Advances In Characterization Techniques porosity by mikeholy

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									       Advances In
Characterization Techniques

      Dr. Krishna Gupta
      Technical Director
  Porous Materials, Inc., USA

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                   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    PMI EUROPE WORK SHOP
                 Topics

 Permeametry
   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 SHOP
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                  Topics

 Mercury Intrusion Porosimetry
    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
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               Topics

 Gas Adsorption
 Conclusions




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          Flow Porometry
     (Capillary Flow Porometry)
Accuracy and Reproducibility
 Most important sources of random &
  systematic errors identified
 Design modified to minimized errors
 Appropriate corrections incorporated



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         Flow Porometry
    (Capillary Flow Porometry)
Accuracy




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          Flow Porometry
     (Capillary Flow Porometry)
Repeatability
 Bubble point repeated 32 times
 Same operator
 Same machine
 Same wetting liquid
 Same filter

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              Flow Porometry
         (Capillary Flow Porometry)
Filter                     Wetting Liquid
                           Porewick Silwick
Sintered Stainless Steel   1.8%           1.2%
Battery Separator          0.2%           1.5%
Paper                      1.7%           1.1%




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               Flow Porometry
          (Capillary Flow Porometry)
     Errors due to the use of different machines
Machine Bubble point   Standard Deviation from
        pore diameter, deviation average of all
        Mean Value, mm           machines
1          18.35            0.53%        -1.34%
2          18.78            0.48%        0.93%
3          18.37            2.34%        0.28%
4          18.63            0.75%        0.13%

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           Flow Porometry
      (Capillary Flow Porometry)
 Operator errors
Machine   Average of Difference between
          mean, mm mean values by
                     operators
                     mm        Percentages
1         18.38      0.058     0.32%
2         18.77      0.005         0.03%
3         18.77      0.222         1.19%
4         18.73      0.213         1.14%
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Technology for Characterization under
 Simulated Application Environment
Compressive Stress
 Arrangement for testing sample
  under compressive stress


Arrangement for testing sample
     under compressive stress



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Technology for Characterization under
 Simulated Application Environment
Compressive Stress
Features:
 Any compressive stress up to 1000
  psi (700 kPa)
 Sample size as large as 8 inches
 Programmed to apply desired stress,
  perform test & release stress

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  Technology for Characterization under
   Simulated Application Environment


            Effect of
 compressive stress
on bubble point pore
           diameter




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Technology for Characterization under
 Simulated Application Environment




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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 Environment



Sample chamber for cyclic
  compression porometer




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Technology for Characterization under
 Simulated Application Environment
Features:
 Any desired stress between 15 and
  3000 psi
 Stress may be applied and released
  at fixed rates
 Duration of cycle 10 s
 Frequency adjustable by changing
  the duration of application of stress
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Technology for Characterization under
 Simulated Application Environment
Features:
 Programmed to
  interrupt after specified number of
  cycles,
  wait for a predetermined length of
  time,
  measure characteristics and then
  continue stressing
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Technology for Characterization under
 Simulated Application Environment
Features:
 Sample can be tested any required
  number of times within a specified
  range
 Fully automated



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Technology for Characterization under
 Simulated Application Environment



 Change of bubble
point pore diameter
    with number of
       stress cycles




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Technology for Characterization under
 Simulated Application Environment


  Effects of Cyclic
  compression on
      permeability




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Technology for Characterization under
 Simulated Application Environment
Aggressive environment


  Pore size of
   separator
  determined
  using KOH
     solution




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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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Technology for Characterization under
 Simulated Application Environment



 Sample chamber for
     determination of
  in-plane (x-y plane)
       pore structure




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Technology for Characterization under
 Simulated Application Environment




       Sample chamber for determination of pore
     structure in a specific direction such as x or y



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  Technology for Characterization under
   Simulated Application Environment
Material                         Bubble point, mm   Mean flow pore diameter, mm
Fuel cell component
   z-direction                   14.1               1.92
   x-direction                   14.6               1.04
   y-direction                   7.60               0.57
 Printer Paper
   z-direction                   12.4               4.20
   x-y plane                     1.11               0.09
Transmission fluid filter felt
   z-direction                   80.4               ―
   x-y plane                     43.3               ―
Liquid filter
   z-direction                   34.5               ―
   x-y plane                     15.3               ―
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               Clamp-On Porometry

  Sample chamber clamps on any
     desired location of sample (No need
     to cut sample & damage the material)


     Typical
chambers for
   clamp-on
  porometer


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        Clamp-On Porometry

Advantages:
 Very fast
 No damage to the bulk material
 Test may be performed on any
  location in the bulk material



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Flexibility to Accommodate a Wide Variety
    of Sample Shape, Size and Porosity
  Shapes:
   Sheets         Hollow Fibers
   Plates         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 Porosity
  Size:
   Micron size biomedical devices
   8 inch wafers
   Two feet cartridges
   Entire diaper



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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

 Fully automated
   Test execution
   Data storage
   Data Reduction
 User friendly interface
 Menu driven windows based software


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           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

