Thermoplastic (Thermo Plastics): Refers to the heat will melt, can flow to die after cooling molding, and then the melting of the plastic after heating, you can use heating and cooling, so that it produces reversible changes (liquid ←→ solid), is called physical changes. The general thermoplastic has a continuous temperature of 100 ℃, polyethylene, polyvinyl chloride, polypropylene, polystyrene and is called four general plastics. Thermoplastic plastics are divided into hydrocarbons, polar gene-containing ethylene, engineering, cellulose and other types. When heated, it is soft and cold, and can be softened and hardened repeatedly to maintain a certain shape. Soluble in a certain solvent, with fusible soluble properties. Thermoplastic has excellent electrical insulation, especially PTFE (PTFE), polystyrene (PS), polyethylene (PE), polypropylene (PP) have very low dielectric constant and dielectric loss, suitable for high-frequency and high-voltage insulating materials. Thermoplastic plastic is easy to process, but the heat resistance is low, easy to creep, its creep degree with load, ambient temperature, solvent, humidity and change. To overcome these weaknesses in thermoplastics, to meet the needs of applications in space technology, new energy development and other fields, various countries are developing heat-resistant resins, such as polyether ether ketone (PEEK), Polyether sulfone (PES), poly-aryl sulfone (Pasu) and Polyphenylene sulfide (PPS).