Effects of bleaching on cotton fabric

Department of Textile Engineering
PROJECT (THESIS) REPORT
Course Code: TE-407
Project Report On:
EFFECT OF BLEACHING PARAMETERS ON BURSTING STRENGTH
AND WHITENESS OF COTTON KNITTED FABRIC

Submitted by:
Kazi Sazed Salman
ID: 111-23-130
Md. Hasan Mojumdar
ID: 111-23-129
Md. Asraful Haque
ID: 111-23-132
Supervised by
Abu Naser Md. Ahsanul Haque
Senior Lecturer,
Depertment of Textile Engineering, DIU
Daffodil International University
102, Shukrabad, Mirpur road,
Dhaka, Bangladesh
December 2014

i
DECLARATION
We hereby declare that, this project has been done by us under the supervision of Abu Naser
Md. Ahsanul Haque, Senior Lecturer of Department of Textile Engineering, Daffodil
International University. We also declare that neither this project nor any part of this
project has been submitted elsewhere for award of any degree.
Supervised by: Submitted by:
____________________________
Abu Naser Md. Ahsanul Haque
Senior Lecturer,
___________________________
Kazi Sazed Salman
Student ID: 111-23-130
___________________________
Md. Hasan Mojumdar
___________________________
Md. Asraful Haque

ii
ACKNOWLEDGEMENT
At first all gratefulness goes to the Almighty ALLAH to give us the strength and ability to
complete the Thesis (project) and this report.
We are grateful to Dr. Md. Mahbubul Haque, Head of the department of Textile
Engineering for giving us the opportunity to accomplish the project work.
We would like to express sincerest gratitude to our respected teacher Abu Naser Md.
Ahsanul Haque, Senior Lecturer of Department of Textile Engineering, Daffodil
International University for his valuable suggestion, encouragement constructive criticism
and for providing gall necessary supports to complete our thesis.
We are also expressing special thanks to Mr. Sumon Chandra Dey, Textile Engineer of
Impress Newtex Composite Textiles Ltd. for his guidance & advice while doing the practical
works for this project. We would like to be thankful to Impress Newtex Composite Textiles
Ltd. for their helpful support to this work. We got the most excellent opportunity and
consider it a rare fortune to work under them.
Last but not least, thanks go to our precious family for their never ending love and inspire at
every stage of our life. Without their continuous support we realize that we would not be a
person what we are right now.

iii
ABSTRACT
This study comprises the effect of different bleaching parameters of Hydrogen peroxide
(H2O2) bleach on scoured single jersey fabrics. There were 7 samples in total with the weight
of 12.5 grams each which were bleached using different parameters of bleaching.
One of the samples was bleached by the general factory sample bleaching parameter. Other
six samples were bleached by changing the concentration of bleaching agent, time &
temperature differently.
After bleaching we tested the whiteness and bursting strength of the samples. The sample
bleached with more peroxide (5.5cc) gives the best whitening result and the sample bleached
for less time (20min) gives lowest result of all. During bursting strength testing the sample
the sample bleached in less temperature (88o
C) gives the best strength result and the sample
bleached in high temperature (108o
C) shows the lowest strength result.

iv
INDEX
Chapter Topic Page no
Declaration i
Acknowledgement ii
Abstract iii
Index iv-vi
Chapter-1 INTRODUCTION 1-7
1.1 Introduction 2
1.2 History of knitting 2
1.3 Fiber type 3
1.4 Fiber Properties 3
1.5 Yarn twist 3
1.6 Fabric structure 3
1.7.1 pretreatment 4
1.7.2 Objective of pretreatment 4
1.7.3 Steps in pretreatment 4
1.8.1 Scouring 4
1.8.2 Objects of scouring 5
1.9.1 Bleaching 5
1.9.2 The aim of bleaching 5
1.9.3 Bleaching agent 6
1.10 Whiteness 6
1.11 Bursting strength 6
1.12 Objects of this project 7
Chapter-2 LITERATURE REVIEW 8-29
2.1 Fiber properties 9
2.2 Fibers identification 9
2.3 Classification of yarn 9
2.4 Common yarns 11
2.5 Properties of yarn 11

v
2.6 Knitting 12
2.7.1 Weft knit structure 13
2.7.2 Warp knit structure 13
2.8 Raw materials 13
2.9 Cam 13
2.10 Knitting Process flow chart 14
2.11 Yarn quality requirement 14
2.12 Effects of knitting parameters 14
2.13 Fabric scouring 15
2.14 Scouring process depends on 15
2.15 Alkaline Enzyme scouring 16
2.16 How to use scouring 16
2.17 Advantages of scouring 17
2.18 Disadvantages of scouring 17
2.19 Scouring effect 17
2.20 Assessment of scouring 17
2.21 Bleaching agent 17
2.22 Types of bleaching agent 17
2.23 Bleaching of cotton with peroxide 17
2.24 Factors of peroxide bleaching 19
2.25 Advantages 20
2.26 Wool bleaching with peroxide 20
2.27 Silk bleaching with peroxide 20
2.28 Synthetic bleaching with peroxide 21
2.29 Bursting strength 21
2.30 Diaphragm bursting test 22
2.31 Reported measurements 23
2.32 Color vision 24
2.33 Physiology of color perspiration 24
2.34 Cone cell of human eye 24
2.35 Theory of color vision 25
2.36 Trichromatic theory 25
2,37 Opponent-process theory 26

vi
2.38 Spectrophotometer 27
2.39 Datacolor-650 27
2.40 Whiteness & yellowness 28
Chapter-3 MATERIALS & METHODS 30-41
3.1 Materials and machines used 31
3.2 Fabric structure and type 33
3.3 Chemicals used 34
3.4 Methods of working 34
3.5 Scouring procedure 35
3.6 Standard recipe of scouring 35
3.7 Process of scouring 36
3.8 Bleaching procedure 36
3.9 Process curve of bleaching 38
3.10 Spectrophotometer working procedure 38
3.11 Working steps 38
3.12 Results from spectrophotometer 39
3.13 BST working procedure 40
3.14 BST test results 41
Chapter-4 RESULTS AND DISCUSSIONS 42-45
4.1 Effect of H2O2 on strength 43
4.2 Effect of H2O2 on whiteness 43
4.3 Effect of Temperature on strength 44
4.4 Effect of Temperature on whiteness 44
4.5 Effect of Time on strength 45
4.6 Effect of Time on whiteness 45
Chapter-5 CONCLUSION 46-47
5.1 Conclusion 47
REFERENCES 48-50

