Comparison of different methods to measure the

Article

Comparison of different methods to measure the transverse wicking behaviour of fabrics

2014, Vol 43(3) 366–382 ! The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1528083712456054 jit.sagepub.com

D Raja1, G Ramakrishnan2, V Ramesh Babu2, M Senthilkumar3 and MB Sampath4 Abstract In this article, three test methods are described to measure the water spreading behaviour of textiles such as rate of absorbency and total absorbent capacity. The methods described are manual method, commercial image analysis method using Photoshop and embedded image analysis method using digital signal processor through MATLAB software (EIAS). With these methods the rate of absorbency and total water absorbent capacity were analysed in 12 different knitted/woven fabrics. In order to compare the three test methods, the correlation among the methods were analysed. A very good correlation (more than 0.9) was found between the manual water spreading tests and commercial image analysis method using Photoshop when compared to manual versus EIAS method. Also Photoshop versus EIAS method correlation was found better than manual versus EIAS method. Keywords Transverse wicking, horizontal spreading, image analysis, drop test, embedded digital image processing

Introduction Clothing comfort is an important aspect for any garment used for sportswear and leisurewear. Every human being sweats during different kinds of activities. 1

Department Department 3 Department 4 Department 2

of of of of

Fashion Technology, Sona College of Technology, Salem, Tamil Nadu, India Textile Technology, Kumaraguru College of Technology, Coimbatore, Tamil Nadu, India Textile Technology, PSG Polytechnic College, Coimbatore, Tamil Nadu, India Textile & Fashion Technology, KSR College of Technology, Tiruchengode, Tamil Nadu, India

Corresponding author: D Raja, Department of Fashion Technology, Sona College of Technology, Salem, Tamil Nadu 636005, India. Email: [email protected]

Downloaded from jit.sagepub.com at PSG COLLEGE OF TECHNOLOGY on May 5, 2015

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Das et al. [1] have stated that in sweating conditions, wicking is the most effective process to maintain a feel of comfort. In case of clothing with high wicking properties, moisture coming from the skin is spread throughout the fabric and may offer a dry feeling; the spreading of the liquid enables moisture to evaporate easily. According to Mahadevan [2] wicking is the ability of a fabric to take in moisture. Kissa [3] has stated that liquid moisture transfer through a textile material consists of two processes – wetting and wicking. In the wetting process, the fibre– air interface is replaced with a fibre–liquid interface and wicking starts as the liquid enters into the capillary formed by two adjacent fibres or yarns. Ghali et al. [4,5] and Hanett et al. [6] have reported that wickability is the ability to sustain capillary flow whereas wettability describes the initial behaviour of a fabric, yarn or fibre when it comes in contact with liquid. Wicking of a drop can be divided into two phases of different kinetics [7,8]. At first, the drop spreads on the substrate and penetrates the porous substrate underneath. During the second phase of the capillary penetration process, all of the liquid is contained within the substrate and spreads radially under the influence of capillary forces. As per AATCC 198 [9], horizontal or transverse wicking is the ability of horizontally aligned fabric specimens to transport liquid along and/or through them by capillary action. Sampath et al. [10] have stated that the analysis of transverse wicking characteristics of the fabric is also as important as the longitudinal wicking because the perspiration (sweat) transfer from skin involves its movement through the lateral direction of the fabric. The influence of longitudinal gravity is not considered in horizontal wicking but being multi-directional, it eliminates the directional effect and the results will be most effective for developing fabrics for sportswear. Therefore objective measurement of the moisture transfer properties of clothing is important to apparel product development. As per AATCC 198 [9], there are two parameters most commonly used to characterise the properties of liquid moisture management performance of fabrics, which are the rate of absorbency and the total absorbent capacity. The former determines the rapidity with which fluid is imbibed while the latter determines the total capacity of the material to absorb and hold fluid. Many authors have tried to find the moisture transfer properties of textile objectively using different test methods. Kissa [11] has measured the spreading area of a drop on textile fabric as a function of time. The area of a spreading liquid was photographed at uniform time intervals with an instant-picture camera. The area depicting the spreading liquid was cut out from the dried photograph and weighed. Kissa found that assuming that the fabric was impermeable to the liquid, the spreading rate could be represented by equation (1) A ¼ Kð=Þu Vm tn

ð1Þ

where A is the area of the liquid drop at time t, V the volume of the drop, the surface tension, the viscosity, and K the capillary sorption coefficient.


