Pore Size Analysis Using Liquid Methods

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Pore Size Analysis Using Liquid Methods

• What can be measured using these techniques?
• Who would be interested in such results?
• A brief overview of measurement fundamentals.
• Meso-/macroporous solids
• Ceramics
• Batteries and Fuel Cells
• Geological samples
• Cement, concrete, stone and bricks
• Pharmaceuticals
• Filters
• Membranes
• Instrument selection for these materials
• Specific features of benefit to such materials

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Pore Size Analysis Using Liquid Methods

• What can be measured using these techniques?
• Pore size distributions (meso/macro, not micro)
• Pores too large for gas sorption
• Through-pores (porometry)
• Who would be interested in such results?
• Anyone who forms powders into solids
• Anyone who makes non-woven fabrics
• Membrane manufacturers

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Meso-/macroporous solids

• Ceramics
• Strength, absorbence, filtration
• Batteries and Fuel Cells
• Electrolyte contact, separator efficiency
• Geological samples
• Oil and gas, strength, liquid permeation
• Cement, concrete, stone and bricks
• Curing, strength, freeze/thaw resistance
• Pharmaceuticals
• Tablet structure, strength, dissolution
• Filters Membranes
• Efficiency

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Ceramics
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Bioceramics
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Battery Pores
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Electrode Pores
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Separator Pores
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Geological
sandstone
Diatomaceous earth
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Cement, Concrete, Mortar etc
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Pharmaceuticals
Tablet porosity provides pathways for the
penetration of fluid into tablets. The
disintegrant particles (with low cohesiveness
compressibility) themselves act to enhance
porosity and provide these pathways into the
tablet. Liquid is drawn up or wicked into these
pathways through capillary action and rupture the
interparticulate bonds causing the tablet to
break apart.
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Pharmaceuticals
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Filters Membranes
Nitrocellulose membrane
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Filters Membranes
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Washburn methods
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Wetting / Contact Angles
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Washburn Equation
Where P is in MPa and r in µm
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Sample Cell
Max measurable intrusion volume
The sample cell or penetrometer (sometimes called
a dilatometer) is used both to contain the sample
and to facilitate the measurement of intrusion
and extrusion volumes.
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Low Pressure Intrusion
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High Pressure Intrusion
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Increasing Pressure Causes Intrusion
Volume
Pressure
Pressure
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Mercury Porosimetry - Overview
Intrusion into internal pores
Compression of solid (rare)
Intrusion into powder voids
Powder compaction
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Results Overview
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Hysteresis

• Intrusion curves are not retraceable.
• (Extrusion curves lie above the intrusion
  curve)
• Can be explained by changes in ? between
• intrusion and extrusion.
• Some mercury remains in the pores

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Entrapment

• Mercury left behind in the pores
• entrapment.
• Entrapment ceases after the first
• few cycles.
• Complex network of pores responsible
• for such entrapment.

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THE state-of-the-art porometer
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sample holders support the sample
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Real-time data presentation
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Repeatability
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Application/Technique Selector
Mercury Porosimeter Capillary Porometer
3D structures ? -
2D structures - ?
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What Defines a Mercury Intrusion Porosimeter?

• Pressure Range
• Lowest pressure defines largest pore.
• Highest pressure defines smallest pore.
• NOTE Effect of Contact Angle
• A lower contact angle shifts pore size range to
  smaller values. Merely mathematical.
• A higher contact angle shifts pore size to larger
  values. Merely mathematical.

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The 3G Series 3G micro 3G Macro 3G z 3G zh
Pore size minimum 0.09 µm or 0.06 µm 0.09 µm lt0.04 µm lt0.02 µm
Pore size maximum 100 µm gt500 µm 500 µm 500 µm
Pressure controllers 1 2 2 2
Controller 1 0-100 psi or 0-150 psi 0-5 psi 0-30 psi 0-30 psi
Controller 2 n/a 0-100 psi 0-300 psi 0-500 psi
Pressure sensors 2 2 3 3
Sensor 1 0-5 psi 0-5 psi 0-5 psi 0-5 psi
Sensor 2 0-100 psi or 0-150 psi 0-100 psi 0-100 psi 0-100 psi
Sensor 3 n/a n/a 0-250 psi 0-500 psi
Flow sensors 1 1 1 or 2 2
Sensor 1 0-100 L/min or 0-200 L/min or 0-20 L/min 0-200 L/min 0-100 L/min 0-10 L/min
Sensor 2 n/a n/a Optional 5, 50, 200 L/min 0-200 L/min
Flow sensor switching n/a n/a manual auto