Mechanical and thermal properties of poly(methyl methacrylate)-grafted-oil palm empty fruit bunch/talc hybrid filled poly(vinyl chloride) composites

Abstract

The aim of this study is to investigate the mechanical and thermal properties of single and hybrid fillers filled poly(vinyl chloride) (PVC) composites. Graft copolymerization of poly(methyl methacrylate) (PMMA) onto oil palm empty fruit bunch (OPEFB) was carried out under nitrogen environment using the free radical initiation technique. Soxhlet extraction was used to remove the PMMA homopolymer from the grafted copolymer. The presence of PMMA functional groups in Fourier transform infra red (FTIR) spectra of grafted OPEFB at peak around 1730 cm-1 proved that grafting process was successfully done. The single fillers (grafted OPEFB, ungrafted OPEFB and talc) and hybrid fillers (grafted OPEFB/talc and ungrafted OPEFB/talc) loadings from 0 to 20 phr were pre-mixed with PVC using a high speed mixer. Methyl butadiene styrene (MBS) impact modifier was also added at 10 phr for the impact strength study. The dried blend formulations were milled into sheets using a two roll mill at 170 °C and then hot pressed at 190 °C. The tensile, flexural, impact strength and elongation at break of hybrid composites decreased as the filler content increased. Both, the tensile and flexural modulus of the hybrid composites are increased tremendously compared to the single composites. Adding MBS increased the impact strength of the single and hybrid composites. Differences in surface morphology between the grafted and ungrafted OPEFB were observed. The glass transition temperature (Tg) of the hybrid composites shifted to higher temperature compared to single composites. The storage modulus of talc filled PVC showed the highest storage modulus compared to other composites. Hybrid PVC composites had better thermal stability than single composites. The increase of water resistance of the hybrid composites proved good filler-matrix interaction. Overall, the study showed that the hybrid PVC composites had good mechanical and thermal properties compared to the single filler PVC composites.