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CHAPTER 3
MATERIALS AND METHODS
3.1 INTRODUCTION
This chapter discusses the materials and methods used in the study.
The following figure gives the overall methodology adopted in the present
study:
Figure 3.1: Flow chart for the methodology
Fibres
Viscose, modal, tencel and bamboo
Tested for properties like fibre tenacity, elongation, length and
fineness
Wicking by new method, data analysis by linear regression
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Yarns
Viscose yarns with various counts 16Ne(36.91tex), 20 Ne
(29.53tex), 24 Ne (24.6tex), 30(19.68tex), 34 Ne (17.37tex),
40 Ne (14.76tex), and 60 Ne (9.84tex)
Viscose yarns with different TPI levels
13.6, 17.53, 18.03, 19.07, 20.2, 30.97
Viscose polyester blended yarns
100% v, 20/80 p/v, 33/67p/v, 50/50p/v, 80/20p/v, 67/33p/v,
100% p
Tested for tenacity, elongation, RKM , imperfections, count , TPI, U% ,thin & thick places, neps and imperfections, yarn
hairiness, Yarn diameter
Count variation
30Ne (19.68tex) & 40Ne(14.76)
Tested for elongation, tenacity, imperfections single
yarn strength, TPI, U%, thin & thick places, neps and
imperfections & Yarn diameter
Twist variation
7.3,8.2,8.3 & 9.5T Pcm
Wicking,data analysis by linear regression
Wicking,data analysis by linear regression
Wicking and Wicking by varying tensions like 0.02g/tex, 0.026g/tex, 0.030g/tex, 0.036g/tex ,0.041g/tex,
0.047g/tex and 0.051g/tex Data analysis by linear regression
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3.2 MATERIALS
3.2.1 Selection of Manmade Cellulosic Fibres
In order to investigate the wicking behaviour of manmade cellulosic fibres -
viscose, modal, tencel, and bamboo fibers of 38mm length and 1.2 denier were
produced in a mill and used in the study.
Fabrics
Cotton fabric (woven) Silk fabric (commercial) Grey fabric (commercial)
Plain Twil Satin
Different sett 60, 72, and 84
Tested for PPI, EPI, warp count, weft count, warp cover factor, weft cover factor total Cover
factor & fabric weight Degumming
Dyeing with acid dyes
Exposure to sunlight 3 days, 6 days & 9 days
Scouring Bleaching
Desizing
Wicking, data analysis by linear
regression
Wicking
Tested for fabric weight, thickness, porosity, tensile strength, elongation, drape coefficient, stiffness, crease recovery, flexural rigidity
Different media Distilled water, acid perspiration,
alkaline pH, Water temperature at 800C
Tested for ends/inch, picks /inch, warp count,
weft count, weight, thickness, tensile strength
and elongation, drape coefficient, flexural
rigidity, stiffness and k/s values
Wicking, data analysis by linear regression
Data analysis by linear regression
Mulberry Tasar
Mercerization
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3.2.2 Selection of Yarns with Various Linear Densities
Viscose staple yarns with various linear densities like 16Ne(36.91tex),
20Ne (29.53tex), 24 Ne (24.60tex), 30 Ne (19.68tex), 34 Ne (17.37 tex), 40 Ne
(14.76 tex) and 60 Ne (9.84tex) were produced in a mill and used in the study.
The details of the viscose staple yarns are given below:
Table 3.1: Details of the viscose staple yarns with various densities
S.No. Yarns Spinning system
Linear Density (Ne/Tex)
1 100% Viscose Ring Spinning 16/36.91 2 100% Viscose “ 20/29.53 3 100% Viscose “ 24/24.60 4 100% Viscose “ 30/19.68 5 100% Viscose “ 34/17.37 6 100% Viscose “ 40/14.76 7 100% Viscose “ 60/9.84
3.2.3 Selection of yarns with different twist levels
A series of viscose staple yarns with twist factors of 24.3, 31.3, 32.2, 34.1,
36.2 and 55.4 tex0.5tpcm was prepared. Details of the viscose staple yarns are
given below:
Table 3.2: Details of viscose staple yarns with different TPcm levels
S.No Fibre content
Spinning system Twist/cm Twist Factor (K)
TPcm (Tex)0.5 Tensions (g/tex)
1. 100%Viscose Ring Spinning 5.4 24.3
0.020, 0.026, 0.030, 0.036, 0.041, 0.046
and 0.051 2. 100%Viscose “ 7 31.3 “ 3. 100%Viscose “ 7.2 32.2 “ 4. 100%Viscose “ 7.6 34.1 “ 5. 100%Viscose “ 8.1 36.2 “ 6. 100%Viscose “ 12.4 55.4 “
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3.2.4 Selection of Fibres
Polyester and viscose staple fibres of 38mm length and 1.2 denier were
used for the study.
