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Synthesis and properties of aromatic polyimide, poly(benzoxazole imide), and poly(benzoxazole amide imide)



Two series of heterocyclic aromatic polymers were synthesized from 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthaltic anhydride) and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride by two-step method. The inherent viscosities were in the range of 24–45 cm3/g. The effects of the rigid benzoxazole group in the backbone of copolymer on the thermal, mechanical, and physical properties were investigated. These polymers exhibit good thermal stability. The temperatures of 5% weight loss (T5) of these polymers are in the range of 403–530°C in air and 425–539°C in nitrogen. The chard yields of these polymers are in the range of 15–24% in air and 54–61% in nitrogen. These polymers also have high glass-transition temperatures and a low coefficient of thermal expansion and good mechanical properties. The poly(benzoxazol imide) has a higher tensile strength and modulus than those of neat polyimide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009