FT–IR spectroscopic study on the photo‐ and photooxidative degradation of nylons

Abstract

SynopsisThe progress of photo-and photooxidative degradation of nylon films were studied by FT-IR spectroscopy. The gases evolved from the photolysis of various nylons and their model amides were also analyzed. The formation of double bonds, changes of crystallinity, and the effect of amino and carboxyl end groups has been studied and discussed. The band shapes of the IR spectra pertaining to the carbonyl groups formed by thermal oxidation or photooxidation were found to be very similar, suggesting that the two oxidation mechanisms might be similar. The broadness of these bands indicates that the carbonyl groups may belong to more than one species. The photodegradation of nylons containing purposely inserted carbonyl groups formed -CH=CH, groups. Carbonyl groups formed during oxidation, and present either as keto groups or part of N-acylamide units make nylons susceptible to degradation reactions entailing mainly a Nonish type I1 mechanism.From ESR s t~d i e s ,~,~ kinetic studies,6 and chemical analyses,' the photolysis mechanisms were suggested to occur by degradation involving direct cleavage of the amide bond according to a Nonish Type I mechanism. Moore suggested that both Type I and Type I1 mechanisms occurred in the degradation of nylons.8Recently, Mazzocchi and Bowen studied the photolysis of N-alkylamides in solution by analyzing the products and concluded that the Type I process was predominant and the Type I1 process was quite ineffi~ient.~ They rationalized

Aging of oily soils on textiles. Chemical changes upon oxidation and interaction with textile fibers

“…Do et al (12,13) did Fourier transform IR studies on photooxidative and thermal oxidative degradation of nylon. They found a decrease in amide and methylene bands and an increase of carbonyl groups upon nylon; where the carbonyl groups were of many origins, such as aldehydes, carboxylic acids, ketones, N-acylamides and α, β-unsaturated carbonyl compounds.…”

“…Coconut oil was purchased from Sigma Chemical Co. (St. Louis, MO) and spermaceti wax from Sargent Welch (Skokie, IL). Radioisotope-labeled [4,8,12,13,17, H]-squalene was obtained from New England Nuclear Products (Boston, MA). An 8% (wt/vol) squalene solution was made with toluene; for radiotracer analysis, an aliquot of 200 µL of 0.01 mCi/mL 3 H-labeled squalene was added to 20 mL of the soiling solution.…”

New Vistas in the Photo-Oxidation of Nylon 6

“…[1][2][3][4][5][6][7][8] Instead, if the available data are sufficiently diagnostic, then one is in a position to test different theories and to discriminate among them (theory testing), as in the present case.…”

Progress in the Area of Degradation and Stabilization of Nylon 66

“…The viscosity changes also show that the postheated samples exhibit a higher level of UVabsorbing fluorescent and phosphorescent species at 294 nm. The shapes of the carbonyl envelope [45] of the infrared (IR) spectrum formed in thermal and photooxidation 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.…”