3.2.5 Selection of Fabric Samples
Different types of fabrics such as commercially available cotton grey,
mulberry and tasar silk fabric and woven fabrics with different pick densities were
used in this study. Cotton woven fabrics with plain, twill and satin structures of
40s count in the warp and 2/80s count in the weft and the pick density variations of
60,72 and 84 were chosen for the construction. Grey cotton material were used to
investigate the effect of wicking behaviour and the fabric properties were tested
and analyzed. Different mediums like distilled water, acid perspiration, alkaline
pH and water temperature at 80oC were used after applying finishing treatments
like scouring, bleaching and mercerization on them and wicking was studied along
the warp, weft and bias directions. Commercially purchased mulberry and tasar
silk fabrics were degummed, dyed and exposed to sunlight for 3 days, 6 days and
9 days respectively and then the fabric properties and wicking behaviour were
investigated.
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Table 3.3: Geometrical properties of woven cotton fabrics
Sample Code FFF
Ends/ cm
Picks/ cm
Warp count
Weft count
Warp cover factor
Weft cover factor
Total factor
Fabric weight (g/m2)
Fabric thickness
(mm)
Porosity %
P60 0.52 35.43 22.83 39.8 43.8 14.27 8.76 18.56 53.49 0.25 86
P72 0.61 35.83 29.92 41 43 14.21 11.59 19.92 62.08 0.28 85
P84 0.64 35.83 32.28 40.2 41.2 14.35 12.78 20.58 65.67 0.3 85
T60 0.33 35.83 23.23 38.6 41.2 14.65 9.19 19.03 60.65 0.3 87
T72 0.39 36.22 28.74 38.4 42 14.85 11.26 20.14 67.11 0.32 86
T84 0.41 36.61 34.25 40.2 42.4 14.67 13.36 21.03 69.02 0.34 86
S60 0.37 35.83 25.20 41.4 41.8 14.14 9.90 19.04 64.71 0.36 88
S72 0.43 36.22 30.31 39.4 47.2 14.66 11.21 20 69.02 0.38 87
S84 0.45 36.22 32.28 41.8 40.8 14.23 12.84 20.54 71.77 0.4 87
FFF = Fabric Firmness Factor
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Table 3.4: Details of grey fabric
S.No Particulars Grey fabric 1. 2. 3. 4. 5. 6. 7. 8.
Ends/cm Picks/cm
Warp count Ne(Tex) Weft count Ne(Tex) Warp cover factor Weft cover factor Total cover factor
Fabric weight
39.76 28.35
50(11.80) 41(14.39)
14.28 11.25 19.80
110g/m2
Chemicals used for scouring
Sodium hydroxide, sodium silicate, wetting agent
Chemicals used for bleaching
Hydrogen peroxide, sodium hydroxide, sodium silicate and soda ash
Chemicals used for mercerization
Caustic soda and acetic acid
Chemicals used for acid perspiration solution
Lactic acid, disodium hydrogen orthophosphate and histidine
monohydrochloride
Chemicals used for alkaline ph solution
Sodium hydroxide
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Table 3.5: Details of mulberry and tasar silk fabrics
Properties Mulberry Tasar Weight (g/m2) 33.69 31.09
Thickness (mm) 0.081 0.081 Ends /cm 49.1 40 Picks /cm 43.2 19
Warp count (dtex) 35.32 41.32 Weft count (dtex) 35.32 47.32
Chemicals used for Silk Fabric Degumming
Soap and soda ash
Chemicals used for dyeing
Turquoise blue acid dyes, Glauber’s salt and acetic acid
3.3 METHODS
3.3.1 Yarn Production
Process Parameters for Spinning
Carding Feed roller speed 0.5rpm Cylinder speed 900 rpm Licker - in 600 rpm Doffer 4.0 rpm
Drawing
Front roller speed 50 rpm Back roller 5 rpm
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Roving No of spindles 4 Twist 30 tpm Roving hank 1.2Ne Feed hank 0.14Ne
Spinning No of spindles 6 Spindle speed 13000rpm
Twist 30/40 tpm TPI 18.64, 20.81, 21.5, 24.03
Roving count 1.18 Ne Twist multiplier 3.4, 3.8 (TM=TPI /COUNT) Twist direction Z
Break draft 1.8 Yarn length 5000m
Yarn contraction 2.37
Figure 3.2: Flow chart for producing polyester viscose blended yarns
Fibers (Polyester and Viscose)
Computerized Carding Machine
Computerized Miniature Draw Frame
Computerized Simplex Roving Machine
Computerized Ring Spinning Machine
Cone Winding Machine
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Polyester and viscose fibres were processed through carding and draw
frame packages. Drawn sliver was passed through simplex frame and spun into
yarns differing in blends of 19.68 tex and 14.76tex with TPcm 7.5, 8.3, 8.6 and 9.6
in computerized ring spinning machine. Polyester and viscose fibres were blended
consisting of, 100% polyester, 80/20 P/V, 67/33 P/V, 50/50 P/V, 20/80 P/V, 33/67
P/V and 100% viscose. A total of twenty eight yarns were produced which are
shown in Table 3.6.
