The basic objective of pretreatment processing is removal of added or natural impurities present in textile fibres to improve the absorbency. BY:ROHIT SINGH

1. 1
Textile Polymers andTextile Polymers and
Requirement ofRequirement of
Pretreatment on ThemPretreatment on Them
Prepared byPrepared by
ROHIT SINGHROHIT SINGH
nitragzb20152019@gmail.comnitragzb20152019@gmail.com
+91 9450316927+91 9450316927
NITRA TECHNICAL CAMPUSNITRA TECHNICAL CAMPUS
GHAZIABADGHAZIABAD

2. TEXTILESTEXTILES
 All the Textiles are PolymersAll the Textiles are Polymers Poly (many);Poly (many);
Mer (single unit)Mer (single unit)
 Example: Ethylene n(CHExample: Ethylene n(CH22=CH=CH22) [Monomer] is formed) [Monomer] is formed
to Polyethylene –(CHto Polyethylene –(CH22-CH-CH22))nn--
 Functionality of polymer should be normally twoFunctionality of polymer should be normally two
[unsaturation or functional groups such as[unsaturation or functional groups such as
-OH, -COOH, etc]-OH, -COOH, etc]
 The arrangement of polymers is normally linear orThe arrangement of polymers is normally linear or
branched not cross-linkedbranched not cross-linked
 Textiles requirements are met by the polymers throughTextiles requirements are met by the polymers through
molecular chain length and molecular weight.molecular chain length and molecular weight.

3. Classification of TextilesClassification of Textiles
 Textiles are basically classified through natural andTextiles are basically classified through natural and
synthetic meanssynthetic means
 Sometimes it would be classified as organic or inorganicSometimes it would be classified as organic or inorganic
(silica, germanium, etc)(silica, germanium, etc)
 Natural fibres are by plant, animal and also by insectNatural fibres are by plant, animal and also by insect
originorigin
 Synthetic fibres are from chemicals [monomers toSynthetic fibres are from chemicals [monomers to
polymers through the process polymerization]polymers through the process polymerization]
 Regenerated and/or modified fibres are from bothRegenerated and/or modified fibres are from both
natural and synthetic meansnatural and synthetic means

4. Important Textile FibresImportant Textile Fibres
 Natural textiles are classified as Cellulosic and NonNatural textiles are classified as Cellulosic and Non
cellulosicscellulosics
 Cotton, linen, jute, sisal, banana fibres are importantCotton, linen, jute, sisal, banana fibres are important
natural cellulosic textile fibresnatural cellulosic textile fibres
 Silk, wool, and some special hairs are some of theSilk, wool, and some special hairs are some of the
important non cellulosic (protein) fibres.important non cellulosic (protein) fibres.
 Polyester, Acrylic, Nylon, Lycra, Polypropylene, etc arePolyester, Acrylic, Nylon, Lycra, Polypropylene, etc are
some of the important synthetic fibres.some of the important synthetic fibres.
 Lyocell / Viscose, cuprammonium rayon, and celluloseLyocell / Viscose, cuprammonium rayon, and cellulose
acetate are some of the regenerated and/or modifiedacetate are some of the regenerated and/or modified
textile fibres.textile fibres.

5. Requirement for PretreatmentRequirement for Pretreatment
 All the natural textile fibres have impurities inAll the natural textile fibres have impurities in
different extent due to various reasonsdifferent extent due to various reasons
 Pretreatment(s) remove the impurities, bothPretreatment(s) remove the impurities, both
natural and added, from the textile polymersnatural and added, from the textile polymers
 Pretreatment(s) facilitate the textiles to carry outPretreatment(s) facilitate the textiles to carry out
the main processing in a efficient waythe main processing in a efficient way
 Pretreatment(s) mostly decide the quality of thePretreatment(s) mostly decide the quality of the
end use productsend use products

6. Scouring on Cotton fibresScouring on Cotton fibres
 Scouring is an alkali treatment on cotton fibre usingScouring is an alkali treatment on cotton fibre using
sodium hydroxide and/or sodium carbonatesodium hydroxide and/or sodium carbonate
 During scouring, the alkali reacts with the naturalDuring scouring, the alkali reacts with the natural
impurities (oil/fat – insoluble) and converts them intoimpurities (oil/fat – insoluble) and converts them into
soluble soapsoluble soap
 For scouring, sodium hydroxide is used in theFor scouring, sodium hydroxide is used in the
concentration of 3%(owm), 3 hours, at boilconcentration of 3%(owm), 3 hours, at boil
 Scouring removes the hydrophobicity and revealsScouring removes the hydrophobicity and reveals
hydrophilicity and promotes absorbencyhydrophilicity and promotes absorbency

