Yaa Characterization Of Pore Construction Inwards Textiles (Part-4)

Characterization of Pore Structure inwards Textiles (Part-4)

Arpita Kothari
M. Tech. Scholar
Department of Textile Technology,
NIT Jalandhar, India
Cell: +91- 7837-696041
Email: geniousarpita@gmail.com

-----Previous Part

5.5 The Relation betwixt the Measured Pore Diameter in addition to the Actual Pore Size:

Many pore cross-section may endure considered to endure elliptical alongside tiddler axis, d, in addition to major axis, nd .Simply yesteryear assigning unlike numbers to the axial ratio, n, a diverseness of pore cross-sections may endure represented. For a pore having elliptical cross-section: [1]

Measured pore diameter, D

The largest particle that tin transcend through the elliptical pore is d. The ratio of the diameter, d, of the largest particle that tin transcend through in addition to the measured pore diameter, D, is the pore cast factor,. It is given by:

The pore cast factors, [d/D], for a few typical cross-sections are listed inwards Table no. 5.

Table 7: Relation betwixt measured in addition to actual pore sizes 

 

   Filtration media       Pore cross-section                                           Shape element

The predictions inwards Table v grip really good alongside the results obtained alongside fabrics. For representative the average sizes of openings inwards polyamide fabrics computed from fiber diameters in addition to meshwork counts are inwards proficient understanding alongside the largest particle that tin transcend through computed from the pore diameters measured yesteryear the porometer.

Measured pore diameters may endure made comparable alongside d yesteryear including a multiplying factor,

Table 8. Comparison of the maximum diameter of particle that tin transcend through the pores obtained from fiber diameter in addition to meshwork count of the stuff in addition to from the pore diameter measured yesteryear Porometer.

5.5. Pore Distribution:

Let Fw,j in addition to Fd,j endure the menstruation rates through moisture in addition to dry out samples respectively at the differential describe per unit of measurement area pj corresponding to pore diameter, Dj, in addition to Fw,j+1 in addition to Fd,j+1 endure the menstruation rates through moisture in addition to dry out samples respectively at the adjacent higher differential describe per unit of measurement area pj+1 corresponding to pore diameter, Dj+1 every bit shown inwards figure 9: [1]

Figure 9: Wet in addition to dry out curves showing menstruation rates at ii consecutive readings.

Pore distribution tin endure represented inwards 3 ways:

5.5.1. Pore size frequency:
Pore size frequency defined yesteryear the pct menstruation through pores inwards a given size range.

Figure 10: pore size frequency

5.5.2. Cumulative Filter Flow:
The quantity [(Fw,j / F d,j) × 100] plotted every bit a business office of pore size is designated every bit cumulative filter menstruation yesteryear PMI inwards its study program. Figure xi shows cumulative filter menstruation every bit a business office of pore diameter. For representative this figure shows that 45 % menstruation is through pores having diameter greater than xv microns. [1]

Figure 11: Cumulative filter menstruation

5.5.3. Flow Distribution:
The pore size distribution function, fF. It is defined inwards the next manner:

Where the leading negative sign incorporates the fact that decrease inwards pore size increases the menstruation rate. The business office is equal to the increment inwards pct menstruation charge per unit of measurement per unit of measurement increment inwards pore diameter. Integration of to a higher house Equation suggests that surface area nether the distribution business office inwards whatever pore diameter attain (Figure 20) gives pct menstruation inwards that diameter range. The distribution business office gives the menstruation distribution over pore diameter. Because gas menstruation charge per unit of measurement through a pore is proportional to the forth mightiness of its diameter in addition to publish of such pores, the pore distribution is expected to endure similar to the menstruation distribution, but shifted to lower pore diameters. Therefore, the menstruation distribution is designated every bit pore distribution. [1]

Since the increment inwards the pct menstruation is determined essentially yesteryear the increment inwards the publish of pores in addition to the pore diameter, a sudden increment inwards pore size distribution suggests that the publish of pores of that diameter is large.

Figure 12: Pore distribution

The 3 quantities describing menstruation distribution are related to each other inwards a elementary manner. For a given alter inwards pore diameters, the pore size frequency (%) is equal to the consequent alter inwards the cumulative filter menstruation (%), which is likewise equal to the surface area nether the menstruation distribution function.

5.6. Gas Permeability:
Gas menstruation rates measured through the dry out sample is used to compute gas permeability using Darcy’s law. According to this law, menstruation of fluids through porous media is proportional to the describe per unit of measurement area slope causing flow.[1]

Figure 13: Plot of measure book menstruation charge per unit of measurement of air versus differential describe per unit of measurement area for a filter.

