New bis(phenoxy)naphthalene‐containing poly(amide‐imide)s having an inherent viscosity in the range of 0.62–1.09 dL/g were prepared by the direct polycondensation of 1,5‐bis(4‐trimellitimidophenoxy) naphthalene (I) and various aromatic diamines using triphenyl phosphite and pyridine as condensing agents in N‐methyl‐2‐pyrrolidone (NMP) in the presence of calcium chloride. The diimide‐diacid (I) was prepared by the condensation of 1,5‐bis(4‐aminophenoxy) naphthalene and trimellitic anhydride. Most of the polymers were soluble in aprotic solvents such as NMP and N,N‐dimethylacetamide (DMAc), and afforded transparent, flexible and tough films upon casting from DMAc solutions. Measurements of wide‐angle X‐ray diffraction revealed that those polymers containing p‐phenylene or oxyphenylene groups were characterized as crystalline polymers. Tensile strength and initial moduli of the polymer films ranged from 61–86 MPa and 1.83–2.21 GPa, respectively. Glass transition temperatures of the polymers were in the range of 231–340°C. The melting points of the crystalline polymers ranged from 375–430°C. The 10% weight loss temperatures were above 512°C in nitrogen and 481°C in air.
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Yang et al. (1993) studied this question.
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