Abstract: (1) A process for preparing thermoplastic polymer sheets reinforced with glass fibers, which comprises the successive steps of:(a) preparing a mat by fall of glass fibers onto a conveyor belt which moves at a speed lower than the fiber feeding speed;(b) preheating the mat to a temperature lower than the polymer melting temperature;(c) deposition on the mat, by fall, of a portion of the required polymer in powder;(d) compression of the mat;(e) deposition on the mat of another portion of the polymer in powder;(f) heating the mat to at least the softening temperature of the polymer;(g) deposition on the mat of the remaining polymer in powder;(h) compression of the mat and of the polymer at a temperature higher by at least 50.degree. C. than the polymer melting temperature with formation of a sheet.

Abstract: A process is described for imparting a better adhesion between reinforcing materials and a plastic matrix, characterized in that it comprises the steps of treating the reinforcing material surface with at least one organic compound of a tetravalent metal selected from the group consisting of zirconium and tin, at a temperature ranging from 250.degree. to 650.degree. C., of applying onto the reinforcing material surface so treated, at a lower temperature, at least one silane coupling agent and, finally, of drying the so-treated reinforcing material.