the model, it is shown that to minimize temperature excursions within laminated sheets (and thus reduce the tendency for delamination and blistering), heater banks should be programmed to cycle in an on-off mode with a rather short cycle period.
    Additional Material: 7 Ill.
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  • 51
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 831-839 
    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 an isopropanol environment on the deformation characteristics of copoly (acrylonitrile-butadiene-styrene) (ABS) and poly (vinyl chloride) (PVC) have been investigated. Creep tests were performed in tension and torsion both in air and in isopropanol. It was noted that accelerated rates of creep were encountered during the tensile tests in isopropanol as compared with air but no differences were noted during the torsion tests. An explanation is proposed that the greatly increased creep strains encountered in tension result from diffusion of the fluid into the polymer. The rate of diffusion is controlled by changes in the free volume which occur on application of uniaxial tensile stresses. The existence of the fluid molecules in the polymer matrix reduce its local creep resistance and produce swelling, both of which are manifested as increased creep strains. The fact that no effects were noted during torsion tests (where the free volume remains constant) or when an unstressed specimen was immersed in the fluid indicates that no significant absorption occurs at the equilibrium (unstressed) free volume.
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  • 52
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    Polymer Engineering and Science 14 (1974), S. 859-867 
    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 simple method for predicting the primary normal stress function, θ, from viscosity data is proposed. A relation between θ and the viscosity function, θ, based on the Goddard-Miller rheological equation of state, is given. An easy-to-use generalized chart for estimating θ from θ is presented; in order to use this chart, viscosity data must be available from the zero-shear-rate value of the “power law region.” The method was applied to six polymer melts, three polymer solutions, and an aluminum soap solution for which θ had been measured experimentally. Even though θ varied by a factor of 103 over the examined range of shear rate, the theory and experiment seldom differed by more than a factor of 2. The generalized chart for θ was combined with Tanner's theory to prepare a graph which may be used to estimate jet swell from viscosity data. Comparison with experimental data of jet swell for 4 polymer melts shows good agreement.
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  • 53
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 730-733 
    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: Polymer solutions and melts can both dissipate mechanical energy in flow, as well as accumulate elastic energy. If the assumption is made that elastic energy can be accumulated only through a decrease of conformational entropy, the general thermodynamic theory for non-linear viscoelastic materials simplifies considerably. In particular, though no generality is lost as far as the constitutive equation for stress is concerned, the energy equation, which allows in principle a calculation of temperature distributions arising from frictional heating and heat removal, reduces to the usual form which is valid for viscous materials.
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  • 54
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    Polymer Engineering and Science 14 (1974), S. 717-723 
    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: During an investigation of the time for ignition of polymeric materials under the influence of radiant heating, it was found that the polymer surface reflectance-absorptance characteristics were a major factor in the variance of the ignition times. A subsequent research study was made of the reflectance-absorptance characteristics of those polymers used in the ignition testing. Reflectance values were obtained over the wavelength of 0.3 to 2.5 microns using a double-beam Cary model 14 spectrophotometer with an integrating sphere reflectometer and over the wavelengths of 1.0 to 10.0 microns using a Gier-Dunkle Hohlraum with a Perkin-Elmer spectrophotometer. Absorptance values were obtained by means of Kirchoff's Law,Drawings and graphs are included which illustrate the test apparatus and type of data collected. A table of average absorptances of several polymers are given and listed according to the particular type of heat source used. \documentclass{article}\pagestyle{empty}\begin{document}$$ \alpha _\lambda + r_\lambda = 1 $$\end{document} Average absorptances of the polymers over the monochromatic wavelength span of the heat sources were calculated using the equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \alpha _{{\rm av}} = \frac{{\int_{\lambda _1 }^{\lambda _2 } {\alpha _\lambda e_\lambda d\lambda } }}{{\int_{\lambda _1 }^{\lambda _2 } {e_\lambda {\rm d}\lambda}}} $$\end{document} Mathematical analyses were developed and are presented for both the integrating sphere reflectometer and Gier-Dunkle Hohlraum unit.Drawings and graphs are included which illustrate the test apparatus and type of data collected. A table of average absorptances of several polymers are given and listed according to the particular type of heat source used.
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  • 55
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    Polymer Engineering and Science 14 (1974), S. 764-767 
    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: Polymer properties were measured as a function of temperature at 5 and 10°C per minute heating rates and as a function of time at constant temperature, using the Du Pont 940 thermal-mechanical analyzer. Data are reported on deflection temperature under load, vicat softening temperature, and creep properties. These results have been correlated with ASTM values. These tests require short times and are applicable to thermoplastics, thermosets, and elastomers.
