Mechanical, morphological and thermal properties of linear low density polyethylene/poly(lactic acid) blends

Melt blending of linear low density polyethylene (LLDPE) and polylactic Acid (PLA) were performed in a twin screw extruder. The blend compositions were prepared in the ratios of 0/100; 15/85; 25/75; 35/65 and 50/50 of PLA/LLDPE. The objective of this work is to study the effect of different content of the PLA on the properties of the blends. The phase morphology and mechanical properties of the thermoplastic blend samples were examined. The blend compositions were optimized by tensile and Izod impact tests. The thermal properties were examined by TGA and DSC. The tensile strength result of the blend with the addition of 50 wt.% PLA decreased by 57% as compared to the neat LLDPE. Examination of images from fracture surface of tensile specimen using scanning electron microscope (SEM) showed the presence of fibrous surface (ductile fracture) for sample with higher content of LLDPE. The TGA results for the PLA/LLDPE blends samples shows two degradation steps of mass loss during heating. DSC results for all polymer blends show two peaks of melting temperature at 125 °C and 165 °C which correspond to melting temperature (Tm) of LLDPE and PLA respectively. This implies that the blends are immiscible.