Intrusion porosimetry

In addition, mercury intrusion porosimetry results are shown together with the pore size distribution in Figure 3.7.3(B). The overlay of the two sets of data provides a direct comparison of the two aspects of the pore geometry that are vital to fluid flow in porous media. In short, conventional mercury porosimetry measures the distribution of pore throat sizes. On the other hand, DDIF measures both the pore body and pore throat. The overlay of the two data sets immediately identify which part of the pore space is the pore body and which is the throat, thus obtaining a model of the pore space. In the case of Berea sandstone, it is clear from Figure 3.7.3(B) that the pore space consists of a large cavity of about 85 pm and they are connected via 15-pm channels or throats. 

Pore shape is a characteristic of pore geometry, which is important for fluid flow and especially multi-phase flow. It can be studied by analyzing three-dimensional images of the pore space [2, 3]. Also, long time diffusion coefficient measurements on rocks have been used to argue that the shapes of pores in many rocks are sheetlike and tube-like [16]. It has been shown in a recent study [57] that a combination of DDIF, mercury intrusion porosimetry and a simple analysis of two-dimensional thin-section images provides a characterization of pore shape (described below) from just the geometric properties. 

Although a number of methods are available to characterize the interstitial voids of a solid, the most useful of these is mercury intrusion porosimetry [52], This method is widely used to determine the pore-size distribution of a porous material, and the void size of tablets and compacts. The method is based on the capillary rise phenomenon, in which excess pressure is required to force a nonwetting liquid into a narrow volume. 

Measurements of particle porosity are a valuable supplement to studies of specific surface area, and such data are particularly useful in the evaluation of materials used in direct compression processes. For example, both micromeritic properties were measured for several different types of cellulosic-type excipients [53]. Surface areas by the B.E.T. method were used to evaluate all types of pore structures, while the method of mercury intrusion porosimetry used could not detect pores smaller than 10 nm. The data permitted a ready differentiation between the intraparticle pore structure of microcrystalline and agglomerated cellulose powders. 

One of the most popular methods to measure the pore size distribution in diffusion layers is mercury intrusion porosimetry (MIP) this technique is... 

Fig. 5.16 Mercury intrusion porosimetry curves of C3S pastes showing differences in capillary porosity distribution.

Figure 2. Cumulative pore volume vs. pore radius for AC-ref, SC-100 and SC-155 Mercury intrusion porosimetry.

Pore size distributions are often determined by the technique of mercury intrusion porosimetry. The volume of mercury (contact angle c. 140° with most solids) which can be forced into the pores of the solid is measured as a function of pressure. The pore size distribution is calculated in accordance with the equation for the pressure difference across a curved liquid interface,... 

WINSLOW, D.N., Advances in experimental techniques for mercury intrusion porosimetry , in reference 9 13, 259-286 (1984)... 

Similarly, we polymerized the same mixture used for the preparation of capillary columns in glass vials and used the product for mercury intrusion porosimetry. Since we found that a strong correlation exists between the "dry" porous properties of the monoliths and their chromatographic performance, even dry porosity measurements may be used to tailor column performance. 

C.M. Nielsen-Marsh, R.E.M. Hedges, Bone porosity and the use of mercury intrusion porosimetry in bone diagenesis studies, Archaeometry 41 (1999) 165-174. 

Table 4. Porosities and pore size distributions derived from mercury intrusion porosimetry.

V. Maquet, S. Blacher, R. Pirard, J.-P. Pirard, M. N. Vyakamum, and R. Jerome, Preparation of macroporous biodegradable poly(L-lactic-co-e-caprolactone) foams and characterization by mercury intrusion porosimetry, image analysis and impedance spectroscopy, J. Biomed. Mater. Res. 66A, 199-213 (2003). 

A. B. Abell, K. L. Willis, and D. A. Lange, Mercury intrusion porosimetry and image analysis of cement-based materials, J. Colloid Interf. Anal. 211, 39-44 (1999). 

The sample was dried completely and a second water penetration experiment was carried out. The maximum uptake of water occurred once again after 24 h of soaking however, the slope of the profile was less pronounced, as illustrated in Fig. 17. Furthermore, the peak intensity was lower in the second experiment, which is evidence of a smaller pore size distribution in the sample, suggesting that some degree of rehydration took place in this sample during the course of the first water penetration study. This result was further verified by mercury intrusion porosimetry. 

These comments apply also to studies of pore size distribution or specific surface area, which have been widely studied using sorption isotherms or, in the former case, mercury intrusion porosimetry (MIP). Gregg and Sing... 

Incorporation of the measured contact angle in mercury intrusion porosimetry data is essential for an accurate determination of the pore size distribution. Both the advancing and static angle methods are suitable to carry out this measurement, leading to very similar results. For most oxidic materials and supported oxides, the contact angle is 140° and incorporation of the actual contact angle is less critical in the pore size determination. However, important deviations are observed in carbon and cement-like materials, with contact angles of > 150° and < 130°, respectively. This has been shown by comparison of the pore size distribution obtained from mercury porosimetry and N2 adsorption measurements. 

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