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Journal of Industrial Textiles 43(3)

In this study, the equations developed by Kissa are applied to a more rigorous measurement of spreading behaviour using the image analysis of frames captured at fast rates, especially in the initial stages. Measurements of the dynamic change of shape of the spreading area of the liquid are also made. Hu et al. [12,13] have developed another method based on the change of the electrical resistance of the fabric with its water content. It consists of six concentric rings (sensors) of different sizes which are then placed on both the surfaces of the fabric. The distance between two consecutive rings is 5 mm except the first one which is at 1.5 mm from the centre. A similar instrument has been developed by Adams et al. [14] to measure the in-plane flow of fluids in a fibrous network. They have used an image analysis technique to obtain the shape and position of a radially advancing fluid front, which can define the directional permeabilities in the plane. Lee et al. [15] have conducted horizontal wicking with a spectrophotometer in order to avoid using balances. They have determined the liquid weight wicked into the fabric by measuring the difference in colour depth between wet fabric and dry fabric. Various researchers like Morent et al. [16] and Perwuelz et al. [17] have proposed the image analysis instead of an analytical balance to determine the extent of horizontal wicking. In the study by Morent, the progression of the liquid front during wicking was recorded with a digital camera and an algorithm was used to calculate the area of the fabric wetted by fluid. Petrulyte et al. [18] have measured the dynamic water absorption of terry woven fabrics using image analysis technique. They have found the terry woven fabrics absorption speed, influence of pile height with respect to liquid retention capacity and the impact of macerating process on absorption process. Transverse wicking measurement is also as important as vertical wicking measurement for engineering and designing sportswear. Transverse wicking behaviour of the fabric or garment is more responsible for sweat evaporation during active sports events. Recent studies are focused on analysis of transverse wicking behaviour of fabric for active sportswear. Work still needs to be done in order to analyse transverse wicking behaviour of textiles quantitatively in the model. Some standards and test methods can be employed to evaluate a fabric’s simple absorbency and wicking properties. However, the existing standards are unable to measure the behaviour of dynamic liquid transfer in clothing materials as the static test results will not serve the purpose of sportswear re-engineering. Dynamic liquid transfer analysis helps to re-engineer the active sportswear products. In this research work, dynamic transverse wicking test methods have been developed using image processing technique. Applying these new methods can be helpful for measuring the transverse wicking in textiles more accurately and cost effectively. Also comparison of the performance of the different test methods helps to understand the test results and the reliability of the test results and devices. In image analysis method, using different software techniques helps find exact colour of pixels (wet area pixels) from the image. Still there is a further scope in terms of speed (using embedded image processing system using digital signal


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processor) and accuracy improvement in the image analysis method. Also the study of spreading measurement by image processing through commercial image processing software like Photoshop has not been done earlier. In the present study, three test methods (two dynamic methods) are described and comparisons are made between three different test methods. The methods are: (i) Manual method; (ii) Commercial image analysis method through Photoshop; and (iii) Embedded image analysis technique using digital signal processor through MATLAB software. The reliability of the three methods is analysed using correlation coefficient analysis.

Material and methods In order to measure the dynamic transverse liquid spreading behaviour (rate of absorbency and total absorbent capacity) using different test methods, 12 different grey fabric samples were procured from the industry. The fabric details are given in Table 1. The knitting machine used to produce the knitted fabrics is given in Table 2. The knitted and woven fabrics were subjected to scouring and bleaching processes using winch and jigger machine, respectively with the following procedure.

