| abstract |
The invention relates to a method for impregnating strands or strips of natural fibres, using the following successive steps: i) the impregnation of the strands or strips by immersion in a bath containing a fine aqueous polymer dispersion; followed by ii) the drying of the strands or strips using a heating system, with the progressive elimination of the water and the gradual melting of the polymer, and the coating of the strands or strips and the molten polymer incorporated into the core of the strands or strips as a binder between the fibres; iii) optionally, the forming of the treated strands or strips into their final shape; and iv) the cooling of the treated strands or strips. The aqueous polymer dispersion comprises at least one semi-crystalline or amorphous polymer and, in the case of an amorphous polymer, has a Tg varying between 50°C and 175°C and, in the case of a semi-crystalline polymer, has a melting point varying between 70°C and less than 220°C, the weight concentration of the polymer in the dispersion being between 5 and 50%, with particles having an average size of less than 10000 nm. The invention also relates to the treated fibres and to the use of same in composite materials. |