Table 3.6: Details of the polyester viscose blended yarns with various
counts and twist levels
S.No Fibre content Spinning system Linear Density
(Ne /Tex) Twist /cm
1. 100%viscose Ring Spinning 30/19.68 7.5, 8.3
40/14.76 8.6, 9.6
2.. 20/80 polyester viscose “ 30/19.68 7.5, 8.3
40/14.76 8.6,9.6
3. 33/67 polyester viscose “ 30/19.68 7.5, 8.3
40/14.76 8.6, 9.6
4. 50/50 polyester viscose “ 30/19.68 7.5, 8.3
40/14.76 8.6, 9.6
5. 80/20 polyester viscose “ 30/19.68 7.5, 8.3
40/14.76 8.6, 9.6
6. 67/33 polyester viscose “ 30/19.68 7.5, 8.3
40/14.76 8.6, 9.6
7. 100% Polyester “ 30/19.68 7.5, 8.3
40/14.76 8.6, 9.6
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3.3.2 Fabric Production Handloom Weaving
Weaving is done by intersecting the longitudinal threads, the warp, i.e. "that
which is thrown across", with the transverse threads, the weft, i.e. "that which is
woven". The major components of the loom are the warp beam, heddles, harnesses
or shafts shuttle, reed and takeup roll. In the loom, yarn processing includes
shedding, picking, battening and taking-up operations which are the principal
motions.The count of warp yarn selected was 2/80s and 40s count for the weft.
Cotton fabric with plain(1/1), twill(2/1) and satin structures(4/1) were woven by
varying the setts namely 60,72 and 84.
3.4 TREATMENT APPLIED FOR FABRICS
Desizing
The woven cotton grey plain, twill and satin fabrics with various pick
densities were desized with 2% of dilute hydrochloric acid for a period of one
hour at a temperature of 50-600C. Then, the fabric is taken out , rinsed
thoroughly in cold water until the water runs.
The commercially purchased cotton grey fabric was scoured, bleached and
mercerized using the procedure given below:
Scouring
Scouring was carried out by adding 7% of sodium hydroxide , 1% of
wetting agent and 2% of sodium silicate at 60-80c for 1 hour. Then the fabric
was taken out and rinsed thoroughly.
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Bleaching
Bleaching was carried out by using 7% hydrogen peroxide, 2%sodium
silicate, 1% soda ash and 0.6%sodium hydroxide at 85-900 c for 1 hour. Then the
fabric was taken out and rinsed thoroughly.
Mercerization
Mercerization was carried out by using 20% of caustic soda at 60-800 C for
half an hour. Acetic acid was added in both hot and cold water while rinsing in
order to remove the traces of alkali present in the fabric. Finally litmus paper was
used to check the acidity or alkalinity of the solution and was found neutral.