© Daffodil Int. University
Page 1
CHAPTER ONE
INTRODUCTION

Page 2
1.1 Introduction
Knitting is a method by which thread or yarn may be turned into cloth or other fine crafts.
Knitted fabric consists of consecutive loops, called stitches. As each row progresses, a new
loops pulled through an existing loop. The active stitches are held on a needle until another
loop can be passed through them. This process eventually results in a final product, often a
garment.
Knitting is an old method of weaving cloth in which thread or yarn are used to make items of
clothing like sweaters and shawls etc. To knit, one generally uses a knitting needle and forms
a series of loops with some thread or yarn through which more yarn is pulled using another
knitting needle. This process is repeated either in round formations or in rows. In modern
times, there are also knitting machines available which can be used to create the same effects
with less effort and in less time. There are two main kinds of knitting stitches called knit and
purl which are very similar in many ways. However, while a knit stitch involves inserting the
needle in front of the loop, a purl stitch involves inserting it behind the loop.
Other knitting stitches are usually variations of combinations of knits and purls. For instance,
when knits and purls are used back and forth to form rows, this formation is called a garter
stitch.
The jersey stitch – which is another formation of rows of pearls and knits – is the knitting
stitch which is most often used in commercial garments? There are many patterns which can
be thus created using different kinds of stitches.
1.2 History of Knitting
Knitting is older than written history. No one knows exactly when people began to knit, but
we do know that as far back as A.D. 200, knitting was an advanced and accomplished art.
The people of Scotland are believed to have been the first to knit with wool. A knitted fabric
stretches more than a woven fabric, and it snaps back to its original size after it is stretched.
For example, a woolen knitted fabric can stretch as much as 30 percent and spring back to its
original size. Long ago people found out how much better a knitted fabric was than a woven
fabric for clothing that needs to stretch and then spring back to fit snugly. Sweaters, mittens,
and stockings are examples of this kind of clothing. Knitting is probably more popular today
than it has been at any other time in history. With the hundreds of different kinds and textures
of yarns available, plus the constant development of new synthetic fibers and various
combinations of them, there is no end to the beautiful and useful things you can learn to
make.

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1.3 Fiber type
It is thought that the ability of a fiber to withstand repeated distortion is the key to its abrasion
resistance. Therefore high elongation, elastic recovery and work of rupture are considered to
be more important factors for a good degree of abrasion resistance in a fiber than is a high
strength. Nylon is generally considered to have the best abrasion resistance. Polyester and
polypropylene are also considered to have good abrasion resistance. Blending either nylon or
polyester with wool and cotton is found to increase their abrasion resistance at the expense of
other properties.
Acrylic and mod acrylic have a lower resistance than these fibers while wool, cotton and high
wet modulus viscose have a moderate abrasion resistance. Viscose and acetates are found to
have the lowest degree of resistance to abrasion. However, synthetic fibers are produced in
many different versions so that the abrasion resistance of a particular variant may not
conform to the general ranking of fibers.
1.4 Fiber properties
One of the results of abrasion is the gradual removal of fibers from the yarns. Therefore
factors that affect the cohesion of yarns will influence their abrasion resistance. Longer fibers
incorporated into a fabric confer better abrasion resistance than short fibers because they are
harder to remove from the yarn. For the same reason filament yarns are more abrasion
resistant than staple yarns made from the same fiber. Increasing fiber diameter up to a limit
improves abrasion resistance. Above the limit the increasing strains encountered in bending
counteract any further advantage and also a decrease in the number of fibers in the cross-
section lowers the fiber cohesion.
1.5 Yarn twist
There has been found to be an optimum amount of twist in a yarn to give the best abrasion
resistance. At low-twist factors fibers can easily be removed from the yarn so that it is
gradually reduced in diameter. At high twist levels the fibers are held more tightly but the
yarn is stiffer so it is unable to flatten or distort under pressure when being abraded. It is this
ability to distort that enables the yarn to resist abrasion. Abrasion resistance is also reported
to increase with increasing linear density at constant fabric mass per unit area.
1.6 Fabric structure
The crimp of the yarns in the fabric affects whether the warp or the weft is abraded the most.
Fabrics with the crimp evenly distributed between warp and weft give the best wear because
the damage is spread evenly between them. If one set of yarns is predominantly on the
surface then this set will wear most; this effect can be used to protect the load-bearing yarns

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preferentially. One set of yarns can also be protected by using floats in the other set such as in
a sateen or twill weave. The relative mobility of the floats helps to absorb the stress. There is
an optimum value for fabric set for best abrasion resistance. The more threads per centimeter
there are in a fabric, the less force each individual thread has to take. However, as the threads
become jammed together they are then unable to deflect under load and thus absorb the
distortion. Again different types of fibers can have different type of structure depending of
their origins and other properties and purpose of uses in textile or other places.
1.7.1 Pretreatments:
Natural fibers and synthetic fibers contain primary impurities that are contained naturally,
and secondary impurities that are added during spinning, knitting and weaving processes.
Textile pretreatment is the series of cleaning operations. All impurities which cause adverse
effect during dyeing and printing is removed in pretreatment process.
Pretreatment processes include de-sizing, scouring, and bleaching which make subsequent
dyeing and softening processes easy. Uneven de-sizing, scouring, and bleaching in the
pretreatment processes might cause drastic deterioration in the qualities of processed
products, such as uneven dyeing and decrease in fastness.
1.7.2 Objective of Pretreatment:
 To convert fabric from hydrophobic to hydrophilic state.
 To remove dust, dirt etc. from the fabric.
 To remove oil & wax from the fiber.
 To achieve the degree of desire whiteness.
1.7.3 Steps in Pretreatment Process of Cotton and Natural Fibers:
1. Singeing
2. De-sizing,
3. Scouring,
4. Mercerization
5. Bleaching.
1.8.1 Scouring
The term ‘scouring’ applies to the removal of impurities such as oils, was, gums, soluble
impurities and sold dirt commonly found in textile material and produce a hydrophilic and
clean cloth.

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1.8.2 Objectives of Scouring:
 To remove natural as well as added impurities of essentially hydrophobic character as
completely as possible
 To increase absorbency of textile material
 To leave the fabric in a highly hydrophilic condition without undergoing chemical or
physical damage significantly.
1.9.1 Bleaching
Bleaching is chemical treatment employed for the removal of natural coloring matter from
the substrate. The source of natural color is organic compounds with conjugated double
bonds , by doing chemical bleaching the discoloration takes place by the breaking the
chromophore , most likely destroying the one or more double bonds with in this conjugated
system. The material appears whiter after the bleaching.
Natural fibers, i.e. cotton, wool, linen etc. are off-white in color due to color bodies present in
the fiber. The degree of off-whiteness varies from batch-to-batch. Bleaching therefore can be
defined as the destruction of these color bodies. White is also an important market color so
the whitest white has commercial value. Yellow is a component of derived shades. For
example, when yellow is mixed with blue, the shade turns green. A consistent white base
fabric has real value when dyeing light to medium shades because it is much easier to
reproduce shade matches on a consistent white background than on one that varies in amount
of yellow.
The purpose of bleaching is to remove colored impurities from the fiber and increase the
whiteness level of fabric.
1.9.2 The aim of bleaching can be described as following:
 Removal of colored impurities.
 Removal of the seed coats.
 Minimum tendering of fiber.
 Technically reliable & simple mode of operation.
 Low chemical & energy consumption.
 Increasing the degree of whiteness.
 Making good appearance of white cloth.

