Thermomechanical properties of shape-memory hydro-epoxy resin

Abstract

The thermomechanical properties and shape-memory performance of a novel shape-memory hydro-epoxy resin system are studied. The system is prepared using hydro-epoxy, maleic anhydride, and poly(propylene glycol) diglycidyl ether (PPGDGE). The glass transition temperature (Tg) is determined using dynamic mechanical analysis, and the results indicate that Tg linearly decreases from 124 to 60 °C as the PPGDGE content increases. The tensile strength drastically increases after the addition of PPGDGE but gradually decreases as the PPGDGE content continues to increase. The room-temperature bend strength decreases as the PPGDGE content increases but increases slightly and then continues to decrease when the PPGDGE content is increased to 6.67 mol%. Moreover, the room-temperature elongation at break increases as the PPGDGE content increases but decreases slightly and then continues to increase when the PPGDGE content is increased to 6.67 mol%. These phenomena are attributed to flexible segment crystallization, which increases the rigidity of hydro-epoxy resin. Finally, investigation of shape-memory behavior of the resin reveals that full recovery can be observed after only a few minutes when the temperature is equal to or above Tg. The shape recovery time first increases and then decreases as the PPGDGE content is increased at Tg, Tg + 10 °C, and Tg + 20 °C, showing a polymer peak value at 6.67 mol% PPGDGE content. These results are attributed to the increase in PPGDGE content.