EFFECTS OF STYRENE-METHYL METHACRYLATE/STYRENE-BUTADIENE COMPOUND ON MECHANICAL PROPERTIES OF POLY(VINYL CHLORIDE)

Abstract

Generally, poly(vinyl chloride) (PVC) without the addition of plasticizer or impact modifier is rigid and brittle. The aim of this research was to improve the mechanical properties of PVC using styrene-methyl methacrylate/styrene-butadiene blend (SMMA/SBR rubber) as an impact modifier. PVC containing SMMA/SBR rubber having SMMA/SBR contents of 2.5, 5, 7.5 and 10 phrs were prepared using two-roll mill set the conditions as follows: temperature of 170 °C and time of 5 min. Then, compression molding was carried out to prepare testing samples. FTIR analysis of SMMA/SBR rubber containing PVC samples showed the slight shift of absorption peak of methyl methacrylate carbonyl group (C=O) from 1730 to 1736 cm-1, indicating the compatibility between additives and PVC. The effects of SMMA/SBR rubber on mechanical properties including impact strength, tensile properties, flexural strength, hardness and heat distortion temperature (HDT) were evaluated by standard tests. The impact strength of SMMA/SBR rubber containing PVC increased significantly with an increase in the SMMA/SBR content (ex. 5 phr and 10 phr SMMA/SBR rubbers produced impact strengths of 3.30 and 6.38 kJ/m2 respectively), resulting from the action of SMMA/SBR rubber phase as an impact modifier as revealed by SEM images. Regarding to the modulus, tensile strength, flexural strength and hardness, these values decreased with an increase in the SMMA/SBR rubber content. In contrast, the HDT slightly increased and elongation at break gradually increased. These results were related to the weak interfacial adhesion between PVC matrix and rubber phase. Furthermore, the migration ability of DINP in PVC containing SMMA/SBR rubber was relatively faster than those in neat PVC due to the fact that DINP migration ability in the interphase was faster than those DINP in PVC matrix.