Preforms are fiber materials that are manufactured for inclusion in plastic molding. Fiber preforms are often manufactured in sheets, continuous mats or as continuous filaments for spray applications.
Preforms are used to enhance the strength and elasticity of plastics. The fibers used in preforms are usually glass, carbon or aramid. The original plastic material, without fiber reinforcement, is known as the matrix and is typically a tough but relatively weak plastic. The extent to which strength and elasticity are enhanced in a fiber reinforced plastic depends on the mechanical properties of both the fiber and matrix, their volume relative to one another, and the fiber length and orientation within the matrix.