Table 1. Fabric particulars. Fabric construction details Sample no. 1 2 3 4 5 6 7 8 9 10 11 12

Fibre

Structure

Count (Ne)

Thickness (mm)

EPC/WPC

PPC/CPC

GSM

Cotton Cotton with Lycra Cotton Polyester/Viscose Polyester/Viscose Polyester/Viscose Cotton-ring Cotton-ring Cotton-ring Cotton-compact Cotton-compact Cotton-ring

Derby RIB 2X2

40 s 44 s

1.06 0.83

24 14

25 16

400 280

Interlock Plain Matt Sateen Plain Plain Twill Plain Single jersey Single jersey

44 s 30 s 30 s 30 s 60 s 40 s 60 s 40 s 2/40 s 2/60 s

0.67 0.37 0.29 0.26 0.20 0.29 0.27 0.28 0.51 0.42

17 26 23 23 30 28 30 28 24 26

18 25 23 23 26 24 26 24 20 24

220 119 108 106 70 100 80 90 160 140

EPC: ends per centimeter; WPC: wales per centimeter; PPC: picks per centimeter; CPC: courses per centimeter. Sample no. 1–3, 11 and 12 are knitted fabrics; Sample no. 4–10 are woven fabrics.


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Table 2. Knitting machine details. Sample no.

Knitted fabric structure

Machine make

Gauge

Diameter in inch

Feeders

1 2 3 11 and 12

Derby Interlock Rib Single jersey

Pai Lung Pai Lung Mayer and Cie Mayer and Cie

19 24 19 24

36 30 30 24

72 72 52 72

Scouring: The bath containing 1.5% NaOH, 1% Na2CO3, and 1 g/L wetting agent was processed at the temperature of 90 C for 60 min by maintaining pH at 10.5–11. Bleaching: The bath containing 2.5% H2O2, 0.3% peroxide stabiliser was treated at 90 C temperature for 60 min by maintaining pH 10.5–11. Then the samples were treated with hot water followed by treatment with 1 g/L peroxide killer followed by hot wash at 80 C temperature for 15 min. Then the samples were neutralised with 0.5 g/L of acidic acid. The polyester/viscose blended woven fabrics were subjected to scouring using 0.5% soap solution (Lisapol) at 80–90 C temperature for 1 h and the fabrics were bleached using 4 g/L of hydrogen peroxide for 1 h at 90 C at pH 10.5–11. Contraction percentage of knitted fabric was measured and was noted as 5% in course wise and 4% in wale wise direction. Sample measuring 10 cm 10 cm and 25 cm 25 cm (based on type of test) was prepared and then placed in climatic chamber at 20 C and 65% RH. The 10 tests were conducted from each sample and the average test results were discussed.

Transverse liquid spread test After full relaxation, the following tests were carried out for all the 12 samples. Rate of absorbency: It is the ability of the fabric to transfer the water by spreading action. In this method, 50 mL of distilled water is allowed to fall on the fabric and the spreading area is recorded with respect to time. Rate of absorbency is calculated from the value of spreading area with respect to time. Sample size used for testing is 10 cm 10 cm. Total absorbent capacity: It is the ability of the fabric to transfer and retain the water by spreading action. In this method, 40 mL of distilled water is allowed to fall on the fabric continuously for every 2 s till the fabric reaches its saturation point. When the sample cannot absorb any more water, the excess water droplets falls down through the fabric. The experiment is stopped at this stage. Time taken from starting to saturation point is noted. Total volume of water retained by the fabric is calculated by multiplying the time taken in seconds for the test with amount of water (40 mL) falling on every 2 s.


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Volume of water in mL = ((time taken for saturation point in seconds/ 2)*40 mL)/1000. Total area of water spread at the saturation point is also noted with respect to time. Sample size used for testing is 25 cm 25 cm. Different test methods of transverse wicking area measurement are correlated with Pearson correlation coefficient. P y yÞ ðx xÞð r ¼ qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi P 2 2 ð y yÞ ðx xÞ

Method I: Measuring water spreading behaviour on the fabric by manual method Apparatus description As shown in Figure 1 in manual method, as per the type of test (rate of absorbency, total absorbent capacity) the fabric sample is mounted on an embroidery frame. The frame is fixed on a slot in the stand without any movement. For measuring total absorbent capacity, a burette is clamped vertically with the help of holder. Burette tip is positioned 6 mm above the surface of the fabric [19]. As per the testing procedure of AATCC method 198-2011, 40 mL of water is allowed to fall on the fabric continuously for every 2 s till the fabric reaches its saturation point. Water flow rate is controlled with the help of water flow rate controller knob. For measuring the rate of absorbency, a 50 mL micropipette is used to place one drop (50 mL) of water on the fabric and the area spread with respect to time is measured manually as per area calculation procedure.

