Prepregs winding

The prepreg winding technique offers better control of fiber volume fraction, but at a cost. Material costs are 1.5 to 2 times higher, and there are additional costs associated with storing the preimpregnated (thermosetting matrix) tows. Preimpregnated tows are used almost exclusively for thermoplastic matrix materials, where there are no shelf-life restrictions. 

Composite processing uses specialized methods. For thermoplastics, glass mat thermoplastic (GMT) is the main method but prepreg, lay-up, tape winding, pultrusion are also used to produce composites. SMC/BMC are the main processes for thermosets but lay-up is currently used for large parts and prepregs are used for high-tech parts. 

However, the high level of patents concerning nanocomposites and prepregs is obvious. On the other hand, the SMC/BMC patent level appears relatively low. The amount of patents concerning laminates, UD composites and filament winding seems to correspond to their level of production. 

In filament winding the fiber is wound to form a desired pattern, usually but not necessarily hollow and cylindrical. The fiber is passed through the resin and then spun onto a mandrel. After the desired number of layers of fiber is added, it is cured. Prepregs can be filament wound. With the advent of new machinery, complex shapes and designs of the filament can be readily wound. 

Hercules Carbon Fiber. [Hercules] PAN-based carbon fibers used for weaving, prepregging, filament winding, pultrusion, and molding compds. 

Shell Chemical has produced EPON HPT epoxy resins, which are used in large parts made of graphite-7 reinforced prepreg material for primary aircraft structures. EPON 9000 series of epoxy resins produced by the same company have been used for fabricating, by wet filament winding process, fuselages and other large components that have been used in the prototype of Beech Aircraft s experimental small business aircraft, the Starship 1. 

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