Methods of Porosity Measurement and Testing

Advance Characterization Techniques
Porosity Testing
Materials Testing
Textile Porosity
Brunauer-Emmett-Teller
Mercury intrusion Porosimetry
Capillary flow Porometry
Atomic force microscopy

1. Porosity Analysis
and
Measurement of
Textile Materials
M Mehran Ali 23-NTU-0008
Aziz Umar 23-NTU-0005

2. Contents:
•Porosity
•Importance –Benefits
•Limitations
•Methods of porosity Measurement
(Procedure –Applications –Flaws)
•Future Advancements
•References

3. Porosity
Porosity refers to the measure of voidsor poresor empty
spaces within a material.
Ratio of total
empty area to
total area
Ratio of total empty
volumeto total
volume

4. Importance of
porosity:
Benefits:
•Ventilation, Air circulation, Breathability,
thermal insulation, lightweight textiles,
filtration applications, medical, etc.
Limitations (Challenges):
•Reduce properties
•Reduce strengthand durability
•Potential for Pilling
•Challenges in Waterproofing , Etc.

5. Methods of porosity
Measurement
Fluid Displacement
Air permeability test
CFP (Capillary flow Porometry)
MIP (Mercury intrusion Porosimetry)
BET (Brunauer-Emmett-Teller)
Water Flow test
AFM (Atomic force microscopy)

6. Fluid Displacement
Method
Working
procedure
Applications
in textiles
Flaws

7. Fluid Displacement
Method
Working
procedure
Applications
in textiles
Flaws
Preparation and initial mass
measurement
Immersion in liquid
Displacement measurement
Calculation

8. Fluid Displacement
Method
Working
procedure
Applications
in textiles
Flaws
•Filtration (Liquid Filtration,
etc.)
•Nonwoven Fabrics
•Sportswear
•Thermal Insulation

9. Fluid Displacement
Method
Working
procedure
Applications
in textiles
Flaws
•Pore Size Distribution
•Fluid selection
•Time consuming
•Temperature sensitivity
•Sample Preparation
sensitivity

10. Air Permeability Test
Working Procedure
Applications in Textiles
Flaws

11. Air Permeability Test
Working Procedure
Applications in Textiles
Flaws
•Sample Preparation
•Placement of sample
•Expose area to air flow
•Apply pressure difference
•Air Flow Measurement
•Calculation of
Permeability

12. Air Permeability Test
Working Procedure
Applications in Textiles
Flaws
Where,
•k = air permeability
•Q = volume of air flow through
the specimen
•L = thickness of the specimen
•A = area of the specimen
•ΔP = pressure difference
•t = time of the test

13. Air Permeability Test
Working Procedure
Applications in Textiles
Flaws
Breathability, Air circulation,
Ventilation
•Sportswear
•Outdoor apparel
•Medical Textiles (Wounds, etc.)
•Home Textiles (Mattress, Pillows,
Curtains, etc.)
•Filtration (Air Filters, etc.)
•Industrial fabrics (Uniforms,
Temporary Shelters, etc.)
•Automotive Textiles (Car Seats,
etc.)

14. Air Permeability Test
Working Procedure
Applications in Textiles
Flaws
•Pore Size Distribution
•Single Parameter
Measurement
•Limited Application Range

15. CFP (Capillary
Flow
Porometry)
Working
procedure
Applications in
textiles
Flaws

16. CFP (Capillary
Flow
Porometry)
Working
procedure
Applications in
textiles
Flaws
•Sample preparation
•Placement of sample
•Wetting the sample
•Apply gas pressure
•Increase gas pressure
•Measure gas flow rate
•Determining Pore Sizes
•Calculating Porosity
•Generating Pore Size
Distribution Graphs

17. CFP (Capillary
Flow
Porometry)
Working
procedure
Applications in
textiles
Flaws
Where,
•r = average pore radius
•γ = surface tension
•θ = contact angle between the
liquid and the solid material.
•P = applied pressure.
Where, •n(r) = pore size distribution
function
•r
min and r max​ = minimum and
maximum pore radii

18. CFP (Capillary
Flow
Porometry)
Working
procedure
Applications in
textiles
Flaws
Pore size distribution
•Nonwoven Textiles
•Sportswear
•Filtration media
•Absorbency Analysis in Towels
and Diapers

19. CFP (Capillary
Flow
Porometry)
Working
procedure
Applications in
textiles
Flaws
•Accuracy depends on
saturation
•Not suitable tight weaves

20. MIP (Mercury
Intrusion
Porosimetry)
Working
Procedure
Applications in Textiles
Flaws

21. MIP (Mercury
Intrusion
Porosimetry)
Working
Procedure
Applications in Textiles
Flaws
•Sample preparation
•Evacuation of air
•Mercury filling
•Pressure application
•Volume measurement

