Synthesis And Characterization Of Novel Thermoset Bismaleimide Based Shape Memory Polymers

Shape memory polymers (SMPs) as a type of smart materials have achievedremarkable advances in recent years. Thermoset SMPs with potential applications inbiomedical devices, aerospace, textiles and household products have attracted greatinterests of researchers for its unique properties. In order to further enhance andbroaden the applications of SMPs, higher transition temperature and property tailorability are necessary for the applications above, especially for aerospace. In thisstudy, a series of SMPs are synthesized mainly based on bismaleimide (BMI) withdifferent glass transition temperatures, and the properties of such SMPs arecharacterized as well. The microstructure, mechanical property, thermal propertyand shape memory property of SMPs BMI resins are characterized by FourierTransform Infrared spectroscopy, X-ray Photoelectron Spectroscopy, DifferentialScanning Calorimetry, Thermal Gravimetric Analysis, Dynamic MechanicalAnalysis，swell test and tensile test, respectively.The results show that this series of SMPs have increasing maximum stress from26.8MPa to50.8MPa and elasticity modulus from249.6MPa to707.4MPa withcrosslinking density increasing. But the thermal stability got worse. The glasstransition temperature(Tg) increasing with crosslinking density ranged from90℃to115℃.The unreacted isocyanate group was observed by FTIR. This led to thecrosslinking density was not as high as expectation. The XPS showed all thesamples had the same chemical compositon, so the different properties of samplesresulted from their chemical structure. The swell test showed that each sample had adifferent crosslinking density. All of samples had strong shape memory and thetemperature had appreciable impact on the shape memory effect due to the entropyof an isolated system never decreases.