Pyrolysis Process in Aramid Fibers Investigated by Py-GC/MS ＆ TGADTA/MS

Poly （ m-phenylene isophthalamine） （PMIA） and Poly（ p-phenylene terphthalamine） （PPTA） are among the most important high-temperature resistant aramid fibers. The pyrolysis behaviors of these two fibers under inert gases were studied using pyrolysis-gas chromatography/mass spectrometry （Py-GC/MS） and thermogravimetric analysis coupled with mass spectrometry （ TGA-DTA/MS ）. The pyrolysis processes of PMIA and PPTA are distinguishing, and the stepwise pyrolysates reflect these differences. A mechanism system of pyrolysis is suggested, which involving hydrolysis and homolysis, At low pyrolysis temperatures, hydrolysis is a primary reaction, and it is very noticeable in the first-step pyrolysis region of PMIA. Elevating pyrolysis temperature, homolysis is enhanced and keep a large advantage in the high temperature range. On the other hand, at higher temperatures, carbonization happens and the homolysis and carbonization of PPTA are emphasized more than of PMIA.