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Journal of Natural Fibers
ISSN: 1544-0478 (Print) 1544-046X (Online) Journal homepage: http://www.tandfonline.com/loi/wjnf20
A study on the interdependence of fabric pore size
and its mechanical and comfort properties
Aisha Rehman, Madeha Jabbar, Muhammad Umair, Yasir Nawab, Mariam
Jabbar & Khubab Shaker
To cite this article: Aisha Rehman, Madeha Jabbar, Muhammad Umair, Yasir Nawab,
Mariam Jabbar & Khubab Shaker (2018): A study on the interdependence of fabric
pore size and its mechanical and comfort properties, Journal of Natural Fibers, DOI:
To link to this article: https://doi.org/10.1080/15440478.2018.1437861
Published online: 08 Feb 2018.
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A study on the interdependence of fabric pore size and its
mechanical and comfort properties
Aisha Rehman, Madeha Jabbar, Muhammad Umair, Yasir Nawab, Mariam Jabbar,
and Khubab Shaker
Faculty of Engineering and Technology, National Textile University, Faisalabad, Pakistan
The study was conducted to investigate the effect of cotton woven fabric
pore size on its mechanical and comfort properties. Using 20/1 Ne cotton
yarn, 10 fabrics with varying pore size were produced in plain weave for this
study. In order to get variable pore sizes, the thread density was changed
along warp and weft direction, keeping the linear density of yarn as con-
stant. It was observed that with increase in pore size, air permeability as
well as moisture management increased but the thermal resistance
decreased. In general, the comfort properties of cotton fabrics were
improved with a higher pore size but for applications requiring heat reten-
tion, the fabrics having smaller pore sizes must be preferred. It was further
observed that the mechanical properties of cotton fabrics do not depend
directly on the pore size, rather they depend on the number of threads, in a
particular direction. The number of threads may be controlled to get
desired pore size and ultimately the desired properties.
Cotton woven fabric; pore
size; thermal resistance;
With the recent advancements in textile technology, there has been varying demands of the end
users regarding fabric properties. The requirements are not only limited to esthetics but also toward
comfortability and functionality. Therefore, the comfort and mechanical properties have become
highly important in case of textile fabrics. There are three basic comfort properties of the fabrics, i.e.,
thermal, tactile, and psychological comfort properties (Oğlakcioğlu and Marmarali 2007). These
properties are based on the transport of water and heat across the fabric through pores. In case of
woven fabrics, the macro-pores result from the yarn spacings along warp and weft directions. More
the number of threads, lesser will be the pore size in the fabric and vice versa. In Figure 1, the
spacing between interlacing yarns is marked as a pore. It can also be observed that the fabric in
Figure 1(a) has 8 threads per inch along warp and weft while the fabric in Figure 1(b) has 10 threads
CONTACT Khubab Shaker email@example.com Faculty of Engineering and Technology, National Textile University,
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/wjnf.
© 2018 Taylor & Francis
JOURNAL OF NATURAL FIBERS
per inch along warp and weft. Clearly, the pore size is more in fabric (a), and less in fabric (b), but
the number of pores per unit area has increased in fabric (b).
Thermal comfort property is defined as ability of the fabric to maintain the temperature of the
skin and how easily it allows transferring the perspiration produced from the body. They depend
mainly on the thermal resistance, air permeability, water vapor permeability, and liquid water
permeability (Behera, Ishtiaque, and Chand 1997). Tactile comfort property defined as how much
stress is generated in the fabric and how it is distributed over the skin. Therefore, this property is
related to the mechanical and surface properties of the fabrics. Psychological comfort is mainly
related to the esthetic appeal, which includes size, fit, color, luster, style, and fashion compatibility.
