Properties and applications of POM (polyoxymethylene): The #1 polyacetal in versatility.
What is the POM?
POM (polyoxymethylene) is a type of polyacetal that is supplied in two basic forms: homo and copolymers. Copolymers are thermally more stable and are commonly used in gears due to their excellent tribological properties. On the other hand, unreinforced homopolymers (POM-H) are the most rigid and resistant thermoplastics, with excellent dimensional stability. However, they become brittle at temperatures below -40°C.
POM exhibits high surface hardness and a low coefficient of friction, which gives it good sliding behavior and wear resistance. In addition, it has a low permeability to gases and vapors, as well as to organic substances. Both homopolymers and copolymers are attacked by strong acids (pH 4) and oxidizing agents, but are not soluble and hardly swell in organic solvents, minerals and food.
Special types of oil-stabilized POM are available that are resistant to aggressive diesel and gasoline fuels up to a temperature of 100°C. However, unstabilized POMs are susceptible to UV rays, so it is recommended to use those that are stabilized or charged with carbon black. Color-stabilized POM formulations are also available.
POM thin films are transparent and burn with a slightly bluish flame. In addition, they are physiologically harmless and some types are suitable for food contact products. Homopolymers have higher crystallinity, giving them better impact resistance, slightly higher stiffness and hardness, while copolymers offer greater convenience and ease of processing. POM shows little tendency to creep under long-term loads and very good flexural strength under continuous cyclic loading.
Characteristics of acetal resin:
– High mechanical strength, rigidity and hardness.
– Excellent ductility and toughness.
– Good dimensional stability.
– Low hygroscopicity.
– Good dielectric and electrical insulation properties.
– Contact with physiologically inert food.
– Can be used in water at 80°C.
– Fatigue resistance.
– Friction and wear resistance.
– Long-term dimensional stability.
– Better thermal stability and higher alkali resistance than acetal homopolymer.
Pros and cons of polyacetals:
Pros:
– High tensile strength with stiffness and toughness.
– Good impact and solvent resistance.
– Shiny molded surface.
– Low static and dynamic coefficients of friction (slippery).
– Many grades have FDA and NSF approvals for food and water contact.
– They can replace die-cast metal components.
Cons:
– Difficult to over mold.
– Poor resistance to acids and bases.
– Subject to UV degradation.
In summary, POM (polyoxymethylene) is a polyacetal material used in various applications due to its mechanical properties, stiffness, toughness, dimensional stability and friction resistance. However, it is important to take into account its limitations, such as its susceptibility to UV degradation and its poor resistance to acids and bases.
We are proud to be a world leader in the supply of thermoplastics! In our catalog you will find a wide variety of options, such as POM (Polyoxymethylene) and antistatic POM (ESD), as well as other engineering plastics with antistatic properties. Our factories are strategically located in China and Vietnam. In addition, in 2012, we opened a distribution center in Ciudad Juarez, Chihuahua, Mexico, and an operations center in El Paso, Texas, USA. We are committed to providing you with quality products and exceptional service! In an ever-changing world, innovative materials that drive progress are essential. POM plastic has proven to be a reliable and sustainable solution for the industry in Latin America.