Thermoplastic composite material made of a semi-crystalline polyamide and method for manufacturing same

A thermoplastic composite material, said thermoplastic composite material comprising reinforcing fibers or a fibrous reinforcement, and a thermoplastic matrix which impregnates said reinforcing fibers or said fibrous reinforcement,

• wherein said thermoplastic matrix comprises one or more polyamides which comprise different amide units A and B and, optionally, amide units C and D, selected as follows:
• A:
• is a major amide unit present at a molar content ranging from 55% to 95%, chosen from x.T units, where x is a C9 to C18, linear aliphatic diamine, and where T is terephthalic acid,
• B:
• is an amide unit different than A, said unit B being present at a molar content ranging from 5% to 45%, according to the Tm of the polyamide based on unit A and said amide unit B being chosen from x′.T units, where x′ is chosen from:
• B1) a branched aliphatic diamine bearing a single methyl or ethyl branching and having a main chain length which is different by at least two carbon atoms compared with the main chain length of the diamine x of said associated unit A, or
• B2) m-xylylenediamine (MXD) or
• B3) a C4 to C18 linear aliphatic diamine when, in the unit A, said diamine x is a C11 to C18 linear aliphatic diamine and x′ is a C9 to C18 diamine when, in the unit A, said diamine x is a C9 or C10 diamine,
• C:
• optional amide unit different than A and than B, chosen from amide units based on a cycloaliphatic and/or aromatic structure or based on x′T as defined above for B but with x′ being different than x′ for the unit B,
• D:
• optional amide unit different than A, than B and than C when C is present, and chosen from the aliphatic amide units derived from:
• amino acids or lactams which are C6 to C12, or mixtures thereof,
• the reaction of a C6 to C18, linear aliphatic diacid and of a C6 to C18, linear aliphatic diamine, or mixtures thereof,
• and under the condition that the sum of the molar contents of A+B+C+D is equal to 100%;
• wherein at least one polyamide of the one or more polyamides is a semi-crystalline polyamide polymer with a glass transition temperature Tg of at least 90° C. and with a melting temperature Tm below or equal to 280° C., wherein a difference between the melting temperature Tm and crystallization temperature Tc, (Tm−Tc), of said semi-crystalline polyamide, does not exceed 50° C.;
• and
• wherein enthalpy of crystallization of said semi-crystalline polyamide, measured by differential scanning calorimetry (DSC) according to standard ISO 11357-3, is greater than 40 J/g.