Carbon Fiber Reinforced Polyimide Shape Memory Composites Preparation And Perfpormance

Shape memory polymer(SMP)is a kind of intelligent material that can sense and react to external stimuli.It can recover large deformation under external stimuli and has shape memory properties.The shape memory properties of polymers can be obtained by designing the molecular structure or adding functional fillers into the polymer to prepare multiphase composites.The composite materials with different functional materials can be deformed and restored by different stimulation methods,which endows them with functional characteristics.However,shape memory composites mostly adopts the thermosetting resin and engineering plastics as the matrix while few researches on high-performance thermoplastic resin matrix.It limits the application range of shape memory composites.In this paper,thermoplastic shape memory polyimides(SMPI 1 and SMPI 2)were prepared by polycondensation reaction of bisphenol A type dietheric anhydride with different kinds of diamines,and their thermal properties,mechanical properties and shape memory properties were systematically studied.The results show that the two kinds of polyimides have excellent thermal stability and mechanical properties.This kind of polyimide by macromolecular chain tangles form network structure gives the polyimide shape memory properties.Under the same stress,in the tensile direction the shape recovery of SMPI 1 was 99.4%,the shape fixity was 99.1%,and the shape recovery of SMPI 2 shape was 85.7%,and the shape fixity was 98.3%.In the bending direction,both SMPI 1 and SMPI 2 maintain nearly 100% shape fixity and recovery.The thermoplastic shape memory composite(SMPC)was fabricated by moulding with continuous carbon fiber as reinforcement.The mass fraction of SMPI in the composite was effectively controlled by diffierent the solid content of polyamide acid.The microstructure,thermal properties and shape memory properties of the composites were systematically studied by various characterization methods.It was found that the polyimide resin matrix was evenly distributed in the composite and the internal quality was great,which endowed the composite with good shape memory properties.In the tensile direction,when the polyimide content was 40%,the shape recovery of the two kinds of composites was as follows: HO-SMPC: 99.3%,CO-SMPC: 93.6%.In the bending direction,when the polyimide content was 40%,the shape recovery of the two kinds of composites remained above 90%.The mass fraction of polyimide was one of the important factors affected composites shape memory properties.Finally,the electrical response characteristics of shape memory composites are studied.It was found that the resistance of composites is directly proportional to the mass fraction of polyimide resin.At the appropriate voltage,the composite achieves non-contact heating using joule heat generated by the electricity,and the electro-shape memory effect occurs when the composite material is heated up to the thermal deformation temperature.As the mass fraction of polyimide in the composite increased,the properties of electric shape memory was enhanced,and controllable shape memory effect occured in the composite by applying different power,which has great reference value for the engineering application of shape memory composite.