Selection of fibers, yarn type, and fabric construction make a great impact on fabric comfort and
mechanical properties. Fiber type, length, and shape affect thermal, water vapor transportation, and air
permeability of the fabric (Varshney, Kothari, and Dhamija 2010). In the same way, yarn type, twist,
hairiness, and spinning technique can alter a fabric’s air permeability, heat transmission, and wicking
properties (Paek 1995;Ünal2010). It was also found that structure of fabric and linear densities of yarn
significantly affect the thermal properties of woven fabrics (Matusiak and Sikorski 2011). Type of weave,
thickness, and cover factor of a fabric plays a vital role in fabric’s comfort properties (Behera, Ishtiaque,
and Chand 1997). However, this article will deal only with the fabric construction.
Most of the work related to comfort and mechanical properties is been conducted by combining
spinning and weaving parameters (Almetwally and Salem 2010; Omeroglu, Karaca, and Becerir
2010), blending of fibers (Varshney, Kothari, and Dhamija 2010; Das et al. 2009), and multilayering
(Shabaridharan and Das 2014; Houshyar et al. 2015). Fabrics resist the evaporation of the sweat from
the human skin into the environment; therefore, the selection of the fiber type, yarn type, and fabric
construction is very important for the evaporation of the sweat from the human skin in both the cold
and hot environment (Tashkandi, Wang, and Kanesalingam 2013). Researchers have worked on the
comfort properties of the woven fabrics made from different spinning techniques (ring, rotor, and
friction) having different weaves (plain and twill). A twill-woven fabric has been found preferable to
a plain-woven fabric in all aspects of comfort (tactile and thermal comfort properties; Behera,
Ishtiaque, and Chand 1997).
Effect of woven structure on the air permeability and moisture management properties was
also found. Six woven samples were prepared using 1 × 1 plain weave and 3/1 twill weave with
different weft sequences. They concluded that fabrics woven in twill weave design and with 3
pick insertion gave significantly better air permeability, shorter wetting time, and better water
spreading rate as compared to plain woven fabrics and those with double or single pick insertion
(Umair et al. 2016). In a comparison between different weaves, it was found that satin weave
shows better comfort characteristics.
There was no significant study found to investigate the interdependence of pore sizes on fabric’s
comfort and mechanical properties which is the topic of this study.
Figure 1. Fabric schematic (a) with 8 threads per inch (b) with 10 threads per inch.
2A. REHMAN ET AL.
Material and methods
Fabric production and desizing
Warp and weft yarns were 100% cotton and had a linear density of 20/1. Total 10 fabric samples
were woven in 1/1 plain weave on Picanol Omni plus model 2005, by varying the number of threads
along warp and weft. The objective was to produce cotton fabrics of varying pore size. Table 1 shows
the list of all samples, along with their construction parameters.
These cotton fabrics were then desized using Bactasol enzyme in amount of 1 mL/L, while
maintaining pH 7 at 70°C for 40 min. The fabric was rinsed with cold water and dried. Iodine
test confirmed that desizing was carried out efficiently.
Measurement of pore size
A digital USB microscope (8 Megapixel) was used for getting the high-resolution images of samples.
Pore sizes were measured manually using the software Digimizer. Images from five different places
were taken for each sample. For this study, only the inter-yarn spaces (macro-pores) were consid-
ered, as described earlier in the Introduction section. An image of selective samples can be seen in
Figure 2. As the cotton yarns have protruding fibers, and the images show quite hairiness in the
fabric too. While determining the inter-yarn spaces (pore), the hairiness on cotton fabric was
neglected and exact distance between yarns was noted. From Figure 2, it can be observed that
majority of pores observed in the fabric are in rectangular/square form. Therefore, the results from
microscopic measurement reported average values of the pore area, A (for rectangular/square pore
shape). For simplification, these results were then converted into equivalent pore diameter, d (for
circular pore shape) using the following relation (Angelova 2012):
Table 1. Constructions of the woven samples.
S. # Warp count, Ne Weft count, Ne Ends/inch Picks/inch
1 20 20 112 43
220 20 5945
320 20 6061
420 20 7746
520 20 7861
620 20 7672
720 20 4274
820 20 4246
920 20 4260
10 20 20 111 63
Figure 2. Pores produced for different cotton fabric constructions.
