Effects of ultraviolet light (315 nm), temperature and relative humidity on the degradation of polylactic acid plastic films

The influence of temperature (30, 45 and 60 °C) and relative humidity (RH) (30%, 50% and 100%) on the degradation of poly(l-lactic acid) (PLA) films were studied. In addition, the effects of ultraviolet (UV) light (315 nm) on the degradation of PLA films were also analyzed. Various analytical techniques were applied to observe changes in the properties of PLA polymer films. FTIR spectroscopy was used as semi-quantitative method to get information about the chemistry of the degradative process. The degradation rate of PLA was enhanced by increasing temperature and RH, factors responsible for a faster reduction of the weight-average molecular weight (Mw), of the glass transition temperature (Tg) and of the percentage of elongation at break. Moreover, UV treatment accelerated these phenomena.