Photodegradation of nylon netting twine exposed in the carbon arc Fade meter was investigated from the relation between mechanical and chemical properties. The progress of photodegradation of the samples after u.v. irradiation was evaluated by measuring breaking strength, molecular weight (viscometeric method) and density.
With increasing of irradiation, a continuous decrease in molecular weight and also an increase in density were observed in proportion to a significant loss of breaking strength. Form these results, the mechanism of the photodegradation of nylon was estimated as follows.
The loss of molecular weight during irradiation suggested the occurrence of photochemical degradation causing the scission of chemical bonds in polymer chain. And also the occurence of reorientation of polymer chain and/or the formation of crosslinking were suggested by the results of the increase in density of nylon fiber with progressive degradation.
The results on breaking strength, molecular weight and density of nylon samples treated with additive (702) showed that this additive acted as a good retardant to photodegradiation of nylon.