Pyrolysis of polyamides

Abstract

Thermal decomposition s of various nylon samples havin g difTcrenL molec ular weights and composition were investigated by several procedures: ( I ) Th e raLc of volaLiliulLion at temperatures between 310 0 and 380 0 C; (2) t he analysis of the volatile produets by mass spectrometry; and (3) a direct m eas urement of volaLili zing m aterial obtained by eHtTying out the pyrolysis within the ionization chamber of a m ass spectromeLer.AcLivation energies based on the rates of volatilization for the variolls amples varied from 15 to 42 kilocalories. The rate behavior, i. e., the observaLion of maxima inLhe rateversus-conversion plots, is close to that given by theory for random d composiLion. The different activatio n energies appear to be the res ul t of a hydrolytic mec hanis m which is sensi t ive to trace polymerization catalysts. Increases in rates were obtained when sulfuric and phosphoric acids were a dded to nylon. The flucLuaLion s found in activation energies, find the production of CO2 indicate that a hydrolytic decomposition mechani sm may be contributing to the over-all process. It appears evident that, compared to a pure hydrocarbon chflin, the polyamides are much more sllseeptible to thermal decomposition.

Effect of structure on the thermal decomposition of polymers

“…When linear samples of polymethylene made from diazomethane are pyrolyzed, maximum-type curves are produced [15]. Commercial linear polyethylene and polyamides also give rate curves with maxima very similar to that for random theory [11].…”

Thermal Characteristics of Coated Textile Fabrics

“…Straus and Wall [21,25], investigated the decomposition of nylon mixtures by experiments on the ra a of volatilization. They concluded that the decomposition is a thermal free-radical decomposition complicated by the residual polymerization catalysts and water strongly bonded to the peptide links.…”

Volatile degradation products of organotin polyesters

“…The presence of cyclopentanone in the degradation products of poly(di-n-butyltin adipate) as well as in poly-(hexamethylene adipamide) supports the view that this material originates from the adipic acid rather than the hexamethylene diamine moiety of nylons 66. 3 Only trace amounts of carbon monoxide were found in both samples of organotin polyesters in contrast to the situation with other polyesters, including poly(ethy1ene terephthalate), where both carbon monoxide and carbon dioxide are produced in larger and about equal amount^.^ Butane most likely originates from the cleavage of the butyl side groups of both organotin polyesters. Carbon dioxide arises from the scission of the carboxyl links, except in the case of poly(di-n-butyltin adipate), where one of the carboxyl groups of the repeat unit participates in the formation of cyclopentanone.…”