Shape memory polymers from bio-based benzoxazine/epoxidized natural oil copolymers

In this research, shape memory polymers (SMPs) fabricated from bio-based benzoxazine resins, i.e. vanillin-furfurylamine-containing benzoxazine (V-fa) and eugenol-furfurylamine-containing benzoxazine (E-fa) resins, and bio-based epoxy resin, i.e. epoxidized castor oil (ECO), are investigated. Effects of ECO mass concentrations on curing characteristics, thermal stability, dynamic mechanical properties, and shape memory properties are determined by differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and shape memory tests, respectively. Storage moduli at the glassy state and glass transition temperatures (T _g) of V-fa/ECO and E-fa/ECO copolymers decrease with increasing ECO mass concentrations. The bending tests performed with a universal testing machine are employed to evaluate the shape memory properties of the developed bio-based copolymers. V-fa/ECO SMPs show excellent shape fixity of 86%–94% at room temperature and high shape recovery at T _g + 20 °C of 81%–96%. V-fa/ECO SMPs can undergo fold-deploy shape memory cycles without altering the shape memory performances for at least 5 cycles. Good balance between shape memory performances and thermo-mechanical properties in the V-fa/ECO copolymer system is obtained when ECO mass concentration is 40% (w/w). (paper)