Preparation and Characterisation of Sustainable Wood Plastic Composites Extracted from Municipal Solid Waste

polymers Article Preparation and Characterisation of Sustainable Wood Plastic Composites Extracted from Municipal Solid Waste Shahnaz Shahani 1 , Zhongquan Gao 1, *, Mumtaz A. Qaisrani 2 , Naveed Ahmed 3 , Haseeb Yaqoob 2 , Fuad Khoshnaw 4 and Farooq Sher 5, * Citation: Shahani, S.; Gao, Z.; Qaisrani, M.A.; Ahmed, N.; Yaqoob, H.; Khoshnaw, F.; Sher, F. Preparation and Characterisation of Sustainable Wood Plastic Composites Extracted from Municipal Solid Waste. Polymers 2021, 13, 3670. https://doi.org/ 10.3390/polym13213670 Academic Editor: Judith Martín-de León Received: 8 August 2021 Accepted: 6 October 2021 Published: 25 October 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China; [email protected] 2 Department of Mechanical Engineering, Khwaja Fareed University of Engineering and Information Technology, Rahim Yar Khan 64200, Pakistan; [email protected] (M.A.Q.); [email protected] (H.Y.) 3 US Pakistan Centre for Advanced Studies in Energy (USPCAS-E), National University of Sciences and Technology, Islamabad 44000, Pakistan; [email protected] 4 School of Engineering and Sustainable Development, Computing, Engineering and Media, De Montfort University, Leicester LE1 9BH, UK; [email protected] 5 Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK * Correspondence: [email protected] (Z.G.); [email protected] (F.S.) Abstract: Municipal solid waste (MSW) contains plastic waste that can be used as a sustainable green substitute to reduce oil footprints, CO 2 emissions, and environmental pollution. This study aims to recycle plastic waste by manufacturing wood-plastic composites and to improve its mechanical properties by using additives, coupling agents, and lubricants. These composites are prepared by mixing 40–70% of wood flour with 20–25% of a polymer matrix. Wood was degraded at 220 ◦ C, and then the composites were processed at 50 ◦ C. The manufacturing process carried out in the study involved wood waste meshing, drying, shredding, drying, trimming, filling, blending, compounding, and extrusion moulding. The compounding of composites was accomplished in twin-screw extruders. Once the mixture was uniformly mixed, its final shape was given by a two-step extrusion moulding. Previously, researchers aimed at enhancing the mechanical properties of the composites, but our research focus was to improve their durability for different industrial applications. The results suggest that the impact strength is 17 MPa with 50% of wood powder ratio while the maximum value for the tensile strength is 32.5 MPa. About 50% of an increase in wood powder resulted in 8.1% bending strength increase from 26.1 to 32.8 MPa. Reducing the plastic matrix and the wood- particles water swelling ratio resulted in better mechanical properties. The wood species also affected the mechanical properties with their excellent dimensional stability and less variability. A high proportion of wood fibre tends to increase its steady-state torque and viscosity. The mechanical properties against different wood-flour proportions indicate that composite materials exhibit superior water swelling behaviour and extrusion quality. Keywords: sustainable chemical engineering; wood plastic; composite materials; municipal solid waste; extrusion; sustainable polymers; moulding process 1. Introduction At present, the world is facing environmental issues due to the municipal solid waste (MSW) generation by-products of human activities. As resource consumption has increased, the problem of high production and non-biodegradability of plastic is the reason behind the rapid reduction of natural resources. The World Bank’s static data show that 1.3 billion tons of MSW is produced worldwide and it is expected to increase to 2.2 billion tons by 2025 and could reach 3.40 billion tons by 2050 [1–3]. About 6.5 billion tons of plastic wastes are produced every year globally in the form of disposed polythene bags, masks, and Polymers 2021, 13, 3670. https://doi.org/10.3390/polym13213670 https://www.mdpi.com/journal/polymers