Chemical Properties
Polyoxymethylene (POM), also known as acetal or polyacetal, is a high-performance engineering thermoplastic valued for its strength, stiffness, and low friction. This semi-crystalline polymer offers excellent dimensional stability and wear resistance, making it ideal for precision parts in mechanical and automotive applications.
Thermal stability: POM possesses an excellent thermal stability, which can endure temperature changes without significant loss of physical properties. This stability makes it ideal for parts requiring high precision and dimensional stability.
Chemical resistance: The material is resistant to a wide variety of solvents and chemicals, including neutral chemicals, aliphatic hydrocarbons, and most oils and greases.
Ultimate Tensile Strength 69 - 83 MPa
Yield Tensile Strength 65 - 69 MPa
Ultimate Compressive Strength 110 MPa
Young’s Modulus (E) 2.9 - 3.2 GPa
Flexural Modulus 2.41 - 3.10 GPa
Elongation at Break 40 - 75%
Rockwell Hardness (R) 120
Melting Point 175 °C
Thermal Conductivity 0.37 W/m·K
Specific Heat Capacity (Cp) 1464 J/kg·K
Coefficient of Thermal Expansion (αL) 8.5×10-5 1/°C
Relative Permittivity (@1 MHz) (εr) 3.8
Electrical Resistivity 1015 Ω·cm
Dielectric Field Strength (Ed) 200 kV/cm
Uses
Acetal resins, also known as polyoxymethylene and polyformaldehyde, are polymers of pure formaldehyde with unusually good mechanical properties. They are resistant to elongation and impact and replace light metals in many uses. The finished polymer has not been related to adverse health effects in humans or animals. They can be thermally degraded, for example, in an overheated molding machine, to produce formaldehyde gas, with its well-recognized irritant and sensitizing properties.
Industrial uses
Polyoxymethylene, or polyacetal, resins arepolymers of formaldehyde. With high molecularweights and high degrees of crystallinity, theyare strong and tough and are established in thegeneral class of engineering thermoplastics.
Although somewhat similar to polyethylenein general molecular structure, polyacetal moleculespack more closely, and attract each otherto a much greater extent, so that the polymer isharder and higher-melting than polyethylene.Polyacetals are typically strong and tough,resistant to fatigue, creep, organic chemicals(but not strong acids or bases), and have lowcoefficients of friction. Electrical properties arealso good. Improved properties for particularapplication may be attained by reinforcementwith fibers of glass or polytetrafluoroethylene.
The combination of properties has led tomany uses such as plumbing fittings, pump andvalve components, bearings and gears, computerhardware, automobile body parts, andappliance housings. Other aldehydes may bepolymerized in a similar way.
