Mercury intrusion porosimetry MIP

This method is based on the fact that a liquid that does not wet a porous solid will enter its pores only under pressure. If the pores are assumed to be cylindrical, the pressure (p) needed to force the liquid into them is given by the Washburn equation 

Typical results (Fig. 8.7) show that the distribution moves to smaller values as hydration proceeds. The observed porosity is mainly in the 3 nm to 1 pm range for young pastes, and in the 3-100 nm range for mature pastes. For mature pastes of low w/c ratio, which according to the Powers-Brownyard theory consist entirely of hydration product, nearly all the porosity is below 50 nm (S77). We shall refer to the porosities obtained using mercury at the maximum pressures employed as mercury porosities. Typical values for mature pastes (Fig. 8.5) are somewhat lower than the calculated free water porosities. 

The earlier literature contains several references to missing porosity, meaning the difference between mercury porosities and total water porosities. The difference clearly arises mainly from the failure of mercury to enter vacated interlayer space but has also been attributed to the encapsulation of gel by CH (D33) or to the presence of large ( 15 pm), closed pores that are not entered (A 15). 

MIP results do not show the sharp distinction in size between capillary and gel pores postulated by Powers and Brownyard (P20). Mikhail et at. (M69) earlier came to the same conclusion from results obtained by Nj sorption. With increasing age, the volume of pores smaller than about 20 nm increases and that of pores larger than about 200 nm decreases, but there is no sign of two separate distributions (Fig. 8.7). The single distribution 

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

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... 

In this study mercury intrusion porosimetry (MIP) analyses were employed to determine the pore size distribution and pore volume over the range of approximately 100 pm down to 7.5 nm diameter, utilising CE Instruments Pascal 140/240 apparatus, on samples previously dried overnight at 150°C. The pressure/volume data were analysed by use of the Washburn Equation [14] assuming a cylindrical nonintersecting pore model and taking the mercury contact angle as 141° and surface tension as 484 mN m [10]. For the monolith... 

Three different sieved size fractions (20-45, 74-105 and 105-450 pm) of a SDDP batch have been characterized for their in vitro dissolution profiles and the textural properties of the three fractions and the original unsieved batch have been investigated by gas adsorption (B.E.T. method). Mercury Intrusion Porosimetry (MIP), light scattering and microscopy (optical and electron) techniques. 

For that purpose, several characterization techniques have been used (Mercury Intrusion Porosimetry (MIP), Particle Size Distribution (PSD), Microscopy and Specific Surface Area (SSA) by gas adsorption). The thus obtained physical characteristics explain the observed dissolution profiles. 

Table 1 Texture analysis results obtained by gas adsorption and Mercury Intrusion Porosimetry (MIP).

Drug Substance (DS) Specific Surface Area (SSA) has been estimated by permeabilimetry, gas adsorption, laser light scattering and Mercury Intrusion Porosimetry (MIP). Because of the simplifying and different assumptions made, none of these experimental methods can provide the absolute SSA value and a perfect agreement between the values obtained by each technique is not found However, differences in theoretical assumptions made for each technique and observed results have been useful for understanding and interpreting the texture of the powder studied. 

Mercury intrusion porosimetry (MIP) tests were performed to characterize the multiple-porosity network of the artificially prepared packing at different dry density values ranging from 1.2 to 1.95 Mg/m ... 

The evolution of hydration and carbonation of powder samples was assessed by XRD, mercury intrusion porosimetry (MIP), FTIR, DTA/TG, EDXRF and SEM. By identifying calcium silicate hydrates (CSH) and calcium aluminate hydrates (CAH) at different ages, not only qualitatively, but also semi-quantitatively, the hydration and carbonation processes could be monitored. The mineralogical analysis was investigated by XRD with a Siemens D-500 diffractometer (40 kV/35 mA) the spectra were collected... 

In this work the merits of the use of a natural fibrous mineral, sepiolite, as a binder to produce titania based monoliths of high mechanical strength and abrasion resistance is discussed. The monoliths of square channels were conformed with an initial 7.5 channels cm and 1 mm wall thickness. TTie textural characterization was made by mercury intrusion porosimetry (MIP), nitrogen adsorption/desorption (BET), and X-ray diffraction (XRD). The mechanical resistance, dimensional changes and weight losses al each stage of heat treatment were also determined. The thermal expansion coefficients (TEC) of the monoliths were determined between 200 and 400 C, since in practice the usual working temperature of DENOX catalysts lies between 250°-350 C. 

Indirect Porosity Mercury intrusion, porosimetry (MIP), gaseous adsorption (BET)... 

The reported experimental approaches include pore intrusion or immersion using suitable Uquids. The most common technique is mercury intrusion porosimetry (MIP) that involves pressurizing the liquid metal in a porous matrix incrementally in order to displace air or a wetting fluid. Mercury is used because it does not wet most surfaces due to its extremely high surface tension that also enables measurements under vacuum. 

Figure 8-4. Pore size distribution of hardened cement paste and mortar determined by mercury intrusion porosimetry (MIP). Age 192 days, stored at 98.5% relative humidity (Burchler et al., 1996a).

Mean (n = 3) SD Helium pycnometry Mercury intrusion porosimetry (MIP) ... 

Few techniques are able to characterise the complex pore structure of hydrated cementitious materials. One of the most used techniques is mercury intrusion porosimetry (MIP). This technique is based on the intrusion of a nonwetting fluid (mercury) into porous structures under increasing pressure. This simple principle often makes users forget about the underlying assumptions and the limitations of the MIP technique. 

The SSA can also be estimated from the pore size distribution measured by nitrogen adsorption desorption (NAD), mercury intrusion porosimetry (MIP) and proton nuclear magnetic resonance ( H-NMR) relaxometry. The surface area calculation from NAD and MIP needs a pore shape assumption usually, cylindrical pores are assumed. The approach using H-NMR and MIP are described and discussed in detail in Chapters 7 and 9, respectively. 

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