n A strong, inert, fibrous material incorporated in a plastic mass to improve mechanical properties. Typical reinforcements are Asbestos, Boron Fiber, Carbon Fiber, Ceramic Fiber, Flock, Glass-Fiber Reinforcement, Graphite, Mica, Sisal, and Whiskers, all of which see. Others sometimes used are chopped paper, macerated fabrics, synthetic fibers, and metal wires. To be effective, a reinforcement must form a strong adhesive bond with the matrix resin, to which end adhesion, promoting substances known as coupling agents are often preapplied to the fibers. Reinforcements differ from Fillers in that they markedly improve modulus and strength, whereas filler do not.