The viscosity changes also show that the post-heated samples exhibit a higher level
of UV absorbing fluorescent and phosphorescent species at 294 nm. The shapes of
carbonyl envelope62 of the IR spectrum formed in thermal and photo-oxidation were
similar, suggesting that both the oxidation mechanisms are the same. The broadness
of these bands indicated that the carbonyl group spectra arise from more than one
species. The presence of keto and part of N-alkyl amide groups made nylon
susceptible to a degradation reaction entailing mainly a Norrish type II mechanism.
Evolution of carbon monoxide, methane and formation of the primary amide groups
was observed in the photodegraded sample under vacuum. The same authors
compared the photodegradation of nylon 6 and nylon 66. The only difference in
nylon 6 and nylon 66 photodegradation reported was evolution of ammonia during