Comparison of Mechanical Properties and Water Absorption Test on Injection Molding and Extrusion - Injection Molding Thermoplastic Hemp Fiber Composite

Abstract Natural polymer-based composites offer many notable benefits such as biodegradability, manageability, biocompatibility and adaptability over conventional petroleum-based composites made from engineered fibers. This explorative research article reports the method of preparation of biodegradable composite from hemp fiber with polylactic acid (PLA) by both injection molding process and extrusion-injection molding process. The composites are reinforced with 25% hemp fiber by weight and 75% PLA matrix for both manufacturing processes. The mechanical properties of the prepared composites like tensile strength, flexural strength and impact strength as well as the results of the water absorption test are examined for both injection molded and extrusion-injection molded composites. The interfacial bonding strength between the fiber and matrix is analyzed by scanning electron microscopy (SEM). The results reveal that the extrusion-injection molded composite possesses higher mechanical strength and better bonding with matrix than the injection molded composite. Thus, extrusion-injection molding technique is recommended for PLA matrix composite preparation which finds specific application in the packaging, construction, automobile industries, etc.