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Advances In Characterization Techniques. Dr. Krishna Gupta Technical Director Porous Materials, Inc., USA. Topics. Flow Porometry. Accuracy and Reproducibility Technology for Characterization under Application Environment Directional Porometry Clamp-On Porometry

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advances in characterization techniques

Advances In Characterization Techniques

Dr. Krishna Gupta

Technical Director

Porous Materials, Inc., USA

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topics
Topics
  • Flow Porometry
  • Accuracy and Reproducibility
  • Technology for Characterization under Application Environment
  • Directional Porometry
  • Clamp-On Porometry
  • Flexibility to Accommodate Samples of Wide Variety of Shapes, Sizes and Porosity
  • Ease of Operation

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topics3
Topics
  • Diffusion Gas Permeametry
  • High Flow Gas Permeametry
  • Microflow liquid permeametry
  • High flow liquid permeametry at high temperature & high presure
  • Envelope surface area, average particle size & average fiber diameter analysis
  • Water vapor transmission rate
  • Permeametry

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topics4
Topics
    • Stainless steel sample chamber
    • Special design to minimize contact with mercury
  • Non-Mercury Intrusion Porosimetry
    • Sample chamber that permits mercury intrusion porosimeter to be used as non-mercury intrusion porosimeter
    • Water Intrusion Porosimeter
  • Mercury Intrusion Porosimetry

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topics5
Topics
  • Conclusions
  • Gas Adsorption

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flow porometry capillary flow porometry
Flow Porometry (Capillary Flow Porometry)
  • Design modified to minimized errors
  • Appropriate corrections incorporated

Accuracy and Reproducibility

  • Most important sources of random & systematic errors identified

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flow porometry capillary flow porometry7
Flow Porometry(Capillary Flow Porometry)

Accuracy

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flow porometry capillary flow porometry8
Flow Porometry(Capillary Flow Porometry)
  • Same operator
  • Same machine
  • Same wetting liquid
  • Same filter

Repeatability

  • Bubble point repeated 32 times

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flow porometry capillary flow porometry10
Flow Porometry(Capillary Flow Porometry)
  • Errors due to the use of different machines

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flow porometry capillary flow porometry11
Flow Porometry(Capillary Flow Porometry)
  • Operator errors

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technology for characterization under simulated application environment

Arrangement for testing sample under compressive stress

Technology for Characterization under Simulated Application Environment

Compressive Stress

  • Arrangement for testing sample under compressive stress

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technology for characterization under simulated application environment13
Technology for Characterization under Simulated Application Environment
  • Sample size as large as 8 inches
  • Programmed to apply desired stress, perform test & release stress

Compressive Stress

Features:

  • Any compressive stress up to 1000 psi (700 kPa)

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technology for characterization under simulated application environment16
Technology for Characterization under Simulated Application Environment

Cyclic stress

  • Stress cycles are applied on sample sandwiched between two porous plates and the sample is tested during a pause in the stress cycle

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technology for characterization under simulated application environment18
Technology for Characterization under Simulated Application Environment
  • Stress may be applied and released at fixed rates
  • Duration of cycle 10 s
  • Frequency adjustable by changing the duration of application of stress

Features:

  • Any desired stress between 15 and 3000 psi

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technology for characterization under simulated application environment19
Technology for Characterization under Simulated Application Environment
  • Programmed tointerrupt after specified number of cycles, wait for a predetermined length of time, measure characteristics and then continue stressing

Features:

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technology for characterization under simulated application environment20
Technology for Characterization under Simulated Application Environment
  • Sample can be tested any required number of times within a specified range

Features:

  • Fully automated

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technology for characterization under simulated application environment24
Technology for Characterization under Simulated Application Environment

Directional Porometry

  • In this technique, Gas is allowed to displace liquid in pores in the specified direction

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clamp on porometry

Typical chambers for clamp-on porometer

Clamp-On Porometry
  • Sample chamber clamps on any desired location of sample (No need to cut sample & damage the material)

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clamp on porometry29
Clamp-On Porometry
  • No damage to the bulk material
  • Test may be performed on any location in the bulk material

Advantages:

  • Very fast

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flexibility to accommodate a wide variety of sample shape size and porosity
Flexibility to Accommodate a Wide Variety of Sample Shape, Size and Porosity
  • Plates

