The Synthesis And Characterization Of Polyimide Film

In this paper, ternary co-polyimide were prepared by reacting3,3’,4,4’-Benzophenonetetracarboxylic with2,6-diaminotoluene(DAT) and4,4’-methylene dianiline(MDA) via atwo-step polymerization procedure. The effect of molar ratio of DAT and MDA, total solidcontent, reaction temperature and time to intrinsic viscosity were testing in this paper. diaminemonomers, including4,4’-diamino-2,2’-dimethylbiphenyl(CH3BZ)、4,4’-diamino-2,2’-difluorobiphenyl(CFBZ) and4,4’-diamino-2,2’-ditrifluoromethylbiphenyl(CF3BZ)were synthesized, then, were used for the polycondensation reactions of polyimide. Thechemical structures of diamine monomers are characterized by Fourier transform infraredspectroscopy (FT-IR), proton nuclear magnetic resonances (1H NMR). The thermalperformance, thermal decomposition kinetics and the mechanical performance of polyimidefilm are investigated by dynamic mechanical analyzer (DMA), FT-IR and thermogravimetricanalysis (TGA), Instron Mechanical Tester and Ubbelohde Type Viscometer.It is found that when the molar ratio of DAT and MDA is0.7:0.3, total solid content is14%, reaction temperature is0oC，and time is2h that we can get a higher intrinsic viscosity.The T_gvalue of the ternary co-polyimide is320oC and the initial modulus is5.5MPa; thethermal decomposition temperatures of the weight loss5%and10%are496and539oC,respectively. The char yield is60%in800oC. The tensile strength and elongation were0.53MPa and18.4%. In different solvents， ternary co-polyimide almost insoluble exceptconcentrate sulfuric acid and concentrated alkaline.The polyimide with methyl shows better thermal stability and mechanical properties. TheT_gvalue of the polyimide is270~300oC and the initial modulus is1.8~3.2MPa; the thermaldecomposition temperatures of the weight loss5%and10%are472~545and526~575oC,respectively. The char yield is51.1~58.0%in800oC. The tensile strength and elongationwere190MPa and5.5~13.1%. In different organic solvents，the polyimide which withtrifluoromethyl and fluoro show better solubility property.