22. MIP (Mercury
Intrusion
Porosimetry)
Working
Procedure
Applications in Textiles
Flaws
•Pore Size Distribution
•Analysis of Nonwoven Fabrics
•Medical Textiles
•Development of Smart Textiles
•Understanding Thermal Insulation

23. MIP (Mercury
Intrusion
Porosimetry)
Working
Procedure
Applications in Textiles
Flaws
•Damage to sample
•Micro pores may not
detect
•Damage structure
•Mercury hazards

24. BET (Brunauer-Emmett-Teller)
Working
Procedure
Applications
in Textiles
Flaws

25. BET (Brunauer-Emmett-Teller)
Working
Procedure
Applications
in Textiles
Flaws
•Sample Preparation
•Place in the instrument
•Remove any gas or moisture
•Introduce adsorptive gas (Nitrogen)
•Increase pressure of gas (forms
Monolayer of gas)
•Further increase pressure (forms
Multilayer of gas)
•Calculate porosity (by formula)

26. BET (Brunauer-Emmett-Teller)
Working
Procedure
Applications
in Textiles
Flaws
Formula
Where,
•V
m = Volume of gas adsorbed at the
monolayer coverage
•ρ = Density of the adsorbed gas
•m = Mass of the material
•ρ
material = density of material

27. BET (Brunauer-Emmett-Teller)
Working
Procedure
Applications
in Textiles
Flaws
•Fiber surface area
•Fiber surface analysis
•Fabric porosity
•Adsorption characteristics
•Coating efficiency (Finishes
effects)
•Medical textiles
•Quality control

28. BET (Brunauer-Emmett-Teller)
Working
Procedure
Applications
in Textiles
Flaws
•Temperature and Pressure
Sensitivity
•Limited Information on Pore Size
Distribution
•Applicability to Homogeneous
Materials
•Sample Pretreatment Challenges

29. Water Flow test:
Working Procedure
Applications in Textiles
Flaws

30. Water Flow test:
Working Procedure
Applications in Textiles
Flaws
•Sample Preparation
•Mounting the Sample
•Water Application
•Measurement of Water
Flow
•Calculation of Porosity

31. Water Flow test:
Working Procedure
Applications in Textiles
Flaws
•Hygiene Products
•Outdoor Apparel
•Medical Textiles
•Filtration Materials
•Sportswear
•Quality Control

32. Water Flow test:
Working Procedure
Applications in Textiles
Flaws
•Sensitivity to Test Conditions
•Not suitable for repellent
coatings
•Limited Information on Pore
Size Distribution
•Inability to Distinguish
Between Open and Closed
Pores

33. AFM (Atomic Force
Microscopy)
Working
Procedure
Applications
in Textiles
Flaws

34. AFM (Atomic Force
Microscopy)
Working
Procedure
Applications
in Textiles
Flaws
Sample
Preparation
Scanning
Process
Topographical
Imaging

35. AFM (Atomic Force
Microscopy)
Working
Procedure
Applications
in Textiles
Flaws
•Pore Size Estimation
•Surface Morphology
•Surface Roughness
•Visualization of Fiber
Networks
•Defects and Irregularities
•Nanostructure Analysis

36. AFM (Atomic Force
Microscopy)
Working
Procedure
Applications
in Textiles
Flaws
•Small Field of View
•Time-Consuming
•Complexity for Inexperienced
Users
•Cost

37. Recent Advancements in
Porosity Analysis
Micro-Computed
Tomography (µCT):
Provides 3D images of a
material's internal
structure with high
resolution.
Nuclear Magnetic
Resonance (NMR)
Imaging:
Create detailed images
of the internal pore
structure.
Focused Ion Beam SEM
(FIB-SEM):
Combines a focused ion
beam to mill the sample
with SEM to image the
surface.

38. Future Trends in Porosity Analysis
Anticipated Technological Advancements:
Integrated Sensing Technologies
Advanced Material Synthesis
AI-Driven Predictive Modeling
Non-Invasive Imaging Techniques
Potential Industry Transformations:
Customization at Scale
Sustainability Focus
Smart and Functional Textiles

39. References:
•www.sciencedirect.com/science/article/abs/pii/S235249282302250X
•journals.sagepub.com/doi/abs/10.1177/0040517506065892
•www.micromeritics.com/Repository/Files/Mercury_Porosimetry_Theory_poster.
pdf
•citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=cd3ba8c9eebd0ef50 703aadb310538a6bb3d4211
•www.tandfonline.com/doi/abs/10.1080/00405000.2011.597567
•www.mdpi.com/2073- 4360/13/3/408
•www.tandfonline.com/doi/abs/10.1080/00405000.2017.1423005
•www.emerald.com/insight/content/doi/10.1108/09556220110396533/full/html
•www.degruyter.com/document/doi/10.1515/jiip- 2013-0084/html