Area calculation The centimeter graph sheet should be kept between transfer sheet and the fabric surface, and the boundary of the water spread area should be traced by using a pencil as shown in Figure 1. From the marked graph sheet the area in mm2 can be found. A total of 10 samples are tested. This method took 10 min to measure water spread area in mm2 for each sample (depends upon the area of manual counting from graph sheet).

Method II: Measuring water spreading behaviour on the fabric by commercial image processing method using Photoshop As shown in Figures 2 and 4, a high resolution Logitech HD Pro webcam c910 with Carl Zeiss optics autofocus facility camera is used to measure the dynamic movement of the liquid over the fabric surface. The camera has the facility to produce razor-sharp images of high-definition 10-megapixel video capture quality and automatic brightness adjustment and colour compensation. The camera is mounted on


372


Figure 1. Investigating liquid spreading behaviour on the fabric. (a) Front view of transverse liquid spreading instrument; (b) Close view of liquid spreading after drop placed; (c) Marking and transferring of liquid spreading area using pencil (keep transfer sheet between graph sheet and the fabric); (d) Transferred line on the graph sheet; (e) Finding the area in mm2 by counting.

a stand, equipped with a LED light, and connected to personal computer via its USB port. The distance between the camera and fabric sample is calculated as per the calibration procedure. For measurement of dynamic liquid spreading rate, the fabric sample (as per the type of test) was mounted on an embroidery frame. The frame was fixed on a slot in the stand without any movement. For measuring total absorbent capacity, a syringe was connected with water reservoir through water flow rate controller knob and it was positioned 6 mm above the surface of the fabric. 40 mL of water was allowed to fall on the fabric continuously for every 2 s till the fabric reached its


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Figure 2. Schematic diagram of commercial image processing method.

saturation point. Water flow rate was controlled with the help of water flow rate controller knob. For measuring the rate of absorbency, a 50 mL micropipette was used to place one drop (50 mL) of water on the fabric and the area spread on the fabric was captured as image with respect to time. The interval of image capture can be set in camera control software as per the requirement. The camera is compatible with image analysis software. The captured image was stored in a separate folder for processing it in Adobe Photoshop tool.

Calibration Before starting the new test, the position of the camera height from the fabric stand was calibrated. For this a black solid circle (20 mm diameter) was drawn on a white paper and it was placed over the embroidery ring where the camera captures the image. Total area of 20 mm diameter solid circle in mm2 ¼ r2 where, r ¼ 10 mm ¼ 3:14 10 10 ¼ 314 mm2 The captured image was transferred into Photoshop and the image resolution was changed into10 pixels/cm. Then the area of circle (as per the procedure mentioned below) was found in terms of pixels. The total pixels were compared with calculated value (314 mm2), when it did not match with the result, the camera height was adjusted and a new image snap was taken. This process was repeated until the Photoshop method result matched with the calculated result.

Area calculation As shown in Figure 3, the required raw image is opened to find the area in commercial image processing software Photoshop. The image quality is adjusted by correcting brightness and contrast (Image menu – Adjustment option). The unwanted areas are removed by cropping the image using crop tool. The image


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Figure 3. Digital processing of captured water spreading image. (a) Raw image received from digital video camera; (b) Quality improved image after adjusting (brightness/contrast); (c) Cropped image; (d) Resized image (resolution: 10 pixels/cm); (e) Dark pixels selected through magic wand selection tool with the help of grow option.

is calibrated by changing the image resolution value into 10 pixels/cm. The darken pixels (water spread area) are selected using magic wand selection tool with the help of tolerance property. The magic wand selection tool from the tool box is taken and clicked over the water spread area and then grow option is used from select menu for further exact selection of water spread area. After exact selection of water spread area, histogram option is used from window menu to know the number of pixels in the selected area, i.e. water spread area in mm2. This method took less than 3 min to measure water spread area in mm2 for each sample.

