Thermomechanical properties of shape-memory hydro-epoxy resin

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 (T_g) is determined using dynamic mechanical analysis, and the results indicate that T_g 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 T_g. The shape recovery time first increases and then decreases as the PPGDGE content is increased at T_g, T_g + 10 °C, and T_g + 20 °C, showing a polymer peak value at 6.67 mol% PPGDGE content. These results are attributed to the increase in PPGDGE content.