JOURNAL OF NATURAL FIBERS 3
Measurement of comfort properties
In order to study the comfort aspect of the developed cotton fabrics, the moisture management,
thermal resistance, and air permeability were assessed.
Moisture management. Moisture management tester was used to check the liquid moisture manage-
ment properties of textile fabrics by following AATCC TM 195-2009 standard test method. The
instrument contains upper and lower concentric moisture sensors, which enclose the test specimen
(Bedek et al. 2011). The samples were cut into the size of 8 × 8 cm
and then conditioned in an
environment controlled at 21°C ± 1°C temperature and 65% ± 2% relative humidity for 24 h. The
sample is placed in chamber and 0.15 g of saline solution is dropped on the top surface of this fabric.
The change in voltage will give the difference of the moisture content in the upper and lower
surfaces of the fabric, is then calculated (Ahmad et al. 2017).
Total six indices have been measured but overall moisture management capability (OMMC) value
was taken for further interpretation because it is related to the overall capability of the fabric to manage
the transport of liquid moisture. OMMC is calculated by combining three measured attributes of
performance, i.e., the liquid moisture absorption rate on the bottom surface, the one-way liquid transport
capability, and the maximum liquid moisture spreading speed on the bottom surface as can be seen in
Equation (1) (“AATCC 195 Liquid Moisture Management Properties of Textile Fabrics,”n.d.).
OMMC ¼C1ARBndv þC2Rndv þC3SSBndv
, and C
are the weighting values for AR
, and SS
) = absorption rate, the average speed of liquid moisture absorption for the top and bottom
(R) = one-way transport capability, difference between the area of the liquid moisture content
curves of the top and bottom surfaces
) = spreading speed, accumulated rate of surface wetting from the center of the specimen
where the test solution is dropped
Thermal resistance. The thermal properties were tested using two different approaches. First, the
fabric touch tester (FTT) was used to provide information about heat flux, thermal conductivity when
compression (TCC), and thermal conductivity when recovery (TCR) through the fabric. The FTT is
based on the principle that when fabric touches human skin, then skin receptors are stimulated, and the
encoded neural information is subjectively interpreted in terms of parameters. The other approach was
based on the sweating guarded hotplate (SGHP) instrument, used to measure the thermal resistance
(Rct) of fabrics under steady-state conditions. The hotplate is porous and provides best simulation of
human skin, and therefore, referred to as “skin model”as it simulates the heat and mass transfer
processes which occur next to human skin. This SGHP is based on the standard test method ISO
11092:2014 (“ISO 11092Textiles —Physiological Effects —Measurement of Thermal and Water-
Vapour Resistance under Steady-State Conditions (Sweating Guarded-Hotplate),”n.d.).
Air permeability. Air permeability of a fabric is a measure of how well it allows the passage of air
through it. The test was performed according to the ISO 9237 on the SDL ATLAS—M021A Air
Permeability tester. According to these test methods, the airflow through a given area of fabric is
measured at a constant pressure drop across the fabric. The fabric is clamped over the air inlet and
then air is drawn through this fabric sample by means of a suction pump. The air valve is adjusted to
4A. REHMAN ET AL.
give a pressure drop of 10 mm across the fabric. The rate of air flow at this point is measured using a
flow meter (Booth 1968).
Determination of mechanical properties
Tear and tensile strength test were performed to study the mechanical properties of the woven fabric
Tensile strength. A tensile strength tester (LRX Plus, Ametek) was used to measure tensile strength
of fabrics according to ISO 13934 standard using strip method. Samples of size 6 × 2 inches were cut
along warp direction and the tensile strength was measured in kgf.
Tear strength. Elmendorf tear strength tester was used to measure tear strength. Samples were cut
according to the ISO 13937 standard test method and tear strength was measured in gf.