Table 3.7: Details of scoured, bleached and mercerized samples
S.No Samples Treatments Medium Direction
1. STWE Scouring water temperature at 800c weft direction
2. STW “ “ warp direction
3. STB “ “ bias direction
4. SDWWE “ distilled water weft direction
5. SDWW “ “ warp direction
6. SDWB “ “ bias direction
7. SAPWE “ acid perspiration weft direction
8. SAPW “ “ warp direction
9. SAPB “ “ bias direction
10. SAWE “ alkaline ph weft direction
11. SAW “ “ warp direction
12. SAB “ “ bias direction
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S.No Samples Treatments Medium Direction
13. BTWE Bleaching water temperature at 800c weft direction
14. BTW “ “ warp direction
15. BTB “ “ bias direction
16. BDWWE “ distilled water weft direction
17 BDWW “ “ warp direction
18. BDWB “ “ bias direction
19. BAPWE “ acid perspiration weft direction
20. BAPW “ “ warp direction
21. BAPB “ “ bias direction
22. BAWE “ alkaline ph weft direction
23. BAW “ “ warp direction
24. BAB “ “ bias direction
25. MTWE Mercerization water temperature at 800c weft direction
26. MTW “ “ warp direction
27. MTB “ “ bias direction
28. MDWWE “ distilled water weft direction
29 MDWW “ “ warp direction
30. MDWB “ “ bias direction
31. MAPWE “ acid perspiration weft direction
32. MAPW “ “ warp direction
33. MAPB “ “ bias direction
34. MAWE “ alkaline ph weft direction
35. MAW “ “ warp direction
36 MAB “ “ bias direction
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Degumming
The commercially purchased mulberry and tasar silk fabrics were
degummed using the following procedure and the percentage of weight loss was
calculated and then dyed with acid dyes.
MULBERRY TASAR Original weight 360 gms 440 gms Soap oil 5% 5% pH 6.5 – 7 6.5 – 7 Time 30 mins 30 mins Temperature 90˚C 90˚C M:L 1:50 1:50 Fabric weight after degumming 290 gms 410 gms Percentage of weight loss 19.44% 6.81%
Dyeing
The degummed mulberry and tasar silk fabrics were dyed with turquoise
blue acid dyes with 5% shade. . The dye bath was prepared by dissolving the dye
in warm water and the fabrics were added to dye bath and continuously agitated
for the uniform penetration of the dye throughout the fabric and the temperature
was raised to 800C for 40 minutes. Then acetic acid was added to the dye bath and
worked for another 15minutes. Finally the fabrics were rinsed thoroughly in hot
and cold water and dried under shade
Exposure to sunlight
The dyed mulberry and tasar silk fabrics were fixed on a cardboard and
exposed to sunlight during the month of March from 10 am to 5pm. The fabrics
were laid flat and exposed for 3days, 6days and 9days respectively and then the
fabric properties were studied.
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3.5 TESTING OF FIBRES, YARNS AND FABRICS 3.5.1 Fibre Testing .
The fibre properties of man made cellulosic fibres like bamboo, tencel,
modal and viscose and polyester fibres were tested. All the tests were carried out
in standard atmospheric condition of R.H.65%+/- 2% and temperature 210 C +/- 1
Degree C. Fibres were conditioned for 24hrs in above atmospheric conditions
before testing.
Measurement of Fibre Length
Fibre length is the one of the most important dimension to evaluate the
quality of the raw material. Oil plate is used to arrange the fibers. Liquid paraffin
oil was used to remove the crimp from the fiber. Then arrange 200 fibers orderly
in a parallel manner, and then the length was measured using 0.5 mm accuracy
measuring scale. An average of 15 readings were taken at random and the mean
value was calculated and recorded .
Measurement of Fibre strength and elongation
Vibroscope & Vibrodyn was used to calculate the strength and elongation
of fibres using BISFA 2004 and ASTM D-3822-07 standards .Measuring range of
force 0-1000 cN, measuring range of elongation max. 1000% at 10 mm gauge
length, gauge length 5-50mm, tension weight 100 mg and testing speed of 0.5 to
300 mm/min. An average of 30 readings were taken at random and the mean value
was calculated.
Measurement of Fibre fineness
Vibroscope 400 is an automatic instrument for the determination of the titer
(dtex, denier) of single fibers. This instrument meets international standards
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BISFA 2004 and ASTM D-3822-07. An average of 30 readings were taken at
random and the mean value was calculated.
