Impregnation Techniques for Thermoplastic Matrix Composites

This paper reviews the techniques available for the impregnation of reinforcing fibres with thermoplastic resins. The key material factors influencing the achievement of impregnation are outlined and the current impregnation technologies are discussed. The techniques are divided into two categories: those that aim to reduce the viscosity in order to achieve rapid impregnation, the pre-impregnation processes, and the processes that attempt to reduce the distance that the resin is required to flow, which involve intimate mixing of constituents prior to melting, the mingling processes. The techniques used to mingle fine polymer powder and continuous fibres are examined and the various elements of a powder impregnation line are reviewed. Applications of powder impregnated composites are also discussed.