Pore size determination by mercury porosimetry

Many commercially important processes involve the transport of fluids through porous media and the displacement of one fluid, already in the media, by another. The role play by pore stnicture is of fundamental importance, and its size distribution determination necess. in order to obtain an understanding of the processes. The quality of powder compacts is also affected by the void size distribution between the constituent particles. For these reasons mercury porosimetry has long been used as an experimental technique for the characterization of pore and void structure. Although quantitative information is contained in mercury intrusion - extrusion curves it can only be elucidated fiilly by the use of a theoretical model for pore structure. 

Mercury porosimetry consists of the gradual intrusion of mercury into an evacuated porous medium at increasingly higher pressures followed by extrusion as the pressure is lowered. The simplest pore model is based upon parallel circular capillaries which empty 

The measured pore size distribution is directly affected by pore shape, the relationship between voids and throats (sites and bonds) and the co-operative percolation effects of the porous structure. 

---

The ultimate tensile test results showed that the samples electrospun with a negative polarity voltage broke at one half the strain, 28% vs. 60%, and only achieved a UTS of 0.23 MPa, one half the positive polarity s 0.51 MPa. While the total porosity of the samples was insignificantly different (74.5% 1.3% positive and 77.4% 1.8% negative), the distribution of pore sizes determined by mercury porosimetry was less uniform for positive samples, with a strong peak at a pore diameter of 5 pm. SEM pictures seemed to show that at the nanostructure level the fibers branched differently. These properties of the fabric were significantly different in ways that may affect its use as a tissue engineering scaffold. 

---