Bubble Pressure, Water Rise and Contact Angle in Porous Materials, 1998 Nonwovens Conference Proceedings
For porous materials, the bubble pressure (or first bubble) and the water rise (or hydrostatic head) are very similar measurements, involving the application of pressure to displace one fluid (kerosene or isopropyl alcohol for bubble pressure and air for water rise) with another fluid (air for bubble pressure and water for water rise). The pressure required is a function of the pore size of the material under test, the interfacial tension between the two fluids, and the contact angle that the fluid interface makes with the interior surface of the pore. By making such measurements with a series of different fluids it is possible to estimate the contact angle of the fluids with the surface of the pore. This allows an absolute measurement of the water repellency of the porous media. It also allows the preparation of Zisman style plots relating the cosine of the contact angle to the surface tension of the fluids.
Bubble Pressure, Water Rise and Contact Angle in Porous Materials, 1998 Nonwovens Conference Proceed