Simple modelling of impregnation in pultrusion process of thermoplastic composites

Abstract

Pultrusion is a continuous process with application in the manufacture of fibre–reinforced composites. This work reports the impregnation process which is one of the major concerns in pultrusion. We set out to develop a model that describes the flow advancement for a thermoplastic matrix when the reinforcements pass through the die. Therefore, the influence of several processing conditions on the impregnation state has been assessed. An analytical model based upon the Darcy's law and Stokes equation was applied to describe the progression of the radial flow front through porous medium. In this investigation, a unidirectional fibrous medium is adopted and the injected fluid is considered to be Newtonian and incompressible. Results show that the geometry of the die, pulling velocity and obviously the fibres permeability are the major factors influencing the degree of wetting. This analytical methodology is a useful tool to control the matrix impregnation.