POWDER SURFACE AREA AND POROSITY: Second Edition.. Questo articolo non è disponibile.POWDER SURFACE AREA AND POROSITY: Second Edition.

The rapid growth of interest in powders and their surface properties in many diverse industries prompted the writing of this book for those who have the need to make meaningful measurements without the benefit of years of experience. It is intended as an introduction to some of the elementary theory and experimental methods used to study the surface area, porosity and density of powders. It may be found useful by those with little or no training in solid surfaces who have the need to quickly learn the rudiments of surface area, density and pore-size measurements. Syosset, New York S. Lowell May, 1983 J. E. Shields Xl List of symbols Use of symbols for purposes other than those indicated in the following list are so defined in the text. Some symbols not shown in this list are defined in the text. d adsorbate cross-sectional area A area; condensation coefficient; collision frequency C BET constant c concentration D diameter; coefficient of thermal diffusion E adsorption potential f permeability aspect factor F flow rate; force; feed rate 9 gravitational constant G Gibbs free energy GS free surface energy h heat of immersion per unit area; height H enthalpy Hi heat of immersion Hsv heat of adsorption BET intercept; filament current k thermal conductivity; specific reaction rate K Harkins-Jura constant I length L heat of liquefaction M mass M molecular weight n number of moles N number of molecules; number of particles N Avagadro's number .

I Theoretical.- 1 Introduction.- 1.1 Real surfaces.- 1.2 Factors affecting surface area.- 1.3 Surface area from size distributions.- 2 Gas adsorption.- 2.1 Introduction.- 2.2 Physical and chemical adsorption.- 2.3 Physical adsorption forces.- 3 Adsorption isotherms.- 4 Langmuir and BET theories.- 4.1 The Langmuir isotherm, type I.- 4.2 The Brunauer, Emmett and Teller (BET) theory.- 4.3 Surface areas from the BET equation.- 4.4 The meaning of monolayer coverage.- 4.5 The BET constant and site occupancy.- 4.6 Applicability of the BET theory.- 4.7 Some criticism of the BET theory.- 5 The single point BET method.- 5.1 Derivation of the single-point method.- 5.2 Comparison of the single-point and multipoint methods.- 5.3 Further comparisons of the multi- and single-point methods.- 6 Adsorbate cross-sectional areas.- 6.1 Cross-sectional areas from the liquid molar volume.- 6.2 Nitrogen as the standard adsorbate.- 6.3 Some adsorbate cross-sectional areas.- 7 Other surface area methods.- 7.1 Harkins and Jura relative method.- 7.2 Harkins and Jura absolute method.- 7.3 Permeametry.- 8 Pore analysis by adsorption.- 8.1 The Kelvin equation.- 8.2 Adsorption hysteresis.- 8.3 Types of hysteresis.- 8.4 Total pore volume.- 8.5 Pore-size distributions.- 8.6 Modelless pore-size analysis.- 8.7 V?t curves.- 9 Microporosity.- 9.1 Introduction.- 9.2 Langmuir plots for microporous surface area.- 9.3 Extensions of Polanyi’s theory for micropore volume and area.- 9.4 The t-method.- 9.5 The MP method.- 9.6 Total micropore volume and surface area.- 10 Theory of wetting and capillarity for mercury porosimetry.- 10.1 Introduction.- 10.2 Young and Laplace equation.- 10.3 Wetting or contact angles.- 10.4 Capillarity.- 10.5 Washburn equation.- 11 Interpretation of mercury porosimetry data.- 11.1 Application of the Washburn equation.- 11.2 Intrusion—extrusion curves.- 11.3 Common features of porosimetry curves.- 11.4 Solid compressibility.- 11.5 Surface area from intrusion curves.- 11.6 Pore-size distribution.- 11.7 Volume In radius distribution function.- 11.8 Pore surface area distribution.- 11.9 Pore length distribution.- 11.10 Pore population.- 11.11 Plots of porosimetry functions.- 11.12 Comparisons of porosimetry and gas adsorption.- 12 Hysteresis, entrapment, and contact angle.- 12.1 Introduction.- 12.2 Contact angle changes.- 12.3 Porosimetric work.- 12.4 Theory of porosimetry hysteresis.- 12.5 Pore potential.- 12.6 Other hysteresis theories.- 12.7 Equivalency of mercury porosimetry and gas adsorption.- II Experimental.- 13 Adsorption measurements-Preliminaries.- 13.1 Reference standards.- 13.2 Other preliminary precautions.- 13.3 Representative samples.- 13.4 Sample conditioning.- 14 Vacuum volumetric measurements.- 14.1 Nitrogen adsorption.- 14.2 Deviation from ideality.- 14.3 Sample cells.- 14.4 Evacuation and outgassing.- 14.5 Temperature control.- 14.6 Isotherms.- 14.7 Low surface areas.- 14.8 Saturated vapor pressure, P0 of nitrogen.- 15 Dynamic methods.- 15.1 Influence of helium.- 15.2 Nelson and Eggertsen continuous flow method.- 15.3 Carrier gas and detector sensitivity.- 15.4 Design parameters for continuous flow apparatus.- 15.5 Signals and signal calibration.- 15.6 Adsorption and desorption isotherms by continuous flow.- 15.7 Low surface area measurements.- 15.8 Data reduction-continuous flow.- 15.9 Single-point method.- 16 Other flow methods.- 16.1 Pressure jump method.- 16.2 Continuous isotherms.- 16.3 Frontal analysis.- 17 Gravimetric method.- 17.1 Electronic microbalances.- 17.2 Buoyancy corrections.- 17.3 Thermal transpiration.- 17.4 Other gravimetric methods.- 18 Comparison of experimental adsorption methods.- 19 Chemisorption.- 19.1 Introduction.- 19.2 Chemisorption equilibrium and kinetics.- 19.3 Chemisorption isotherms.- 19.4 Surface titrations.- 20 Mercury porosimetry.- 20.1 Introduction.- 20.2 Pressure generators.- 20.3 Dilatometer.- 20.4 Continuous-scan porosimetry.- 20.5 Logarithmic signals from continuous—scan porosimetry.- 20.6 Low pressure intrusion-extrusion scans.- 20.7 Scanning porosimetry data reduction.- 20.8 Contact angle for mercury porosimetry.- 21 Density measurement.- 21.1 True density.- 21.2 Apparent density.- 21.3 Bulk density.- 21.4 Tap density.- 21.5 Effective density.- 21.6 Density by mercury porosimetry.- References.