Soybean oil-based thermosets with N-vinyl-2-pyrrolidone as crosslinking agent for hemp fiber composites

Soybean oil-based thermosets from acrylated epoxidized soybean oil (AESO) with a highly reactive vinyl monomer, N-vinyl-2-pyrrolidone (NVP), as crosslinking agent to replace styrene (St) were formulated for the fabrication of hemp fiber composites. The theoretical miscibility of NVP-AESO and St-AESO systems were discussed based on the group contribution method. The AESO resin with 30 wt% NVP exhibited a slightly higher viscosity than the counterpart with St, while the maximum curing temperature of the former was considerably lower than that of the latter. The composites from 20 wt% NVP resin gained comparable mechanical properties and higher glass transition temperature (Tg) to the composites with 30 wt% St. Further increase in NVP usage to 40 wt% resulted in the composites with higher tensile strength, tensile modulus, flexural strength, flexural modulus, storage modulus, and Tg of 29.6%, 22.4%, 22.5%, 20.6%, 21.6%, and 47.2%, respectively, when compared to those of the St-based composites.