POM (copo): Polyoxymethylene (copolymer)
- Short Name
- POM (copo)
- Name
- Polyoxymethylene (copolymer)
- Group
- ETP - Engineering Thermoplastics
- General Properties
- Polyoxymethylene (POM), also known as acetal, polyacetal, and polyformaldehyde, is an engineering thermoplastic used in precision parts that require high stiffness, low friction and excellent dimensional stability.
- Chemical Formula
- Structural Formula
-
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Properties
- Glass Transition Temperature
- -75 to -60 °C
- Melting Temperature
- 140 to 175 °C
- Melting Enthalpy
- 181 to 220 J/g
- Decomposition Temperature
- 385 to 400 °C
- Young's Modulus
- 2600 to 3200 MPa
- Coefficient of Linear Thermal Expansion
- 110 to 150 *10¯6/K
- Specific Heat Capacity
- 1.48 to 1.50 J/(g*K)
- Thermal Conductivity
- 0.23 to 0.31 W/(m*K)
- Density
- 1.39 to 1.43 g/cm³
- Morphology
- Semi-crystalline polymer
- General properties
- Good stiffness, toughness and stability. Low humidity absorption. Good dimensional stability. Good electrical insulation properties. Good resistance to creeping and fatigue. Good sliding properties
- Processing
- Injection molding, extrusion
- Applications
- Automobile industry. Instrument and apparatus engineering. Electrical/electronics industry. Medical engineering. Household goods. Food technology
Internet Links
NETZSCH Measurements
- Instrument
- DSC 204 F1 Phoenix®
- Sample Mass
- 10.55 mg
- Isothermal Phase
- 7 min
- Heating/Colling Rates
- 10 K/min
- Crucible
- Al, pierced
- Atmosphere
- N2 (40 ml/min)
Evaluation
As a semi-crystalline polymer, POM-C shows a glass transition at -71°C (both heatings, midpoints) with step heights (Δcp) of 0.09 J/(g.K) and melting peak temperatures of 170°C (1st heating, blue) and 168°C (2nd heating, green). The difference in melting temperature values is due to the better contact between the sample and crucible bottom after the first melting of the material.
The peak temperature (2nd heating, 168°C) of POM-C is 13 K lower than that of POM-H (on page 117), and the melting enthalpy differs by approx. 9% (178 J/g for POM-C, 195 J/g for POM-H). However, there is no linear relation between these
results and the actual degrees of crystallinity of the present samples, since the literature values for melting enthalpies for a crystallinity of 100% (316 to 335 J/g for POM (Homo) and 181 to 192 J/g for POM (Copo)) are strongly deviating.
The peak temperature (2nd heating, 168°C) of POM-C is 13 K lower than that of POM-H (on page 117), and the melting enthalpy differs by approx. 9% (178 J/g for POM-C, 195 J/g for POM-H). However, there is no linear relation between these
results and the actual degrees of crystallinity of the present samples, since the literature values for melting enthalpies for a crystallinity of 100% (316 to 335 J/g for POM (Homo) and 181 to 192 J/g for POM (Copo)) are strongly deviating.