Crystalline semiaromatic copolyamides exhibiting especially a glass transition temperature Tg higher than 142 DEG C, and therefore an excellent stability of the polymer at elevated temperatures, as well as a melting temperature Tm lower than 290 DEG C. …??They have a structure containing the repeat units (I), (II), optionally (II') and (III): (I) denoting: …IMAGE… (II) denoting: …IMAGE… (II') denoting: …IMAGE… and (III) denoting: …IMAGE… with R1, R2, R3 and R4 denoting alkyl groups containing from 1 to 3 carbon atoms, and A denoting …IMAGE… …??These copolyamides, which can be easily converted by a melt route, make it possible to obtain moulded articles, filaments or films in the case of which an excellent retention of mechanical properties as a function of temperature is observed.
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