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  • 56
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    Polymer Engineering and Science 14 (1974), S. 778-781 
    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: Electron microscopy studies indicate that the microfibrils are a well defined element of many uniaxially oriented polymers. On the basis of these results it was inferred that the mechanical responses of uniaxially oriented polymers are similar to those of a parallel ensemble of the microfibrils. An important consequence of this microfibrillar model is that the type of load transfer is independent of crystallite aspect (length/diameter) ratio. The analysis of anisotropy in modulus of uniaxially oriented nylon 6, however, indicates that the load transfer characteristics of these polymers are dependent on crystallite dimension. A series response is observed only with fibers or films of low and intermediate draw ratio. Highly oriented structures, however, exhibit a nearly isotropic response in load transfer. These results show that uniaxial polymers must be analyzed in terms of a model where the crystallites are embedded in an “amorphous” matrix. The equations are derived for modulus, strength, and coefficient of diffusion in terms of crystallite dimensions, and the results compared with the experimental data.
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  • 57
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974) 
    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
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  • 58
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    Polymer Engineering and Science 14 (1974), S. 827-830 
    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 phase diagram for several polybutene-1 and polystyrene resins in carbon tetrachloride have been determined. These show: Almost the entire phase diagram is a two-phase region.The composition of each phase is mainly of one polymer type.Increasing the molecular weight of either polymer diminishes compatibility.To our knowledge, this is the first example of phase separation in common solvent polymer solutions that involves a poly α-olefin. Viscosity and surface tension data on the equilibrium phases indicate the phases have the same surface tensions but far different viscosities. The upper phase is mainly polybutene-1 and is much more viscous than the lower phase which is mainly polystyrene. Slight agitation of the phases gives an “emulsion” that may be cast into a polymer film. The film has a continuous phase of Form III polybutene-1 and a dispersed phase of polystyrene. The polystyrene may be extracted from the film by immersion in methyl ethyl ketone to give a porous polybutene-1 film.
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  • 59
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    Polymer Engineering and Science 14 (1974), S. 853-858 
    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: Computer simulation technology is used to define the problems in scale-up of extruders from 2.5 to 3.5, 4.5, 6.0, and 8.0 inches in diameter. It is shown that the conventional practice of scaling-up channel depths by the square root of the diameter ratio does not take full advantage of the potential output capacity of larger extruders and a faster rate of channel depth increase is proposed. It is also shown that inherent limitations resulting from decreasing barrel surface area and increasing flight clearance with increasing screw diameter will always result in a higher discharge temperature from the larger machine at any practical output rate. Frictional heat generation and heat removal requirements increase with increasing diameter, regardless of the scale-up system used, and these limit the output capability of the larger sizes at low discharge temperatures.
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  • 60
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    Polymer Engineering and Science 14 (1974), S. 868-872 
    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 Contraves balance rheometer has been used in a study of the gelation and fusion process of three DOP-based PVC-plastisols and the results compared with those obtained with the Brabender plastograph. The tensile properties of samples fused at different temperatures have also been determined. The rheometer results relate to the temperature dependence of the viscosity, shear modulus, and loss angle of the plastisols used. The viscosity- and modulus-temperature curves are to some extent reminiscent of the torque-temperature curves obtained with the plastograph; the fusion temperatures are slightly different. The loss-angle-temperature curves measured with the rheometer exhibit sharp maxima in the vicinity of the Tg-point of the base polymer. The shear modulus decreases with time when the temperature is kept constant (above the fusion point). This effect is possibly associated with crystallite melting. The temperature necessary to reach the maximum strength plateau of films fused at various temperatures was found to agree (within 10°C) with the maximum in the modulus-temperature curves (minimum in loss-angle-temperature curves) when the rheometer shear rate was sufficiently low. On the whole, the rheometer allows for better temperature control. Also, the fact that the results are given in terms of viscosity and shear modulus may have some advantage in interpreting gelation and fusion data.
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  • 61
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    Polymer Engineering and Science 14 (1974), S. 92-97 
    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 electret potentials developed by reverse osmosis electret membranes help control the undesirable deposition of charged colloidal particles on the membrane surfaces during membrane desalination. These antifouling electret membranes should help prevent the costly flux declines normally associated with deposition of colloidal iron oxides on the reverse osmosis membrane surfaces.Homocharge and heterocharge behavior of cellulose acetate membrane electrets have been studied. Asymmetric reverse osmosis membranes and dense membrane films were studied. The homocharge and heterocharge of cellulose acetate reverse osmosis electret membranes have been explained.
