Thermal conductivity and diffusivity of chemicals

A broad variety of macrostructures of chemicals exists depending on the form of molecular building units, starting with simple molecules through to molecular complexes containing a high number of simple units. Molecular complexes can take the form of chains, tubes, planes and globes The attraction forces vary from covalent, mostly within the building units, up to ionic and Van der Waals forces that predominantly exist between the molecular complexes. Then materials vary from porous through strongly anisotropic up to dense ones, so the thermal conductivity/diffusivity can vary widely. Such macrostructure is highly sensitive to any heat treatment and for porous materials to moisture or adsorbed gases on the pore surfaces. Therefore, to characterise thermal conductivity/diffusivity detailed information must be available on macrostructure, heat treatment, density and, for porous materials, moisture content or adsorbed gases on pore surfaces.

Expansivity and density

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Emissivity and other infrared optical properties
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Specific heat capacity

Chemicals represent  a large range of organic materials and they can be solid or liquid. Heat capacity data are available for most pure products. For mixtures, the data can be obtained by calculation according to the ratio of the different components. In the case of chemicals, Cp measurement is mostly influenced by the atmosphere around the sample (especially oxidative atmosphere).