Test Description:
Capillary flow analysis characterizes a material’s porosity, its pore size and pore volume. The test instrument typically uses a naturally wetting fluid with a very low surface tension, such as alcohol, to characterize the material’s porosity.
Because of the wetting fluid‚ slow surface energy, the wetting fluid will spontaneously fill the porous space in a porous material. Once wetted, a force is required to evacuate the fluid from the material’s pores. To accomplish this, the instrument subjects the wetting liquid to a differential pressure whereby the liquid is forced from the pores of the porous material. As the differential pressure is increased, the wetting liquid exits the sample’s largest pore first. This pore size represents the largest through pore in the sample and is commonly referred to as the sample’s bubble point. As the differential pressure is further increased, the wetting liquid is forced to exit the sample’s smaller pores.
A differential pressure versus airflow rate curve is then created for the wetted and dry sample. From this information, the material’s pore size distribution, pore volume, bubble point, and fluid flow characteristics are described.
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Applications
Wicking
by Product
