Influence of impurities on the pyrolysis of polyamides

Abstract

A study has been m ad e of the effect of dryin g a nd purification of polycaprolacta m (ny lon-6) on its thermal d ecomposition . The conclusions drawn from p reviou work, t hat a h ydrolytic mechanism is a t least p art iall y operating due to th e presence of water a nd ac id poly m er ization catalysts, are confirmed . Purification of t he materia l decreases t he rate of d egradation and t he production of CO2, and increases t he preexponential factor a nd t he a ct ivation e nergy. The h ydrolytic decomposit ion, which competes with t he t herma l freerad ical degradation process, wo uld be expected to produce carboxylic acids a nd a min es, t he former decomposing further to form CO2 The preexponentiaJ fac tor is increased by sample purification from 10 7 to 10 10 a nd t he activation energy from 34 to 43 k cal /mole. Thc decomposition behavior of the purest sample is a nearly perfect example of the ra ndom decomposit ion of linear polymer cha ins. All other samples of polyamides thus fa r studied also appear to d ecompose by ra ndom or nearl y random m echa nisms.