Mercerizing is a finishing process for cotton that improves properties like luster and strength. It involves treating cotton with a strong alkaline solution, usually sodium hydroxide. John Mercer discovered the process in 1844. The sodium hydroxide penetrates the cotton fibers and reacts with hydroxyl groups, swelling the fibers longitudinally and altering the cellulose structure. This gives mercerized cotton increased luster, strength, dye uptake, and other improved qualities. The degree of mercerization depends on processing conditions like tension, concentration and time in the alkaline solution.

1. Shyamoli Textile Engineering College
Presentation On
Mercerizing

2. Contents
1.Mercerization
2.Creator Mercerization
3.Mercerizing Definition
4.Objective
5.Theory
6.Types of Mercerization
7.Flowchart of mercerizing
8.Surface of cotton
9.Fiber cross section
10.Condition point for mercerizing
11.Which stage cellulose can be merceraized
12.Fabric mercerizing machines
13.Requrements of good wetting agents
14.Different steps in mercerizing cycle
15.Degree of Mercerization
16.Test of Mercerizing
17.Purpose of Mercerizing

3. Mercerization is a finishing treatment of cotton with
a strong caustic alkaline solution in order to improve
the luster, hard and other properties, was names
after its discoverer, John Mercer, and has been in
use for sometime. It has been seeing an increase in
application recently.
Mercerization

4. John Mercer (21 February 1791 – 30 November 1866) was an English
dye and fabric chemist and fabric printer born in Great
Harwood, Lancashire. In 1844 he developed a process for
treating cotton, mercerization, that improves many of its qualities for
use in fabrics.
Creator Mercerization

5. It is a treatment for cotton articles and natural fibres composed by cellulose in a
concentrated solution of caustic soda (300 g/l), under tension and ambient
temperature.
Fibre swelling and simultaneously there is a longitudinal shrinkage, modifying
the morphological structure of the fibre and achieving a shinier surface, resistant
to wear and washing.
Mercerizing Definition :
Objectives:
Fig : Mercerizing Cotton

6. Types of
Mercerization
Tension
Mercerization
Slack
Mercerization

7. THEORY
Since concentrated sodium hydroxide (operational solution that includes
chemicals) is used in mercerization process, the reactions that take place
with the cellulose fibers are intermolecular reactions. That is, the sodium
hydroxide that is concentrated this much, penetrates inside the micelles
(crystallites) and a structure called hydrate cellulose emerges.
Cell – OH Cell – OH + NaOH Cell – ONa + H2O Cell – ONa + H2O
75% 25%
Sodium hydroxide reacts with the hydroxyl groups inside the
macromolecule in such a way that it either produces sodium cellulosate or
it links to the molecules through the pulling forces. Although both of them
take place in mercerization, 75% is on linking’s side through the force of
pull.

8. Flowchart of mercerizing

12. THE CONDITION OR CONSIDERABLE POINTS FOR MERCERIZATION
Tension
Concentration
of caustic
soda solution.
Time
period.
Tensile
strength
Wetting
Agent
agent
Staple
length

13. WHICH
STAGE
CELLULOSE
CAN BE
MERCERIZED
After
desizing
After dyeing
On greige
goods
After
bleaching
After
scouring

14. Fabric mercerising machines

15. REQUREMENTS OF GOOD WETTING AGENTS:
*It should posses a high wetting power.
*It should enable the alkali to swell the cotton fiber rapidly.
* Should not be preferentially absorbed by the fiber being treated.
*It should disperse perfectly.
*It should be soluble in caustic soda solution.
*It should not give rise to excessive foaming or turbidity in the solution
or deposits on the fiber and machine parts.
*It should not discolor the fiber permanently.
*Its effects of mercerizing liquor should be permanent.
*It must be easily removable.
*It should able to reduce the surface tension of water.
*It should not be injurious to the workers.
*Should not interfere with the caustic recovery from the wash liquors
after mercerization.
*Should be available at an economical price.

16. Pre
tensioning
.Shrinking
Lye
tensioning
Squeezing
Washing and
tensioning
Final caustic
content
Different steps in
mercerizing cycle

17. Determination of Degree of Mercerization
The effect of mercerization depends on the conditions of mercerization. A
quantitative assessment of the degree of mercerization is carried out
mainly in three different ways i.e. variation in the mercerized product,
external appearance (lustre) and internal appearance (x-ray diagram) etc.
Determination of deconvolution count
In this method cotton hairs are cut in large number of hair fragments 0.2 mm long.
They are then mounted in liquid paraffin on a microscopic slide, and then counted
the proportion of fragments free from twist on convolution during mercerization. The
result is expressed as percentage and is called" Deconvolution Count". If the figure is
above 20, the fabric is mercerized. The ratio of the two sets of data may be used to
estimate the degree of mercerization. The disadvantage of this method is that the
extent of deconvolution is influenced by the maturity of cotton and by the structure
of material that is twist of the yam or weave of cloth.

18. Determination of swelling index
Untwisting number of single yarn can give reliable means for estimating
degree of swelling of cellulose in non-polar liquids such as carbon
tetrachloride and benzene. Strong alkali solution and cadoxen (cadmium
ethylene di amine complex of 3.6%) also causes large amount of
untwisting. In this method, the yarn together with the weight (0.8 g) is
hanged into the measuring cylinder containing sufficient amount of solvent
as to dip the upper end of the yam. The yam is then allowed to untwist
and the number of revolutions made by weight are measured for 3 min.
Swelling index = (Untwisting number in solvent) / Untwisting number in
water)
Swelling index increases with degree of mercerization. In this method
there is no necessity of untreated sample.

19. Benzopurpurine
test
Sodium
hydroxide
spotting test
Goldthwait
Red-Green test
Staining test
Test of
Mercerizing

20. MERCERIZING IN SIM GROUP:
Parameter:
Steam cylinder= 20
Temp= 100°C
Pressure = 2-2.5 pa
1th pressure = 0.21 mPa
Padder= 0.21mpa
2nd pressure= 0.31 mpa
Padder= 0.24mpa
Caustic soda = 1L on 766gm= 50 boom
18 boom= 3000L
Sometime they add
 mercerize oil
 acetic acid
 wetting agent
Scouring caustic= 30-50g/l

21. 1.The main changes occurring in the alkaline treatment of
cotton are:Solubility in solvents is increased;
2.The length of yarn or area of cloth is reduced;
3.Tensile strength is increased;
4.Absorption of dyestuff is increased;
5.Physical compactness of either cloth or yarn is increased;
6.Water absorption is increased;
7.Reactivity with oxygen (air) is increased;
8.Reactivity of cotton at lower temperatures is increased;
9.Sodium hydroxide (caustic soda) is preferentially absorbed
during the process;
10.Luster is increased;
Purpose of Mercerizing