POM (copo): Polyoxymethylene (copolymer)

General Properties

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POM (copo)

Polyoxymethylene (copolymer)

In contrast to the homopolymer, the POM copolymer, also designated POM-C, is formed by copolymerization of trioxane and 1,4-dioxane. The properties of POM-H and POM-C are similar; however, the two polymers diff er in properties such as impact strength, chemical resistance (POM-C is more resistant), hardness and strength (POM-H is more stable). Additionally, POM-C has a lower Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).melting temperature than POM-H.

Structural Formula

Properties

Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.Glass Transition Temperature	-75 to -60°C
Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).Melting Temperature	140 to 175°C
Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).Melting Enthalpy	181 to 220 J/g
Decomposition reactionA decomposition reaction is a thermally induced reaction of a chemical compound forming solid and/or gaseous products. Decomposition Temperature	385 to 400°C
Young's Modulus	2600 to 3200 MPa
Coefficient of Linear Thermal Expansion (CLTE/CTE)The coefficient of linear thermal expansion (CLTE) describes the length change of a material as a function of the temperature.Coefficient of Linear Thermal Expansion	110 to 150 *10^-6/K
Specific Heat Capacity	1.48 to 1.50 J/(g*K)
Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.Thermal Conductivity	0.23 to 0.31 W/(m*K)
DensityThe mass density is defined as the ratio between mass and volume. 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

NETZSCH Measurement

Instrument	DSC 204 `F1` `Phoenix^®`
Sample Mass	10.55 mg
IsothermalTests at controlled and constant temperature are called isothermal.Isothermal Phase	7 min
Heating/Colling Rates	10 K/min
Crucible	Al, pierced lid
Atmosphere	N₂ (40 ml/min)

Evaluation

As a semi-crystalline polymer, POM-C shows a Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.glass transition at -71°C (both heatings, midpoints) with step heights (Δc_p) of 0.09 J/(g*K) and melting peak temperatures of 170°C (1st heating, blue) and 168°C (2nd heating, red). The difference in Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).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 (2^nd heating, 168°C) of POM-C is 13 K lower than that of POM-H, 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 / Degree of CrystallinityCrystallinity refers to the degree of structural order of a solid. In a crystal, the arrangement of atoms or molecules is consistent and repetitive. Many materials such as glass ceramics and some polymers can be prepared in such a way as to produce a mixture of crystalline and amorphous regions.crystallinity of the present samples, since the literature values for melting enthalpies for a Crystallinity / Degree of CrystallinityCrystallinity refers to the degree of structural order of a solid. In a crystal, the arrangement of atoms or molecules is consistent and repetitive. Many materials such as glass ceramics and some polymers can be prepared in such a way as to produce a mixture of crystalline and amorphous regions.crystallinity of 100% (316 to 335 J/g for POM (Homo) and 181 to 192 J/g for POM (Copo)) are strongly deviating.