A styrene-free soybean oil-based thermosetting (IM-AESO) resin was formulated from acrylated epoxidized soybean oil (AESO) and methacrylated isosorbide (IM) as a comonomer. The IM was synthesized from isosorbide with methacrylate anhydride (MAA) by a solvent-free, ultrasonic-assisted method. The formulated IM-AESO blend was further modified with MAA to impart the resin (IM-MAESO) with higher degree of unsaturation through replacing the hydroxyl groups of AESO with methacrylate groups. Results indicated that both the IM-AESO and IM-MAESO resins had much lower viscosities, activation energies, and curing temperatures as well as higher polymerization rates and curing degrees than pure AESO due to the incorporation of IM as a reactive diluent. The combination of stiff IM and flexible AESO resulted in biobased networks with superior flexural strengths, flexural moduli, flexural strains, storage moduli, and glass transition temperatures. MAA modification gave rise to the crosslinking degree and hence flexural properties and dynamic mechanical properties of the resins when curing. The biobased thermosets were used as matrices for the preparation of hemp fiber- and bamboo fiber-reinforced composites to evaluate the effects of resin composition and fiber type on the performance of the composites. The composites from hemp fibers with the thermosets indicated much higher flexural strengths, flexural moduli, flexural strains, storage moduli, and glass transition temperatures than those from bamboo fibers. MAA modification for AESO significantly increased the storage modulus and glass transition temperature of the composites, but showed an insignificant effect on flexural properties of the composites.

Styrene-free soybean oil-based thermosets and their natural fiber composites

253rd National Meeting (2017)

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