Method III: Measuring water spreading behaviour on the fabric by EIAS Apparatus description Basic instrument setup procedure is same as method II (Photoshop method). Instead of image processing setup, the new instrument was developed with embedded coding in digital signal processor (DSP) with MATLAB tool (EIAS).


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As shown in Figure 4, the DSP kit is connected via RS232 in to the USP port. The DSP kit receives main supply and this power supply is reduced into 12 V using step down transformer. The developed software through MATLAB is capable of adjusting to record number of frames per second. The software has the provision to

Figure 4. Experimental setup of embedded image processing method using DSP. DSP: digital signal processor.


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Figure 5. Schematic diagram for assessing water spreading area.

change interval time (seconds) of image capture. For each sample, the recording is started approximately 1 s before drop falling. This is for the purpose of taking reference frame. From the experimental system (Figure 4), the captured videos are transferred and stored simultaneously in the computer. The stored videos are converted into individual frames using MATLAB coding. Individual frames are transferred into embedded Blackfin ADSP-BF532 DSP kit through RS-232 cable. Using background subtraction algorithm (Figure 5) the processor will subtract reference frame with successive frame and the resulting output image is the difference image. The difference image is the binary image, which is obtained by thresholding. The area of spreading is calculated based on the number of the white pixels for each successive frame. The thresholding process may vary depending on the lighting conditions, so there should be constant lighting conditions. The final calculated areas are sent back to computer for plotting the graph with the help of MATLAB software. This method took less than a minute to measure water spread area in mm2 for each sample. EIAS method is used to measure the transverse wicking area in each and every second, i.e. continuous measurement and similar to the Photoshop method images can be captured continuously with a fixed delay. Due to continuous measurement both the method can be referred to as dynamic method.

Results and discussion Rate of absorbency test Ten tests were conducted in all the three methods for the above sample to compute the average values. Comparison was done between manual method, commercial image analysis method using Photoshop, and EIAS method. The water spreading area was measured for 5 s, 10 s, 30 s, 60 s and 120 s and was noted immediately after 50 mL of water was allowed to fall on the fabric as shown in Table 3. The rate of spreading or the rate of absorbency in mm2 per second (Table 4) can be calculated from water spreading area with respect to time.


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Table 3. Measured liquid spreading area in mm2 in three methods. Liquid spreading area in mm2 with respect to time Manual Sample no. 5 s 10 s 30 s 60 s

120 s 5 s

10 s 30 s 60 s

120 s 5 s

10 s 30 s 60 s

120 s

1 2 3 4 5 6 7 8 9 10 11 12

149 305 315 623 712 695 1089 911 1187 841 548 801

107 203 216 332 411 381 615 498 747 382 382 563

155 296 314 636 719 690 1129 940 1257 831 627 810

98 221 221 328 295 462 593 421 737 410 443 567

158 353 387 621 585 623 962 855 1447 752 682 992

63 104 125 162 216 184 341 301 421 205 271 362

105 173 194 312 396 342 593 503 638 318 361 497

124 243 254 492 534 497 895 692 943 694 398 587

131 285 286 589 621 601 986 820 1098 777 473 673

Photoshop

67 127 135 167 220 192 351 279 467 239 291 393

EIAS

127 257 269 518 567 538 921 734 995 715 454 643

136 275 298 597 643 619 1011 848 1153 787 527 734

61 141 122 142 231 202 470 218 478 222 345 405

135 266 261 401 472 561 802 604 821 625 576 655

145 301 289 705 468 584 923 688 1201 725 632 811

Table 4. Rate of absorbency measured in three methods. Rate of absorbency in mm2/s Manual Photoshop EIAS Sample no. 5s 10 s 30 s 60 s 120 s 5 s 10 s 30 s 60 s 120 s 5 s 10 s 30 s 60 s 120 s 1 2 3 4 5 6 7 8 9 10 11 12

