Effects of PE-g-MA on Tensile Properties, Morphology and Water Absorption of LDPE/Thermoplastic Sago Starch Blends

Abstract

Effects of polyethylene-grafted maleic anhydride (PE-g-MA) on tensile properties, morphology and water absorption of LDPE/ Thermoplastic sago starch (TPSS) blends were studied. TPSS was prepared by mixing starch (65 wt. %) and glycerol (35 wt. %) and stored overnight at room temperature. The mixture then was melt-compounded using a heated 2 roll-mills at 150°C for 10 minutes. LDPE/TPSS blends with different TPSS loadings, with and without the addition of PE-g-MA were prepared by using a Haake Rheomix mixer at 150°C. All mixing were carried out for 10 minutes at a rotor speed of 50 rpm. Tensile test specimens were cut out from the compression molded sheets. Results indicated that the mixing torque of LDPE/TPSS blends reduced with increasing TPSS loading. The tensile strength and elongation at break of LDPE/TPSS/PE-g-MA blends were greater than LDPE/TPSS blends particularly at higher TPSS loadings. The interfacial properties between LDPE and TPSS were improved after PE-g-MA addition as evident from the tensile fracture surface morphology using a scanning electron microscopy. Chemical functional groups formed after the addition PE-g-MA were studied with FTIR. Equilibrium water uptakes for LDPE/TPSS/PE-g-MA blends were higher than those of LDPE/TPSS blends.