Epoxy resins are a versatile and reliable choice for composite materials due to their superior chemical resistance, high temperature performance, and strong adhesion strength and flexibility. Epoxies come in liquid, solid and semi-solid forms and are usually cured by reaction with amines or anhydrides. They are widely used as structural adhesives because of their wide range of applications, from wind energy to aerospace, marine, automotive and infrastructure. The main benefits of using epoxy include its ability to adapt to different products, its low shrinkage, strong mechanical properties, resistance to liquids and corrosive environments, superior electrical properties, good performance at elevated temperatures, and good adhesion to substrates.
Resin selection is based on fabric compatibility, service conditions and desired characteristics of the finished part. Mold manufacturing, molding and laminating operations can be performed with any system. Epoxy resins offer advantages over thermosetting or thermoplastic resins that may have traditionally been used in similar processes. Polyester resins are less expensive but offer less corrosion resistance and are less tolerant than epoxies.
The low viscosity of epoxy also allows the use of various composite manufacturing processes such as resin transfer molding (RTM or infusion), filament winding, pultrusion, and prepreg techniques. Epoxies are generally stronger than polyesters and stronger than epoxies as they are a hybrid form of polyester resin that has been reinforced with epoxy. Depending on the type of resin used, it also helps to offer a variety of benefits including corrosion or temperature resistance and electrical insulation. Fiber-reinforced epoxies can be used with a variety of composite manufacturing processes and may require different temperatures and cure rates to be effective in their specific applications.
The resin also has fewer open sites in its molecular chain making it more resistant to water penetration. In short, the versatility of epoxy resin chemistry with respect to the easy fabrication of durable, lightweight and resistant structures is clearly evident. Thermoplastic resins are characterized by materials such as ABS, polyethylene, polystyrene and polycarbonate but epoxy offers more advantages than these materials.