Pustevolum

Pustevolum is a term used in materials science and related fields to denote the fraction of a given volume that is not occupied by solid material, i.e., the empty space within a sample. The word combines the Polish pusty meaning empty with volum, a root related to volume, and has surfaced in some recent discussions as a concise synonym for porosity or void fraction in porous media.

Formally, pustevolum is defined as V_empty / V_total, where V_total is the total volume of the sample and V_empty is the volume of void space not occupied by solid. It is closely related to porosity, but some sources distinguish between total porosity and accessible porosity, the latter referring to void space that can be reached by a fluid.

Determination employs several methods: gas adsorption and desorption (for micro- and mesopores), mercury intrusion porosimetry, helium pycnometry in combination with mass or density measurements to obtain skeletal volume, and imaging techniques such as X-ray computed tomography to map the 3D pore structure. The choice of method depends on the pore size range and whether closed pores are included.

Pustevolum is a key parameter in fields such as catalysis, energy storage, insulation, filtration, and construction materials, where pore structure influences transport, surface area, and mechanical properties.

See also porosity, void fraction, pore volume, skeletal volume.