Determination of hydroperoxides in ultraviolet-irradiated nylon 66

✍ Scribed by Anthony Anton

• Publisher: John Wiley and Sons
• Year: 1965
• Tongue: English
• Weight: 346 KB
• Volume: 9
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1965.070090503

✦ Synopsis

According 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.