Shapes:

  • Sheets
  • Hollow Fibers
  • Pen tips
  • Discs
  • Cartridges
  • Rods
  • Diapers
  • Tubes
  • Odd shapes
  • Powders
  • Nanofibers

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flexibility to accommodate a wide variety of sample shape size and porosity31
Flexibility to Accommodate a Wide Variety of Sample Shape, Size and Porosity
  • 8 inch wafers
  • Two feet cartridges
  • Entire diaper

Size:

  • Micron size biomedical devices

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flexibility to accommodate a wide variety of sample shape size and porosity32
Flexibility to Accommodate a Wide Variety of Sample Shape, Size and Porosity

Materials:

  • Ceramics
  • Nonwovens
  • Metals
  • Composites
  • Textiles
  • Gels
  • Sponges
  • Hydrogels

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ease of operation
Ease of Operation
  • Fully automated
    • Test execution
    • Data storage
    • Data Reduction
  • User friendly interface
  • Menu driven windows based software

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ease of operation34
Ease of Operation
  • Graphical display of real time test status and results of test in progress
  • Many user specified formats for plotting & display of results
  • Minimal operator involvement

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advanced permeametry
Advanced Permeametry
  • Different directions; x, y and z directions, x-y plane
  • At elevated temperatures, high pressure & under stress
  • Very low or very high permeability

Capability:

  • A wide variety of gases, liquids & strong chemicals

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diffusion gas permeametry38

Change of outlet gas pressure with time for two samples measured in the PMI Diffusion Permeameter.

Diffusion Gas Permeametry

(dVs/dt) = (TsVo/Tps)(dp/dt)

Vs = gas flow in volume of gas at STP

Vo = volume of chamber on the outlet side

Flow rate < 0.75x10-4 cm3/s

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high flow gas permeametry
High Flow Gas Permeametry
  • Can measure flow rates as high as 105 cm3/s
  • Can test large size components
  • Uses actual component; Diaper, Cartridges, etc.

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microflow liquid permeametry
Microflow Liquid Permeametry
    • Ceramic discs
    • Membranes
    • Potatoes
    • Other vegetables & fruit
  • Uses a microbalance to measure small weights of displaced liquid, 10-4 cm3/s
  • Measures very low liquid permeability in materials

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high flow liquid permeametry at high temperatures and high pressures
High Flow Liquid Permeametry at High Temperatures and High Pressures
  • Measures high permeability of application fluids at high temperature through actual parts under compressive stress

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high flow liquid permeametry at high temperatures and high pressures44
High Flow Liquid Permeametry at High Temperatures and High Pressures
  • Compressive stress on sample 300 psi
  • Liquid: Oil
  • Flow rate: 2 L/min

Capability:

  • Temperature 100C

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envelope surface area average particle size average fiber diameter measurement46
Envelope Surface Area, Average Particle Size & Average Fiber Diameter Measurement

Envelope Surface Area

  • Computes surface area from flow rate using Kozeny and Carman relation

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envelope surface area average particle size average fiber diameter measurement47
Envelope Surface Area, Average Particle Size & Average Fiber Diameter Measurement

Envelope Surface Area

  • [Fl/pA] ={P3/[K(1-P)2S2m]}+[ZP2p]/[(1-P)S(2ppr)1/2]

F = gas flow rate in volume at average pressure, pl = thickness of sample per unit time p = pressure drop, (pi-po)

p = average pressure, [(pi+po)/2], where pi is the inlet rb = bulk density of sample

pressure and po is the outlet pressure ra = true density of sample

A = cross-sectional area of sample m = viscosity of gas

P = porosity (pore volume/total volume) = [1-(rb/ra)]

p = average pressure, [(pi+po)/2], where pi is the r = density of the gas at

inlet pressure and po is the outlet pressure the average pressure, p

S = through pore surface area per unit volume Z = a constant. It is shown to

of solid in the sample be (48/13p)

K = a constant dependent on the geometry of the pores in the media. It has a value close to 5 for random pored media

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envelope surface area average particle size average fiber diameter measurement48
Envelope Surface Area, Average Particle Size & Average Fiber Diameter Measurement
  • Comparison between BET and ESA Methods

