Prepreg is one of the building blocks in the ever expanding composites industry. The process of impregnating composite fibers with specialty resins transforms carbon fiber, fiberglass, aramids and other fibers from a raw state to a product that can be engineered to make parts and assemblies as diverse as golf shaft to a critical aerospace part.
‘Prepreg’ is a composites-industry slang term, meaning ‘fiber pre-impregnated with resin,’ the fiber being anything from unidirectional carbon to woven glass or aramid, and the resin either epoxy, polyester, phenolic or even thermoplastics such as PEEK or PEKK. Prepreg was invented as a practical method to insure a uniform distribution of resin and fiber throughout a composite part.
Structural composites are now part of our everyday life. Beginning with the early high end aerospace applications, prepreg is now widely used in sporting goods, industrial applications, aerospace tooling, automotive, aircraft interiors, as well as the traditional defense and aerospace applications.
Prepreg falls into two major industry uses: Copper Clad Laminates (CCL) for printed circuit boards and Structural Composites for all other uses.
Prepreg is generally used in several fiber orientations.
- UD Tape – individual tows are aligned and then spread to form an impregnated unidirectional tape
- Woven – individual tows are woven together to form a fabric before impregnation
- Non-woven – tows are arranged in a non-woven mat before impregnation
Prepreg is produced in two major resin classifications –Thermoset and Thermoplastic. Thermoset prepregs have been produced for 50 plus years in various forms. Thermoplastic prepregs are a newer set and have a lot of interest in the marketplace for a variety of applications.