Poly-benzimidazole films

Kawahara, M. et al.. Synthesis and proton conductivity of sulfopropylated poly(benzimidazole) films. Solid State Ionics, 136/137, 1193, 2000. 

Transparent, flexible, and tough films with deep orange color are cast from HMPA solution of poly(benzothiazole) from 15 and 29.26 The tensile strength of 69Mpa and the tensile modulus of 2.7 GPa are obtained for aromatic poly(ben-zoxazole) (28) from 15 and 29. These values are higher than those of hexafluoroisopropylidene-unit-containing poly(benzimidazole). 

The air dried poly(arylene ether benzimidazole) films displayed excellent resistance to methylene chloride, hydraulic fluid (Skydrol) and jet fuel (HyJet IV)... 

Poly(benzimidazoles) are speciality polymers that have found only a few civilian applications outside the military area and in space research. PBI fibers have been used for thermally stable protective clothing and as precursors in the production of graphite fibers. Hollow fibers and films of PBI are used to purify sea and brackish water according to the reverse osmosis process. 

Structural studies of polymer surfaces. Materials that have been studied include PMMA [239], PMMA-polypyrrole composites [240], polyfchloromethyl styrene) honnd 1,4,8,11-tetrazacyclotetradecane, polyfchloromethyl styrene) honnd thenoyl triflnoroacetone [241], poly(dimethyl siloxane)-polyamide copolymers [242], PS [243], ion-implanted PE [244], monoazido-terminated polyethylene oxide [245], polynrethanes [246], polyaniline [247], flnorinated polymer films [248], poly(o-tolnidine) [249], polyetherimide and poly benzimidazole [250], polyfnllerene palladinm [251], imidazole-containing imidazolylethyl maleamic acid-octadecyl vinyl ether copolymer [252], polyphenylene vinylene ether [253], thiophene oligomers [254], flnorinated styrene-isoprene derivative of a methyl methacrylate-hydroxyethyl methacrylate copolymer [255], polythiophene [256], dibromoalkane-hexaflnorisopropylidene diphenol and bisphenol A [257], and geopolymers [258]. 

Phosphoric acid-doped (PA) poly-benzimidazole (PBI) films attain proton conductivities >0.25 S cm at temperatures above 150°C (Xiao et al 2005). The shift to higher temperatures of fuel cell operation, enabled by the use of these membranes, improves the fuel tolerance to carbon monoxide impurities, enhances the electrode kinetics, and alleviates humidification requirements. The problem is that the higher temperature not only accelerates the kinetics of desired electrode reactions, but also those of degradation processes. Moreover, PBI membranes function poorly under ambient conditions. PEFCs using PBI PEMs are suitable for residential applications, but they are currently not envisaged for automotive applications. 

Table 14. Unoriented thin film properties of poly(arylene ether benzimidazole)s...

Poly(p-phenylenebenzobisthiazole) with poly(2,5,(6 )-benzimidazole) MC of oriented macromolecules films and fibers had high modulus and strength Hwang a/., 1983... 

Poly-2,5(6) benzimidazole Methane sulfonic acid, HCOOH/cresol Solvent nature affects the morphologies of polymer films thus the extensibility and mechanical properties of films. DSC, Rheovibron viscoelastometer, WAXS [Wereta et at, 1978]... 

The early work on properties of molecular composites was done by Hwang et al. (1983a, b). They performed experimental studies of solution processing of films based on poly(p-phenylene benzobisthiazole) with both poly(2,5 (6 ) benzimidazole (ABPBI) and poly(2,5 (6 ) benzothiazole) (ABPBT). The films were shown to possess very high modulus and strength values, which improve upon heat treatment. The uniaxial modulus of highly oriented molecular composites was shown to follow the linear rule of mixtures. 

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