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envelope surface area average particle size average fiber diameter measurement49

6

d =

Sr

Envelope Surface Area, Average Particle Size & Average Fiber Diameter Measurement

d = the average particle size

S = specific surface area of the sample (total Surface area/mass)

r = true density of the material

Average particle size

  • Computes from surface area assuming same size & spherical shape of particles

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envelope surface area average particle size average fiber diameter measurement50
Envelope Surface Area, Average Particle Size & Average Fiber Diameter Measurement
  • Comparison between BET and ESA Methods

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envelope surface area average particle size average fiber diameter measurement51
Envelope Surface Area, Average Particle Size & Average Fiber Diameter Measurement
  • (4pAR2)/(mFl) = 64 c1.5[1+52c3]

Average fiber diameter

  • Computed from flow rate using Davies equation

P  0.7-0.99

c = packing density (ratio of volume of fibers to volume of sample)

= (1-P)

p = pressure gradient

A = cross-sectional area of sample

R = average fiber radius

m = viscosity of gas

F = gas flow rate average pressure

L = thickness of sample

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envelope surface area average particle size average fiber diameter measurement53
Envelope Surface Area, Average Particle Size & Average Fiber Diameter Measurement
  • Average fiber diameter can also be computed from the envelope surface area. Assuming the fibers to have the same radius and the same length;

Df = 4V/S = 4/Sr

Df = average fiber diameter

V = volume of fibers per unit mass

S = envelope surface area of fibers per unit mass

r = true density of fibers

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water vapor transmission

Principle of Water vapor transmission analyzer

Water Vapor Transmission

Transmission under pressure gradient

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water vapor transmission55

Change of pressure on the outlet side of two samples of the naphion membrane in the PMI Water Vapor Transmission Analyzer

Water Vapor Transmission

Transmission under pressure gradient

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water vapor transmission56

Line diagram showing the operating principle of PMI Advanced Water Vapor Transmission Analyzer

Water Vapor Transmission

Transmission under concentration gradient

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water vapor transmission57

Water vapor transmission rate through several samples

Water Vapor Transmission

Transmission under concentration gradient

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mercury intrusion porosimetry

Stainless Steel Sample Chamber of The PMI Mercury Intrusion Porosimeter

Mercury Intrusion Porosimetry

Stainless Steel Sample Chamber

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mercury intrusion porosimetry59

The PMI Mercury Intrusion Porosimeter

Mercury Intrusion Porosimetry

Special design to minimize contact with mercury

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mercury intrusion porosimetry60
Mercury Intrusion Porosimetry
  • Sample chamber is evacuated and pressurized without transferring the chamber and contacting mercury
  • Automatic cleaning of the system by evacuation
  • Separation of high-pressure section from low-pressure section

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mercury intrusion porosimetry61
Mercury Intrusion Porosimetry
  • Automatic drainage of mercury
  • In-situ pretreatment of the sample
  • Fully automated operation
  • Automatic refilling of penetrometer by mercury

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non mercury intrusion prosimetry

Sample Chamber for use to perform non-mercury intrusion tests in the PMI Mercury Intrusion Porosimeter

Non-Mercury Intrusion Prosimetry

Sample Chamber That permits Mercury Intrusion Porosimeter to be used as a Non-Mercury Intrusion Porosimeter

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water intrusion porosimeter aquapore
Water Intrusion Porosimeter (Aquapore)
  • Water used as intrusion liquid
  • Can test hydrophobic materials
  • Can detect hydrophobic pores in a mixture
  • Uses absolutely no mercury

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gas adsorption
Gas Adsorption
  • Capable of very fast measurement (<10 min) of single point and multi-point surface areas
  • The PMI QBET for fast surface area measurement
  • A new technique developed by PMI

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conclusions
Conclusions
  • Recent advances made in the technology of measurement and novel methods of measurement of properties using porometry, permeametry, porosimetry and gas adsorption have been discussed

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conclusions67
Conclusions
  • Results have been presented to show the improvements in accuracy and repeatability of results and ease of operation of the test.

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conclusions68
Conclusions
  • compressive stress
  • cyclic compression
  • aggressive conditions
  • elevated temperatures
  • high pressures

have been illustrated with examples

  • Measurement of characteristics under application environments involving:

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thank you
Thank You

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