Fatty acid-based comonomers as styrene replacements in soybean and castor oil-based thermosetting polymers

In this study, a fatty acid-based comonomer is employed as a styrene replacement for the production of triglyceride-based thermosetting resins. Styrene is a hazardous pollutant and a volatile organic compound. Given their low volatility, fatty acid monomers, such as methacrylated lauric acid (MLA), are attractive alternatives in reducing or eliminating styrene usage. Different triglyceride-derived cross-linkers resins were produced for this purpose: acrylated epoxidized soybean oil (AESO), maleinated AESO (MAESO), maleinated soybean oil monoglyceride (SOMG/MA) and maleinated castor oil monoglyceride (COMG/MA). The mechanical properties of the bio-based polymers and the viscosities of bio-based resins were analyzed. The viscosities of the resins using MLA were higher than that of resins with styrene. Decreasing the content of MLA increased the glass transition temperature (Tg). In fact, the Tg of bio-based resin/MLA polymers were on the order of 60°C, which was significantly lower than the bio-based resin/styrene polymers. Ternary blends of SOMG/MA and COMG/MA with MLA and styrene improved the mechanical properties and reduced the resin viscosity to acceptable values. Lastly, butyrated kraft lignin was incorporated into the bio-based resins, ultimately leading to improved mechanical properties of this thermoset but with unacceptable increases in viscosity.