The Effect of a Hydrophobic Coating on the Photodegradation of Dyed Nylon 6 Yarns

Nylon 6 is one of the most widely used polymers in the world. For some nylon products, hydrophobic coatings are used for impregnation. However, it has been suggested in the literature that coating could accelerate aging. Therefore, in this paper, we focused on the degradation process of dyed nylon yarns with and without perfluorinated coating under accelerated weathering conditions. To monitor the degradation process, we used methods such as tensile test, molecular weight analysis, ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, energy dispersive X-ray analysis, and scanning electron microscopy. We found that the hydrophobic coating is unlikely to have a negative effect on the degradation process. However, the coating decomposes during weathering, and its concentration on the fiber's surface decreases. The type of dye used was identified as the most significant factor influencing the degradation rate. This was explained by the screening effect of dyes in the UVA region of the light spectrum. Manufacturers of nylon products, which require a pleasant appearance and safety, should, therefore, consider a careful selection of dyes.