Results and discussion
Pore size determination
Majority of the pores in cotton fabric were rectangular in shape, as shown in Figure 2. Therefore, the
area of the pore sizes were measured first and then converted into diameter. Pore sizes were not
equally distributed in the fabrics and to ensure the better accuracy of results about 40 readings were
taken for each fabric. Table 2 shows the average pore sizes of all samples. It can be seen from Table 2
that as we increase EPI and PPI pore size fabrics were more tightly hence, substantially reduced pore
size. The individual readings of pore size plotted (in descending order) for sample 2, 3, 4, and 5 are
shown in Figure 3.
Another point that needs to be considered along with pore size is the number of pores per unit
area of fabric. For all the 10 fabrics, the number of pores per inch
is also given in Table 2.
Pore sizes vs air permeability
Total four readings were taken for air permeability of each cotton fabric from which two readings
were taken from face side and two readings were taken from back side of the fabric. It can be seen in
Figure 4 that with increase in pore size, air permeability increases. Moreover sample 8 showed the
maximum value of the air permeability as it has maximum value of the pore size. It has small
number of pores per unit area, but the accumulative area of all the pores is highest for this fabric.
Therefore, it is can be deduced that air permeability has direct relationships with the pore sizes. It
can be justified by the fact that fabric having lower pore sizes will offer more resistance to air than
fabric having high pore sizes (Umair et al. 2016).
Table 2. Pore sizes with mean value and SD.
Pore area, A (mm
Pore dia (mm) Number of pores per inch
Min Max Mean
1 0.0010003 0.007309914 0.001811 0.048 4816
2 0.0025229 0.004785516 0.003212 0.06395 2655
3 0.0011189 0.002859002 0.00147 0.0432 3660
4 0.0019141 0.003741199 0.00251 0.0565 3542
5 0.0008704 0.001653157 0.00118 0.03879 4758
6 0.0004374 0.00113264 0.00062 0.02803 5472
7 0.0020963 0.005518608 0.002791 0.059616 3108
8 0.0088029 0.014897099 0.0103 0.1145 1932
9 0.0039773 0.008323768 0.004979 0.0796 2520
10 0.0000147 0.001264965 0.00029 0.01922 6993
JOURNAL OF NATURAL FIBERS 5
Pore sizes vs moisture management properties
OMMC is an index of the overall capability of a fabric to transport liquid moisture as calculated by
combining three measured attributes: the liquid moisture absorption rate on the bottom surface, the
one-way liquid transport capability, and spreading speed on the bottom surface. Cotton woven
fabrics with high absorption rate and greater spreading speed have higher value of OMMC and vice
versa. Therefore, OMMC has direct relationships with the water transmission and water absorbency.
Grading system for OMMC can be seen in Table 3.
Figure 5 shows the comparison between pore sizes and OMMC. It can be seen that OMMC has direct
relationship with pore sizes as higher pore sizes promote moisture absorption and its transportation. All
Figure 3. Pore sizes of selected fabric samples.
y = 10157x - 206.65
R² = 0.8593
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
Air permeability (mm/sec)
Figure 4. Relationship between pore size and air permeability.
Table 3. Grading for overall moisture management capability (OMMC).
Grade 1 2 3 4 5
OMMC 0.00–0.19 0.20–0.39 0.40–0.59 0.60–0.80 >0.80
Very poor Poor Good Very good Excellent
6A. REHMAN ET AL.
the fabrics showed very good OMMC grading, except the one with lowest pore size. This is generally the
effect of material, as cotton has good moisture absorption and spreading rate.
Pore size vs thermal properties
Thermal conductivity is the major index defined in the thermal module of FTT. Human body skin
temperature is normally around 32–35°C, while normal room temperature is around 20°C.
Therefore, a temperature difference of 12–15°C exists between skin and fabric. FTT heats upper
plate up to 10 K higher than that of lower plate, which is kept at same temperature as surrounding
environment. It also records the heat flux through cotton fabrics dynamically during compression.
TCC is the energy transmitted per degree per millimeter when compresses the specimen. TCR is the
energy transmitted per degree per millimeter when the specimen recovers. Qmax is the maximum
thermal flux measured.
