Method for preparing an impregnated fibrous material by reactive pultrusion

A method for manufacturing at least one impregnated fibrous material comprising a fibrous material made of continuous fibers and a thermoplastic polymer having a glass transition temperature Tg more than or equal to 40° C., or a melting temperature Tm less than or equal to 400° C., the glass transition temperature Tg and the melting temperature Tm being measured by DSC according to standard ISO 11357-2:2013 and ISO 11357-3:2013, respectively,

• wherein said method comprises a step of impregnating, in a pultrusion head, said fibrous material by injecting a reactive composition in the melt state comprising at least one precursor of said thermoplastic polymer in the presence of said fibrous material,
• said fibrous material being, when it enters said pultrusion head, divided in its thickness into n layers, n being from 2 to 20,
• each layer circulating in said pultrusion head in a channel that is specific to it,
• said reactive composition being injected in each channel and/or between said layers when they are recombined at the exit from each channel,
• said channel being heated to a temperature such that the reactive composition has an initial melt viscosity of less than 50 Pa·s, the melt viscosity being measured by oscillatory rheology at a temperature Tm≤T≤Tm+50° C. for a semi-crystalline polymer or Tg+220° C. for an amorphous polymer, at 10 rad/see under nitrogen flushing with 5% deformation on a rheometer apparatus between two parallel planes 25 mm in diameter, the impregnation starting at the moment of injection and ending before or after said layers are recombined by superposition to form said at least one impregnated fibrous material, in which said at least one precursor of said thermoplastic polymer is at least partly polymerized.