Optimization of mechanical, thermal and hydrolytic degradation properties of Poly (lactic acid)/Poly (ethylene-co-glycidyl methacrylate)/Hexagonal boron nitride blend-composites through electron-beam irradiation

摘要

The main objective of this work is to investigate the influence of electron beam irradiation on mechanical, thermal and hydrolytic degradation properties of Poly (lactic acid) (PLA)/Poly (ethylene-co-glycidyl metha-crylate) (PEGM)/Hexagonal boron nitride (HBN) blend-composites for optimizing the properties. The previous studies have reported that the blending of PLA and PEGM with weight ratio (PLA: PEGM) (80:20) reduce the brittleness and improve the toughness. However, the heat deflection temperature (HDT) and other tensile properties were found to be reduced. It was found that HDT can be improved with the incorporation of HBN particles. So far, the effect of PLA/PEGM blending on the hydrolytic degradation properties of PLA was not studied. Hence, in the present work, the hydrolytic degradation test on prepared blend and blend-composites was performed. It is observed that blending of PEGM with PLA significantly retards the hydrolytic degradation of PLA. Further reduction in the hydrolytic degradation of PLA was observed in the blend-composites. To analyze the impact of electron beam irradiation, the prepared specimens of pure PLA, PLA/PEGM blend and PLA/PEGM/ HBN blend-composites were irradiated to high energy (4.50 MeV) electron beam (E-beam) at different radiation doses. It is observed from the DSC thermograms of irradiated PLA, PLA/PEGM blend and PLA/PEGM/HBN blend-composites; the glass transition temperature (T-g) is shifted to higher temperature with irradiation. This is attributed to the polymer chains scission and crosslinking caused by E-beam irradiation. Interestingly, the E-beam irradiated blend-composites having a high HBN concentration (i.e. 5 phr and 10 phr) showed higher T-g as compared to the other unirradiated and irradiated samples. Further, the notched impact strength and HDT were remarkably improved with E-beam irradiation in the case of 5 phr and 10 phr blend-composites. The improvement in the yield strength and tensile modulus has also been noticed in the case of E-beam irradiated blend-composites as compared to unirradiated blend-composites. The E-beam irradiation of prepared blend and blend-composites also helps to accelerate the hydrolytic degradation. The E-beam irradiated PLA/PEGM/HBN 5 phr blend composite shows high HDT, high notched impact strength, good yield strength, better tensile modulus and also exhibit fast hydrolytic degradation as compared to the other E-beam irradiated blend and blend-composites and unirradiated PLA. Hence, the E-beam can be employed to optimize the mechanical, thermal and degradation properties of the final product as per the desired application.