Effect of dianhydride structure on the properties of phenylacetylene terminated polyimide
The thermosetting polyimide resins(PI)with different molecular structures were synthesized by four monomers of 2,3,3',4'-biphenyltetracarboxylicdianhydride(α-BPDA),hexafluorodianhydride(6FDA),4,4'-oxydiphthalicanhydride(ODPA),3,3',4,4'-benzophenonetetracarboxylicdianhydride(BTDA)along with diamine monomers and phenylacetylene based end capping agents.By means of FTIR,XRD,DMA,rheology,TGA test,the effects of different dianhydride structures on physical and chemical properties of thermosetting polyimides were studied.The results indicated that the structure of dianhydride had a significant effect on the glass transition temperature and thermal oxidation stability of polyimide resin.The PI synthesized by α-BPDA and BTDA with rigid molecular chain and good stability had higher glass transition temperature and thermal decomposition temperature.The ether bond structure was beneficial to reduce the viscosity of the resin.The PI synthesized by α-BPDA with asymmetric twisted biphenyl structure had good process performance and heat resistance,the minimum melt viscosity,glass transition temperature and 5％thermal decomposition temperature(in air)was 0.81 Pa·s,322 ℃,and 534 ℃,respectively.
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