High density polyethylene and poly(ethylene terephthalate) in situ sub-micro-fibril blends as a matrix for wood plastic composites

Wood plastic composites were prepared based on in situ formed poly(ethylene terephthalate) (PET) sub-micro-fibril reinforced high density polyethylene (HDPE) matrices, using a two-step reactive extrusion technology. The use of ethylene-glycidyl methacrylate (E-GMA) copolymer improved phase compatibility in the sub-micro-fibril blends (SMFBs) with 75% HDPE and 25% PET. Most of in situ formed PET fibrils were less than 500 nm in diameter. The PET fibrils obviously increased mechanical properties of the blend, especially the moduli. The subsequent addition of 40 wt.% wood flour did not influence the size and morphology of PET fibrils, and the fibrils and wood fibers had a synergic reinforcement effect on composite properties. Compared with the HDPE/wood composites, the SMFB/wood system had 65% higher tensile strength, 95% higher tensile modulus, 42% higher flexural strength, and 64% higher flexural modulus, respectively. The technology offers a way to use engineering plastics (i.e., PET) for high performance WPC manufacturing. (C) 2011 Elsevier Ltd. All rights reserved.