Polyoxymethylene (POM), also known as polyacetal or acetal, is a high-performance engineering thermoplastic used in various applications due to its excellent mechanical properties, low friction coefficient, high stiffness, and dimensional stability. It is a polymer made up of repeating formaldehyde units (-CH2O-). POM is often categorized into two main types:
Homopolymer POM
This type consists of repeating units of only one type, either -CH2O- or -CH2OCH2-. It exhibits high tensile strength, stiffness, and excellent creep resistance, making it suitable for precision parts and components in automotive, consumer electronics, and industrial applications.
Copolymer POM
This type contains repeating units of both -CH2O- and -CH2OCH2-. Copolymer POM offers improved thermal stability and chemical resistance compared to homopolymer POM. It is often used in applications requiring enhanced performance in harsh environments, such as chemical processing equipment and medical devices.
POM has several key properties that make it desirable for various engineering applications:
High stiffness
Low friction
Excellent dimensional stability
Chemical resistance
Good machinability
Despite its excellent properties, POM does have some limitations, including susceptibility to degradation under prolonged exposure to ultraviolet (UV) radiation and certain chemicals, such as strong acids and bases. Additionally, it may exhibit notch sensitivity, which means it is susceptible to cracking under stress concentrations.
Overall, POM’s combination of mechanical strength, dimensional stability, and low friction make it a versatile material in various industries, including automotive, aerospace, electronics, and consumer goods.