Processing with Thermosetting Resin Matrices

Processing with thermosetting resin matrices 14.3.3.1 Low pressure impregnation (LPi) [74]... 

As a result, technology has been developed to enable the use of long fibres (around 2 mm) in a thermoplastic resin matrix. These are produced, not by classical physical mixing, but by a process analogous to the pultrusion process with thermosetting resin matrices, with internal lubrication additives to counteract the chopping effect of injection moulding. Similar effects have been measured with other fibres, such as aramid and carbon, and with other matrices, such as polypropylene and poly(phenylene sulphide). 

The fabrication of composite laminates having a thermosetting resin matrix is a complex process. It involves simultaneous heal, mass, and momentum transfer along with chemical reaction in a multiphase system with time-dependent material properties and boundary conditions. Two critical problems, which arise during production of thick structural laminates, are the occurrence of severely detrimental voids and gradients in resin concentration. In order to efficiently manufacture quality parts, on-line control and process optimization are necessary, which in turn require a realistic model of the entire process. In this article we review current progress toward developing accurate void and resin flow portions of this overall process model. 

Fig. 2.24 The production process for C fibers. Starting with pitch or polyacrylonitrile the fluids are spun into oriented fibers, thermoset, carbonized, and graphi-tized to carbon fibers. Surface treatment improves bonding to resin matrix.

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