Synthetics: Photodegradation of Nylon 6.6 knitted net as a result of dyeing

Exposure of samples to light results in significant and accelerated reductions in tensile strength, elongation at break and work of rupture of fibre compared to undyed net fibre in the rigid direction. The effect may be explained by dye-sensitised degradation of the dyed net in the rigid direction. The reduction appears to be related mainly to the dye structure. Exposure of Tectilon- and Lanaset-dyed samples to light resulted in a loss in mechanical properties to different extents. Dyed samples with Lanaset Green B, which is a mixture of anthraquinone dyes, show the highest degradation on exposure. Lanaset Grey G is a mixture of metal complex dyes and dyed samples with this dye exhibit the lowest degradation on exposure. Dyed samples with Tectilon acid dyes show intermediate degradation behaviour. The net undergoes degradation after 350 hours' exposure, although this effect is more significant at longer (750 hours) exposure periods. Surface damage to exposed net fibres, as observed by SEM, reveals a combination of types of physical and chemical damage. The exposed samples exhibit cracks and pits on the surface of the fibre. The analysis of these data by ANOVA tests suggests that there is a statistically significant link between the exposure of the various samples to light and their subsequent degradation, as measured by changes in physical properties. The results of the investigation will assist in the selection of appropriate dyes for the coloration of museum conservation net and are also relevant for outdoor performance nylon products.