ABSTRACT:The technical viability of using rice husk ashes (RHA) as alternative fillers in polypropylene was studied. Three types of RHA, white rice husk ash (WRHA), black rice husk ash (BRHA) and amorphous rice husk ash (AMRHA) at 10-40wt% filler loading were investigated. The RHA composites were compounded by twin screw compounders and the mechanical properties of the composites evaluated. Incorporation of the RHA fillers increased the flexural modulus of the composites, particularly the BRHA composities. Modulus of the RHA composites were found to be in good agreement with theoretical values predicted by equation of Lewis and Nielsen. The increase in modulus was offset by lowering of the tensile strength, elongation at break and impact properties. Theoretical treatments of the ultimate tensile strength performed based on the model proposed by Nicolai and Nicodemo showed reasonably good agreement. The mechanical properties of the RHA composites were of comparable values with the prepared polypropylene composites filled with commercial Neu burg silica. Transformation of the crystalline RHA to amorphous RHA resulted in composites with improved tensile strength. No coupling agent was used in this study.KEY WORDS Rice Husk Ash / Filler / Polypropylene / Composites / Mechanical Properties/ Incorporation of fillers into a polymer is known to cause substantial changes to the mechanical properties of the composities. As polymer composites are increasingly used in various mechanical applications, the mechanical properties are perhaps the most basic and important behaviors that need to be investigated in order to evaluate the performance of the composities when they are subjected to stress.term of modulus of elasticity, ultimate tensile strength, impact resistance, etc. The term mechanical is applied for this category of properties because they are often used to indicate the suitability of a material for use in mechanical applications, parts that carry a !oak, absorb shock, etc. 1 The principal objective of this study is to investigate the technical viability of using the rice husk ashes which are usually regarded as waste products as alternative low cost fillers in polypropylene. In this investigation, the mechanical properties of the polypropylene/ rice hush ash (RHA) composites are investigated in term of their modulus, tensile and impact properties. Modulus is a measure of The basic characterization of the mechanical properties are usually determined by tests resulting in various deformation versus stress dependencies, for instance the stressstrain diagrams. Examinations of such dependencies yield mechanical characteristics in * To whom correspondence should be addressed. 1002Mechanical Properties of RHA/PP Composites the stiffness of a material subjected to shear loading. Addition of filler normally improves the stiffness of the composities. Tensile test is among the most widely employed test method to characterize the mechanical properties of composites. From such a test, enomorous amount of important information m...

Abstract. The mechanical properties and crystalline characteristics of polypropylene (PP) and nano precipitated calcium carbonate (NPCC) nanocomposites prepared via melt mixing in an internal mixer and melt extrusion in a twin screw extruder, were compared. The effect of maleic anhydride grafted PP (PP-g-MAH) as a compatibiliser was also studied using the internal mixer. At low filler concentration of 5 wt%, impact strength was better for the nanocomposites produced using the internal mixer. At higher filler loading of more than 10 wt%, the extrusion technique was more effective to disperse the nanofillers resulting in better impact properties. The impact results are consistent with the observations made from Scanning Electron Microscope (SEM) morphology study. As expected, the flexural modulus of the nanocomposites increased with filler concentration regardless of the techniques utilised. At a same filler loading, there was also no significant difference in the moduli for the two techniques. The tensile strength of the mixed nanocomposites were found to be inferior to the extruded nanocomposites. Introduction of PP-g-MAH improved the impact strength, tensile strength and modulus of the mixed nanocomposites. The improvements may be attributed to better interfacial adhesion, as evident from the SEM micrographs which displayed better dispersion of the NPCC in the presence of the compatibiliser. Though NPCC particles have weak nucleating effect on the crystallization of the PP, addition of PP-g-MAH into the mixed nanocomposites has induced significant crystallization of the PP.

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