Thermal degradation and physical aging of linear low density polyethylene and poly(l-lactic acid) blends

Abstract

Abstract Melt blending of linear low density polyethylene (LLDPE) and poly(l-lactic acid) (PLLA) was performed in an extrusion mixer with post extrusion blown film attachment with and without a compatibilizer-maleic anhydride grafted low density polyethylene. The blend compositions were optimized for tensile properties as per ASTM D 882-91. Based on this, LLDPE 80 (80 wt% LLDPE and 20 wt% PLLA) and M-g-L 80/4 (80 wt% LLDPE, 20 wt% PLLA and 4 parts compatibilizer/100 parts of resin were found to be an optimum composition. The thermal gravimetric profile and thermal endurance of these blends were characterized as per ASTM E1641-07 and E1877-05. The effect of physical aging on mechanical and thermal properties of these blends was evaluated. The PLLA showed the highest Arrhenius activation energy, relative thermal index and strongest thermal endurance of all samples followed by M-g-L 80/4 and LLDPE 80. The thermo-oxidation coefficient improved with addition of compatibilizer in the blends. With increasing pH, the hydrolytic degradation of the blend films increased, while both the tensile strength and the elongation at the break of the blend films decreased.