Study On Preparation And Properties Of Shape Memory Polycaprolactone-based Biomass Composites

Shape Memory Materials(SMP)are relatively new kind of smart materials that can be deformed in response to external stimuli and have a controlled shape.Due to the versatility of the actuation method,the large number of shape variables and the low cost,they have found a wide range of applications in many fields.Biomass materials not only have the advantages of being environmentally friendly,widely available and biocompatible,but also have very unique properties such as being highly degradable,lightweight and strong,and are often used to make composite materials.In order to overcome the disadvantages of existing fixators,such as bulky and heavy,poor environmental protection,poor permeability and poor biocompatibility,a lightweight and high-strength shape-memory wood composite and a low-cost,degradable lignin/polycaprolactone shape-memory composite were developed using a shape memory polycaprolactone material as the matrix and two biomass materials,wood and lignin,respectively.composites.The wood/polycaprolactone composite was prepared using a hot pressing process after the lignin had been removed from the wood by chlorite dissolution and impregnated with a polycaprolactone solution.The properties of the composites were tested to show that the mechanical properties of the composites were excellent,with a storage modulus of 2592.3 MPa for the monolayer and a yield strength of 16.77 MPa for the three-layer composite,and the glass transition temperature of the monolayer was reduced from67.01°C to 64.51°C for the pure polycaprolactone,improving the bio-friendliness of the composites.The shape memory reversion rate is fast and the performance is relatively remarkable.The designed spiral structure of the bone external fixator not only adapts to fit the body part,but also improves the breathability of the material and promotes rapid healing of the injured area.Lignin/polycaprolactone composite films were prepared by graft modification.The thermal decomposition temperatures of the composites were higher for all three lignin ratios and increased gradually with the increase in lignin ratio.Due to the increased intermolecular forces within the material,its melting point is higher than that of polycaprolactone.The film has a high shape recovery rate,which can be completed within20 s,with excellent shape memory effect.The lignin/polycaprolactone composite sheets prepared by co-pressing have a shape memory recovery rate of more than 90% and a fast recovery rate.Due to the softening of the internal molecular chains by hot pressing,which lowers their melting point,the mechanical properties of the composite at a lignin mass fraction of 10% are optimal.