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1.9.3 Bleaching Agent
A bleaching agent is a substance that can whiten or decolorize other substances. Bleaching
agents essentially destroy chromophores (thereby removing the color), via the oxidation or
reduction of these absorbing groups. Thus, bleaches can be classified as either oxidizing
agents or reducing agents.
Type of Bleaching Agents
1. Oxidative Bleaching Agents
2. Reductive Bleaching Agents
3. Enzymatic Bleaching Agents
1.10 Whiteness
Whiteness and blackness are experiences of perceptions by humans. Similar to all perceptual
experiences they are subjective and depend strongly on illumination, surround and a number
of other perceptual phenomena.
In the textile, paper and plastic industries, white materials are commonly employed for many
aesthetic and technical applications. Due to their high lightness and achromatic nature white
materials are also very important to provide the necessary base for dyeing, printing and
finishing. Most textile materials, however, are polymers containing natural colorants which
affect their appearance. Two common approaches are used to improve the whiteness of textile
materials: chemical bleaching and fluorescent whitening.
1.11 Bursting Strength
Tensile strength tests are generally used for woven fabrics where there are definite warp and
weft directions in which the strength can be measured. However, certain fabrics such as
knitted materials, lace or non-woven do not have such distinct directions where the strength is
at a maximum. Bursting strength is an alternative method of measuring strength in which the
material is stressed in all directions at the same time and is therefore more suitable for such
materials. There are also fabrics which are simultaneously stressed in all directions during
service, such as parachute fabrics, filters, sacks and nets, where it may be important to stress
them in a realistic manner. A fabric is more likely to fail by bursting in service than it is to
break by a straight tensile fracture as this is the type of stress that is present at the elbows and
knees of clothing.
When a fabric fails during a bursting strength test it does so across the direction which has
the lowest breaking extension. This is because when stressed in this way all the directions in
the fabric undergo the same extension so that the fabric direction with the lowest extension at

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break is the one that will fail first. This is not necessarily the direction with the lowest
strength.
1.12 Objects of this project
 Learn to preparation of samples in dyeing lab
 Learn to prepare liquor according to recipe
 Learn to use sample dyeing machine
 To bleach different samples with different parameters
 Determine the effects of bleaching on S/J fabric
 Learn to use spectrophotometer for whiteness testing
 Learn to use Bursting Strength Tester for bursting strength testing of the fabric
 To get some specific ideas on changing of parameters during bleaching.

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CHAPTER TWO
LITERATURE REVIEW

Page 9
2.1 Fibers Properties
Mechanical Process: This is the response to applied forces and recovery like-
 Abrasion resistance
 Flexibility
 Stress
Absorption properties: This is a measure of the quantity of water vapor or liquid water
orabsorbed by fabric.
 Water vapor absorption
 Water absorption
Thermal properties: The behavior of textile in the presence of heat or when exposed to a
flame.
 Heat resistance capacity or
 Specific heat
2.2 Fibers Identification
Test Wool Acrylic Cotton
Burning test/
Flammable test
Non-flammable,
Hair burn smell
Flammable
Petroleum flame
Flammable
Paper burn smell
Chemical test
(acid & alkalis)
wet finish
Acid (+)
Alkalis (-)
Acid (+)
Alkalis (+)
Acid (-)
Alkalis (+)
Microscopic test
(Cell structure of
yarn)
2.3 Classification of Textile yarn:
 Spun yarn
 Filament yarn

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Classification of yarn
a) Mono filament:
b) Multi filament:
c) Staple:
d) Two ply yarn:
e) Multi ply:
f) Cords:
g) Cable:
h) Loop yarn:

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i) Spun yarn: Spun yarn are made by twisting together of fibers.
j) Filament yarn: Filament yarns are made by the assembly of continuous filament.
k) Mono-filament: Consists of only a single continuous.
l) Multi filament: Made from multiple filaments.
m) Complex/Novelty/Fancy: This has special effects on its own appearance.
n) Cords: cords are made by twisted plied yarn.
o) Cables: Cables are produced by plying cords.
p) Slub yarns: Contains partially bulky/fluffy region
q) Loop yarns: This yarn requires a base yarn (core yarn) around which the fancy or
effect yarn is wrapped.
2.4 Common yarn used in the fully fashioned knitwear
Basic type:
1. 100% Acrylic
2. Acrylic mélange
3. Blended Acrylic
4. 100% wool
5. Mixed wool
6. 100% cotton
7. Blended cotton
Fancy type:
1. Chenille
2. Angora tweed
3. Nep/slub yarn
4. Loop yarn (Popcorn, Boucle)
5. Mohair
6. Tape yarn
7. Kashmiri like etc.
2.5 Properties of Yarn
Wool:
 Bulky/fluffy appearance
 Poor strength
 Good resistance to acid
 Poor resistance to sun-light and insects
 End use for sweater and suiting
 Mainly fibers collects from sheep fleece

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 Garment become heavier and also more weighted
 Garment appearance is not shine
 More expensive product
 Warmth feelings
Acrylic:
 Sources are Acrylonitrille – Ethylene or Acetylene
 Bulky/fluffy appearance like wool
 More shiny than wool
 Good strength
 Light in weight
 Good resistance to sun-light and insects
 Wet finish & dry finish applied
 End uses heavy knitwear product
 Less expensive than wool
 Warmth feeling
Cotton yarn:
 Smooth surface
 Cool feeling (suitable for hot)
 More expensive
 Moisture absorbency high
2.6 knitting
Knitting: It is a process of fabric manufacture by converting yarn into loop form and then
these loops interlock/intermesh/interloped together which form a structure is called knitting
or knitted structure.
Wales: vertical column of knitted fabric.
Course: horizontal column of knitted fabric.
Loop: bending of yarn is called loop.
WPI = Wales per Inch
CPI = Course per Inch

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2.7.1 Weft Knit Stitches
It is the most common types used by the manufacturer in produce textile knitted products
such as Shirts and Socks. In terms of color patterning, weft knit may be knitted with multiple
yarns to produce interesting pattern design. There are few types or technique to produce weft
knit structure, Single jersey, Purl, and Rib are some of the technique that been used to
produce weft knitted structure
2.7.2 Warp Knit Stitches
Warp knitted is produced from a set of warp yarn. It is parallel knitted to each other down the
length of the fabric. Since knitted fabric may have hundreds of wales, warp knitted is
typically done by machine.
2.8. Raw material:
Raw material is a unique substance in any production oriented textile industry. It plays a vital
role in continuous production and for high quality fabric.
Types of raw material:
1. Yarn
2. Fabric
3. Dye stuff
4. Chemical and auxiliaries
2.9 Cam:
Cams are the devices which convert the rotary machine drive into a suitable reciprocating
action for the needles and other elements. The cams are carefully profiled to produce
precisely-timed movement and dwell periods and are of two types, engineering cams and
knitting cams.
There are 3 types of cams: Knit cam, Tuck Cam, Miss Cam

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2.10 Process Flow Chart of Knitting:
Yarn in Package Form
↓
Place the yarn cone in the creel
↓
Feeding the yarn in the feeder via trip tape positive feeding arrangement and tension device
↓
Knitting
↓
Withdraw the rolled fabric and weighting
↓
Inspection
↓
Numbering
2.11 Yarn Quality Requirements:
Yarn quality parameters such as
 Breaking strength,
 Elongation,
 Twist,
 Moisture contents,
 Yarn winding,
 Yarn lubrication
 Yarn hairiness
 Quality raw material feed to knitting
2.12 Effects of knitting Parameter in fabric production:
o Stitch Length
1. GSM decrease with the increase of stitch length
2. If stitch length increase then fabric width increase and WPI decrease.
3. For deep shade stitch length should be higher and vice-versa.
o GSM
1. Gray GSM should be less than finish GSM
2. GSM increase with increase of stitch length and it is adjusted by VDQ pulley
3. Enzyme Level
4. Color
5. If shrinkage increase then GSM increase.

