Process investigation of a liquid PA-12/carbon fibre moulding system

A new RTM-type process has been developed to process complex geometry components utilising a thermoplastic matrix. The matrix is an anionically polymerised liquid PA-12 (APLC-12) system which may be injected into a fibre preform, with polymerisation occurring in-situ. The initially low melt viscosity can be utilised to good effect for the impregnation of all types of composite fabrics, yielding fibre volume fractions as high as 60%. Large, complex-shaped components can be manufactured using low injection pressures. A melt processing system was established and a test mould was constructed. Different geometries were used to investigate the processing characteristics and residual stress build-up effects of the unreinforced PA-12, composite plates and composite sandwiches. An industrial-scale dosing/mixing unit was also designed and developed, and used to produce carbon-fibre/PA-12 laminates for measurement of mechanical properties. Mechanical properties were tested and the results obtained were found to be comparable to those obtained from commingled carbon-fibre/PA-12 laminates.