摘要:

The thermal degradation of random and block copolymers of terephthaloyltrans-2,5-dimethylpiperazine/isophthaloyltrans-2,5-dimethylpiperazine were investigated in terms of rates, activation energies, degradation products, and electrical properties. The rates of degradation and the nature of the volatile degradation products indicate that both random and block copolymers follow a nearly random free-radical type of cleavage in vacuum with activation energies between 59 and 61 kcal/mole. In the temperature range 390=440°C, the block copolymers are significantly more stable in a vacuum (the rates of degradation are two to four times slower) than the random copolymers. In contrast to the random copolymers, the block copolymers showed only slight frequency dependence of their dielectric constants and dissipation factors between 0.1 and 100 kcps.

ISSN:0022-233X    

DOI:10.1080/10601326708053760

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Stress relaxation properties of SiB-2 and poly(dimethyl siloxane) were compared in air and pure nitrogen. The effect of a protective filler system was also investigated for these materials. In addition, stress relaxation experiments were conducted on unfilled SiB-1 and SiB-1.5 in air only.

ISSN:0022-233X    

DOI:10.1080/10601326708053761

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

A computer program for calculation of concentration-dependent sedimentation coefficients is presented. Provision is made for rejection of outlying experimental points. The method yields extremely rapid and precise results from original data without any intermediate steps.

ISSN:0022-233X    

DOI:10.1080/10601326708053762

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Poly-4-vinylbiphenyl (PVB) fractions of various molecular weights could be reacted with alkali metals in dimethoxyethane to form polyradical anions which were found to be stable at low temperature. The study of the line width of ESR signals obtained with high and low molecular weight PVB polyradical anions indicated electron delocalization over the polymer chains and extensive intramolecular exchange.

ISSN:0022-233X    

DOI:10.1080/10601326708053763

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/10601326708053764

出版商:Taylor & Francis Group    

年代:1967

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:10.1080/10601326708053749

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor