摘要:

Iodine iSocyanate was added to polyisoprene and converted to the methyl iodocarbamate derivative and the iodourea derivative. The thermal stability of these modified polymers was compared to polyisoprene using simultaneously run thermogravimetric analysis and differential thermal analysis. Both modifications showed initial weight losses starting at about 125°C which correspond to cyclization reactions. Beyond 350°C, the iodourea derivative showed greater thermal stability than the polyisoprene or the methyl iodocarbamate derivative. This enhanced thermal stability is believed due to the formation of a semi-ladder polymer structure.

ISSN:0022-233X    

DOI:10.1080/00222337108069389

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Water, carbon dioxide, and condensable condensate produced during the oxidation of polyisoprene popcorn polymer were determined gravimetrically. For pure polyisoprene popcorn polymer from which 4.6% soluble polymer and volatiles were removed, the rates of water and carbon dioxide production during the early stages of the autoxidation were linear and amounted to approximately 2 moles of water and 0.2 moles of carbon dioxide for every 10 moles of oxygen reacted.

ISSN:0022-233X    

DOI:10.1080/00222337108069390

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

A new reduced copolymer composition equation weighing the effects of units through the antepenultimate is derived for the first time. The simplification obtained is placed into context with previously published work.

ISSN:0022-233X    

DOI:10.1080/00222337108069391

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The standard deviation [sgrave] is known to be an absolute measure of Gaussian (G) distributions, because it (or multiples of it) always determines a constant fraction of the material. However, this is not true for distribution functions other than Gaussian. The weight fractions corresponding to weight standard deviations (±[sgrave]w) of Schulz-Flory distributions depend on the polymolecularity index xw/xn, approaching a limiting value of W(xw± [sgrave]w) = 86.5 for xw/xn→∞. The use of weight standard deviations is meaningless for generalized logarithmic normal (LN) distributions if xw/xn52. The weight fractions W(Xn± [sgrave]n) around the number-average degree of polymerization of G and LN distributions first go through a maximum before decreasing with increasing xw/xn. The weight fractions W(xn± [sgrave]n) decrease steadily with higher xw/xn.

ISSN:0022-233X    

DOI:10.1080/00222337108069392

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

When three different polymers are dissolved in a common solvent and the total polymer concentration is above a certain value, three liquid layers are obtained because of the limited compatibility of the polymer components with one another. Tests have been carried out at room temperature on solutions of polystyrene t polyvinyl acetate + polyvinyl chloride in tetrahydrofuran, and polystyrene t polyvinyl acetate t atactic polypropylene in benzene. Analysis of the individual layers yielded the following results: each polymer is always contained in each layer; the mixing ratios of the polymers in the three layers are generally different from one another and differ also from the mixing ratio of the starting mixture; each of the three layers is distinguished from the others by the fact that a specific polymer has been accumulated therein in preference to the other polymers. Concerning the quantitative distribution of the polymers among the layers, some laws could be found which can be explained qualitatively on the grounds of molecular-physical considerations. A solution of polystyrene t polyvinyl acetate t polyvinyl chloride t atactic polypropylene in tetrahydrofuran (equal amounts of polymers, total concentration about 10 g/100 ml) forms four layers, the composition of which was also determined by analysis.

ISSN:0022-233X    

DOI:10.1080/00222337108069393

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222337108069394

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/00222337108069378

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor