Plastic deformation assessment of sawdust-rPET composites under bending load

Due to the scarcity of raw wood materials and the current state of the market's economic growth, the development of novel composite materials utilizing alternate raw material sources is crucial. Sawdust and waste polymers, such as empty bottles, are excellent sources of low-cost materials for making useful and cost-effective wood-plastic composites. This article's main goal is to ascertain how different filler contents and percentages, as well as two different types of polymer matrices, affect the mechanical properties of sawdust-reinforced composite in the plastic range of force-deflection diagram of bending test. Sawdust-plastic composites based on waste polyethylene terephthalate (PET) and biodegradable polymers were produced by the flat press method and prepared for mechanical testing. This study examined comprehensively the plastic range of the three-point bending test. The limit of proportionality (LOP), bending strength or modulus of rupture (MOR), plastic potential “P_P”, four tangent moduli as well as approximated plastic work “A_W”, total plastic work “B_W” and the values of approximation error “ΔW” were measured using three-point bending test. The finite element method (FEM) analysis was also conducted to prepare a numerical model and compare its results with experimental results. According to the study's findings, the bending features of rPET-reinforced composites declined as the filler percentage increased. Among all the rPET-reinforced composites, the 40 % sawdust filled composite had the best mechanical performance. When compared to the rPET matrix, the biodegradable polymer demonstrated superior mechanical performance in the plastic zone of the bending test. However, both the 40 % sawdust-filled rPET composite and the biodegradable composites filled with 50 % sawdust fulfilled the ANSI standard as an appropriate replacement for medium-density fiberboard (MDF) for interior applications.