Thursday, July 11, 2013

Fiber Immaturity


           Fibre maturity (in case of Cotton Fiber) is a fibre characteristic which expresses
the relative degree of thickening of the fibre wall. In other words, it is the
measure of primary and secondary wall thickness.

The fibre maturity is usually estimated by several indirect tests which are foten
used to find out the proportion of fibres containing a maturity greater than
some selected level.

A fiber will be matured if a high degree of wall thickening took place into the
fiber content during cotton growth.

Things upon which the textile fiber maturity depends: There are several
factors upon which the fibre maturity is basically depends. By changing these
factors you can also measure that which factors is working behind to be a fibre
matured or which not.
The factors are –
1. Weather: If the weather doesn’t favor, the fiber gets less chance to be
matured.
2. Types of Soil: It is proved that, in some country the fibers grows well and
becomes well matured and on some other country; due to the soil, fibers don’t
be so much matured and grows low quality fibres.
3. Plant Diseases: If proper care is not taken to the fibres, these become less
matured due to several diseases.
4. Pests: Some pests is good for Plants and some are bad. So be careful to
apply any pesticides on any plants.
5. Dead Fibers: It is natural that the dead fibers will be immature.

Importance of maturity:

1. Nep formation:

The immature thin walled fibres are more flexible than thick walled fibre. So
they blend and tangle more easily forming neps. If these neps appear in the
dyed cloth they show up as spechs of lighter shade.

One of the main troubles caused by the presence of these thin walled
immature fibres is nepping. It is created during processing, starting at the
gin. It also occurs for some natural causes like fragments of seed pods
which attached to fibre. Where rubbing between surfaces occurs e.g. during
carding, minute knots of tangled fibre are caused.



2. Dyeing faults:

 Immature fibres can not be dyed evenly. If in a fabric there is yarn of
immature fibres, shade variation will occur. The thinner the secondary cell
wall, the lighter the shade will be.

3. Fineness:

 The immature fibres can not produce fine fabric and yarn. Immaturity
decreases the wt. of unit length of fibre and thus reduces fineness. As a
result the accuracy of the test is badly affected.

4. Less yarn strength:

 Due to immaturity, yarn strength reduces and for that breakage of yarn
occurs during spinning.
 
5. Less production:

 Ends down is increased due to immaturity. As a result production is less.

6. Fabric quality:
Immature fibres are less absorbent and have uneven surface. So they are
uncomfortable in handle and weaving.

7. Yarn hairiness:

 Immature fibre leads to yarn hairiness.

8. Problem in spinning:

 The immature fibre, the fragments of seed pod attached to a fibre, which
creates great problem during spinning.

Effect of immaturity in Textile Processing:

. Nep formation.
. Problem in spinning.
. Uneven dyeing shade.
. Problem in fineness measuring.
. Less yarn strength.
. Less production.


 Types of fibres:

1. Normal fibre.
2. Thin walled fibres.
3. Dead fibres.


1. Normal fibre:


Normal fibres with a well-developed cell wall and pronounced convolutions in
the raw state and become rod-like after swelling. It is denoted by ‘N’. In normal
fibres no empty spaces are seen in longitudinal section.

2. Thin walled fibres:

Thin walled fibres having the structure and characteristics lying between
normal and dead fibres. It is denoted by ‘T’ 

3. Dead fibres:


Dead fibres appear ribbon like even after swelling. They are extremely
immature fibre. If the cell-wall is less than one-fifth of the total width of the
fibre is termed as dead fibre.


Maturity ratio:

Maturity ratio of a method of numerically expressing the maturity of a sample
of cotton fibre. It is the ratio of actual degree of wall thickening to a standard
degree of wall thickening.

 So, Maturity ratio =
g thickenin wallcell of degree Standardg thickenin wallcell of degree Actual

In other words, Maturity ratio is the ratio which expresses the actual fibre wt.
per centimeter H, in relation to a standard fibre wt. per centimeter Hs.

Degree of cell wall thickening:

The degree of wall thickening may be expressed as the ratio of the actual cross-
sectional area of the wall to the area of the circle with the same parameter.

