APPLICATION OF RICE HUSK ASH AS FILLERS IN POLYPROPYLENE - EFFECT OF TITANATE, ZIRCONATE AND SILANE COUPLING AGENTS

The effects of applying titanate (LICA 38), zirconate (NZ 44) and sila nes (PROSIL 2020 and PROSIL 9234) coupling agents to rice husk ash (RH A) in polypropylene composites are described. RHA consists predominant ly of silica. Polypropylene composites of 10-40 wt% filler loadings we re compounded using a Brabender twin screw extruder. The melt flow ind ex decreased with filler content but for the composite treated with th e built-in peroxide generator (PROSIL 2020), the reverse was true. For most of the composites, the flexural modulus increased with filler co ntent while tensile strength, elongation at break and Izod impact stre ngth showed a decrease. PROSIL 2020 coupling agent improved the tensil e strength of the composites most, while the impact properties were en hanced by the LICA 38 and the PROSIL 9234 coupling agents. None of the coupling agents increased the stiffness of the composites except for NZ 44 at maximum filler loading. The mechanical properties of the RHA composites were compared to polypropylene composites filled with comme rcial fumed silica and talc,