Injection pultrusion improvements

Dub6 et al. (1995) addressed both the issues of volatiles and fibre wetting with reaction injection pultrusion (RIP) process used to produce thermoplastic polyurethane and thennoset polyisocyanurate matrix composites. The low viscosity constituents used in RIP help in improving fibre impregnation, while the small volume of the impregnation bath reduces emissions. 

Vinyl ester resins are similar to unsaturated polyester resins in that they are cured by a free radical initiated polymerisation. However, they differ from the polyesters in that the unsaturation is at the ends of the molecule rather than along the polymer chain. Unlike polyesters, vinyl esters show a greater resistance to hydrolysis as well as lower peak exotherm temperatures and less shrinkage upon cure. Cured vinyl ester resins exhibit excellent resistance to acids, bases and solvents. They also show improved strain to failure, toughness and glass transition temperatures over polyesters. They can be used in filament winding, pultrusion, resin injection, vacuum moulding and conventional hand lay-up. 

The tool face is commonly the surface imparted to the outer surface of the composite and must be smooth, particularly for aerodynamic surfaces. The other surface frequently may be of lower finish quality and is imparted by the disposable or reusable vacuum bag. This surface can be improved by the use of a supplemental metal tool known as a caul plate. (Press curing, resin transfer molding, injection molding, and pultrusion require a fully closed or two-sided mold.) Figure 4.13 shows the basic components of the tooling for vacuum bag or autoclave processed components. Table 4.22 shows the function of each... 

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