TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The fibrous reinforcement with long fibers, has a circular section with length to diameter of greater than 1000, preferably greater than 2000, and preferably comprises fibers of glass, carbon, ceramic and/or aramid.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The reactive precursor composition comprises the components (a) and (b). Preferred Components: The amide unit C1 is present where a partial replacement of unit B1 is takes place at a molar rate of up to 25% with respect to the unit B1. The unit D1 is present where a partial replacement of unit B1 is takes place at a molar rate of up to 70% with respect to the unit B1. The difference between the melting temperature and the crystallization temperature of the polymer matrix is not greater than 50 degrees C, preferably not greater than 30 degrees C. The enthalpy of crystallization of the polymer matrix, as measured by differential scanning calorimetry according to ISO 11357-3, is greater than 40 J/g, preferably greater than 45 J/g. The unit A1 is present at a molar rate of 55-80%, preferably 55-70% by relative to all units of the polymer. The unit A1 is: 9x T, where the unit B1 is 2-methyl pentamethylene diaminex T, meta-xylylenediaminex T (both preferred), 10x T, 11x T, 12x T, 13x T, 14x T, 15x T, 16x T, 18x T, 17x T, 18x T, with a molar ratio of unit B1 of 30-45%; 10x T, where the unit B1 is 2-methyl pentamethylene diaminex T, meta-xylylenediaminex T (both preferred), 9x T, 11x T, 12x T, 13x T, 14x T, 15x T, 16x T, 17x T, 18x T, with a molar ratio of unit B1 of 25-45%; 11x T, where the unit B1 is 2-methyl pentamethylene diaminex T, meta-xylylenediaminex T (both preferred), 9x T, 10x T, 12x T, 13x T, 14x T, 15x T, 16x T, 17x T, 18x T, with a molar ratio of unit B1 of 20-45%; or 12x T, where the unit B1 is 2-methyl pentamethylene diaminex T, meta-xylylenediaminex T (both preferred), 9x T, 10x T, 11x T, 13x T, 14x T, 15x T, 16x T, 17x T, 18x T, with a molar ratio of unit B1 of 20-45%. The reactive prepolymer (a) has a number average molecular weight of 500-10000, preferably 1000-6000. The extender is an optionally substituted aliphatic, cycloaliphatic or aromatic diepoxide. Preferred Method: The method comprises: (k1) carrying out melt impregnation of a fibrous reinforcement with the reactive precursor composition, in an open or closed mold or outside the mold to obtain a molding composition with fibrous reinforcement; (k2) heating the obtained composition with polyaddition mass in the molten state for polymerization reaction, between components (a) and (b) of the reactive precursor composition, with chain extenders; and (k3) implementing by binding or by another implementation system and simultaneously with step (k2) polymerization. The method comprises simultaneous or delayed one step implementation including molding and shaping the fibrous reinforcement impregnated with step (k1) to form the final composite part in a mold, where the implement is performed according to a technique of a resin transfer molding, injection compression, pultrusion or infusion. The units C1 and/or D1 replace a part of unit B1 with a molar rate up to 70%, preferably less than 40% relative to the molar content of the unit B1. EXAMPLE - No suitable example given.