Resins from Soybean Oil-Based Additives for Natural-Fiber Sheet Molding Compound (SMC) Composites: Synthesis and Characterization

摘要

Unsaturated polyester is the most common resin type used in sheet molding compound (SMC) for automotive applications. Research is ongoing at Mississippi State University (MSU) to use natural cellulosic fibers to replace the fiberglass for the SMC composites. Thermosetting resins were synthesized from the soybean oil, which was suitable to build not only the crosslink between the functional groups on the unsaturated polyester chains, but also the free radicals to the hydroxyl group on the surface of kenaf fibers. Maleinated acry-lated epoxidized soybean oil (MAESO) was synthesized by free radical polymerization using the hydroxyl groups on the acrylated epoxidized soybean oil (AESO) reacted with maleic anhydride (MA). MAESO was blended into the unsaturated polyester resin to fabricate the natural fiber-reinforced polymer composites. Laminated sheet molding compound (LSMC) process was used to fabricate the composites. Mechanical properties such as flexural strength and modulus, tensile strength and modulus were evaluated to obtain an optimum and comparative SMC formulation for natural fiber composites in automotive applications. Fracture morphology of the composites was also examined to address interfacial compatibility at the interface between the hydroxyl group-rich surface of kenaf fibers and synthesized resin matrix.