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  • 62
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    Polymer Engineering and Science 14 (1974), S. 167-176 
    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: Glassy, amorphous thermoplastics experience a nearly universal susceptibility to crack and craze formation in the combined presence of stress and a chemical environment. This susceptibility has been evaluated for styrene-acrylonitrile copolymers according to the factors which effect craze initiation and those which limit the rates of flaw propagation. Molecular weight, styrene-acrylonitrile ratio, rubber content, and rubber phase morphology are variables which were found to affect flaw initiation and propagation. Fundamental characterization of the chemical parameters which control the initiation of craze formation in polysulfone and polycarbonate is also presented. In particular, “3-dimensional” solubility parameters have been observed to be a reasonable means of characterizing susceptibility to environmental stress cracking.
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  • 63
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    Polymer Engineering and Science 14 (1974), S. 206-211 
    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 mechanism of weathering degradation of polyolefins is discussed. Variations in spectral radiation, temperature, density, polymer absorption spectra, orientation, and sample thickness are related to property deterioration. Organic ultraviolet stabilizers, zinc oxide stabilization, and UV catalyzed degradation are briefly reviewed.
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  • 64
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    Polymer Engineering and Science 14 (1974) 
    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
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  • 65
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    Polymer Engineering and Science 14 (1974), S. 260-263 
    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: Amorphous polycarbonate sheets up to 1/4 inch in thickness have been crystallized both thermally and by acetone vapor sorption. For thick sheets acetone vapor sorption is the superior technique and a method has been developed for assuring homogeneous crystallized sheets. The crystallized polycarbonate can be cold rolled providing there is a residual acetone content to act as a plasticizer for the sheet. The tensile stress strain characteristics of the as-crystallized sheets as well as the rolled crystallized sheets have been determined as a function of the residual acetone content. It is shown that a crystallized polycarbonate whose thickness is reduced by 74 percent can achieve a true stress at fracture of 27,180 psi and a strain of 33 percent. These values are significantly greater than the values obtained for rolled amorphous polycarbonates.
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  • 66
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    Polymer Engineering and Science 14 (1974), S. 273-275 
    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: Two series of glass-reinforced diallyl phthalate molding compounds from two different manufacturers were evaluated using a Rheometrics, Inc. Mechanical Spectrometer and a Brabender Torque Rheometer. Comparison of reactivity and minimum viscosity as measured by these two instruments is presented. The Mechanical Spectrometer appears capable of differentiating smaller changes in melt viscosity than does the Brabender Torque Rheometer.
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  • 67
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    Polymer Engineering and Science 14 (1974), S. 288-291 
    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: Results are presented of friction and thermal tests of molded polyimide and pyrrone polymers. The coefficient of sliding friction up to surface velocities of 2 m/sec (394 ft/min) and the coefficient of thermal expansion from 300 to 500°K (80 to 440°F) were measured. An apparatus was constructed to measure simultaneously the coefficient of sliding friction and the friction-generated temperature. Measurements were made at a nominal pressure-velocity product of 0.25 MN/msec (7100 lb/in.2 × ft/min) and at temperatures between 300 and 500°K (80 and 440°F).
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  • 68
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    Polymer Engineering and Science 14 (1974), S. 338-341 
    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: 7 Ill.
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  • 69
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    Polymer Engineering and Science 14 (1974), S. 81-91 
    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 biochemistry and stereochemistry of proteins are reviewed and related to molecular structure and specifically to the properties governing fiber formation. The conformation of amino acids, polypeptides and proteins are discussed. The amino acid composition of protein is considered in relation to structure, chain length and molecular weight. General descriptions are also given for typical synthetic polypeptides as well as for non-fibrous natural proteins used in fiber manufacture. Mechanisms and modes are presented for fiber formation including a discussion of molecular criteria involving intermolecular cohesive and crystalline configurational forces which are involved in the fiber forming process. These effects are related to treatments and processes, including thermal, mechanical and chemical modifications, which can be applied to protein for the purpose of forming fibers.
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  • 70
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    Polymer Engineering and Science 14 (1974), S. 112-119 
    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 theoretical model for the simulation of dynamic operation of a plasticating extruder is proposed. The model can be recommended as a tool to study various dynamic situations of interest in the operation of an extruder. Several responses to changes in operating conditions are discussed. They indicate the occurrence of transient maximas and occasional oscillations. The controlling of flow rate by adjusting a valve at the die seems to cause temporary local high peaks in pressure, whereas its control through screw speed seems to be satisfactory.
