Polymer composites

A material which is composed of two materials with a defined interface is known as composite.  These two materials are known as reinforcing material and matrix material. Reinforcing material is usually in the form of fibers, sheets or particles. These materials are embedded in a matrix material.  Common practice in selection of these materials is a strong, low density material is preferred for reinforcing material and a ductile material for matrix material. Composites are expensive material and nowadays widely used in diesel piston, brake-shoes, pads and tyres.  Commonly used fiber materials are glass fibers, carbon fibers and aramids. The resins used for thermosetting are polyesters and epoxides. Resins used as thermoplastic are polyolefins, polyimides, vinylic  polymers, polyacetals, polyphenylens and polycarbonates. To achieve flame retardance, flame retardant additives like fillers and pigments are also used here. Two main examples for polymer composites are Fiberglass and Kevlar. Fiberglass is synthesized by reacting polyester with carbon-carbon double bonds in its backbone and styrene over a mass of glass fibers.  Kevlar is an aromatic polyamide or aramid.