Equation suggests that the slope of the plot inwards Figure thirteen is the production of describe per unit of measurement area in addition to permeability. If the permeability is constant, the slope should increment alongside increment inwards pressure. The linear behaviour observed inwards Figure thirteen suggests that the permeability has a style to decrease alongside increasing pressure. This is expected to endure due to the lawsuit of describe per unit of measurement area on pore structure.

5.7. Envelope Surface Area:
The surface surface area of through pores, which let gas to transcend through, is considered the envelope surface area. menstruation charge per unit of measurement of gas through a porous media tin endure expressed yesteryear the next equation:[1]

Where,

This technique measures the envelope surface area, which tin non endure measured yesteryear whatever other technique. The technique has the added payoff of experimental simplicity.

Errors are introduced inwards the measuring tin endure reduced if the menstruation is primarily viscous. When the volumes of shut pores in addition to blind pores are negligible, the porosity, which enters inwards to calculation, is primarily due to through pores. However, if the book of shut in addition to blind pores is appreciable, the porosity value would endure greater than that due to alone the through pores in addition to would innovate errors inwards the envelope surface surface area calculation. Errors are likewise introduced when the largest pore diameter is much larger than the average pore diameter, because large diameter pores brand excessively depression contribution to surface area, patch at that spot contribution to menstruation is much inwards excess of their number.

6. Development inwards characterization technique:

6.1. Flowmetry alongside extended capability:
The technique is beingness constantly updated in addition to has undergone many changes during the recent years. [4]

• Advanced Flow Porometry[3] (Fully Automated & Computer Controlled Device)
• Microflow Porometry (Measures really depression permeability samples)
• In-Plane Porometry (Directional Porometry) (Measures pore construction inwards whatever orientation & of layers)
• Compression Porometry (Measures pore construction of sample nether stress)
• Cyclic Compression Porometry (Measures pore construction of sample nether cyclic stress)
• Clamp-On Porometry (no ask of sample cutting from mass material)
• Nanopore Porometry (Measures pore diameter downwards to O.005m)

6.2. Digital Image Analysis:

• A novel image-based PSD conclusion method has been developed for nonwoven geotextiles 
• The method uses planar in addition to cross-sectional views to capture the 3D construction of a nonwoven geotextile using an optical low-cal microscope[8]
• The method consists of 3 steps: specimen preparation, ikon analysis, in addition to pore opening size determination.
• The ikon analysis method was developed using diverse mathematical morphology algorithms to decide geotextile pore opening sizes, O95 in addition to O50 Finally, the measured values were checked against the manufacturer’s reported AOS values

7. Summary in addition to conclusions:

• Pore size in addition to its distribution is 1 of the really of import physical parameter, which tin endure defined yesteryear many characteristics.
• Each technique used for characterizing the pore construction has their ain capabilities in addition to limitations.
• Each of the feature may endure critical inwards for sure goal occupation application.
• Flow porometry is a highly versatile technique capable of measuring many pore characteristics.
• The ikon analysis method is unique in addition to tin mensurate fiber thickness in addition to pore opening sizes inwards a given image.
• It is clear that adequate characterization of textiles is essential for evolution of novel textiles in addition to deciding suitability of textiles for applications.

8. References:

1. “Wetting Liquid Extrusion Techniques: Part I- Capillary Flow Porometry”, doc Akshaya Jena, Porous Materials, Inc., USA
2. “Pore Structure of Textile Material”, V. K. Kothari & A. Mukhopadhyay, Indian Textile J., 109, No. xi (1999) pp. 8-23.
3. “Capillary menstruation porometry alongside Extended Capability”, doc Krishna Gupta, Porous Materials Inc. USA.
4. Presentation on “Advances inwards pore construction evaluation yesteryear porometry”, doc Akshaya Jena, doc Krishna Gupta, Porous Materials, Inc., USA.
5. Brochure of Porous Materials, Inc., USA.
6. Presentation on “Methods for characterization of porous materials”, Centre of excellence POEMES, Bulgarian Academy of Sciences.
7. Presentation on “Pore Structure of Advanced Textiles” , doc Akshaya Jena & doc Krishna Gupta, Porous Materials, Inc., New York, USA.
8. “Digital Image Analysis to Determine Pore Opening Size Distribution of Nonwoven Geotextiles”, Ahmet H. Aydilek, Seyfullah in addition to Tuncer, Journal of Computing inwards Civil Engineering, Oct 2002, pp.280- 290.
9. N.C.Ray, Presentation on, “Pore size measuring in addition to its analysis” 

 1   2   3   4   

Share this post