Epoxy resins and composites from epoxidized linseed oil copolymers with cyclohexene oxide

Abstract

New materials were made by copolymerization of epoxidized linseed oil (ELO) and cyclohexene oxide (CHO) catalyzed by tris(pentafluorophenyl)borane (BCF). Pure polymerized ELO and polymerized CHO were prepared to study reactivity and properties of starting components in the presence of the selected catalyst. The catalyst furnished high conversion of CHO at a very high rate. Properties of epoxy resins are improved by increasing the amount of CHO. The copolymerization in bulk is fast at room temperature with increasing CHO content, turning violent even at low catalyst loadings, hence, the amount of CHO is limited to about 10% to allow for manageable pot life and heat management. Post-curing is required for improving mechanical properties. The materials are hard, transparent, clear glasses, with glass transitions around 45 °C. Tensile strengths of 27 MPa and flexural moduli over 1 GPa were observed. The feasibility of using these highly hydrophobic triglyceride-based epoxy resins in glass-reinforced composites and foams was demonstrated successfully. Potential applications for these novel systems are in optical materials, potting, encapsulating, and casting resins, foams and as matrix resins in composites. The preparation involves a simple mixing process and an inexpensive epoxidized vegetable oil.