Pyrolysis–molecular weight chromatography–vapor‐phase infrared spectrophotometry: An on‐line system for analysis of polymers. IV. Influence ofcis/transratio on the thermal degradation of 1,4‐polybutadienes

摘要

AbstractThe influence of thecis/transratio of 1,4‐polybutadienes on the volatile products formed during temperature‐programmed thermal degradation to 15 weight loss has been investigated using a mass chromatograph (a gas chromatograph which directly provides mass numbers of resolved components of a mixture) and an “on the fly” vapor‐phase infrared spectrophotometer. In order of amounts, major volatile products were 4‐vinyl‐1‐cyclohexene (dimer), 1,3‐butadiene (monomer), cyclopentene, and 1,3‐cyclohexadiene. With increasing trans content, the relative quantities of 4‐vinyl‐1‐cyclohexene decreased strongly, cyclopentene increased strongly, 1,3‐butadiene decreased moderately, and 1,3‐cyclohexadiene increased moderately. For a high‐trans polybutadiene, increasing the heating rate produced relatively more monomer and dimer but less cyclopentene. Mass chromatograms from 1,4‐polybutadienes which had been heated to 15 weight loss in their prehistory were similar to those obtained from 1,2‐polybutadiene, indicating that 1,4‐polybutadiene undergoes isomerization prior to degradation. Mechanisms for the formation of the main volatile pr