Preparation And Evaluation Of Shape Memory Epoxies

As a kind of important functional materials, SMPs (shape memory polymers) have undergone a rapid development since 1980s, which are widely applied in the fields of aerospace, power electronics, medicine, packaging and intelligent control system. Nowadays, large amount of thermoplastic SMPs, e.g. PNBE, TPI, SMPU, has been engineering applied. However, the reports on thermosetting SMPs are rarely covered. As a leading candidate for future deployable space structure, shape memory epoxy has been studied abroad, of which the key technical data are protected; whereas in China, few research institutes engage in research on shape memory epoxy.In this paper, chemical synthesis was applied with the selection of proper resin and curing additives. A series of shape memory epoxy polymers (SMEPs) which have different shape transition temperatures were prepared. Moreover, the shape memory property and thermomechanics of the materials were measured. The details include the following:SMEPs were prepared by epoxy resin E-51 and varying contents of curing agent DDM (4,4'-diaminodiphenyl methane) and m-PDA. Totally, six types of specimens with different transition temperatures were prepared.Froze and recovery experiments were performed on these prepared SMEPs in a temperature-controlled cabinet. Through the analysis on the radius change of the samples in the recovery process, the freezing rate at room temperature, the critical shape transformation temperature and the relation between the shape recovery rate and temperature are received. Further theoretical discussions on these results were also performed.The glass transition temperature Tg of the SMEPs were investigated by DSC, and other thermal mechanical properties such as storage modulus, loss modulus and tangent loss angle were tested by DMA. On this basis, the selection of curing agent and its proportion were analyzed to figure out the influence to the thermomechanical properties.The researching results of this paper are useful in further preparing high-performance SMEPs, understanding the fundamental thermomechanics of SMEPs, establishing the corresponding thermomechanical constitutive equations and promoting their engineering application.