Short Name

POM (homo)

Name

Polyoxymethylene (homopolymer)

Group

ETP - Engineering Thermoplastics

General Properties

Chemical Formula

Structural Formula

Glass Transition Temperature

-85 to -75 °C

Melting Temperature

175 to 190 °C

Melting Enthalpy

316 to 335 J/g

Decomposition Temperature

365 to 390 °C

Young's Modulus

2600 to 3200 MPa

Coefficient of Linear Thermal Expansion

160 to 180 *10¯6/K

Specific Heat Capacity

1.48 to 1.50 J/(g*K)

Thermal Conductivity

0.30 to 0.37 W/(m*K)

Density

1.39 to 1.43 g/cm³

Morphology

Semi-crystalline polymer

General properties

Good stiffness, toughness and strength. Low humidity absorption. Good resistance to creeping and fatigue. High recovery capability. Good sliding properties. Food-compatible

Processing

Injection molding, extrusion, blow molding

Applications

Automobile industry. Instrument and apparatus engineering. Electrical/electronics industry. Food industry. Household goods

Internet Links

The high degree of crystallinity of POM-H is reflected in the above DSC curve. It is dominated by a distinctive melting effect at 183°C (1st heating, blue, peak temperature) and 181°C (2nd heating, green, also peak temperature) as well as a quite small glass transition step at -77°C (midpoint). The height of the glass transition step Δcp is a measure for the amorphous content in the material while the melting enthalpy (here 195 J/g in the 2nd heating) is related to the crystalline content (in this case 62%); the larger the melting enthalpy, the larger the crystalline content.
For semi-crystalline polymers, the magnitude of the glass transition and the height of the melting enthalpy are inversely proportional (i.e., if the heat of fusion increases, the glass transition step gets smaller and vice versa).