It can be seen in Figure 6 that as the pore size increases, the thermal properties of fabric tends to
decrease. Similarly, with increment in pore size a slight decrement in TCR was observed (Figure 7)
and same trend was observed in case of TCC (Figure 8). Increase in pore size makes fabric structure
more open and loss in heat energy will be high as transfer rate will be more.
y = 0.6241x + 0.5851
R² = 0.7531
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
Figure 5. Comparison between pore size and overall moisture management capability.
y = -1478.5x + 1016.6
R² = 0.3334
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
Figure 6. Effect of pore size on Qmax (W/m
JOURNAL OF NATURAL FIBERS 7
The cotton fabric thermal resistance results using skin model are shown in Figure 9. The results of
skin model are also in accordance with those from FTT. There is a decreasing trend for thermal
resistance with increase in the pore diameter. The highest thermal resistance is offered by the cotton
fabrics that has the lowest pore size and vice versa.
Pore sizes vs tensile strength
Plotting a graph between pore size and tensile strength does not show any co-relation between
the two. It means the mechanical behavior of fabric is not related with its pore size. The tensile
strength of fabric is largely a function of the number of yarns present along a particular
direction (warp or weft) and the strength of individual yarns. The tensile strength of cotton
fabrics was tested along the warp direction, and the results are shown in Figure 10.Theresults
show that with increasing number of yarns, the tensile strength is increasing. The tensile
strength was tested for one direction only, as the fabric will show a similar behavior in the
other direction also.
y = -64.698x + 48.099
R² = 0.3563
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
Figure 7. Effect of pore size on thermal conductivity when recovery (W/m.K).
y = -30.065x + 44.345
R² = 0.4239
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
Figure 8. Effect of pore size on thermal conductivity when compression (W/m*K).
8A. REHMAN ET AL.
Pore size vs tear strength
However, we can correlate the pore size with number of warp/weft threads. More the number of
threads, smaller is the pore size; and with increase in number of threads in fabric, tear strength
decreases. This effect can be explained that the cotton fabrics which have less thread density
result in easy slippage of the yarns giving high tear strength. Due to this reason, the fabrics with
higher pore size have also a high tear strength along warp, provided that the number of threads
is same in warp direction. Figure 11 shows that the tear strength is decreasing with increase in
the weft thread density. The tear strength was tested for one direction only, as the fabric will
show a similar behavior in the other direction also.
A comparison was carried out between different pore sizes of cotton fabrics and their comfort and
mechanical properties. It was found that cotton fabric having larger pore sizes will be better for
summer clothing as it gives high air permeability and moisture management properties. Also, it will
have a higher heat flux, allowing the dissipation of heat generated by the body. Fabric with smaller
y = -0.4297x + 0.0616
R² = 0.7191
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
Thermal resistance (clo)
Figure 9. Effect of pore size on thermal resistance (clo).
y = 4.8214x + 110.56
R² = 0.7698
25 45 65 85 105 125
Tensile strength (N)
Figure 10. Comparison between the number of ends per inch and tensile strength.
JOURNAL OF NATURAL FIBERS 9
pore sizes provides more warmth and hence more suitable for winter clothing. As far as mechanical
properties are concerned, they indirectly depend on the pore size in terms of number of yarns per
unit length. More the number of yarns, smaller is the pore size and higher is the tensile strength.
AATCC 195 Liquid Moisture Management Properties of Textile Fabrics. n.d.. American Association of Textile
Chemists and Colorists. Research Triangle Park, NC, USA.
Ahmad, S., A. Rasheed, A. Afzal, and F. Ahmad, eds. 2017. Advanced textile testing techniques. New york: CRC Press.
Almetwally, A. A., and M. M. Salem. 2010. Comparison between mechanical properties of fabrics woven from compact
and ring spun yarns. Autex Research Journal, 10 (March):35–40.
Angelova, R. A. 2012. Determination of the pore size of woven structures through image analysis. Central European
Journal of Engineering 2 (1):129–35. doi:10.2478/s13531-011-0045-2.
