The effect of microstructure on flow promotion in resin transfer moulding reinforcement fabrics

The resin transfer moulding (RTM) process is becoming increasingly important for the manufacture of continuous fibre-reinforced thermosetting resin matrix composites, The RTM process is a closed mould technique which reduces volatile emissions relative to traditional hand lay-up methods, The fibres, generally as several layers of fabric, are prepared as a preform and laid in the closed mould. The resin is injected, at one or more points, and flows through the mould to form the finished product. In the manufacture of high-performance composite structures, the now of resin is constrained by the high volume fraction of reinforcement fibres required to achieve the performance, Commercial fabrics are becoming available which are woven with specially designed mesoscale architecture to promote flow of the resin, The flow rates in a series of such fabrics have been studied. The microstructures of the resulting composites have been examined using brightfield optical microscopy. A Quantimet image analyser was used to quantify the structures on both the mesoscale and the microscale. The flow rate has been shown to be related to the presence of both large and more modest sized pore space in the reinforcement architecture.