Preparation And Research On Shape Memory Epoxy Resin

Shape memory polymer (SMP) can change its shape and recover to the original shapeunder certain conditions, this shape memory performance has extensive application inmedical and aerospace. As one part of thermoset shape memory polymer, shape memoryepoxy resin has the advantages of greater mechanical properaties and easy fabrication,which can also regulate its ability through changing material kind, component proportionand curing process.To obtain shape memory ability, the crosslinking degree of epoxy resin must low, andthe curing degree must enough high to hold enough mechanical property. In this paper theraw materials of the shape memory polymer include epoxy resin E-51, curing agentMeTHPA (methy tetrahydrophthalic anhydride), accelerator2E4MZ (diethyl four methyimidazole). A series of shape memory resins with low crosslinking degree were preparedby cured in medium temperature, adjusting the content of anhydride curing agent, andchanging the curing time. The esterification conversion ratio of epoxy group wascalculated by FT-IR spectroscopy; the Tg (glass transiton temperature) of cured epoxyresins were measured by Vicat softening point temperature detector, DSC (differentialscanning calorimeter), and DMA (dynamic mechanical thermal analyzer); The shape fixityratio, shape recovery ratio, and the recovery time of the shape memory epoxy resin weremeasured by a domestic device. The influences of recovery temperature, hold time, foldnumber, specimen’s thickness, specimen’s bending curvature on recovery time were alsotaken into account.The study showed that, the esterification conversion ratio of epoxy group was morethan91%, the Tg was between70~95℃, the bending strength was between80~95MPa,the charpy Notched impact strength was between1.2~2.2KJm-2; the shape fixity ratio wasup to99%; the shape recovery ratio approached100%; the recovery time increased withthe increase of hold time and deformation numbers, while decreased with temperaturerising; recover to the same angle, the thicker one needed more recovery time, and therecovery time at low temperature increased after going through high temperature cycling.When recovery temperature was up Tg, all samples could recovery the whole shape,whether fold at low temperature and recover at higher temperature or fold at hightemperature and recover at lower temperature.