Capability:
 A wide variety of gases, liquids &
  strong chemicals
 Different directions; x, y and z
  directions, x-y plane
 At elevated temperatures, high
  pressure & under stress
 Very low or very high permeability
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Diffusion Gas Permeametry




  Principle of diffusion permeameter

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Diffusion Gas Permeameter




  The PMI Diffusion
      Permeameter




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           Diffusion Gas Permeametry

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




         (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

 Uses actual component; Diaper,
  Cartridges, etc.
 Can measure flow rates as high as
  105 cm3/s
 Can test large size components



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     High Flow Gas Permeametry




PMI High Flow Gas
     Permeameter




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    Microflow Liquid Permeametry

 Measures very low liquid
  permeability in materials
    Ceramic discs
    Membranes
    Potatoes
    Other vegetables & fruit
 Uses a microbalance to measure
  small weights of displaced liquid, 10-4
  cm3/s                   PMI EUROPE WORK SHOP
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 Pressures


   The PMI high pressure, high
    temperature and high flow
           liquid permeameter




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High Flow Liquid Permeametry at High
  Temperatures and High Pressures
Capability:
 Temperature 100C
 Compressive stress on sample 300 psi
 Liquid: Oil
 Flow rate: 2 L/min



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


      The PMI Envelope
  Surface Area, Average
     Fiber Diameter and
   Average Particle Size
               Analyzer




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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 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, p             l = thickness of sample
      per unit time                                              p = pressure drop, (pi-po)
  p = average pressure, [(pi+po)/2], where pi is the inlet       r b = bulk density of sample
      pressure and po is the outlet pressure                     r a = 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
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      media. It has a value close to 5 for random pored media
Envelope Surface Area, Average Particle Size
  & Average Fiber Diameter Measurement
   Comparison between BET and ESA
     Methods
Sample ID   ESA surface BET surface ESA particle BET particle
            area (m^2/g) area (m^2/g) size       size
                                      (microns)  (microns)
Magnesium 11.13         12.16        0.43           0.39
stearate A
Magnesium 6.97          7.13         0.69           0.67
stearate B
Glass       0.89        0.915        14.82          14.83
bubbles A
Glass       1.76        1.91         22.25          20.53
bubbles B                          PMI EUROPE WORK SHOP
Envelope Surface Area, Average Particle Size
  & Average Fiber Diameter Measurement
  Average particle size
   Computes from surface area
    assuming same size & spherical
    shape of particles
                   6
              d=
                   Sr
  d = the average particle size
  S = specific surface area of the sample (total Surface area/mass)
  r = true density of the material


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Envelope Surface Area, Average Particle Size
  & Average Fiber Diameter Measurement
   Comparison between BET and ESA
     Methods
Sample ID   ESA surface BET surface ESA particle BET particle
            area (m^2/g) area (m^2/g) size       size
                                      (microns)  (microns)
Magnesium 11.13         12.16        0.43           0.39
stearate A
Magnesium 6.97          7.13         0.69           0.67
stearate B
Glass       0.89        0.915        14.82          14.83
bubbles A
Glass       1.76        1.91         22.25          20.53
bubbles B                          PMI EUROPE WORK SHOP
Envelope Surface Area, Average Particle Size
  & Average Fiber Diameter Measurement
  Average fiber diameter
   Computed from flow rate using Davies
    equation
   (4pAR2)/(mFl) = 64 c1.5[1+52c3]
  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                            PMI EUROPE WORK SHOP
Envelope Surface Area, Average Particle Size
  & Average Fiber Diameter Measurement



   Measured fiber
      diameters in
  microns plotted
 against the actual
   fiber diameters




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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

Transmission under pressure gradient




     Principle of Water vapor transmission analyzer

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          Water Vapor Transmission

Transmission under pressure gradient


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




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      Water Vapor Transmission

Transmission under concentration
gradient

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




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     Water Vapor Transmission

Transmission under concentration
gradient


            Water vapor
      transmission rate
        through several
               samples




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   Mercury Intrusion Porosimetry

Stainless Steel Sample Chamber


  Stainless Steel Sample
    Chamber of The PMI
       Mercury Intrusion
            Porosimeter




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    Mercury Intrusion Porosimetry

Special design to minimize contact with
mercury


      The PMI Mercury
 Intrusion Porosimeter




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   Mercury Intrusion Porosimetry

 Separation of high-pressure section
  from low-pressure section
 Sample chamber is evacuated and
  pressurized without transferring the
  chamber and contacting mercury
 Automatic cleaning of the system by
  evacuation

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   Mercury Intrusion Porosimetry

 Automatic refilling of penetrometer
  by mercury
 Automatic drainage of mercury
 In-situ pretreatment of the sample
 Fully automated operation



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     Non-Mercury Intrusion Prosimetry

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

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




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



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Water Intrusion Porosimeter
        (Aquapore)




The PMI Aquapore




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            Gas Adsorption

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


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             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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              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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                Conclusions

 Measurement of characteristics
  under application environments
  involving:
    compressive stress
    cyclic compression
    aggressive conditions
    elevated temperatures
    high pressures
  have been illustrated with examples
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Thank You
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