Development of wood-substtuted composites from PVC

Abstract

Wood plastic composite is generally a combination of thermoplastic and natural filler. This kind of thermoplastic composites evolves as structural polymer composites, which have many beneficial properties such as low density and good mechanical properties, as well as good insulation and environmental resistance. In this study, three species of woodflours i.e. rubber wood, mixed wood, and teak wood, are used as a reinforcing agent in a polyvinylchloride matrix because these woods are abundant and widely grown in Thailand. The effects of particle loading (0-60 phr), particle sizes (<150 to 600-850 µm), and species of woodflours on mechanical properties, thermal properties, water absorption, and weathering aging behaviors of the obtained PVC wood composites are characterized. The results reveal that, the composite strengths decrease about 14% with increasing particle loading up to 60 phr but moduli increase about 40% of the unfilled PVC matrix. The decrease of strength of PVC wood composites is attributed to some interfacial defects between the woodflour and the PVC matrix. The effects of particle sizes on the mechanical properties of PVC wood composites are found to decrease with increasing the particle size up to 600-850 µm. In addition, the woodflour types have no significant effect on the mechanical and thermal properties of the PVC wood composites. However, the types of woodflours can cause the variation in color and texture of the obtained composites. Furthermore, the natural weathering after 1 month exposure in Bangkok, Thailand, results in the decrease in the composites flexural strength about 5% and the composites flexural modulus about 9% i.e. a particle loading of 60 phr. All the specimens also show a significant color fading. Finally, the suitable formulations of PVC wood composites are to use a woodflour loading of 40 phr at average particle size of 180-250 µm and 250-450 µm.