Study On Preparation And Performance Of TiNi Wire/Epoxy Resin Shape Memory Composite

Shape memory materials (SMMs) are kinds of intelligent materials which can recover to their initial shape upon appropriate external stimulus. In SMMs, shape memory alloy (SMA) and shape memory polymer (SMP) have been widely used in practical applications. The SMAs possess shape memory effect, superelasticity and large recovery stress. While SMPs have the advantages of light weight, high deformability, adjustable shape transformation temperature and superior molding property. If the shape memory composites (SMCs) combined with SMAs and SMPs are developed, high functionality of SMMs can be expected to promote the active deployable structure, remote control mechanism and self-repairing system. In this thesis, a new type of epoxy shape memory polymer is prepared through chemical method and the carbon/epoxy SMCs and TiNi wires/epoxy SMCs are also prepared through this method. The mechanical property and shape memory property of composites are studied. We also investigate the influence of TiNi wires interface treatment for property of composite materials. The space deployable structure sample is designed and prepared. The details include the follows.1) The E51 series and E44 series epoxy shape memory polymer with different degree of cure and content of toughening agent are prepared. The mechanical property and shape memory property of epoxy shape memory polymer are characterized and the results show that the shape fixed rate and shape recover rate of polymers are above 98%. With increasing degree of cure, an increase in the mechanical property and shape memory transition temperature (Tg) can be observed. A decrease in the mechanical property and Tg occurs with increasing the content of toughening agent. Considering the mechanical properties and shape memory properties, we think that the epoxy shape memory polymer with 70-80% degree of cure and 10-20% content of toughening agent can be used to prepare shape memory composite materials.2) The epoxy shape memory composite with nanographene paper (GNPs) and graphene (RG) are prepared. The shape memory effects and thermo-mechanical properties of composites are studied. The ultimate tensile strength of RG 2.0 is 42 MPa, which is about 23% greater than that of primitive epoxy, and the recovery time is 16s. The ultimate tensile strength of GNPs 1.0 is 48 MPa, which is about 25% greater than that of primitive epoxy, and the recovery time is 18s. The composites are superior to primitive epoxy in shape memory effect and recovery speed. The overall performance of composite material is improved.3) Chemical corrosion by acid, coupling agent, electrochemical deposition of zinc oxide and planting carbon nanotubes on the surface of TiNi wire are adopted to process on the surfaces of TiNi wire. Single-fiber pull-out model was employed to study the interfacial behaviors of the shape memory alloys (SMA) composite. When the composites are processed through electrochemical deposition of zinc oxide and planting carbon nanotubes on the surface of TiNi wire, the binding strength of composite is 38.9MPa and 60.2MPa, respectively. Compared to other process, the effect of planting carbon nanotubes on the surface of TiNi wire is the best.4) The shape memory properties, the mechanical properties at room temperature and high temperature of TiNi/epoxy shape memory composite are systematic studied. With the adding of TiNi wires, the tensile strength and elasticity modulus of composite at room temperature and high temperature conditions can be improved at the same time, foe the high temperature mechanical properties especially. The shape recover stress of composite also is significantly improved.5) On the basis of preliminary work the space deployable structure sample are prepared using TiNi/epoxy shape memory compsite. The thickness and structure of the sample are designed. The expand performance of sample are tested. The sample can return to original shape after 20s with heating in water bath and after 3min return to its original shape with electric heating condition.