Wood fiber reinforced polyethylene and polypropylene composites with high modulus and impact strength

Wood plastic composite with high modulus and impact strength were manufactured by combining polyethylene (PE) or polypropylene (PP) with wood fiber (WF) using twin-screw extruder techniques. The advantage of using low melt viscosity polymer matrices is that it enhances the modulus and reduces the overall viscosity of the system. SEM analysis of the composites indicates that the polymer molecules penetrate into the vessels and cracks of the cellulose fiber, which decreases the number of voids and produces a higher density composite with improved mechanical performance. The addition of maleic anhydride-grafted polyolefin as a compatibilizer improves the level of adhesion between the wood fiber and the polyolefin matrix. The impact strength of the composites with compatibilizer is 60% higher than those without. Young's moduli of WF/PE and WF/PP with compatibilizer were 4.4 and 5.4 GPa, respectively, meanwhile the impact strengths of WF/PE and WF/PP were 44 and 24 J/m, where the WF content was 50wt%.