Let us go back to the basics. There are two kinds of processes through which a polymer is developed: addition polymerization and step-growth polymerization. Composite plastics are made when a couple of identical materials having different characteristics bond collectively to produce a final piece with the desired material and mechanical properties. These composite materials can be of two kinds, fibre and particle reinforced. You can know in detail about them from persons who work for or has studied about Fibreglass Reinforced Plastic Moulded Products in detail. Fibre-reinforced plastic is that group wherein the flexibility and mechanical strength of the plastics are enhanced through the amalgamation of fibre materials. The matrix, a core material with no fibre reinforcement, is hard but relatively weaker and must be made durable by adding powerful reinforcing fibres or filaments. It is the fibre which is vital in differentiating the parent polymer from the FRP. Most of the