Comparison of Resistance and Biodegradability Properties of Wood-Plastic Composites from Wood Flour/PHB/HDPE/Starch

Abstract

In this study, mechanical and biodegradability properties of wood-plastic composite were investigated. Beech wood flour (WF) 40 wt% was used as a reinforcing base material, maleic anhydride (MA) as a coupling agent, and nano clay to improve the properties were added. The polymer studied was polyhydroxy-butyrate (PHB) and the other polymer was high-density polyethylene (HDPE). Three groups of composites were produced, in two groups each of the polymers alone and in the third group a combination of two types of polymers was used as a matrix. Starch 8 wt% and 12 wt% was used instead copolymer. The specimens were mixed using a twin-screw extruder, made with an injection-molding machine, and subjected to mechanical tests: tensile strength and modulus, bending strength and modulus, impact resistance tests and * Corresponding author Wood and Fiber Science, 54(2), 2022, pp. 81-89 https://doi.org/10.22382/wfs-2022-09 biodegradability tests. In mechanical properties, it was observed that wood-plastic composite with PHB base material has lower resistance properties than composites containing HDPE. With the addition of starch, all resistance properties were significantly reduced compared with the control sample without starch in all three groups of composite samples. Starch could not play the role of copolymer well in any of the groups. The third group of samples showed better results in terms of mechanical strength resistance properties than the first group. Tensile strength and Modulus, bending strength and Modulus, impact resistance increased compared with the first group. In the biodegradability test, the samples were buried at a height of 25 cm for three months. Weight loss was due to the destruction of WF, starch, and natural polymers by soil microorganisms. The weight loss trend of the samples was increasing until the end of the second month and then decreasing.