It is denoted by ‘.’.

Assess of the fibre maturity:

One of the troubles caused by immature fibres was faulty dyeing. This
difference between the dyeing properties of mature and immature fibres is
employed in the Goldthwaite test to give a visual indication of the maturity of a
sample of cotton. Two dyes are used on the same bath, a red and a green dye,
mature fibres are stained red and immaturity fibres green, the red colour being
developed in the cellul0ose of the secondary wall. Hence little or no secondary
wall thickening – no red.

Monday, July 8, 2013

E-book of Textile Testing



                                                Physical Testing of Textiles
Authors: B. P. Saville (editor)
Publisher: CRC Pr I Llc
Publication Year: 1999
Type: pdf
Size: 13.1MB
Pages: 332
Download




Physical Properties of Textile Fibres


Authors:W. E. Morton (editor), J. W. S. Hearle (editor)
Publisher: CRC Pr I Llc
Publication Year: 2008
Type: pdf
Size: 32.2MB
Pages: 765  
Download

                                                                Fabric Testing

Authors: Jinlian Hu (editor)
Publisher: CRC Pr I Llc
Publication Year: 2008
Type: pdf
Size: 12.2MB
Pages: 408

                                                      
Download
 











Sunday, July 7, 2013

Scouring process,overview of textils scouring


                 Scouring is a process by which all natural & additive impurities such as oil, wax, fat, hand dust, etc. are removed to produce a hydrophilic & clean textile material. It is one of the vital processes of wet processing. On cotton fibers, this treatment removes fatty and pectic substances, softening motes and
preparing the material to absorb the subsequent treatment agents.
Objects:
1.    To make the fabric highly hydrophilic.
2.    To remove impurities such as oils, waxes, gum, husks as nearly as possible.
3.    To increase absorbency of fabric or textile materials without physical & chemical damage.
4.    To produce a clean material by adding alkali.
5.    To make the fabric ready for the next process.
6.    To remove non-cellulosic substance in case of cotton.                                                                                                                                                                                                                      
Scouring process depends on:
1.    The type of cotton.
2.    The color of cotton.
3.    The cleanliness of cotton.
4.    The twist & count of yarn.
5.    The construction of the fabric.
6.    The shade% & type of shade of finished product.


                                                                                                                Chemicals used in Scouring process:
Main Chemicals
                 Use
Caustic soda
Neutralize acidic materials, saponify glycerides, solubilise silicates.
Surfactants
Reduce surface tension & minimize interfacial tension.

Detergents
Emulsify oil, fats, waxes, & remove oil-borne stains.
Chelating agents
Deactivate metal ions.
Sodium silicate
Penetrate & break down lignins.
Soda ash
Maintain pH.
Solvent
Assist emulsification by dissolving oily materials,


Scouring process:
1.    Batch process.
2.    Semi-continuous process.
3.    Discontinuous process.
4.    Modern process.
 
kier boiler
Scouring process of cotton:
Generally, there are two principle of cotton scouring.
1.    Discontinuous (kier boiling process or winch dyeing machine )
2.    Continuous (scouring in ‘J’ or ‘L’ box) 

                                       J box Process
Scouring process of silk:
ʘ Impurities present in silk.
ʘ Sericin up to 30% (main impurities)
Mineral matter, coloring matter, traces of waxes & fats =1-1.5%
ʘ the removing of these impurities in silk are called degumming.

Scouring of jute :(Bast fiber)
ʘ Bast fiber, jute, linen etc. multicellular fiber, having polygonal shape. The cells are cemented with each other by lignin which is non-cellulosic unit & is about 11-14%.
ʘ If strong alkali is used for jute scouring, its strength is reduced as lignin is removed & cells are separated. So mild alkali is used in jute scouring at low temperature.
Assessment of Scouring:
1. Drop test:
ʘ In a pipette, a solution of 0.1% direct red or congo red is taken & droplet of solution put on the different places of the fabric. Then the absorption time of the fabric is observed.
ʘ The standard time of absorption of one drop of solution is 0.5-0.8 sec.

                              

 

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