Polypropylene (PP)-based wood polymer composites: Performance of five commercial maleic anhydride grafted PP coupling agents

Five different maleic anhydride grafted polypropylene (PP) coupling agents (CAs) have been tested in wood polymer composites with wood contents of 40% and 60%. The tested CAs cover a wide range of backbone molecular weight (M w 55–181 kDa) and also vary in MA graft level (0.5–1.5%). Furthermore, one PP copolymer-based product is among them. Mechanical properties (flexural strength, impact strength and heat deflection temperature) and water absorption (WA) have been evaluated as responses. Finally, dynamic rheological measurements on several compounds have been performed. The results show that the backbone polymer structure of the CA is the most important factor for its efficiency. Molecular weight seems to have an influence on WA properties. As regards to rheological measurements, a lubricant-like effect of a CA indicates a reduced capability for compatibilization at the interface.