Synthesis, characterization, and shape-memory performances of monoamine-toughened epoxy resin

Epoxy resins were toughened by octylamine, dodecylamine, and hexadecylamine, respectively. The curing temperature and the curing kinetics were studied by non-isothermal differential scanning calorimetry (DSC) to optimize the cure conditions. The mass ratios of the monoamine to the total mass of triethylenetetramine and monoamine were varied to obtain polymers with different compositions. The cured polymers were analyzed by DSC, scanning electron microscopy (SEM), and mechanical analyses. Shape-memory performance was evaluated by fold-deploy tests. The glass transition temperature (T-g) decreased with increasing carbon numbers of monoamine, and the decrease in T-g scaled with the content of monoamines added in the system. The elongation increased with an increase in monoamine content and alkyl chain length. The better toughness of the monoamine-rich system was further confirmed by the results of SEM. The strain fixity ratio increased with a decrease in monoamine content. The strain recovery ratios of all systems were greater than 98%.