Technology for rapid impregnation of fibre bundles with a molten thermoplastic polymer

Composites consisting of long, discontinuous fibres and a thermoplastic polymer find increasing application because of the good overall compromise between their mechanical properties, processing possibilities and cost. Pellets containing a thermoplastic polymer and long fibres allow injection or compression moulding of high-quality products. The pellets are usually produced by a pultrusion process. However, pultrusion with thermoplastics suffers from a compromise between optimised impregnation quality and high production speed. A high production speed means low cost. In other words, a compromise between price and quality exists. This paper presents a significantly modified process which uses powered rotating spreader pins with a convex conical shape. Thus, the physical basis of the compromise between price and quality is altered, and a good quality can be obtained at a fibre-bundle linear speed of about 1 m/s.