2.52 4.16 5.00 6.48 8.64 7.36 13.64 12.04 16.84 8.20 10.84 14.48

1.05 1.73 1.94 3.12 3.96 3.42 5.93 5.03 6.38 3.18 3.61 4.97

0.14 0.27 0.28 0.55 0.59 0.55 0.99 0.77 1.05 0.77 0.44 0.65

0.04 0.08 0.08 0.16 0.17 0.17 0.27 0.23 0.31 0.22 0.13 0.19

0.01 0.02 0.02 0.04 0.05 0.05 0.08 0.06 0.08 0.06 0.04 0.06

2.68 5.08 5.40 6.68 8.80 7.68 14.04 11.16 18.68 9.56 11.64 15.72

1.07 2.03 2.16 3.32 4.11 3.81 6.15 4.98 7.47 3.82 3.82 5.63

0.14 0.29 0.30 0.58 0.63 0.60 1.02 0.82 1.11 0.79 0.50 0.71

0.04 0.08 0.08 0.17 0.18 0.17 0.28 0.24 0.32 0.22 0.15 0.20

0.01 0.02 0.02 0.04 0.05 0.05 0.08 0.07 0.09 0.06 0.04 0.06

2.45 5.64 4.88 5.68 9.24 8.08 18.78 8.73 19.12 8.87 13.80 16.18


0.98 2.21 2.21 3.28 2.95 4.62 5.93 4.21 7.37 4.10 4.43 5.67

0.15 0.30 0.29 0.45 0.52 0.62 0.89 0.67 0.91 0.69 0.64 0.73

0.04 0.08 0.08 0.20 0.13 0.16 0.26 0.19 0.33 0.20 0.18 0.23

0.01 0.02 0.03 0.04 0.04 0.04 0.07 0.06 0.10 0.05 0.05 0.07

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Table 5. Three test methods correlation coefficient value. Correlation coefficient R2 value Rate of absorbency Method

5s

10 s

30 s

60 s

120 s

Manual vs. Photoshop method Manual vs. EIAS method Photoshop vs. EIAS method

0.978 0.879 0.910

0.974 0.849 0.915

0.995 0.884 0.910

0.996 0.880 0.901

0.993 0.864 0.887

Results show (Table 5) that the rate of absorbency measurement through manual and Photoshop methods have Pearson correlation coefficient R2 to be 0.978, 0.974, 0.995, 0.996 and 0.993 for rate of absorbency at 5, 10, 30, 60 and 120 s, respectively. The dynamic transverse liquid spreading measurements done by the commercial image analysis method (Adobe PhotoshopÕ ) are in parallel with the manual transverse water spreading method. For manual and EIAS methods the correlation coefficient R2 was 0.879, 0.849, 0.884, 0.88 and 0.864 for rate of absorbency at 5, 10, 30, 60, 120 s, respectively. The dynamic transverse liquid spreading measurements done by the EIAS are also in parallel with the manual transverse spreading method. Similarly, between Photoshop and EIAS methods the correlation coefficient R2 was 0.910, 0.915, 0.901 and 0.887 for rate of absorbency at 5, 10, 30, 60, 120 s, respectively. The dynamic transverse liquid spreading measurements done by the Photoshop are also in parallel with the EIAS transverse spreading method.

Total absorbent capacity After fabric reaches the saturation point, the area and total volume of water falling on the fabric are calculated with respect to time. Ten tests are conducted in all the three test methods for the above sample to compute the average value as shown in Table 6. Total volume of water in mL absorbed by the fabric is calculated from number of seconds taken by the fabric to reach saturation point and the total number of drops (40 mL) falling on the fabric till it reaches the saturation point. Volume of water in mL = ((time taken for saturation point in seconds/2)*40 mL)/ 1000. The graph shown in Figure 6 compares the volume of water in mL absorbed per unit volume of fabric (mL/mm3) in all the three methods. Manual and Photoshop method results are well correlated than the EIAS method. The results are obtained from total volume of water absorbed in mL with respect to saturation point area in cm2 (from Table 6). Fabric volume in mm3 was calculated by multiplying saturation point area in mm2 with fabric thickness in mm.


