Dynamic capillary effects in liquid composite moulding with non-crimp fabrics

A technique is presented to measure the capillary pressure drop DPg during infiltration of non-crimp fabrics by a liquid matrix. Three types of liquids are used: polyethylene glycol (PEG) dissolved in water, a thermoset epoxy resin and a reactive thermoplastic system. Results show that epoxy resin behaves as a non-wetting liquid with a DPg of 14 kPa when injected under constant pressure. The PEG and the thermoplastic system exhibit a wetting behaviour with DPg of K5.4 and K13.8 kPa, respectively. Constant flow rate experiments furthermore indicate that DPg increases with the fluid velocity, closely following the velocity dependence of the dynamic wetting angle. Thus, a thermodynamically wetting resin may well behave as a non-wetting fluid during Liquid Composite Moulding, when viscous forces dominate over capillarity.