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  • 71
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    Polymer Engineering and Science 14 (1974), S. 143-146 
    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: Low profile polyesters and sheet molding compounds, SMC, are two of many resin-glass composites that have been commercialized in the past few years. They have evolved through application of earlier technologies and have opened up possibilities for fiber-reinforced plastics. Because of rapid growth, insufficient time has been spent documenting the technical aspects of making SMC. Techniques are thus described that we have used to characterize the rheological properties of the resin mix during its transition from liquid-like (viscous) behavior of the initial formulation through the solid-like (elastic) behavior of the resultant SMC.
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  • 72
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    Polymer Engineering and Science 14 (1974), S. 16-21 
    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 concentration dependence of the rheological response of aqueous Separan solutions was measured. The shear and primary normal stress response in steady shearing flow, and the relaxation of shear stress following cessation of steady shear flow, were measured with four different polymer solution concentrations. Two different nonlinear constitutive equations, Bird-Carreau and Meister, were used to analyse the data. The Bird-Carreau model fit the steady shear data very well and the parameters obtained from steady shear data allow reasonable estimates of the stress relaxation of these systems. The Meister model provided a fit of the transient stress relaxation data and could be used to estimate the steady shear response. No quantitative molecular theory was developed in this work. However, the nature of the concentration dependence of the Bird-Carreau parameters suggests that as the polymer concentration of aqueous Separan solutions decreases from 2.0 to 0.05 weight percent the solutions should be modeled less by an entangled network theory and more as slightly overlapping hydrodynamic units. The concentration where this behavior seems to be changing appears to be about 0.25 percent by weight of polymer.
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  • 73
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    Polymer Engineering and Science 14 (1974) 
    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
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  • 74
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    Polymer Engineering and Science 14 (1974), S. 298-307 
    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 procedures developed in this paper enable the die designer to estimate the dimensions of the die at the exit and to define a flow channel within the body of the die appropriate to the required dimensions and output rate of the extruded product. Design procedures are given for predicting die swell (and hence die exit dimensions) from a knowledge of product dimensions, output rate and the basic shear, elasticity, and viscosity data. Within the body of the die the length and included angle of a convergent tapered section should be such that the critical tensile deformation rate is not exceeded. At the die entry the taper angle is related to the tensile and shear viscosities. Analytical expressions based on flow data are given for predicting pressure drops resulting from flow through circular and slot dies of constant cross-section and through conical and wedge-shaped dies. A numerical example shows how the theory may be applied to the design of a die for a thin-walled tube. For the resultant die design, the likely effects are predicted to changes in output rate and melt temperature for the chosen material, of changes in grade of the same type of polymer, and of changes in polymer type.
    Additional Material: 8 Ill.
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  • 75
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 322-331 
    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: It was theorized that the heat stability of PVC may be improved by exchanging the “weak” (allylic and tertiary) chlorines by groups of higher bond strength, e.g., phenyl. Thus PVC was phenylated by φ3Al in carbon disulfide slurry for various times (1 to 5 hrs) and temperatures (from -30 to +45°C). The φ3Al concentration, temperature and time of φ3Al treatment greatly affect the ultimate heat stability of PVC. Significant improvement in the heat stability was obtained by treating PVC in carbon disulfide at 25°C for 1 hr. The mechanism of phenylation was studied by model experiments in which the possible structural irregularities in PVC were simulated by small molecule chlorine compounds, i.e., 3-chloro-1-butene, 1,3-dichloro-1-butene, 4-choro-2-pentene were models for terminal and inchain allylic chlorines, t-butyl chloride was the model for tertiary chlorine at branch site, and isopropyl chloride simulated regular secondary chlorines. The reactions between φ3Al and these chlorides were carried out at 35°C for various times and the NMR spectra were analyzed. The φ3Al + tBuCl reaction in carbon disulfide gives t-butylbenzene (Wurtz coupling) and isobutylene oligomers. Evidently φ3Al (or the φ2AlCl formed) dehydrochlorinates tBuCl to isobutylene which rapidly oligomerizes in the presence of Lewis acids. In aromatic diluents, i.e., benzene, chlorobenzene, and o-chlorotoluene, Friedel-Crafts t-butylation of the diluent occurs; in mesitylene t-butylation is absent presumably because of steric hindrance and small amounts of t-butylbenzene are formed by Wurtz coupling. All the allyl chlorides examined are rapidly phenylated by φ3Al in carbon disulfide at 35°C and yield the expected products: 3-chloro-1-butene → 1-phenyl-2-butene; 1,3-dichloro-1-butene → 1-chloro-3-phenyl-1-butene; 4-chloro-2-pentene → 4-phenyl-2-pentene. The kinetics of phenylation by φ3Al of model compounds have been studied and the following rate constants were obtained: kallyl = too fast to measure, ktBuCl = 1.0, and kiPrCl = 9 × 10-4 l/mole min. Evidently the rate of the φ3Al + RCl reaction is mainly determined by the stability of the R⊕ intermediate: substituted allylic⊕ ≫ tertiary⊕ ≫ secondary⊕.