Table 3.8: Fibre testing and standards
Nature of the Test Testing Standards Instrument Fibre length BISFA 1998 Oil Plate Method
Fibre Fineness BISFA 2004 &
ASTM D-3822-07 Vibroscope 400
Fibre strength and Elongation
BISFA 2004 & ASTM D-3822-07
Vibroscope &Vibrodyn
3.5.2 Yarn Testing
The yarn properties like count, twist, single yarn strength and elongation,
RKM, imperfections, count, hairiness, and yarn diameter were tested. All the tests
were carried out in standard atmospheric condition of R.H.65%+/- 2% and
temperature 210 C +/- 1 Degree C. Yarns were conditioned for 24hrs in above
atmospheric conditions before testing.
Table 3.9: Yarn testing and standards
Nature of the Test Testing Standards Instrument
Single yarn strength gms , elongation and RKM
Uster standard method Uster Tensorapid 3
Yarn Hairiness Uster standard method
Uster Hairiness Index Tester -4
Twist per inch ASTM D 1422 -99 Microprocessor Twist Tester
Lea count ASTM D 1578 – 93 ASTM D 1907 -07 Statex CSP System
U%, Thin places -50%perkm,Thickplaces+50%perkm Nep+200%perkm, Yarn Imperfections Per km
ASTM D 1425 - 96 Uster Tester 4
Yarn Diameter Image Analyser
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Measurements of Twist
In the microprocessor twist tester, the twisting and untwisting jaws are
driven by a fractional H.P single phase motor. A speed control device is provided
on the left hand side of instrument by which the motor speed can be varied while
conducting the twist tests. The gauge length of the specimen can be selected upto a
minimum of 25cm(10inches ) by moving the non rotating jaw assembly. A scale is
fixed on the instrument to read the actual gauge length. A direction reverse switch
and two counters are fixed on the instrument for testing the twist of the yarns .An
average of 15 readings were taken at random and the mean was calculated. . Measurements of Single Yarn Strength & Elongation
Uster Tensorapid 3 was used to determine the strength and elongation .This
instrument is works on the principle of CRE (Constant Rate of Elongation). It also
gives estimated RKM value for yarn. Strength and Elongation are displayed
following each test. This can be expressed by the “Length of yarn in km” at which
yarn will break of its own weight”. This is equivalent to breaking load in g/tex.
RKM is the short expression for “Ressikilometer” – “Breaking-kilometer”.An
average of 100 tests were carried out at random and the mean value was
calculated. Measurements of yarn count
Yarn count and count CV% were measured on Statex yarn count system
which is a combination of electronic balance and computer, Using this system,
readings were taken from the yarn samples and the mean value was calculated. Measurements of U%, thin places, thick places and imperfections
Uster Eveness tester 4 was used to determine the U%. Uster evenness tester
consists of a device to apply uniform tension in yarn during testing and suitable
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counter for recording the number to thin places, thick places and number of neps
present in the yarn.
Measurements of Yarn Diameter
Diameter was assessed using image analysis technique. For each twist step,
a yarn photo is captured and examined by a Motic microscope with 40x
magnification. For analysis of the yarn images, "Image-Pro-Plus 2.0" software was
used. The image analysis was performed using the sequence: process, image,
acquise, segmentation, processing and measurement. An average of 20 readings
was taken at random and the mean was calculated.
Measurements of Hairiness Index
The yarn hairiness was measured using Uster Tester-4 using the uster
standard method . Hairiness index has been defined as the total length of
protruding fibres with reference to the sensing length of 1cm. It provides the
signals and helps in the interpretation of results.
Yarn Quality Index
In order to compare the relative performance of the six yarns, the yarn
quality index was followed.
Tenacity, elongation and evenness are combined into one integrated index
called yarn quality index (YQI)). YQI is defined as follows:
Tenacity X Elongation
YQI = ------------------------------- Evenness
This formula has been suggested by Barella (1975).
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Determination of Twist Factor
Twist factor was calculated using the formula turns per cm divided by the
square root of tex.
Tex Twist factor K = Turns per cm/ tex
Determination of Packing Factor
Packing factor was calculated from yarn diameter considering standard
density of viscose (1.5gcm -3).
Packing Factor = Yarn density in g/cm3 /Fibre density/g/cm3
Yarn density =(Yarn linear density in tex x 1.2727x10 -5) / (Yarn diameter in
cm)2g/cc.
