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1

Digitale Medien

Crystallinities of copolymers of ethylene and 1-alkenes (1988)

Clas, S.-D. ; Heyding, R. D. ; McFaddin, D. C. ; [weitere]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 26 (1988), S. 1271-1286

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ISSN: 0887-6266

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: Random copolymers of ethylene with 1-butene, 1-octene, and 1-octadecene have been prepared using a homogeneous vanadium-based catalyst system. Comonomer contents determined by 13C-NMR analysis of polymer solutions are in the range 1-10 mol%. Crystallinities were estimated by means of density measurements, x-ray diffraction, differential scanning calorimetry, laser Raman spectroscopy, and CPMAS 13C-NMR spectroscopy. The results are compared with those obtained for heterogeneous copolymers of ethylene containing 1-4 mol% 1-butene. As the comonomer content is increased, the crystallinity decreases. The dimension perpendicular to the 110 plane in orthorhombic crystallites decreases linearly with crystallinity. This decrease in crystallite size is accompanied by an increase in the size of the orthorhombic unit cell. For copolymers containing large amounts of 1-octene and 1-octadecene, a second crystalline form appears. Differences in estimates of crystallinity are discussed in terms of looser packing in highly branched copolymers and the extent to which the second crystalline form participates in the phase structure.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/polb.1988.090260611

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2

Digitale Medien

A cooperative molecular weight distribution test (1973)

Adams, H. E. ; Ahad, E. ; Chang, M. S. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 17 (1973), S. 269-282

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The development of gel permeation chromatography (GPC) has provided a convenient tool for the rapid determination of molecular weight distribution. The question has arisen as to the suitability of the method for specification purposes. The present work, suggested by the Naval Air Systems Command, represents an attempt to assess the precision of the method through a series of tests carried out by a number of laboratories using identical procedures on the same samples. Ten laboratories agreed to take part. Naval Ordnance Station, Indian Head, worked out standard conditions for operation of the chromatograph, for calibration of the columns, and for analysis of the GPC curves. Two samples of polystyrene were used by the various organizations for calibration of their instruments. Number-average molecular weight, heterogeneity index, and cumulative molecular weight distribution curves were determined on four samples of carboxyl-terminated polybutadiene (CTPB) and two samples of hydroxyl-terminated polybutadiene (HTPB), all unidentified except by letter code. All laboratories used identical directions for setting up CTPB and HTPB calibration curves which were based on curves determined from vapor-pressure osmometer molecular weights and GPC count numbers of fractionated material. Variation among the different laboratories was 0.15 in heterogeneity index, and a maximum of 1200 in molecular weight provided one aberrant set of values was eliminated. The six samples had heterogeneity indices from 1.15 to 1.54, while molecular weight varied from approximately 3000 to 6000. The average coefficient of variation of the molecular weight values was 6.2 ± 0.7%, which is quite acceptable. Variation in heterogeneity index was too great for specification purposes when considered among the different laboratories, but may be sufficiently good when measured by any one laboratory.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1973.070170121

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3

Digitale Medien

A valid method of calibration which includes correction for dispersion in gel permeation chromatography (1972)

Swartz, T. D. ; Bly, D. D. ; Edwards, A. S.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 16 (1972), S. 3353-3360

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Two independently derived distribution function methods validate both the calibration curve and the dispersion correction of the “effective linear calibration” method used in gel permeation chromatography (GPC). Experimental conditions are specified for making the method more useful by permitting linear extrapolation of the calibration line, \documentclass{article}\pagestyle{empty}\begin{document}$ V_R = C_1 + C_2 \log M, $\end{document} and for using a minimum number of standards. The independent methods quantitatively relate known differential of integral distribution functions for standard samples to their respective chromatograms. As such, they are useful calibration methods also, but are limited in scope and range.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1972.070161224

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4

Digitale Medien

Thermal behavior of cast polyurethane elastomers (1988)

Pandya, M. V. ; Deshpande, D. D. ; Hundiwale, D. G.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 35 (1988), S. 1803-1815

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Thermal properties like glass transition temperature (Tg), initial decomposition temperature (idt), integral procedural decomposition temperature (ipdt), and temperature at various % weight loss of a number of polyurethane systems are reported in this paper. Glass transition temperature was determined on TMA, and other thermal properties were determined by thermogravimetry. The experiments were designed to understand various factors such as length of chain extender moiety, flexibility of chain extender units by substitution of ether link in the diol chain, nature of bonds (unsaturation) in the extender unit, and nature of diisocyanates.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1988.070350708

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5

Digitale Medien

Low temperature deposition of a CaF2 insulator layer on GaAs (1989)

Vere, A. W. ; Mackey, K. J. ; Rodway, D. C. ; [weitere]

Weinheim : Wiley-Blackwell

Advanced Materials 1 (1989), S. 399-400

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ISSN: 0935-9648

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/adma.19890011109

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6

Digitale Medien

The electroinitiated polymerization of N-vinylcarbazole with zinc bromide, IIPart I: cf.12.. Kinetics of polymerization (1973)

Phillips, D. Colin ; Davies, D. H. ; Smith, J. D. B.

New York : Wiley-Blackwell

Die Makromolekulare Chemie 169 (1973), S. 177-189

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ISSN: 0025-116X

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Beschreibung / Inhaltsverzeichnis: Die elektroinitiierte Polymerisation von N-Vinylcarbazol (VCZ) wurde in Aceton bei 25°C mit Zinkbromid als Katalysator unter Verwendung von Platinelektroden eingehend untersucht. Die Polymerisationsgeschwindigkeit erwies sich als direkt abhängig von der Stromstärke, der Zinkbromid-Konzentration und dem anfänglichen Wassergehalt des Solvens.Die Molekulargewichte der entstandenen Polymeren (1000-6000) sind unabhängig von der Stromstärke, der Zinkbromid-Konzentration und dem Umsetzungsgrad des Monomeren zum Polymeren, werden jedoch beeinflußt durch Wasser, die Monomerkonzentration und das Elektrodenmaterial. Die chemische Zusammensetzung der Polymeren ändert sich nicht mit der Stromstärke, der Zinkbromid-Konzentration, dem Umsetzungsgrad und dem Elektrodenmaterial. Sie ändert sich jedoch ein wenig mit dem Wassergehalt des Acetons.

Notizen: The electroinitiated polymerization of N-vinylcarbazole (VCZ) in acetone solvent at 25°C with zinc bromide, as catalyst, and platinum electrodes was investigated in detail. The polymerization rate was found to be directly dependent on current strength, zinc bromide concentration and the initial water content of the solvent.The molecular weights of the formed polymers (1000-6000) are independent of current strength, zinc bromide concentration and degree of conversion of monomer to polymer, but are affected by water, monomer concentration, and by the type of electrodes used. The chemical composition of the polymer is invariant with current strength, zinc bromide concentration, degree of conversion, and electrode material but does vary slightly with the water content of acetone.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/macp.1973.021690117

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7

Digitale Medien

Test methodology for the determination of optimum fusion welding conditions of polyethylene (1989)

Saint-Royre, D. ; Gueugnaut, D. ; Reveret, D.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 38 (1989), S. 147-162

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The fusion welding behavior of a medium density polyethylene resin has been studied for a wide range of heating rates using a recently developed test methodology. With this method, the thermal and physical phenomena occurring at the interface of two thin polyethylene pieces assembled by fusion can be studied. It consists of a thermal welding phase and a phase of mechanical separation of the welded assembly. For the mechanical phase, an adaptation of the T-peel test was used. These conditions make it possible to determine the thermal welding parameters (temperature, time) for optimal mechanical quality of the joint, according to a criterion established by optimization of the peel test used. The variations in minimum temperature required for an optimum weld, as a function of heating rate, can be simulated with a numerical model based on the concept of macromolecular interdiffusion. Consistent with the experimental behavior, the numerical model involves two parameters characteristic of the diffusion behavior of the polyethylene resin. Thus, these parameters characterize the weldability of the polyethylene resin under study.

Zusätzliches Material: 8 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1989.070380114

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8

Digitale Medien

Mixing studies in the single screw extruder (1985)

Bigio, D. I. ; Boyd, J. D. ; Erwin, L. ; [weitere]

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 25 (1985), S. 305-310

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ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Laminar mixing in a single screw extruder between two miscible liquids is considered. Studies are presented which examine the mixing performance in single screw extruders with mixing sections, variable geometry screws, and multi-viscosity mixtures. Model extruders, set up on engine lathes, were used to mix colored silicone rubber which eventually cured in the screw channel. The cured silicone was then removed and sliced to measure the mixing. Results show mixing as a function of both down channel location and total average strain. For the mixing section study, results support the theory of interfacial area reorientation as the key mechanism in mixing section performance. Increasing viscosity ratio for the multi-viscosity study showed a decrease in mixing rate.

Zusätzliches Material: 13 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760250510

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9

Digitale Medien

Studies on akroflex CD antioxidant loss from neoprene rubber. I. The determination of antioxidant content and the loss mechanism during aging (1974)

Smith, J. D. B. ; Jerson, D. D. ; Meier, J. F.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 18 (1974), S. 3543-3553

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: An analytical procedure for determining the antioxidant (i.e., Akroflex CD) content in neoprene rubber has been developed. The method is based on the infrared absorption analyses of chloroform extractables from the cured rubber at 1600 cm-1 and 1300 cm-1. Good agreement is found between these two independent sets of measurements. In an attempt to elucidate the antioxidant loss mechanism found with neoprene, thermal aging studies were carried out over the temperature range of 80°-200°C. Using the infrared analytical procedure, antioxidant loss rates at the different temperatures were established. The activation energy value (5.1 kcal/mole) for the loss rate as well as other aging data suggest that the antioxidant is lost by a diffusion mechanism.

Zusätzliches Material: 9 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1974.070181205

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10

Digitale Medien

Deterioration of plastic films under soil burial conditionsIssued as N.R.C.C. # 18807. (1981)

Colin, G. ; Cooney, J. D. ; Carlsson, D. J. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 26 (1981), S. 509-519

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The deterioration of polyolefin, poly(ethylene terephthalate), and polyamide films under soil burial conditions extending up to 32 months has been investigated. Based on changes in their elongation at break, the films can be ranked in order of increasing sensitivity to degradation: Polyester ≃ polypropylene 〈 low-density polyethylene ≃ high-density polyethylene 〈 nylon 6.6. The degraded nylon 6.6 and polyethylene films were characterized by infrared and luminescence spectroscopy and scanning electron microscopy, as well as by wet analysis for hydroperoxides. From a comparison with the well-known oxidative sensitivity of nylon 6.6 in oxygenated water at slightly elevated temperatures, the rapid deterioration of nylon 6.6 film during soil burial was also concluded to be an oxidative process. The somewhat smaller, but significant, embrittlement of the polyethylenes studied could not be simply explained by thermal oxidation (with only trace oxidation products detectable) or microbiological attack (deterioration being unaffected by surface activation to enhance wettability).

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1981.070260211

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