Preparation Of Carbon Nanotube/Water-based Epoxy Shape Memory Composite And Its Thermo-mechanical Coupling Behavior Under Thermal Shock

In this paper,the carbon nanotube(CNT)/water-based epoxy(WEP)SMPCs were prepared by freeze drying and hot pressing molding,the mechanical and shape memory properties,and the thermos-mechanical coupling behavior under of the CNT/WEP SMPCs under the thermal shock were studied.The temperature difference energy(TDE)harvesting and conversion performance of the CNT/WEP SMPCs were investigated.Firstly,the epoxy emulsifier(EP-g-TX100)was made from epoxy resin,toluene diisocyanate(TDI)and non-ionic surfactant Triton X-100 copolymers,and WEP emulsion was made by reverse technology.The CNT/WEP SMPC films were prepared by combining CNTs,WEP emulsion and curing agent.The morphology and structure of WEP emulsion,CNTs dispersion,and CNT/WEP SMPCs were observed by scanning electron microscope.The mechanical properties of WEP and CNT/WEP SMPCs were tested by tensile testing machine,and the shape memory properties of WEP and CNT/WEP SMPC films were tested with the thermal mechanical analyzer(TMA).The results showed that the WEP emulsion was successfully prepared.EP-g-TX100 was significally improved the CNTs dispersion in water and WEP matrix.CNTs were dispersed uniformly in aqueous solution,and there was no aggregation phenomenon in water and WEP matrix.The mechanical properties of CNT/WEP SMPCs were better than that of WEP.The CNT/WEP SMPCs showed the best performance when the mass fraction of CNTs was 1.0%,and the tensile strength reached 39.5 MPa,and the shape recovery rate and shape fixed rate were reach to 100%and 98%,respectively,under iso-strain condition(5%),30?to70?circulating in the thermal shock,CNTs improved the output stress of WEP effectively.Secondly,the thermo-mechanical coupling behaviors of the CNT(1.0 wt%)/WEP SMPCs under iso-strain were tested by TMA.When the smaller temperature change rate and the greater the temperature change range,when the upper limit test temperature was far higher than the T_g of the composites,the minimum limit tes temperature was far lower than the T_g of the composites,the output stress peak and wave amplitude of the composites were higher.Under iso-strain condition(7.1%),30?to 70?circulating in the thermal shock,the output stress was between0.3 MPa to 2.1 MPa,which was significalty improve by addition of CNT.In addition,the thermo-mechanical coupling behavior of the CNT(1.0 wt%)/WEP SMPCs under iso-stress were tested by TMA.The results showed that when the upper limit test temperature was above the T_g of the CNT/WEP SMPCs,there was a phenomenon of thermal shrinkage and cooling expansion,which was more obvious with the larger the temperature change interval and the smaller the temperature change speed.Under the action of thermal shock,the CNT/WEP SMPCs had the ability to collect TDE.For example,when the stress was 0.60MPa and the temperature change speed is 1?/min,the energy density collected and released by the CNT/WEP SMPC film(0.3 mm thickness)up to 3.56 k J/m~3 and 3.07 kJ/m~3,respectively.The CNT/WEP SMPCs had excellent mechanical and shape memory properties,also exhibited the ability to harvest and convert TDE.This study provides an effective evaluation method and basic data for TDE harvesting and conversion performance based on shape memory polymer,which has important scientific and practical significance.