No. of seconds

441 372 253 46 67 62 28 95 74 112 150 98

Sample no.

1 2 3 4 5 6 7 8 9 10 11 12

431.2 346.5 374.4 23.8 89.2 122.1 64.2 96.5 84.6 104.7 128.4 78.3

Area in cm2

449 388 249 52 64 64 26 91 78 114 162 102

No. of seconds 410.5 337.9 348.5 25.3 92.4 133.1 67.3 95.7 84.3 109.6 123.4 76.8

Area in cm2 570 317 238 45 69 67 24 86 65 108 128 94

No. of seconds 376.4 306.2 235.0 25.9 124.6 138.3 78.2 123.6 104.2 133.7 157.5 83.5

Area in cm2 8.82 7.44 5.07 0.92 1.34 1.23 0.55 1.90 1.48 2.24 3.01 1.95

Total vol. of liquid 431.2 346.5 374.4 23.8 89.2 122.1 64.2 96.5 84.6 104.7 128.4 78.3

Area in cm2 8.98 7.76 4.99 1.03 1.28 1.28 0.53 1.82 1.56 2.27 3.25 2.03

Total vol. of liquid

Photoshop

Manual

EIAS

Manual

Photoshop

Total absorbent capacity in mL

Time taken to reach saturation

Table 6. Time taken to reach saturation and total absorbent capacity measured in three methods.

410.5 337.9 348.5 25.3 92.4 133.1 67.3 95.7 84.3 109.6 123.4 76.8

Area in cm2

11.40 6.34 4.75 0.91 1.39 1.34 0.48 1.72 1.29 2.16 2.56 1.87

Total vol. of liquid

EIAS

376.4 306.2 235.0 25.9 124.6 138.3 78.2 123.6 104.2 133.7 157.5 83.5

Area in cm2

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Figure 6. Comparison of fabric absorbent capacity in ‘volume of water (in mL) absorbed per unit volume of the fabric’ (mL/mm3).

Table 7. Three test methods correlation coefficient value. Correlation coefficient R2 value Method

Total water absorbent

Area to reach saturation

Manual vs. Photoshop method Manual vs. EIAS method Photoshop vs. EIAS method

0.9985 0.934 0.937

0.9982 0.916 0.928

Results show (Table 7) that the total absorbent capacity measurement through manual and Photoshop methods has the correlation coefficient R2 to be 0.9985 and the area to reach saturation correlation coefficient R2 to be 0.9982. The total absorbent capacity measurements done by the commercial image analysis method (Adobe PhotoshopÕ ) are in parallel with the manual method. For manual and EIAS method the correlation coefficient R2 was 0.934 for the total absorbent capacity measurement and correlation coefficient R2 was 0.916 for the total area to reach saturation results. The total absorbent capacity measurements done by the EIAS are in parallel with the manual method. Similarly, between the Photoshop and EIAS method the correlation coefficient R2 was 0.937 for the total absorbent capacity measurement and correlation coefficient R2 was 0.928 for the total area to reach saturation results. The total absorbent capacity measurements done by the Photoshop are in parallel with the EIAS method.

Conclusion Three test methods namely manual, commercial image analysis method using Photoshop software, embedded image analysis system using digital signal processor


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methods were described. The commercial image analysis method using Photoshop and EIAS method can be used to measure the rate of absorbency and total absorbent capacity of the fabric objectively. When compared to commercial analysis method, the EIAS method takes less time for testing because of fully automatic calculation through MATLAB coding with DSP. Three test methods were compared for its rate of absorbency and total absorbency statistically. A good correlation (more than 0.9) was found between manual and commercial image analysis method. Commercial image analysis test result has shown good correlation with manual method as compared with manual versus EIAS method. Also Photoshop versus EIAS method correlation was found better than manual versus EIAS method. Comparison of the performance of the different devices helps to understand the test results of the devices and ensures the reliability of the instrument and its results. The two new developed methods can be useful for the industry to measure the dynamic transverse wicking behaviour of the fabrics to design a new active sportswear. Acknowledgements We thank the management of Sona College of Technology, Salem for their valuable suggestions and providing necessary facilities for carrying out this research work.

Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

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