    Additional Material: 13 Ill.
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  • 76
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 352-356 
    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 effect of insoluble gel material, crystalline aggregates, and suspension particle membranes on the physical and mechanical properties of solution cast films of suspension PVC has been studied. The chemical structure and morphology of the insoluble gel material was also studied. The suspension particle membranes are found to contain significant amounts of hydroxyl and carbonyl groups but are still predominately PVC. These particles affect the transparency of cast films as well as the surface topography by forming discrete clusters upon drying which are uniformly distributed throughout the films. Finally, insoluble gel material is found to have no significant effect on the low and high speed mechanical properties of the films.
    Additional Material: 5 Ill.
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  • 77
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 371-381 
    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: Recent morphological studies of plasticized and unplasticified poly(vinyl chloride) (PVC) are reviewed. Suspension polymerized PVC contains particles in a number of different size ranges 100-200Å, 1000-5000Å, 1μ and larger. The larger size particles are broken down during plasticization but both the 100Å and the 1000Å suspension particles retain their identity. The visibility, and presumably, coalescence of these particles is a function of the processing conditions. In particular, the size of the 100Å particle increases with plasticizer content and is most distinct as characterized both by small angle x-ray scattering and electron microscopy for milling temperatures in the 160-170°C. range. Consideration is given to the effect of these particles, their structure, and interrelationship on the rheological properties of the resins.
    Additional Material: 17 Ill.
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  • 78
    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: Plasticized poly(vinyl chloride) formulations were prepared in solid and foam form, and mechanical hysteresis was measured by low-speed tension and compression on an Instron tester and by high-speed rebound on a resiliometer. Hysteresis was greatest in copolymers with vinyl acetate, at low plasticizer concentration, with inefficient plasticizers, at high concentrations of reinforcing fillers, at high expansion to low density, and at high speed of testing. Conversely, resilience was greatest at high plasticizer concentration, with more efficient plasticizers, with non-reinforcing fillers, and at high density.
    Additional Material: 1 Ill.
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  • 79
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    Polymer Engineering and Science 14 (1974), S. 401-412 
    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 concentric cyclinder dilatometer was designed and built to study the influence of shear on the crystallization kinetics of polymers. This instrument allows crystallization to be followed at both constant temperature and shear rate. Several samples of polyethylene oxide (Carbowax 4000, Carbowax 20-M, and WSR-205) were used. A low molecular weight fraction of the Carbowax 20-M, as well as the unfractionated material, was crystallized under shear. The WSR-205 was studied only in a mixture with Carbowax 4000. It was shown that the kinetics of crystallization of uncrosslinked melts of polyethylene oxide are altered by shear. The induction times for the appearance of crystallinity are shorter in the sheared systems than in the quiescent melts. The Avrami exponents are also higher for crystallization in sheared melts than in quiescent systems and increase with decreasing supercooling. The high values of the Avrami exponent are attributed to the disruption of crystalline aggregates into particles larger than the critical sized nucleus. These particles will persist in the melt and continue to grow spontaneously. A continuous infusion of growing particles into the melt occurs.At constant temperature and shear rate, the induction time of the crystallization curve is influenced by polymer molecular weight. In moderate to high molecular weight samples, the effect of shear becomes saturated at very low shear rates. Decreasing the molecular weight separates the crystallization curves. The curves from the higher shear rates appear at the shorter induction times. However, decreasing the molecular weight below that at the critical entanglement molecular weight allows the nucleation rate, strongly dependent upon the supercooling, to influence the relative positions of the sheared crystallization curves.
    Additional Material: 12 Ill.
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  • 80
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 478-480 
    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: Chemical batch-to-batch variations of an acrylonitrile-modified epoxy potting compound were monitored by infrared spectroscopy and correlated to capacitance and hardness measurements of the cured product before and after exposure to high humidity. The reversion resistance of the cured material was dependent upon the amount of a carbonyl functionality in the uncured potting compound. This relationship is an approach to assess the reversion resistance of these types of potting compounds.
