MIP involves placing a dried sample of the material into a penetrometer, which is then filled with mercury. The apparatus applies incremental pressure on the mercury, forcing it to intrude into the pores of the material. The pressure and volume of mercury intruded are recorded at each step. Using the Washburn equation, the pore size distribution, volume, and surface area can be calculated. The relationship between applied pressure and pore diameter is given by:
\[ d = \frac{-4 \gamma \cos \theta}{P} \]
where \( d \) is the pore diameter, \( \gamma \) is the surface tension of mercury, \( \theta \) is the contact angle, and \( P \) is the applied pressure.
