USE OF COPOLYAMIDES FOR MANUFACTURING COMPOSITIONS WITH STABLE RIGIDITY UNDER THE EFFECT OF HUMIDITY

摘要

The invention is mainly aimed at the use of a semicrystalline copolyamide having the formula A / X sub 1 /sub Y, in which: - A is a repeating unit obtained by polycondensation - of at least one C-lactam sub 6 /sub to C sub 18 /sub, or- at least one amino acid from C sub 6 /sub to C sub 18 /sub, or- of at least one repeating unit XY obtained by polycondensation of at least one linear aliphatic diamine (X) at C sub 4 /sub to C sub 18 /sub and at least one dicarboxylic acid aliphatic (Y) in C sub 6 /sub to C sub 18 /sub; and- X sub 1 /sub Y is a repeating unit obtained from the polycondensation of at least one cycloaliphatic diamine (X sub 1 /sub), and at least one acid aliphatic dicarboxylic (Y) at C sub 6 /sub to C sub 18 /sub, the mass ratio between comonomer A and comonomer X sub 1 /sub Y being 60 / 40 to 90/10 to prepare articles whose tensile modulus, measured according to the ISO 527 standard, does not vary by more than 20% between the dry state and the water-saturated state. The invention also relates to a composition comprising 25 to 65% by weight of said semi-crystalline copolyamide, 35 to 75% by weight of reinforcements, 0 to 10% by weight of at least one impact modifier, 0 to 10% by weight of at least one viscosity modulating agent, 0 to 20% by weight of at least one filler and 0 to 5% by weight of additives. Finally, it relates to a process for manufacturing said composition as well as a molded object that can be obtained from said composition.