    Additional Material: 4 Ill.
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  • 81
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 706-716 
    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 study of materials which are positive-temperature-coefficient resistors. Such materials, composed of conductive particles dispersed in a crystalline polymeric matrix, have been found to be of limited stability. An example is carbon black in high-density polyethylene. On repeated cycling through the anomaly temperature or on extensive heating at or above the anomaly temperature, the room temperature resistivity rises and the anomaly height falls to zero. This phenomenon has been shown to be caused by the absorption of oxygen by the polymer matrix which alters the structure, reduces the crystallinity, and induces an unusual form of crosslinking of a reversible nature.
    Additional Material: 15 Ill.
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  • 82
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    Polymer Engineering and Science 14 (1974), S. 760-763 
    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 flux models can be used to accurately predict the transmission or absorption of radiant energy through an absorbing scattering plastic. The apparent absorbing and scattering coefficients are dependent upon the physical characteristics of the body and the incident radiation as well as the actual absorption and scattering coefficients of the material. The apparent interfacial reflectivity can be estimated from the degree of scattering within the material.
    Additional Material: 6 Ill.
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  • 83
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    Polymer Engineering and Science 14 (1974), S. 773-777 
    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 rheological investigation of the saturated fatty acids as lubricants for PVC was made in a Sieglaff-McKelvey rheometer over a wide temperature range. Results reveal that with an increase in carbon chain, fatty acids became more effective in reducing the melt viscosity of PVC. It was also discovered that the maximum viscosity variation due to these materials was observed at 350°F. At test temperatures of 400°F and above, no major viscosity differences were observed. Furthermore, the changes in the melt viscosity were more pronounced at shear rates less than 200 sec-1. The usefulness of the measured viscosity variations at the critical test temperature of 350°F was shown by extrusion. An excellent correlation between the apparent melt viscosity and extrusion melt temperature was found. The criticalness of the test temperature in assessing the effect of lubricants on PVC flow is discussed.
    Additional Material: 4 Ill.
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  • 84
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    Polymer Engineering and Science 14 (1974), S. 791-796 
    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 theory is presented which describes the dynamics of blade-coating of a viscoelstic fluid onto a moving sheet. The method begins with the usual “lubrication” approximation, and develops the solution as a perturbation about the Newtonian case. Viscoelasticity is described by an empirical constitutive equation which shows non-Newtonian viscosity and finite normal stress behavior consistent with typical observations of polymeric fluids. Theoretical results indicate a small increase in coating thickness due to departure from Newtonian behavior, and a significant decrease in the magnitude of the pressure developed under the blade. Consequently, the blade loading can be reduced significantly by viscoelastic effects. The results for the loading may be an artifact of the specific constitutive model, since it can be shown that some viscoelastic fluids, specifically an “elastic Newtonian” fluid, would exhibit increased loading relative to the inelastic Newtonian case.
    Additional Material: 4 Ill.
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  • 85
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    Polymer Engineering and Science 14 (1974), S. 806-809 
    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 and processing behavior of commercial plastics is determined not only by the characteristics of the base resin but also by the presence of additives of various kinds. In this study the influence of a number of additives on the rheological behavior of molten ABS was investigated using a capillary extrusion rheometer and a Weissenberg rheogoniometer. The additives studied included molding lubricants, rubber impact modifiers, flame-retardant additives, and residual unreacted components remaining from the polymerization process. The mechanisms by which these species affect flow characteristics are described.
    Additional Material: 6 Ill.
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  • 86
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    Polymer Engineering and Science 14 (1974), S. 553-559 
    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 theoretical model for melting in reciprocating screw injection molding machines is proposed. The model permits the calculation of the solid bed profile as a function of time during the injection cycle. It consists of a dynamic extrusion melting model for the rotation period, a transient heat conduction model with a phase transition for the screw rest period, and a proposed model for the drifting of the beginning of melting during the injection cycle.
    Additional Material: 9 Ill.
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  • 87
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    Polymer Engineering and Science 14 (1974), S. 573-576 
    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 rheology of a high molecular weight polyisobutylene “Vistanex” L-80 is measured at 20°C under constant stress creep loading in simple shear and simple elongation and compared with published data for biaxial extension. These data can be reduced to a single curve by the application of simple geometric parameters and instability during extensional flows may be interpreted on the basis of the Considère construction. The results are further extended by dynamic measurements to estimate the viscoelastic response of this material over a time scale of nine orders of magnitude. The rheological response shows an approximately linear relationship with stress up to elongation strains of 1.0, and, because of this, the results do not illuminate the present controversy over the selection of different equations of state to represent non-linear polymer melt flow. However, this body of data, which the authors believe to be the most comprehensive presently available in terms of strain level and deformation geometry, does demonstrate that a viscoelastic polymer can respond to different deformation geometries in a simple manner.
