The effect of paper sludge, content and polymer types on the physical properties of wood- plastic composites

In this study two types of paper sludge, prepared by Mazandaran wood and paper company and Latif papermaking company along with wood flour utilized as plastic filler in polypropylene and high density polyethylene based composites. Weight percentage ratio of coupling agent, polymer and filler were kept constant 2%, 38%, and 60% in all formulations, respectively and composites were prepared by varied ratios of paper sludge and wood flour include 0: 60, 40: 20, 20: 40, and 60:0. Density, water absorption and thickness swelling of injection molded composites then measured. The results indicated the gradual substitution of wood flour by paper sludge increases the density of composites, and improves their water absorption and thickness swelling. The ratio of paper sludge to wood flour had statistically significant difference on all these properties, but the paper sludge type showed statistical difference just on the density of composites. Further to that, polypropylene based composites demonstrated lower density, water absorption and thickness swelling compared to high density polyethylene based ones.