To make surfaces scratch-proof, a method is available that involves bonding hard material to the surfaces. Melamine resins, which are waterproof, are often used as decorative laminates for table tops. Also, the technique of irradiation crosslinking (forming knots between molecules) is used to increase the heat resistance, mechanical strength, and hardness of melamine resins. The plastics mixed with a reinforcement, filler, or material that gives special characteristics are known as "composite plastics." Inorganic fillers or reinforcements are used as reinforcement materials. Typical plastics of this type are glass fiber-reinforced plastics, abbreviated as FRP. Because of their high hardness, they are used for inner walls of aircraft and for fishing boats. Other reinforcement materials include carbon fiber and aramid fiber. Plastics reinforced by these materials are used for rockets.
The plastics mixed with magnetic material are known as " plastic magnets." These magnets can easily be shaped into various forms. Plastics intrinsically have excellent insulating properties. However, plastics can be made electrically conductive if conductive material is mixed in them. This type of composite plastics are known as " conductive plastics." For example, the enclosures of television sets and personal computers are made of plastic, which is known to cause radio interference because of its high insulating properties. To deal with this situation, conductive plastics have been employed recently.