A resin, sometimes referred to as “plastic,” is used to transfer stress between the reinforcing fibers of a composite material. Resins act as a glue to hold the fibers together, and protect the fibers from mechanical and environmental damage. There are two major groups of resins – thermosets and thermoplastics – which are are made of polymers (large molecules made up of long chains of smaller molecules). Common thermosets include polyester, epoxy, vinyl ester and polyurethane. Common thermoplastics include ABS, polyethylene, polystyrene, and polycarbonate.