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6. GSM control according to buyer requirement.
o Count
1. If count increase then fabric width increase
2. GSM depends on yarn count
o Gauge
1. For finer gauge finer count should be use
2. If machine gauge increase then fabric width decrease
3. If gauge decrease then stitch length increase.
o Feeder
1. Production increase with increase of feeder no.
2. Feeder is settled in case of stripe fabric.
o Design
1. Cam setting
2. Set of needle
3. Size of loop shape.
2.13 Scouring of fabric
Yarns and fabrics may be dirty, contain natural waxes or oils, or have been treated with size
or lubricants used in spinning, weaving or knitting. These can all interfere with dyeing, often
leading to non-level results. Scouring is a large topic, and the process used depends on the
fiber type and its condition. True scouring of grease cellulosic fabrics is typically done, after
desizing, at the boil or at higher temperature in pressure vessels, with as much as 10 grams
sodium hydroxide per litter of water, plus surfactants, and the process may last for several
hours. Commercial scouring of wool may use solvents, similar to dry cleaning, as part of the
process. White fabrics sold at retail have normally be scoured at the mill; “natural” fabrics
usually have not (some “natural” fabrics have been scoured but not bleached).
Art dyeing literature often refers to what amounts to laundering as scouring. This is
inadequate for grease fabrics, but often quite acceptable for white goods. A long machine
wash with the hottest water possible, about a gram of soda ash per litter of water (about a
teaspoon per gallon) and some (preferably optical brightener free) detergent, followed by two
rinses is usually acceptable. Sodium hexametaphosphate may be helpful if the water is hard.
Woven white cottons often contain starch that will not be removed by such a limited process.
2.14 Scouring process depends on:
 The type of cotton

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 The color of cotton
 The cleanliness of cotton
 The twist and count of the yarn
 The construction of the fabric.
2.15 Alkaline Enzyme Scouring of Cotton Textiles
The invention relates to a process for treatment of cellulosic material, as for example, knitted
or woven cotton fabric, comprising the steps of preparing an aqueous enzyme solution
comprising pectinase, treating the cellulosic material with an effective amount of the aqueous
enzyme solution under alkaline scouring conditions; e.g., pH of 9 or above and a temperature
of 50° C. or above, in a low calcium or calcium-free environment, yielding a modification of
the cellulosic material such that exhibits an enhanced respond to a subsequent chemical
treatment.
Traditionally, cotton scouring has required the use of harsh alkaline chemicals (caustic),
extreme temperatures and large volumes of water. Expenses include not only the cost of the
caustic and energy, but also the cost of treating waste water to remove residual caustic and
by-products.
Today, textile producers have a new, effective alternative to chemical scouring with the
advent of the Cottonase enzyme. This novel enzyme not only cleans better than chemical
scouring, but also greatly reduces the need for extensive waste water treatment and energy
consumption. The Cottonase enzyme is a versatile, economically viable and environmentally
friendly alternative to chemical scouring in cotton preparation.
2.16 How to Scouring Textile Fabric:
 Simply wash the fabric; this includes PFD fabric, in the washing machine in hot water
with Soda Ash. Do not add any fabric softeners to the wash.
 Using an large enamel or stainless steel pot, fill the pot at least half full and place one
ounce of soda ash into the pot per pound of cotton or linen fabric/fiber.
 Place fabric into water; swish it around using a stainless steel spoon.
 Bring water to a boil.
 Adjust heat to a low boil/hard simmer and allow to boil for two hours. stir the fabric
every 15 minutes or so to make sure that the fabric is being adequately scoured
 After two hours remove from heat source, allow fabric to cool down until the fabric is
at room temperature.
 Remove the fabric from the water and rinse.

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2.17 Advantages of scouring:
 The process is a continuous process. So consumes less time.
 The process is economical.
 This is the most popular process.
2.18 Disadvantages of scouring:
 The result of scouring is not good as compared with kier boiler.
 The process is not hydrophilic as kier boiler.
 Damages some fiber strength & other properties.
2.19 Estimation or Scouring Effect:
The scouring effect can be estimated by carrying out one of the following tests-
 Measurement of weight loss.
 Test of (absorbency) Immersion test.
 Drop test.
 Wicking or column test.
2.20 Assessment of Scouring:
In a pipette a solution of0.1% direct red or Congo red is taken and droplet of solution put on
the different places of the fabric. Then the absorption time of the fabric is observed. The
standard time for the absorption of one drop of solution is 0.5-0.8 sec up to 1 sec.
2.21 Bleaching Agent
A bleaching agent is a substance that can whiten or decolorize other substances. Bleaching
agents essentially destroy chromophores (thereby removing the color), via the oxidation or
reduction of these absorbing groups. Thus, bleaches can be classified as either oxidizing
agents or reducing agents.
2.22 Type of Bleaching Agents
 Oxidative Bleaching Agents
 Reductive Bleaching Agents
 Enzymatic Bleaching Agents
2.23 Bleaching of Cotton with Hydrogen Peroxide
Hydrogen peroxide is virtually the only bleaching agent available for protein fibers and it is
also used very extensively for the cellulosic fibers. Hydrogen peroxide is a colorless liquid

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soluble in water in all proportions. It is reasonably stable when the pH is below 7, but tends to
become unstable as the alkalinity increases. Commercial hydrogen peroxide, therefore, is
made slightly acid so that it will not lose strength during storage. Solutions of hydrogen
peroxide of more than 20 volumes cause intense irritation when they come into contact with
skin and should be washed away immediately.
Cotton is usually bleached in 1-volume liquor at the boil. The most important factor in
bleaching is to achieve the right degree of stability in the bleach liquor. If the pH were too
low no per hydroxyl ions are set free and bleaching does not take place; when the liquor is
too unstable the whole of the oxygen is liberated and escapes into the atmosphere before it
has had time to act upon the cotton.
The bleaching liquor must be made alkaline, otherwise it would be too stable, but it is
virtually impossible to adjust to the optimum pH with alkali alone and there is a marked
tendency for the liquor to is too unstable, however carefully it has made alkaline. It is,
therefore, necessary to add a stabilizer, and of all the substances, which have been, tried
sodium silicate is the most effective.
Hydrogen peroxide is a stable chemical under acidic conditions and needs the addition of an
alkali for activating it. Above pH 10, it is extremely unstable when it gets decomposed under
water and oxygen.
2H2O2 = 2H2O + O2
This liberated oxygen, however, has no bleaching action and the catalysts are therefore a
cause of loss of bleaching power. In fact, hydrogen peroxide is used bleaching under alkaline
conditions (pH 10) after stabilizing at this pH by adding sodium silicate, borax, phosphate
etc. Generally bleaching is done at 80ºC to 85ºC temperature.
Hydrogen peroxide solution at any concentration can be stable or unstable depending upon
the several factors listed below.
 pH: Stable in acidic solution and unstable in alkaline baths.
 Temperature: As temperature increases the solution becomes increasingly unstable.
 Buffers: Silicates, Phosphates, Borax, Proteins and others tend to stabilize peroxide.
 Metals:Ca and Mg in the presence of silicates tend to stabilize baths; (b) other metals
as Cu, Fu, etc. tends to stabilize bleach solutions.
 Hard water: Depending upon the hardness of water and the metals making it hard,
peroxide is unsterilized.
It was at one time believed that the bleaching action of hydrogen peroxide was due to the
liberation of nascent oxygen but this explanation is no longer tenable. It is known that under
certain conditions, particularly with regard to pH, hydrogen peroxide will liberate hydrogen
and per hydroxyl ions in the following manner:
H2O2 = H+
+ HO2-

