The resistance of poly-(l-lactide) to gamma radiation: effect of initial preparation and crystallinity

Abstract

In order to investigate the resistance of poly-(l-lactide) (PLLA) to high-energy radiation, two varieties of samples with substantial differences in microstructure and crystallinity are prepared and exposed to the gamma radiation to various absorbed doses (up to 300 kGy). Since the PLLA morphology is sensitive to preparation conditions and radiation, surface microstructures are analyzed by scanning electronic microscopy. The chain scission degradation is followed using a gel permeation chromatography, while the additional characterization is conducted by differential scanning calorimetry, wide-angle X-ray diffraction method and IR spectroscopy. Presented results show that the quenched samples are more susceptible to radiation than initially high crystalline ones. Furthermore, the radiation leads to two considerably dissimilar recrystallization dynamics, connected with initial structural differences and the presence/absence of taut-tie chains. Radiation-induced increase in the crystallinity (more than 25% of initial value) for the quenched samples is noticeable at low radiation doses.