Bedek, G., F. Salaün, Z. Martinkovska, E. Devaux, and D. Dupont. 2011. Evaluation of thermal and moisture
management properties on knitted fabrics and comparison with a physiological model in warm conditions.
Applied Ergonomics 42 (6):792–800. Elsevier Ltd. doi:10.1016/j.apergo.2011.01.001.
Behera, B. K., S. M. Ishtiaque, and S. Chand. 1997. Comfort properties of fabrics woven from ring-, rotor-, and
friction-spun yarns. Journal of the Textile Institute 88 (3):255–64. doi:10.1080/00405009708658549.
Booth, J. E. 1968. Principle of textile testing. 4th ed. London: Chemical Publishing.
Das, B., A. Das, V. K. Kothari, R. Fangueiro, and M. De Araújo. 2009. Studies on moisture transmission properties of
PV-blended fabrics. Journal of the Textile Institute 100 (7):588–97. doi:10.1080/00405000802125097.
Houshyar, S., R. Padhye, O. Troynikov, R. Nayak, and S. Ranjan. 2015. Evaluation and improvement of thermo-
physiological comfort properties of firefighters’protective clothing containing super absorbent materials. The
Journal of the Textile Institute 106 (12):1394–402. doi:10.1080/00405000.2014.995930.
ISO 11092 Textiles —Physiological Effects —Measurement of Thermal and Water-Vapour Resistance under Steady-
State Conditions (Sweating Guarded-Hotplate). n.d. International Organization for Standardization, Vernier,
Matusiak, M., and K. Sikorski. 2011. Influence of the structure of woven babrics on their thermal insulation properties.
Journal of Fibres and Textiles 19 (5):46–53.
Oğlakcioğlu, N., and A. Marmarali. 2007. Thermal comfort properties of some knitted structures. Fibres & Textiles in
Eastern Europe 15 (5):94–96. http://fibtex.lodz.pl/64_26_94.pdf.
Omeroglu, S., E. Karaca, and B. Becerir. 2010. Comparison of bending, drapability and crease recovery behaviors of
woven fabrics produced from polyester fibers having different cross-sectional shapes. Textile Research Journal 80
Paek, S. L. 1995. Effect of yarn type and twist factor on air permeability, absorbency, and hand properties of open-end
and ring-spun yarn fabrics. Journal of the Textile Institute 86 (4):581–89. doi:10.1080/00405009508659036.
Shabaridharan, K., and A. Das. 2014. Analysis of thermal properties of multilayered fabrics by full factorial and
Taguchi method. Journal of the Textile Institute 105 (November):29–41. doi:10.1080/00405000.2013.809186.
y = -48.376x + 4220.6
R² = 0.8557
40 45 50 55 60 65 70 75 80
Figure 11. Comparison between the number of picks per inch and tear strength.
10 A. REHMAN ET AL.
Tashkandi, S., L. Wang, and S. Kanesalingam. 2013. An investigation of thermal comfort properties of Abaya woven
fabrics. Journal of the Textile Institute 104 (8):830–37. doi:10.1080/00405000.2012.758351.
Umair, M., T. Hussain, K. Shaker, Y. Nawab, M. Maqsood, and M. Jabbar. 2016. Effect of woven fabric structure on
the air permeability and moisture management properties. The Journal of the Textile Institute 107 (5):596–605.
Ünal, P. G. 2010. Investigation of some handle properties of fabrics woven with two folded yarns of different spinning
systems. Textile Research Journal 80 (19):2007–15. SAGE Publications. doi:10.1177/0040517510369410.
Varshney, R. K., V. K. Kothari, and S. Dhamija. 2010. A study on thermophysiological comfort properties of fabrics in
relation to constituent fibre fineness and cross-sectional shapes. The Journal of the Textile Institute 101 (6):495–505.
Taylor & Francis. doi:10.1080/00405000802542184.
JOURNAL OF NATURAL FIBERS 11