Research article

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The high molecular weight biphenyl-based polyarylene ether nitrile copolymers were synthesized by nucleophilic substitution reaction of 2,6-dichlorobenzonitrile (DCBN) with varying molar ratios of 4,4’-dihydroxybiphenyl (BP) and hydroquinone (HQ). The BP content of the copolymers has influence on glass transition temperature (T_g), initial decomposition temperature (T_id), mechanical properties and the crystallinity. All the copolymers could be dissolved in NMP, DMF and DMAc on heating, and were stable up to 450°C with a high char yield above 50% at 800°C in nitrogen atmosphere. The glass transition temperature, the melting temperature and tensile strength of copolymers were found to increase with increase in concentration of the BP units in the polymer. The dynamical viscosity and the storage modulus have been influenced by the BP concentration, frequency, temperature and time. This rheological results show that these copolymers have best thermoplastic processability and stability at 300–400°C.