Page 19
Hydrogen peroxide (H2O2) is a universal bleaching agent and is used extensively for the
bleaching of cotton materials. The advantages in its use are:
 It can be employed for bleaching fibers like wool, silk and jute also.
 It requires less manipulation of fabric and hence less labor.
 The loss in weight in bleaching is less than that with hypochlorite bleaching
 Less water is required with peroxide bleaching and there is no need for souring after
bleaching.
 Peroxide bleached goods are more absorbent than hypochlorite bleached goods.
 After – yellowing of white goods bleached with peroxide or less than with
hypochlorite bleached goods.
 Peroxide bleaching is safer in regard to chemical degradation and
 Continuous scouring and bleaching in one operation is possible by employing
peroxide.
2.24 Factors of Peroxide Bleaching:
Temperature
Cotton and Bast fibers are bleached at 80 - 95°C in bath processes, while blends of cotton and
regenerated cellulose fibers are bleached at 75 - 80°C. The bleaching time is generally
between 2 and 5 hours. In a pressurized high temperature (HT) apparatus cotton can also be
bleached at temperatures of 110 - 130°C in only 1 to 2 hours.
Time
During the impregnation processes the temperature and as well the retention time varies
widely. During a cold bleach process a dwell time of 18 to 24 hours is necessary. In the pad
steam process under atmospheric pressure the bleaching time is generally between 1 to 3
hours. The above mentioned processes describe batch processes. Today a lot of continuously,
intelligent finishing equipment exists in which the bleaching step is only one of some other
treatments and the reaction time of the impregnated material in such steamer is only between
7 to 20 minutes.
pH
The pH value depends on the fibers to be bleached and pre-treatment.NaOH is used in case of
H2O2 bleaching. This is used to bring the PH up to 9-10 because H2O2 become active at this
PH or oxidation is start at this pH. For the bast fibers, such as linen, weaker alkaline or soda
alkaline baths are used in order to avoid a cottonizing. Regenerated cellulose fibers are more
sensitive. Therefore, they are only bleached in weak alkaline baths. Alkali sensitive animal
fibers must be bleached in very weak alkaline solutions. Phosphates and ammonia are most
widely used as alkalization source. With tetrasodium pyrophosphate simultaneously a
stabilization of the bleaching liquor can be attained.

Page 20
Water Quality
Soft Water free of iron and copper impurities is recommended for peroxide bleach treatment.
Peroxide Stabilizers
High pH and temperature lead to the faster decomposition of peroxide bleaching liquor and
degradation of cellulose. The role of the stabilizer is simply to control or regulate these
effects the act as buffers, sequestrates and in special cases, enhancing performance of the
surfactant used in the bleach bath.
For caustic alkaline bleach sodium silicate, organic stabilizers or the combination of both are
suitable. In weak alkaline baths the addition of tetrasodium pyrophosphates can be used alone
or together with an organic stabilizer.
2.25 Advantages of Peroxide Bleaching:
 Among the oxidizing bleaching agents, only hydrogen peroxide provides a high
bleaching effect at reasonable costs, especially if modern short-term bleaching
processes are used with only a few minutes bleaching time.
 Peroxide bleaching keeps the fiber quality intact.
 Cotton can be bleached with peroxide in a single stage. Other processes require two or
three bleaching stages, (desize with scour, scour with bleach etc.).
 No separate pretreatment is necessary because hot, alkaline bleaching has not only a
bleaching but also a cleaning effect; it therefore combines the advantages of an
alkaline extraction with the bleaching treatment.
 Animal fibers can only be bleached with peroxide to a high and stable degree of
whiteness. Corrosion of stainless steel equipment does not occur during peroxide
bleaching.
 The spent peroxide baths still contain residuals of hydrogen peroxide which fever the
degradation of the organic impurities in the effluent, and this helps to decrease the
chemical oxygen demand (COD).
2.26 Bleaching of Wool with Hydrogen Peroxide
After scouring, wool may be bleached by immersion or pad and dry techniques, using
alkaline or acid solutions. This peroxide bleaching on wool would give satisfactory result in
whiteness level.
2.27 Bleaching of Silk with Hydrogen Peroxide
Prior to bleaching, silk is usually degummed. Hydrogen Peroxide addition assists this process
and it is universally used as the bleaching agent for natural silk, usually in an alkaline
solution.

Page 21
Industrial Scouring/Bleaching/Dyeing machine for knitted fabric
2.28 Bleaching of synthetic fibers Hydrogen Peroxide
When used alone, synthetic fibers do not normally require bleaching. However, blends of
synthetic fibers with natural or regenerated fibers, e.g. cotton-polyester are frequently
bleached. The most popular bleaching agent is Hydrogen Peroxide and it is used in both batch
and continuous processes.
2.29 Bursting Strength
Tensile strength tests are generally used for woven fabrics where there are definite warp and
weft directions in which the strength can be measured. However, certain fabrics such as
knitted materials, lace or non-woven do not have such distinct directions where the strength is
at a maximum. Bursting strength is an alternative method of measuring strength in which the
material is stressed in all directions at the same time and is therefore more suitable for such
materials. There are also fabrics which are simultaneously stressed in all directions during
service, such as parachute fabrics, filters, sacks and nets, where it may be important to stress
them in a realistic manner. A fabric is more likely to fail by bursting in service than it is to

Page 22
break by a straight tensile fracture as this is the type of stress that is present at the elbows and
knees of clothing.
When a fabric fails during a bursting strength test it does so across the direction which has
the lowest breaking extension. This is because when stressed in this way all the directions in
the fabric undergo the same extension so that the fabric direction with the lowest extension at
break is the one that will fail first. This is not necessarily the direction with the lowest
strength.
2.30 Diaphragm Bursting Test
The British Standard describes a test in which the fabric to be tested is clamped over a rubber
diaphragm by means of an annular clamping ring and an increasing fluid pressure is applied
to the underside of the diaphragm until the specimen bursts. The operating fluid may be a
liquid or a gas.
Two sizes of specimen are in use, the area of the specimen under stress being either 30mm
diameter or 113mm in diameter. The specimens with the larger diameter fail at lower
pressures (approximately one-fifth of the 30mm diameter value). However, there is no direct
comparison of the results obtained from the different sizes. The standard requires ten
specimens to be tested.
Bursting Strength Testing method

Page 23
In the test the fabric sample is clamped over the rubber diaphragm and the pressure in the
fluid increased at such a rate that the specimen bursts within 20 ± 3 s. The extension of the
diaphragm is recorded and another test is carried out without a specimen present. The
pressure to do this is noted and then deducted from the earlier reading.
Bursting Strength tester
2.31 The following measurements are reported:
 Mean bursting strength kN/m2
 Mean bursting distension mm
 Liquid
 Piston
 Rubber
 diaphragm
 Specimen
 Clamp
The US Standard is similar using an aperture of 1.22 ± 0.3 in (31 ± 0.75mm) the design of
equipment being such that the pressure to inflate the diaphragm alone is obtained by
removing the specimen after bursting. The test requires ten samples if the variability of the
bursting strength is not known.
The disadvantage of the diaphragm type bursting test is the limit to the extension that can be
given to the sample owing to the fact that the rubber diaphragm has to stretch to the same
amount. Knitted fabrics, for which the method is intended, often have a very high extension.