3.5.3 Fabric Testing
The cotton woven fabric with different structures and sett were tested for
properties like weight, thickness, tensile strength and elongation, crease recovery,
bending length, flexural rigidity, drape coefficient, fabric firmness factor and
porosity whereas the dyed and exposed mulberry and tasar silk fabrics were tested
for properties like weight, thickness, tensile strength and elongation, bending
length, flexural rigidity, drape coefficient and k/s values. The commercially
purchased cotton grey fabric was tested for EPI, PPI, warp cover factor, weft cover
factor, total cover factor and fabric weight. All the tests were carried out in
standard atmospheric condition of R.H.65%+/- 2% and temperature 270 C +/- 2
Degree C. Fabrics were conditioned for 24hrs in above atmospheric conditions
before testing.
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Table 3.10: Fabric testing and standards
Nature of the test Testing Standards Instrument Thickness (mm) IS: 7702 – 2006 Mag thickness tester
Crease recovery (Angle) IS 4681 Mag crease recovery tester
Tensile strength (Kgs) and Elongation (%) ASTM D 1776 Mag electronic tensile strength
tester
Bending length (cm) IS 6490, ASTM D 1338
Mag stiffness tester
Fabric weight (g/m2) ASTM 3776-96 Paramount quadrant balance Drape coefficient (%) IS 8357 Mag drapemeter
Measurement of Fabric weight
A sample size of 20cm x12.5 cm was cut using the template and the weight
was calculated using the quadrant balance. Ten samples were cut from the same
material by using the template and readings were taken in grams per square meter
and the mean fabric weight was calculated and recorded.
Measurement of Fabric thickness
Mag thickness tester is a hand operated instrument to determine the
thickness of the fabric; each sample was placed in between the pressure foot and
anvil. The thickness of the fabric was indicated in the dial gauge, in the terms of
millimeter. The thickness was measured at ten different places of each sample at
random and the mean value was calculated and recorded.
Measurement of Tensile Strength and Elongation
The principle used in the tester is CRE (Constant Rate of Elongation). Five
samples each were cut from warp and weft directions. The sample size is 12” x 2”.
Each sample was clamped between the jaws and care was taken to see that the
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sample were perpendicular to the load. The load was applied and the reading was
recorded in kilograms and elongation in millimeters was noted as soon as the
sample was broken. Five such readings were taken and the mean strength and
elongation was calculated.
Measurement of Fabric drape
Fabric samples and ammonia paper of 12.5cm diameter was cut using the
template; and weighed using an electronic balance. Each sample was placed on the
circular disc and ammonia paper underneath the disc and the drape meter is
operated. Image of the draped sample, can be obtained on the ammonium paper
.This image was traced and cut along the traced outline. It was then weighed using
electronic balance. The drape co-efficient was calculated for each sample using the
following formula.
Drape co-efficient = W2-W1 100
Where W2 = the weight of the drape pattern
W1 = the weight per unit area of the paper
Measurement of Fabric Stiffness
The principle used in the tester is cantilever principle. The samples were cut
according to the template size in both warp and weft randomly. The sample was
placed lengthwise on the platform and the scale is placed over the specimen such
that the zero of the scale coincides with the datum mark on the body of the
instrument. Now the scale was pushed forward gently and till the tip of the fabric
coincides with the index line on the side of the platform. Ten readings were taken
for each sample and the mean values were calculated and recorded. From these
values, flexural rigidity was computed by substituting bending length and weight
in grams per centimeter square in the formula
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Flexural rigidity (mg.cm) = WC3
where
W = fabric mass in g/cm2
C = bending length in cm Measurement of Crease recovery
This instrument consists of a circular dial which carries the clamp for
holding the sample. Directly under the center of the dial is a knife edge and an
index line for measuring the recovery angle. The scale of the instrument is
engraved .The dimension of the specimen is 2 inch by 1inch. Warp and weft
crease recovery was reported separately to the nearest degree. The mean value of
ten readings in each direction was calculated and recorded.
Determination of Porosity %
Porosity is defined as the fraction of void space in a porous medium:
Porosity % = 1- ρa / ρb Where ρa is the fabric density (g/cm3) and ρb is the fibre density (g/cm3).
Fabric density is calculated by dividing the fabric weight per unit area by fabric
thickness. This equation includes the inter –fibre porosity as well as the inter-yarn
porosity of the fabric. The porosity of the plain twill and satin structures with
various pick densities were captured by a microscope (CT Belgium) under 40
magnification.
