ISSN:
0449-296X
Schlagwort(e):
Physics
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Four phenyl-substituted polyquinoxalines have been prepared by the reaction of combinations of two tetraamines, 3,3′-diaminobenzidine and 3,3,′4,4′-tetraaminodiphenyl ether, with two bisbenzils, 4,4′-dibenzil and 4,4′-oxydibenzil. The polymers were prepared by melt and solution polymerizations. Melt condensations were performed at 180, 220, and 280°C. and samples were periodically removed and characterized. The solution polymerizations consisted of two stages, initially forming an intermediate molecular weight polymer (ηinh 0.6-1.0) which was advanced at 400°C. to final polymer (ηinh 1.5 to 2.2). Clear yellow films, cast from m-cresol solution, exhibited good toughness and flexibility. The phenyl-substituted polyquinoxalines exhibited excellent oxidative and thermal stability. Polymer decomposition temperatures in air were generally about 550°C. Isothermal aging at 371°C. (700°F.) in air showed weight retentions as high as 93 and 50% after 100 and 200 hr., respectively. Weight-average molecular weight determination by light-scattering technique on a polymer with an ηinh of 2.16 suggested a value of 247,000. Certain physical properties of the phenyl-substituted polyquinoxalines are compared with those of the corresponding ordinary polyquinoxalines to illustrate the advantageous effect of introducing a phenyl group on the quinoxaline ring.
Zusätzliches Material:
6 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1967.150050626
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