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  • 1
    Electronic Resource
    Electronic Resource
    Development of potentially degradable materials for marine applications. II. Polypropylene-starch blends (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 405-415 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of exposure of unstabilized polypropylene-starch blends, with or without a metal catalyst (e.g., cobalt (III) acetylacetonate), autooxidant (e.g., fatty acid), and a metal containing plasticizer (e.g., aluminum stearate) to the marine environment was studied for about six weeks at two different locations in New Jersey. Starch tends to absorb water. Unstabilized polypropylene degrades significantly during processin in air, as indicated by melt index values. Thus, for blends of unstabilized polypropylene-starch (no additives), prepared under controlled conditions and exposed to plain seawater, there seems to be no microbial activity or chemical degradation, as indicated by no surface erosion and practically no change in molecular weight and tensile properties. However, for unstabilized polypropylene starch blends containing metal catalyst, auto-oxidant, or plasticizer exposed under soft mud, surface erosion due to microbial activity is evident. In addition, chemical degradation due to the presence of degradative additives has been confirmed, as observed by a decrease in molecular weight and tensile properties. Changes in thermal characteristics of these blends after exposure to the marine environment have been studied.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430220
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  • 2
    Electronic Resource
    Electronic Resource
    The conducting behavior and stability of conducting polymer composites (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 637-641 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Results of measurements of the electrical conductivity of low density polyethylene/polypyrrole and polystyrene/polypyrrole composites are reported. It is observed that the electrical conductivity of the composite vs. concentration follows the power law predicted by the percolation theory. The manufacturing process influences the homogeneity of the composite at microscopic scale and thus the percolation threshold. Annealing studies show that the stability of the electrical conductivity of the composite is related to the thermal expansion of the polymers and the relaxation of the polymer chains. The decrease of the electrical conductivity of the composite is attributed to the interruption of the percolation path.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350802
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  • 3
    Electronic Resource
    Electronic Resource
    Further studies on biodegradation of aliphatic poly(ester-amides) (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1999-2006 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Two types of aliphatic poly(ester-amides) (PEAs) were subjected to microbial degradation in basal mineral salt broth, under the attack of a yeast, Cryptococcus laurentii, at 20°C. PEA-I copolymers were made by the anionic ring-opening copolymerization of ∊-caprolactone and ∊-caprolactam, whereas PEA-II copolymers were synthesized by a two-step polycondensation reaction of hexanediol-1,6, hexanediamine-1,6, and adipolyl chloride. These copolymers were found to be readily degradable under biotic conditions, based on weight loss, GPC, NMR spectroscopy, and tensile property measurements. Compared to abiotic hydrolysis, biodegradation occurred much faster under milder conditions. Furthermore, NMR spectroscopic analysis proved that the biodegradation of poly(ester-amides) involves the enzymatic hydrolysis of ester groups on the backbones of polymers into acid and hydroxyl groups. No breakdown of amide bonds was observed under the given biotic conditions. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070501118
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  • 4
    Electronic Resource
    Electronic Resource
    Electrical behavior of carbon black-filled polymer composites: Effect of interaction between filler and matrix (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 1159-1164 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of interaction between carbon black and polymer on electrical behavior was studied using the ESR method. The polymer matrices used were HDPE, LDPE, and ethylene/vinyl acetate (EVA). Two kinds of carbon blacks (CB), high structure CSF-III and low structure FEF, were used as a conductive filler. Compared to that of the HDPE/FEF compound, the positive temperature coefficient (PTC) intensity is lower and electrical reproducibility is worse for the HDPE/CSF-III compound; however, it can be improved significantly by radiation cross-linking. On the other hand, the cross-linking has no practical effect on the PTC intensity of the LDPE/CSF-III compound while it can be achieved by mixing the compound for a longer time. The great PTC intensity was obtained in the HDPE/EVA/CSF-III compound, and it is greater than that of HDPE/CSF-III or EVA/CSF-III. We explain these results using the concept of interaction between the filler and matrix. The absorption of the polymer on the carbon black surface may be physical or chemical; the latter is caused by the free-radical reaction between the polymer and carbon black, and it can occur during the radiation or preparation process of the compound. These “bound polymers” are essentially important for materials to have a great PTC intensity and good reproducibility. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070510701
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal ignition kinetics of wood sawdust measured by a newly devised experimental technique (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 14 (1995), S. 266-270 
    Details
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The activation energies of two wood sawdusts were determined using an experimental technique based on the crossing-point temperature concept, which was derived from the transient model of self-heating in a solid. The two samples used in this study were treated and untreated sawdust. The activation energies measured were 106 ± 4 kJ mol-1 for the treated sawdust and 90 ± 3 kJ mol-1 for the untreated sawdust. These values are similar to those in previously published results which were obtained using the steady-state model. The transient model provides a quicker yet sufficiently accurate method of determining thermal ignition kinetics.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prs.680140409
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  • 6
    Electronic Resource
    Electronic Resource
    Conformations of polymer chains in voids with an external electric field by Green's function methods (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1167-1172 
    Details
    ISSN: 0887-6266
    Keywords: gel electrophoresis ; DNA electromobility ; polymer configurations ; polymer mobility ; polymer conduction ; dispersive transport ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The statistical conformations of a length of polymer chain, such as DNA, trapped in a void within a gel under the influence of an external electric field, have been studied by the method of Green's functions. Based upon a rectangular box approximation for the void shape, the method gives an explicit analytical expression for the end-to-end distance (Rx) as a function of applied field strength, number of chain segments coiled within the void, and size of a chain segment. Results of calculations show that the field compresses the entrained coil into more compact configurations, as would be expected. Such compression is believed to affect the electrophoretic mobility of a long chain molecule like DNA in a dilute gel. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330802
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  • 7
    Electronic Resource
    Electronic Resource
    Chemically oxidized polypyrrole: Influence of the experimental conditions on its electrical conductivity and morphology (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 642-647 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of synthesis conditions on the electrical conductivity and the morphology of a chemically oxidized polypyrrole was investigated. It was found that the electrical conductivity of polypyrrole was strongly dependent on the pyrrole/FeCl3 ratio, which controls the redox potential of the reaction medium. The reaction temperature and the reaction duration also influence the electrical conductivity of the polypyrrole. A considerable influence of the nature of the solvent used on the aggregation state of polypyrrole particles was demonstrated. Optimal experimental conditions are proposed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350803
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