Fabric Firmness Factor (FFF)
This was calculated using the formula given by Milasius (2000):
21
21
21 T/T3/21T/T3/2
2T/T3/21
1
2average SS
T'P
112
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Where T1, T2 and Taverage are, respectively, the warp count, weft count and
average count in Tex. P’ is the Milasius weave factor and is the fibre density S1
& S2 are the ends and picks per decimeter.
Crossing Over Firmness Factor (CFF) This was defined by Morino et al., (2005) using the following formula:
CFF= Ne /Ni
Where
Ne = number of crossing over lines in the complete repeat
Ni = number of interlacing points in the complete repeat
Floating Yarn Factor (FYF)
The formula for calculating FYF is given below:
FYF= ((Type I-IX -1) x En) /Ni
Where En = existing number of Type I-IX in the complete repeat.
Color Measurement
The samples are measured using premier color scan spectrophotometer
5100in Day 65 daylight and 10 degree standard observer. The output of the
spectrophotometer is reflectance data from 400nm to 700nm.
The color yields of the dyed and sunlight exposed samples were evaluated
by the Kubelka –Munk equation
K/S = (1-R) ²/ 2R
Where R – reflectance at maximum absorption wavelength (nm)
S – scattering coefficient
K - absorption coefficient
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The colour differences are expressed as ΔE which is calculated by the
following equation
E = √ (ΔL*)² +(Δa*)²+ (Δb*)² ……………………(3.1)
Where ΔE is the CIELAB color difference between batch and standard.
Here ΔL*, Δa* and Δb* and ΔE* are in commensurate units. ΔL denotes the
difference between lightness (where L*= 100) and darkness (where L* = 0). Δa* is
the difference between green ( -a*) and red ( + a*) and Δb the difference between
yellow (+b*) and blue ( - b*).
The commercially purchased cotton grey fabric was tested for the following
parameters.
EPI (Ends per cm)
In woven fabric the warp yarns are commonly referred to as ‘end’ and the
number of warp threads per inch width of cloth stated as ‘ends per inch’.
One inch counting class- This is the most commonly used method. The
counting glass is placed on the fabric and the number of threads per inch is
counted through this small microscope. The threads per inch were counted at
different places and the mean value was calculated.
PPI (Picks per cm)
In woven fabric the weft yarn are commonly referred to as “picks” and the
number of weft threads per inch length of cloth stated as “picks per inch”.The ends
per inch and picks per inch were measured by an ordinary counting glass
according to ASTM-D 3775-03. Ten readings were taken and average value was
calculated.
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85
Warp count and Weft count
The warp and weft count were measured by using the Beesley balance as
per ASTM – D 1059. Ten readings were taken and average value is noted for the
study.
Cover factor
The cloth cover factor was calculated using the following formula.
Cloth cover factor Kc = K1+K2 28KK 21
Where K1 = warp cover factor
K2 = weft cover factor
To determine the cover factor, ends/inch and picks/inch of the fabrics were
counted by pick glass. ASTM –D 1059 -01 were used to measure the warp and
weft count. This test method determines the count of all types of fabrics in which
the yarns are intact and can be removed in measurable length. The counts of the
warp and weft were calculated from the mass and the measured length of the yarn
in terms of “mass per unit length”.
. 3.6 STATISTICAL ANALYSIS 3.6.1 Regression Analysis
Regression analysis involves identifying the relationship between a
dependent variable and one or more independent variables. A model of the
relationship is hypothesized, and estimates of the parameter values are used to
develop an estimated regression equation. Various tests are then employed to
determine if the model is satisfactory (www.britannica.com).
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86
3.6.2 Correlation Coefficient
Correlation analysis is used to determine whether the values of two
variables are associated. The two variables should be random samples, and should
have a normal distribution (possibly after transformation).A correlation coefficient
is a numerical, descriptive measure of the strength of the linear relationship
between two variables. Values for the correlation coefficient range between -1 and
+1, with a correlation coefficient of +1 indicating that the two variables have a
perfect, upward-sloping (+) linear relationship and a correlation coefficient of -1
showing that the two variables are perfectly related in a downward-sloping (-)
linear sense. A correlation coefficient of 0 demonstrates that the variables have no
relationship, and are independent. A correlation coefficient is determined through
statistical analysis of sample data as it is fitted to a modeled linear equation
(www.investorglossary.com).
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