    Additional Material: 4 Ill.
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  • 88
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    Polymer Engineering and Science 14 (1974), S. 597-603 
    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: Problems associated with single-lap shear testing of a structural epoxy adhesive are discussed relative to analyses of the epoxy by infrared spectroscopy, gel permeation chromatography, scanning electron microscopy and other instrumental methods. The value of analytical techniques for assessing the adhesive's cure are shown, including a peculiar correlation of lap shear bond strength with the adhesive's initial uncured state as defined by infrared spectroscopy and gel permeation chromatography. This resulted in the development of definitive batch-to-batch adhesive quality control methods and specifications involving the water content, curing agent, and oxirane concentrations of the uncured system.
    Additional Material: 13 Ill.
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  • 89
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    Polymer Engineering and Science 14 (1974), S. 633-640 
    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 a series of thermoplastics reinforced with unidirectionally oriented short fibers are reported. Both organic and inorganic fiber reinforcements were used in fiber volume fractions of 0.10 to 0.50. A number of these composites were found to have excellent strength and stiffness properties combined with good toughness and low density. The dependence of composite properties on the properties of the constituent materials is discussed. Fiber efficiency factors for strength and modulus are presented and models for predicting composite mechanical behavior are reviewed.
    Additional Material: 8 Ill.
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  • 90
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    Polymer Engineering and Science 14 (1974), S. 677-677 
    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: No. Abstract.
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  • 91
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    Polymer Engineering and Science 14 (1974), S. 687-690 
    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: Rigid, glassy plastics differ over a wide range in the amount of energy they can absorb before fracturing under the influence of an applied stress. It is here proposed that molecular structure influences energy absorption more significantly by determining the onset of fracture than by its effect on the energy-dissipating processes themselves. Emphasis has been placed, therefore, on finding a relationship between molecular structure and the onset of fracture. Since many relationships between molecular structure and bulk mechanical response have already been established, it should be a useful step to relate the onset of fracture to bulk mechanical responses. The hypothesis is developed that the appropriate bulk property is the stress-deformation function of the material. The observed stress-deformation function is of such a nature that a highly non-homogeneous deformation is produced at any point of stress concentration. Typically, this is a narrow region in which the material is highly deformed while the deformation in adjacent material is still slight. Fracture initiation is postulated to occur in such a region of high deformation. Differences among polymers in the shape of the stress-deformation function are demonstrated experimentally. These differences correlate with tough-brittle behavior. An explanation is proposed in terms of the probability of fracture initiation.
    Additional Material: 2 Ill.
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  • 92
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    Polymer Engineering and Science 14 (1974), S. 691-695 
    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: We wish to investigate the path dependence of yield processes in glassy polymers and to understand this dependence, if any, in terms of molecular mechanisms. To this end the effect of sudden strain-rate change on the yield behavior of bisphenol-A polycarbonate has been investigated. In the experiment, a specimen was initially deformed at a constant elongation rate R1; at an elongation Δlc the rate was suddenly changed to another constant elongation rate R2. R1 was either lower or higher than R2. The yield stress subsequent to the rate change was found to be lower than if the entire deformation was at R1. These results can be satisfactorily explained in terms of Robertson's theory of the yielding of glassy polymers if it is assumed that the “bond flexing” in his theory manifests itself in anelastic deformation.
    Additional Material: 7 Ill.
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  • 93
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    Polymer Engineering and Science 14 (1974), S. 724-729 
    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: It was found after heating that the thermal expansion of polyurethane decreased markedly in several hundred hours at constant temperature; after cooling the thermal contraction decreased with time but more slowly. The role of cross-linking as a possible cause of this effect is discussed. Creep during the expanded phase after heating is shown to be much greater than creep after thermal expansion has stabilized at the same temperature. Experiments are described which suggest that the effect of temperature on creep results primarily from thermal expansion rather than from thermal oscillation.
    Additional Material: 4 Ill.
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  • 94
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    Polymer Engineering and Science 14 (1974), S. 737-753 
    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: Models of chain addition polymerizations have been analyzed for effects of reaction parameters on thermal behavior during reaction and, consequently, on properties of the polymer formed. Emphasis was placed on the investigation of thermal drift phenomena in particular. Several dimensionless parameters were identified and their role in predicting thermal behavior was established.
