Grafted triglycerides comprising an acrylated triglyceride grafted with a fatty acid residue containing 4 to 28 carbon atoms. Also described are methods for making a grafted triglyceride and for curing a material selected from vinyl esters and unsaturated polyesters and mixtures thereof and optionally a reactive diluent. The method includes the steps of mixing a grafted triglyceride of the present invention with a material selected from vinyl esters, unsaturated polyesters and mixtures thereof to form a mixture, and curing the mixture to form a cured resin system. A cured resin system comprising a cured product obtained by the foregoing method and composites containing the cured product and a filler or reinforcing material are also disclosed. This method also includes use of the grafted triglycerides to make toughened resin and composite systems with reduced hazardous air pollutants without significantly reducing the glass transition temperature and significantly increasing the viscosity.