Mitsui Petrochemical Industries, Ltd.

Toshiji Nishimura

Yurimasa Zenitani

Tohru Taguchi

Akio Ikeda

A polyamide comprising from 60 to 100% by mole of divalent terephthaloylalkylenediamine constituent units (a), from 0 to 40% by mole of divalent diacyloylalkylenediamine constituent units (b) and from 0.1 to 5% by mole of trivalent diacyloylalkylenediamine units (c), said constituent units (a), (b) and (c) being arranged at random to provide a branched linear structure, said polyamide being free from a gel-forming cross-linked structure and soluble in concentrated sulfuric acid and having: an intrinsic viscosity [.eta.] of from 0.5 to 3 dl/g, as measured in concentrated sulfuric acid at a temperature of 30.degree. C., a melting point of from 280.degree. C. to 370.degree. C. and a glass transition temperature of from 100.degree. C. to 160.degree. C., as measured by means of a differential scanning calorimeter at a heating rate of 10.degree. C./min., and a crystallinity of from 10 to 30%, as measured by X-ray diffractometry. The polyamide has an excellent gas-barrier property, and thus, it is useful in applications where a gas-barrier property is particularly required, alone or in blend or lamination with other melt-moldable polymers.

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Iwakuni, Japan

Toshiji Nishimura