Determination of hydroperoxides in ultraviolet-irradiated nylon 66

Abstract

SynopsisAccording to mechanisms described in the literature, photodecomposition of nylon 66 proceeds through the abstraction of the hydrogen on the carbon u to the amide NH group by a free radical which has been activated by photo absorption. In the p r o p agation phase, the a-carbon radical could readily react with atmospheric oxygen to form a hydroperoxide. The formation of a hydroperoxide in the photodecomposition scheme for nylon 66 has been detected but has not been measured quantitatively.With the colorimetric method described in this paper, it is now possible to determine the peroxide content in a polyamide to a level of 1 Wole/g. with a relative precision of leas than 5%. The polyamide is dissolved in tetrafluoropropanol, to which aliquots of potassium iodide and glacial acetic solutions are added. The absorbance of the liberated iodine is measured in a 1-cm. cell a t 400 mp and the hydroperoxide concentration determined from a calibration curve constructed from hydrogen peroxide solution standards. The rate of peroxide formation, which is dependent on the wavelength of ultraviolet radiation, can be correlated to the strength loss exhibited by a nylon 66 yarn free from antioxidant and delustrant. In addition, an increase in the level of thermal degradation will accelerate yarn strength loss and peroxide formation under ultraviolet exposure. The hydroperoxide begins to decompose a t about 100OC. Yam finish will contribute to the peroxide formation during exposure.

Effect of Hydroquinone on Light-Induced Degradation of Nylon 6 Dyed with SolubilizedVat Dyes

“…Interest in the processing of wool and wool blends on the short staple system [ 1,2,3,5,9] has increased because of apparently higher profit from these yams [7] compared to those made by conventional methods. Short staple wool is scarce and so the available wool must be shortened by cutting or stretch-breaking the fibers in the sliver state [8], These fiber-shortening methods add to cost, however, because the wool must be processed into tops before the fibers can be shortened.…”

“…This lamp emits radiation from 3500-6500 A, so photodegradation of nylon should proceed via photo-oxidation. This is because many researchers have reported that incident radiation of a wavelength longer than 3000 A causes photo-oxidation of the polymer [ 1,22,23,27].…”

Photocatalytic Degradation of Polyamide 66; Evaluating the Feasibility of Photocatalysis as a Microfibre-Targeting Technology

“…The absorbance of the carbonyl band generally falls between 1900 and 1600 cm −1 and the reference peak can be the CH 3 rocking band or the CH 2 scissoring band which correspond to vibrations of groups not affected by oxidation [44,[51][52][53][54]. High CI indicates a high degree of polymer degradation [53].…”

Effects of Light on Materials in Collections: Data on Photoflash and Related Sources

“…This is equivalent to about 10 5 xenon strobe flashes over the display lifetime of undyed nylon. Anton (1965) showed that 20 hours of exposure to light between 340 and 415 nm caused a detectable decrease in tensile strength of undyed nylon-6,6 samples. Based on data for the Atlas Weather-Ometer xenon source, this exposure amounted to approximately 3  10 21 nearultraviolet plus blue photons/cm 2 .…”