Page 24
2.32 Color vision
Color vision is the ability of an organism or machine to distinguish objects based on the
wavelengths (or frequencies) of the light they reflect, emit, or transmit. Colors can be
measured and quantified in various ways; indeed, a human's perception of colors is a
subjective process whereby the brain responds to the stimuli that are produced when
incoming light reacts with the several types of Cone cells in the eye. In essence, different
people see the same illuminated object or light source in different ways.
2.33 Physiology of color perception
Perception of color begins with specialized retinal cells containing pigments with different
spectral sensitivities, known as cone cells. In humans, there are three types of cones sensitive
to three different spectra, resulting in trichromatic color vision.
Each individual cone contains pigments composed of Opsinapoprotein, which is covalently
linked to either 11-cis-hydroretinal or more rarely 11-cis-dehydroretinal. The cones are
conventionally labeled according to the ordering of the wavelengths of the peaks of their
spectral sensitivities: short (S), medium (M), and long (L) cone types. These three types do
not correspond well to particular colors as we know them. Rather, the perception of color is
achieved by a complex process that starts with the differential output of these cells in the
retina and it will be finalized in the visual cortex and associative areas of the brain.
For example, while the L cones have been referred to simply as red receptors, micro
spectrophotometry has shown that their peak sensitivity is in the greenish-yellow region of
the spectrum. Similarly, the S- and M-cones do not directly correspond to blue and green,
although they are often described as such. The RGB color model, therefore, is a convenient
means for representing color, but is not directly based on the types of cones in the human eye.
The peak response of human cone cells varies, even among individuals with so-called normal
color vision; in some non-human species this polymorphic variation is even greater, and it
may well be adaptive.
2.34 Cone cells in the human eye
Cone type Name Range Peak wavelength
S β 400–500 nm 420–440 nm
M γ 450–630 nm 534–555 nm
L ρ 500–700 nm 564–580 nm

Page 25
2.35 Theories of Color Vision
There are two major theories that explain and guide research on color vision: the trichromatic
theory also known as the Young-Helmholtz theory, and the opponent-process theory. These
two theories are complementary and explain processes that operate at different levels of the
visual system.
2.36 Trichromatic Theory
Evidence for the trichromatic theory comes from color matching and color mixing
studies. Young and Helmholtz carried out experiments in which individuals adjusted the
relative intensity of 1,2, or 3 light sources of different wavelengths so that the resulting
mixture field matched an adjacent test field composed of a single wavelength. Individuals
with normal color vision needed three different wavelengths (i.e., primaries) to match any
other wavelength in the visible spectrum. This finding led to the hypothesis that normal color
vision is based on the activity of three types of receptors, each with different peak sensitivity.
Consistent with the trichromatic theory, we now know that the overall balance of activity in S
(short wavelength), M (medium wavelength), and L (long wavelength) cones determines our
perception of color as shown in the figure below.
Trichromatic Theory
Several color perception phenomenon cannot be explained by the trichromatic theory alone,
however. For example, it cannot account for the complementary afterimages in which the
extended inspection of one color will lead to the subsequent perception of its
complementarycolor (see demonstration below). Complementary afterimages are better
explained by the opponent-process theory.

Page 26
2.37 Opponent-Process Theory
Developed by WealdHerring (1920/1964), the opponent-process theory states that the cone
photoreceptors are linked together to form three opposing color pairs: blue/yellow, red/green,
and black/white. Activation of one member of the pair inhibits activity in the other.
Consistent with this theory, no two members of a pair can be seen at the same location, which
explains why we don't experience such colors as "bluish yellow" or "reddish green". This
theory also helps to explain some types of color vision deficiency. For example, people with
dichromatic deficiencies are able to match a test field using only two primaries. Depending
on the deficiency they will confuse either red and green or blue and yellow.
The opponent-process theory explains how we see yellow though there is no yellow cone. It
results from the excitatory and inhibitory connections between the three cone types.
Specifically, the simultaneous stimulation of red (L cones) and green (M cones) is summed
and in turn inhibits B+Y-, which results in the perception of yellow. However, when blue
light is present, the S cone is activated, the B+Y- cell receives excitatory input and blue is
perceived.
Opponent-Process Theory
You can see the opponent relationships between red and green, and blue and yellow. View
the four-color patch afterimage stimuli below for 30 seconds. Then remove the color stimuli
by moving your cursor mouse over the image causing it to become a blank white field. When
you fixate at the dot in the center of the field you should notice that the original colors are all
reversed - where you saw red it is now green and vice versa. Likewise is for blue and yellow.
In fact, as you have seen, both theories are needed to explain what is known about color
vision. The trichromatic theory explains color vision phenomena at the photoreceptor level;
the opponent-process theory explains color vision phenomena that result from the way in
which photoreceptors are interconnected neutrally.

Page 27
2.38 Spectrophotometer
Spectrophotometry uses photometers that can measure a light beam's intensity as a function
of its color-wavelength known as spectrophotometers. Important features of
spectrophotometers are spectral bandwidth, the range of colors it can transmit through the test
sample, and the percentage of sample-transmission, and the logarithmic range of sample-
absorption and sometimes a percentage of reflectance measurement.
A spectrophotometer is commonly used for the measurement of transmittance or reflectance
of solutions, transparent or opaque solids, such as polished glass, or gases. However they can
also be designed to measure the diffusivity on any of the listed light ranges that usually cover
around 200 nm - 2500 nm using different controls and calibrations. Within these ranges of
light, calibrations are needed on the machine using standards that vary in type depending on
the wavelength of the photometric determination.
An example of an experiment in which spectrophotometry is used is the determination of the
equilibrium constant of a solution. A certain chemical reaction within a solution may occur in
a forward and reverse direction where reactants form products and products break down into
reactants. At some point, this chemical reaction will reach a point of balance called an
equilibrium point. In order to determine the respective concentrations of reactants and
products at this point, the light transmittance of the solution can be tested using
spectrophotometry. The amount of light that passes through the solution is indicative of the
concentration of certain chemicals that do not allow light to pass through.
The use of spectrophotometers spans various scientific fields, such as physics, materials
science, chemistry, biochemistry, and molecular biology. They are widely used in many
industries including semiconductors, laser and optical manufacturing, printing and forensic
examination, and as well in laboratories for the study of chemical substances. Ultimately, a
spectrophotometer is able to determine, depending on the control or calibration, what
substances are present in a target and exactly how much through calculations of observed
wavelengths.
2.39 Some features of Datacolor-650 spectrophotometer
 This high-precision, close-tolerance, reference grade spectrophotometer has special
capabilities to handle fluorescent materials.
 Exceptional inter-instrument agreement, easy maintenance, exceptional stability
 Automated UV control-UV Exc, UV Inc, 420nm, 460nm and UV calibration modes
 Optional Vertical Configuration
 High-precision, close-tolerance, reference grade spectrophotometer with capability to
handle fluorescent measurements
 Automated zoom lens and specular port
 Multiple viewing apertures with automatic aperture recognition
 Automatic gloss compensation

