Investigation of curing kinetics and internal strains to enhance performances of bisphenol A based shape memory polymers

Shape memory polymers (SMPs) are an emerging class of polymers that can memorise temporary shapes and recover permanent shapes upon an external stimulus. These multi-functional materials have attracted researchers' interest due to their endemism thermomechanical and shape memory properties. Extensive fundamental research has been done on this field and recently synthesised SMPs and their composites (SMPC) have shown great potential for innovative and high-tech applications such as space exploration, medical and biomimetic devices etc. To date, researchers have improved SMP properties via polymer synthesis techniques, matrix reinforcement and incorporation of nano additives. However, neither of work has investigated the effect of polymer curing process on SMP performances with the aid of curing kinetics and internal strains. In this research, a bisphenol A based SMP was synthesized, and the progress of the chemical reaction was experimentally monitored using DEA, DSC kinetic models and FTIR. The DEA has provided the start and end of the crosslink generation. Simultaneously, measured internal strain through a novel embedded distributed optical fibre sensing network showed the shrinkage and expansion of the SMP at curing, which also correlates with DEA results. Most importantly, SMP and SMPC recovery time has improved by 20 and 16% compared to the DGEBA/SMPC-100. Moreover, tensile strength and ultimate tensile modulus have been increased by 13% and 7%, respectively. Overall, the proposed research approach provides an act of courage to researchers to further enhance SMP thermomechanical and weak and delicate shape memory properties without changing chemical structure or composition.