Polymethyl methacrylate (PMMA) is a linear polymer without side chains, characterized by high density and crystallinity. It can be divided into homopolymethyl methacrylate and copolymethyl methacrylate based on the chemical structure of its molecular chain. The key distinction lies in their properties: homopolymethyl methacrylate has high density, crystallinity, and melting points, but poor thermal stability and a narrow processing temperature range (about 10°C), with slightly lower acid-base stability; while copolymethyl methacrylate has lower density, crystallinity, melting points, and strength, but good thermal stability, resistance to decomposition, a wide processing temperature range (about 50°C), and better acid-base stability. It is an engineering plastic with excellent overall performance, featuring good physical, mechanical, and chemical properties, especially superior wear resistance. Commonly known as "SAI Steel" or "DA Steel," it is the third most widely used engineering plastic. It is suitable for manufacturing wear-resistant and abrasive parts, transmission parts, as well as parts for chemicals, instruments, and other applications.