Effect of coupling agents on rice-husk-filled HDPE extruded profiles

Lignocellulosic composites are diversifying their applications into various fields as they can meet the requirements of the respective applications by changing the matrix, fiber resource and processing ingredients. In this research work we explored the potential of extruded rice-husk-filled high density polyethylene (HDPE) composite profiles for structural applications. The structure and the properties of the interface in fiber-reinforced composites play a crucial role in determining the performance properties of the composites. An optimum degree of adhesion between the fiber and the matrix is required for efficient stress transfer from the matrix to the fiber. Generally, coupling agents are used to improve the adhesion between lignocellulosic filler and the polymer matrix in structural composite materials. In this study, four different coupling agents based on ethylene-(acrylic ester)-(maleic anhydride) terpolymers and ethylene- (acrylic ester) - (glycidyl methacrylate) terpolymers were used to enhance the performance properties of the composites. The results indicated that these coupling agents enhanced the tensile and flexural strength of the composites significantly, and the extent of the coupling effect depends on the nature of the interface formed. Incorporation of coupling agents enhanced the resistance to thermal deformation and the water absorption properties of the composite, whereas it reduced the extrusion rate significantly. Among the four coupling agents used, EGMA1-the one with a glycidyl methacrylate functional group and without any methyl acrylate pendant group on the polymer backbone-was found to be the best coupling agent for the rice-husk-filled HDPE composites. (C) 2004 Society of Chemical Industry.