Page 28
 Datacolor spectrophotometers provide high resolution color measurement and
excellent short and long-term repeatability
 The optional 3.0 mm aperture can measure unusually small sample areas
 The exceptionally large (30mm) aperture means you can maximize the surface area to
be measured – ideal when measuring color without regard to a textured surface.
Spectrophotometer (Datacolor-650)
2.40 Whiteness and Yellowness Indices in a Spectro-Eye
Yellowness
Yellowness is defined as a measure of the degree to which the color of a surface is shifted
from preferred white (or colorless) towards yellow.
Yellowness, as defined by ASTM E 313, has been applied successfully to a variety of white
or near-white materials, including paints, plastics, and textiles. In terms of colorimeter
readings, it was YI=100(1-B/G) where B and G are respectively amber blue (B) and green
(G) colorimeter readings. Its derivation assumed that, because of the limitation of the concept
to yellow (or blue) colors, it was necessary to take account of variations in the amber or red
colorimeter readings.

Page 29
Yellowness according to ASTM E 313 (D 1925) was developed specifically for determining
the yellowness of homogeneous, non-fluorescent, nearly colorless, transparent, nearly white
translucent or opaque plastics, as viewed under daylight lighting conditions. It can also be
applied to materials other than plastic fitting this description. The indices can be calculated,
rounded, and adjusted in the last retained significant digit to minimize the residual error in the
white point values. The equation is: YI=100(CxX-CzZ)/Y, where Cx and Cy standard
coefficients described in the standard and correspond with observer angle and color
temperature.
Whiteness
Whiteness is defined as a measure of how closely a surface matches the properties of a
perfect reflecting diffuser, i.e. an ideal reflecting surface that neither absorbs nor transmits
light, but reflects it at equal intensities in all directions. For the purposes of this standard, the
color of such a surface is known as preferred white.
ASTM E313 – measuring procedure and settings are described in the same standard (ASTM
E313: whiteness and yellowness of paper) like the Yellowness indices. This method is based
on the use of colorimeter readings B and G. The idea was that chromaticity factor G-B
required three times the weighting of the lightness factor G of the lightness. The equation is:
WI=G-4(G-B)=4B-3G
Different whiteness & yellowness values of different fabrics

Page 30
CHAPTER THREE
MATERIALS & METHODS

Page 31
3.1 Materials& Machines:
S/J fabric &cutting Scissors
Scissors was used for
sampling the S/J fabric by
cutting them in equal size and
exact weight.
Electronic Balance
Electronic balance was used
for determining the weight of
the samples.
Lab Sample Dyeing m/c
This is the machine where
some of the samples
bleaching were done. Only
temperature can be controlled
by this m/c, not the time.

Page 32
Digital Lab Sample Dyeing
m/c
Rests of the sample bleaching
were done in this machine.
Both time & temperature can
be controlled by this machine.
Digital Sample Dryer
This machine was used for
drying of the wet samples
after washing.
Spectrophotometer
Spectrophotometer was used
for the whiteness test of the
bleached sample.

Page 33
Bursting Strength Tester
Bursting strength tester m/c
was used for testing the
bursting strength of scoured-
bleached samples.
Electronic pipette
This pipette was used for
measuring the amount of
peroxide to be taken for
bleaching recipe.
3.2 Fabric Structure & Type:
Fabric Type : Knitted Fabric
Specification Type : Single Jersey fabric
Fabric GSM : 120-30
Color : Off white
Each Sample Weight : 12.5 gm.
Fabric Treatment : Scoured in regular factory parameter.

Page 34
3.3 Chemicals used:
Chemical Name Functions
Caustic Soda (NaOH) Used for scouring of the gray S/J fabric
Hydrogen Peroxide (H2O2) Used for bleaching of scoured S/J fabric
Detergent Used for hot wash of scoured-bleached S/J
fabric
Wetting agent To increase the wet pick up of the fabric
3.4 Method of working:
Bursting strength testing
Whiteness testing
Drying
Hot washing
Bleaching in 7 different parameters
Scouring in factory parameter
Gray S/J fabric

Page 35
3.5 Scouring Procedure:
Fabric is preparing for industrial Scouring-Bleaching
3.6 Standard recipe of scouring:
This recipe of scouring is for knitted fabric. Different recipe is used for woven fabric
scouring process.
Alkali (NaOH) : 2 to 5 gm per litre.
Soda ash : 1 gm per litre (to adjust PH)
pH : 10.5
Wetting agent : 1 gm per litter.
Sequestering agent : 1 gm per litter.
Detergent : 1 to 2 gm per litter.
Temperature : 100 to 125o
C.
Time : 6 hours (close vessel) or 8 hours (open vessel)
M : L : 1 : 10

Page 36
3.7 Process of scouring:
The fabric is loaded in the m/c and kept in rope form.
The hot liquor is pumped and sprayed by circular tube on to the fabric
The liquor passes slowly over the packed cloth and collects at the false bottom of
the kier.
The liquor again pumped into the heater by a centrifugal pump and this cycle is
repeated
After scouring ,the fabric is washed in 800
C water to remove impurities.
3.8 Bleaching procedure:
Bleaching processes were done in 7 different recipes and processes. Sample wise bleaching
process& recipeare described below.
Sample no-1 (Standard Sample)
Recipe:
Hydrogen Peroxide (H2O2) : 2.00 g/L (Stock Solution 5%)
Temperature : 98o
C
Time : 30 min
M:L : 1:10
Sample weight : 12.5 g
Sample no-2
Recipe:
Temperature : 98o
C
Time : 30 min
M:L : 1:10
Sample no-3
Recipe:
Temperature : 98o
C
Time : 30 min
M:L : 1:10

Page 37
Sample no-4
Recipe:
Temperature : 108o
C
Time : 30 min
M:L : 1:10
Sample no-5
Recipe:
Temperature : 88o
C
Time : 30 min
M:L : 1:10
Sample no-6
Recipe:
Temperature : 98o
C
Time : 40 min
M:L : 1:10
Sample no-7
Recipe:
Temperature : 98o
C
Time : 20 min
M:L : 1:10
For sample no- 1, 4, 5, 6, 7: required peroxide is 5ml
For sample no- 2: required peroxide is 5.5 ml
For sample mo-3: required peroxide is 4.5 ml

Page 38
3.9 Process curve for bleaching:
Process curve for sample bleaching
3.10 Spectrophotometer (Datacolor-650) working procedure:
Sample Presentation and Measurement Overview:
When positioned correctly, the sample rests between the sample holderand the front
panel door. The sample must completely cover the aperture opening.
Reflectance Measurements:
1. Grasp the sample holder and pull forward.
2. Position the sample, then carefully bring arm back up to normal operating position.
3.11 Working steps
i. First the standard recipe bleached sample was taken as the standard whitening index
for the whiteness test
ii. Then the other samples were tested against the value of the standard sample.
iii. Different values were found for different samples.
iv. We took all the sample results and compared them.
v. Tests were done under D-65 light index.
Temperature (o
C)
Time (min)
Chemical
+ Fabric
25
88/98/108
0 |‐‐‐‐‐‐ 20/30/40 ‐‐‐‐‐‐|
Stop heating
Start heating Wash
sample

