Novel shape memory polymer from bio-based polybenzoxazine/bio-based epoxy copolymers

Abstract

Shape memory polymers (SMPs) are known as smart polymer materials which can be deformed and fixed in a temporary shape and can recover to its original shape upon an external stimulus such as temperature which is the main stimulus for general SMPs. In this research, a renewable natural resource based on vanillin-furfurylamine benzoxazine (V-fa) and eugenol-furfurylamine benzoxazine (E-fa) are developed to substitute the use of petroleum based polybenzoxazine. The as-synthesized V-fa and E-fa show the degradation temperature at 5% weight loss to be as high as 343 and 310°C and char content to be 66 and 54%, respectively. Effects of epoxidized castor oil (ECO) content at 10-50wt% filled in bio-based polybenzoxazine on thermal, mechanical and shape memory properties of bio-based polybenzoxazine/bio-based epoxy SMPs are thoroughly investigated. The results reveal that with increase in ECO content, storage modulus and glass transition temperature of V-fa/ECO and E-fa/ECO copolymer decreased providing the values of 2.27 GPa to 1.60 GPa and 158°C to 100°C, respectively for V-fa/ECO copolymer and 1.53 GPa to 1.16 GPa and 40°C to -17°C, respectively for E-fa/ECO copolymer. In shape memory properties, the V-fa/ECO SMPs show shape fixity values at a room temperature of 86-94% and the values decrease with increasing ECO content, while the temporary shape at room temperature of the E-fa/ECO SMPs cannot fixed. Additionally, the V-fa/ECO SMPs provided the shape recovery values at Tg+20°C of 81-96% and the values increase with increasing of ECO content. Furthermore, it was observed that the V-fa/ECO copolymer having 40wt% of V-fa content exhibits good balance properties between shape memory performance and thermomechanical properties and it can be greatly recovered to the original shape for 5 cycles.