| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 107 === A Novel diamine 3-(2-(5-aminobenzimidazolyl))aniline(m/IM/NH2), containing benzimidazole backbone was synthesized. The polyimides (PIs) were prepared by polycondensation of the diamines and Naphtha-lenetetracarboxylic dianhydride(NTDA). They had inherent viscosities in the range of 1.01~1.59 dL/g, and they could form tough and flexible films. The PIs exhibited high thermal stability with 10% decomposition temper-ature more than 530℃ in nitrogen, and their onset temperature was more than 500℃ in nitrogen. These films exhibited good mechanical properties with tensile stress around 92~135 MPa. However, the mechanical proper-ties of PIs significantly decreased when phosphoric acid doping level in-creased. This situation could be improved via crosslinking reaction of methyl group, cross-linked PIs would form close packing, and it led to decrease of phosphoric acid doping level, but it could still maintain high proton conductivity. The PIs when phosphoric acid doping level exceeded 240%, exhibited higher proton conductivity than m-PBI. For example, the proton conductivities of m6BPBI2PF1.5DMB0.5 and C5-m6BPBI2PF1.5DMB0.5 were 65.6 and 61.0 mS/cm at 160℃, respec-tively. Thus, these PIs could be the promising materials alternative to m-PBI membrane for high-temperature fuel cells applications because of their high proton conductivity and good oxidative stability.
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