    Additional Material: 16 Ill.
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  • 95
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    Polymer Engineering and Science 14 (1974), S. 768-772 
    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: Plastics injection molding is a complex, multi-variable process which has not yet been clarified. The hardware controller is difficult to build without a realistic mathematical model. One powerful technique for solving such a difficulty is to employ digital control technology which can utilize sophisticated control strategies in order to optimize the system performance. Machine operation and resultant production can be tightly controlled by using computer monitoring, data storage and data logging. This paper presents elements of the various problems that process engineers may encounter in designing a computer-controlled system for plastics injection-molding machinery. The variables of the process and a functional analysis of process control are discussed. A hardware system design; including specification of computer, selection of peripheral devices, system design, and input/output interfacing; is presented.
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  • 96
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    Polymer Engineering and Science 14 (1974), S. 797-800 
    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 specially-designed mold with interchangeable cavity plates was built and used with an Instron capillary rheometer, type MCR, to investigate the injection molding process. Flow patterns in the mold cavity were illustrated with a visual tracer technique. The complete deformation history of the tracers was recorded on a motion picture for several runs. The flow patterns provide data for computing the components of the rate-of-deformation tensor which is used to identify specific shear and extensional flows. The tracer marks in the cross section of a molding offer information on the skin thickness and the dimensions of the core channel.
    Additional Material: 6 Ill.
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  • 97
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    Polymer Engineering and Science 14 (1974), S. 801-805 
    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: Fatigue tests under reversed tension-compression have been made on polystyrene specimens in both the unnotched and notched condition. For the notched specimens subject to a stress amplitude of 2500 psi, the log of the fatigue life was found to be a linear function of the log of the notch size. From the data, it was possible to determine an inherent flaw size for polystyrene subject to alternating loading and this value is compared to corresponding values obtained from static tests. Fracture surfaces were examined by scanning electron microscopy and the changes produced by notching are discussed.
    Additional Material: 6 Ill.
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  • 98
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    Polymer Engineering and Science 14 (1974), S. 817-822 
    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: Proper drying techniques prior to molding can eliminate the overall effects of moisture on the physicochemical properties of polycarbonate. Problems associated with moisture in polycarbonate during molding are described in detail. Moisture absorption is very rapid with the maximum allowable moisture content of 0.03 percent reached within 30 minutes at 49 percent RH and 75°F. Molding with excess moisture content causes a chemical and physical degradation resulting in reduction in tensile impact strength, tensile elongation, ultimate tensile strength, proportional limit and molecular weight. New and existing techniques and procedures for degradation detection were investigated, such as intrinsic viscosity, infrared spectrometry, and thermal methods of analysis. Gel permeation chromatography (GPC) proved the most satisfactory. GPC provided information on the average molecular weight and polydispersity.
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  • 99
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    Polymer Engineering and Science 14 (1974), S. 848-852 
    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 reviews a series of high-melting thermoplastic polyether esters prepared by transesterification from dimethyl terephthalate, polytetramethylene ether glycol (MW 600-2000), and 1,4-butanediol. The resulting copolyesters exhibit a two-phase domain structure consisting of amorphous polyether ester soft segments and crystalline tetramethylene terephthalate hard segments. By proper selection of the relative amounts of soft and hard segments, polymers ranging from relatively soft elastomers to impact resistant elastoplastics may be obtained. The preparation, polymer structure as well as the physical and environmental properties of polyether esters are discussed. The combination of good melt flow properties, excellent melt stability, and rapid hardening rates permits the processing of these polymers by a wide variety of methods. The excellent processing characteristics in conjunction with the unusual physical and mechanical properties of segmented polyether esters has led to their wide acceptance.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 137-142 
    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: Capillary rheometry of four butadiene-acrylonitrile copolymer raw elastomers was performed at 125°C over a wide shear rate range. The data were corrected for the effect of pressure on viscosity, for pressure loss in the barrel and at the capillary entrance, for the non-Newtonian velocity profile (Rabinowitsch correction) and for the temperature rise at high shear rates (shear heating). The corrected results were compared to the tensile stress strain data obtained at comparable strain rates. The agreement between the capillary flow data and the tensile stress strain data was quite good, however, some slight systematic differences were noted. The difference was interpreted as the consequence of slipping of materials at the capillary wall. Die swell values were measured and presented as functions of shear rate and capillary length. Extrudate distortions are described.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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