Styrene-Free Soybean Oil Thermoset Composites Reinforced by Hybrid Fibers from Recycled and Natural Resources

The development of sustainable fiber-polymer composites using renewable or recycled feedstocks has received considerable attention from both academia and industry. In this study, a soybean oil based thermoset composite is demonstrated, which is water-degradable, styrene-free, and exhibits excellent mechanical property. Hybrid recycled polyethylene terephthalate, bamboo, polyester and ES (ethylene-propylene side by side) fibers are used as reinforcements. Acrylated epoxidized soybean oil is used as the polymer matrix. Glyceryl trimethacrylate is synthesized and used as a reactive diluent to replace the volatilizable and toxic styrene which is a widely used industry practice. It is found that the prepared composites exhibit excellent toughness (∼50 kJ/m² impact strength), satisfactory tensile strength (∼30 MPa), and suitable T_g (>110 °C). More excitingly, the cross-linked polymer matrices in composite can be degraded in water via an autocatalytic manner under a mild 190 °C, while the polymer matrices are stable at service temperature. This work provides a feasible way to develop renewable and recyclable polymer composites to satisfy sustainability demands.