Rotational Molded Maple/Hemp Fiber-Reinforced LLDPE Hybrid Composites: Morphological and Mechanical Properties

Abstract

Background: Rotational molding is still a growing sector of the general polymer production. But to further improve this process, the design and production of new products with better properties must be performed. For this reason, the development of polymer composites is of interest, especially when natural fibers are used. In this case, the addition of rigid particles leads to higher mechanical properties compared to the base matrix. Unfortunately, very limited information on the production of rotomolded composites can be found in the literature. Objective: To develop rotomolded hybrid composites based on natural fibers (hemp and maple wood) in a thermoplastic resin (linear low density polyethylene). Method: The mechanical properties of the final parts were measured as a function of fiber concentration, size, ratio and surface treatment via maleic anhydride addition in solution. Results: The optimum processing conditions (rotational speed, oven temperature, and cycle time) and composition were obtained for the materials studied. The production of hybrid composites was also investigated by using a blend of both fibers with different sizes to further improve the properties of the rotomolded parts. Conclusion: The best results were obtained at 20% wt. when a 75/25 ratio of maple/hemp fibers was used. The tensile modulus and strength increased by 63 and 17% respectively compared to the matrix. Also, the impact strength was improved by 16% at 27.5% wt. when a 75/25 ratio of maple/hemp fibers was used compared to untreated fibers. Keywords: Hemp, hybrid composites, LLDPE, maple, rotomolding, surface treatment.