Page 39
Testing the whiteness of the bleached samples in Datacolor-650
3.12 Results obtained from Spectrophotometer
Sample Whiteness Index DELTA WI
(BATCH WI - STD WI)
Sample no-1
(STD WI)
58.65 0
Sample no-2 61.46 2.81
Sample no-3 51.86 -6.79
Sample no-4 59.32 0.67
Sample no-5 55.55 -3.1
Sample no-6 61.00 2.35
Sample no-7 48.53 -10.12

Page 40
Screenshot of whiteness test in Datacolor-650 spectrophotometer
3.13 Bursting Strength Testing Working Procedure
Working Steps:
1. First we took a sample for the testing of its bursting strength
2. Then we opened the strength testing lid and spaded the fabric perfectly
3. Then we put the lid off and started the machine for the work
4. One operator operated the machine through the computer system
5. Through the machine the working process was visible clearly
6. the diaphragm forced the fabric and after a while the fabric got busted
7. we took the read of time, pressure & other values from the computer
8. other samples were tested in the same way
9. we took all the data & information and compared them

Page 41
Bursting strength testing of sample
3.14 Bursting strength test result
Sample Bursting strength (kPa)
Sample no-1
(STD)
627.3
Sample no-2 614.3
Sample no-3 630.5
Sample no-4 598.4
Sample no-5 638.1
Sample no-6 609.7
Sample no-7 630.6

Page 42
CHAPTER FOUR
RESULTS &
DISCUSSIONS

Page 43
4.1 Effect of peroxide concentration on bursting strength
Sample-1 was bleached in regular factory parameter (2.0 g/L). And so that’s why we
considered it as our standard and tested other sample parameters against this.
In Sample-2 According to the result, we can see that, by increasing the bleaching agent
amount (2.2 g/L); the strength of the fabric decreases. In sample-3, we have decreased the
amount of peroxide agent (1.8 g/L). From the result, we can see that strength increases here
slightly.
4.2 Effect of peroxide concentration on whiteness
In sample-2 (2.2 g/L) whitening index or the whiteness of the sample increases for increasing
peroxide amount and we have got the best whiteness value of the samples for sample-2.
Whereas for sample-3 (1.8 g/L) whiteness decreases for the lack of bleaching agent.
630.5
627.3
614.3
605
610
615
620
625
630
635
1.8 g/L 2 g/L 2.2 g/L
Strength (kPa)
strength (kPa)
51.86
58.65
61.46
46
48
50
52
54
56
58
60
62
64
1.8 g/L 2 g/L 2.2 g/L
Whiteness
Whiteness

Page 44
4.3 Effect of bleaching temperature on bursting strength
In standard sample, the temperature was 98o
C.
In sample-4 temperature was increased (108o
C). For the increase in temperature, some
damage occurred in the fiber. So the strength of the sample decreased.
In sample-5 we decreased the temperature (88 o
C). The fibers of the fabric didn’t get much
damage and so that strength increased here. We have got the best strength result for reducing
the temperature.
4.4 Effect of bleaching temperature on whiteness
The whiteness gets increased in sample-4 because of the increase in temperature (108o
C).
But the whiteness falls for the lack of temperature in sample-5 (88 o
C).
638.1
627.3
598.4
570
580
590
600
610
620
630
640
650
88(°C) 98(°C) 108(°C)
Strength (kPa)
55.55
58.65
59.32
53
54
55
56
57
58
59
60
88(°C) 98(°C) 108(°C)
Whiteness

Page 45
4.5 Effect of bleaching time on bursting strength
In Sample-6 we have increased the bleaching time (40 min) in the standard of 30 minuites.
We have got that for giving heat for more time, the strength of the sample decreases.
And in sample-7, it got the shortest bleaching time than other samples. And we got better
strength of fabric here.
4.6 Effect of bleaching time on whiteness
Here, for the increase in reaction time (40 min), whitening index is increased for ample-6.
And in sample-7, for the shortest time bleaching (20 min), we got the worst whitening index.
630.6
627.3
598.4
580
590
600
610
620
630
640
20 minutes 30 minutes 40 minutes
Strength (kPa)
48.53
58.65
61
0
10
20
30
40
50
60
70
20 minutes 30 minutes 40 minutes
Whiteness

Page 46
CHAPTER FIVE
CONCLUSION

Page 47
5.1 Conclusions:
Bleaching is an essential process for the white fabric production. By doing this project we
have got very good idea about the bleaching parameter effects. During bleaching we have to
look after these points:
 Increasing the amount of bleaching agent can increase the whiteness of the fabric. But
it can affect the strength.
 Bleaching temperature should not raise more than 100o
C because for increasing the
temperature, the strength gets much damaged. So the bleach should be done in the
range of 95-99o
C for the better strength and good whiteness
 Bleaching time should not extend more than range. Though the whiteness increases,
but the fibers get so much damaged for the temperature.
 Amount of peroxide bleach, time and temperature should not decrease than the range
without reason. Because of that the whiteness is not properly obtained though the
strength gets improved. After all we know that bleaching process is done for obtaining
the whiteness from the fabric.
So considering all the facts, we can say that the standard recipe for bleaching is the best in
overall. Here we can get good whiteness and better strength of the fabric. So for the factory
production that standard recipe is used as default bleaching recipe.

Page 48
REFERENCES
 http://textilelearner.blogspot.com/2011/03/textile-bleaching-process_5937.html
(26.11.2014)
 http://www.textileworld.com/Issues/2009/March-
April/Dyeing_Printing_and_Finishing/Gentle_Bleaching (26.11.2014)
 http://www.slideshare.net/mainulrony/scouring-13515271 (27.12.2014)
 http://www.slideshare.net/tadele_asmare/bleaching-18854378 (27.11.2014)
 http://www.datacolor.com/products/ (29.12.2014)
 http://industrial.datacolor.com/portfolio-view/datacolor-650/ (29.11.2014)
 http://en.wikipedia.org/wiki/Textile_bleaching (29.11.2014)
 http://thesmarttime.com/pretreatment/scouring-bleaching-of-cotton.html (29.11.2014)
 http://textilelearner.blogspot.com/2013/08/preparatory-process-of-cellulosic-
fiber.html (29.11.2014)
 http://textilelearner.blogspot.com/2014/03/bleaching-pro_8997.html (30.11.2014))
 www.burstingstrengthtester.com/bursting_strength_tester.html (30.11.2014)
 http://l-w.com/produkt/lw-bursting-strength-tester/ (30.11.2014)
 http://textilelearner.blogspot.com/2012/12/bleaching-of-cotton-fiberfabric-with.html
(01.12.2014)
 http://greenopedia.com/hydrogen-peroxide-bleach-alternative (01.12.2014)
 www.thwingalbert.com/bt21-burst-strength-tester.html (01. 12.2014)
 http://textilelearner.blogspot.com/2012/02/bursting-strength-test-diaphragm-of.html
(01.12.2014)
 http://textilelearner.blogspot.com/2011/08/pretreatment-object-of-pretreatment.html
(01.12.2014)
 www.smitherspira.com/services/primary-pack-testing/burst-strength (02.12.2014)

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