7. Bleaching of Cotton FibreBleaching of Cotton Fibre
 Bleaching is another important pretreatmentBleaching is another important pretreatment
next to scouring, performed on cotton fibresnext to scouring, performed on cotton fibres
 Bleaching removes the unwanted naturalBleaching removes the unwanted natural
colouring pigments.colouring pigments.
 Bleaching could be performed by two types ofBleaching could be performed by two types of
techniques; reductive and oxidativetechniques; reductive and oxidative
 Reductive technique is not followed nowadaysReductive technique is not followed nowadays
due to its inefficient performance on cottondue to its inefficient performance on cotton

8. Oxidative Bleaching on CottonOxidative Bleaching on Cotton
 Normally oxidative bleaching action is performed in theNormally oxidative bleaching action is performed in the
industries on cotton fibre substratesindustries on cotton fibre substrates
 Though number of bleaching agents are available in theThough number of bleaching agents are available in the
chemical market, few bleaching agents are being usedchemical market, few bleaching agents are being used
extensivelyextensively
 Calcium hypochlorite, Sodium hypochlorite andCalcium hypochlorite, Sodium hypochlorite and
Hydrogen peroxide are the most frequent usedHydrogen peroxide are the most frequent used
bleaching agents in the conventional cotton processingbleaching agents in the conventional cotton processing
unitsunits

9. Pretreatment on SilkPretreatment on Silk
 Silk is a natural fine filament materialSilk is a natural fine filament material
 Original silk filament contains two proteinOriginal silk filament contains two protein
substrates; one is fibrous protein called Fibroin,substrates; one is fibrous protein called Fibroin,
another one is gummy protein called Sericinanother one is gummy protein called Sericin
 Fibroin is responsible for the fibre polymerFibroin is responsible for the fibre polymer
composed of sixteen amino acids.composed of sixteen amino acids.
 Sericin is a gum considered impurity and to beSericin is a gum considered impurity and to be
removed from the material based on theremoved from the material based on the
considerations.considerations.

10. ……continuedcontinued
 Silk pretreatment requires mainly the removalSilk pretreatment requires mainly the removal
of gummy substance (sericin) which ifof gummy substance (sericin) which if
performed fully makes the silk pure of fibreperformed fully makes the silk pure of fibre
protein and pure whiteprotein and pure white
 The removal of sericin from silk filament isThe removal of sericin from silk filament is
called degumming which is performed bycalled degumming which is performed by
applying 2%owm soap, 1%owm sodiumapplying 2%owm soap, 1%owm sodium
carbonate at 95carbonate at 95oo
C for 2 hoursC for 2 hours

11. ……continuedcontinued
 If required only hydrogen peroxide bleaching isIf required only hydrogen peroxide bleaching is
performed on degummed silk, since alkaline pHperformed on degummed silk, since alkaline pH
damages protein textiles, but hydrogendamages protein textiles, but hydrogen
peroxide’s pH could be altered by situationsperoxide’s pH could be altered by situations
 Degumming is performed in different ways; ¼Degumming is performed in different ways; ¼thth
removal, ½ removal, ¾th removal and fullremoval, ½ removal, ¾th removal and full
(100%) removal, depending on the market /(100%) removal, depending on the market /
commercial / end use product’s considerationscommercial / end use product’s considerations

12. Pretreatment on WoolPretreatment on Wool
 Wool is another protein polymer (Keratin) composedWool is another protein polymer (Keratin) composed
of 20 different amino acids with some similarities andof 20 different amino acids with some similarities and
differences with silkdifferences with silk
 Unlike cotton and silk, wool contains differedUnlike cotton and silk, wool contains differed
impurities on the basis of species, country, place, etc ofimpurities on the basis of species, country, place, etc of
the animalthe animal
 Fats (grease) and vegetable matters are the majorFats (grease) and vegetable matters are the major
impurities in wool to be consideredimpurities in wool to be considered
 The removal of wool fats (grease) is called as degreasingThe removal of wool fats (grease) is called as degreasing
 The removal of vegetable matters is performedThe removal of vegetable matters is performed
generally by carbonizationgenerally by carbonization

13. ……continuedcontinued
 Nowadays degreasing is mostly done by 2 ways; one isNowadays degreasing is mostly done by 2 ways; one is
by controlled mild alkaline scouring method and theby controlled mild alkaline scouring method and the
other is by solvent extraction methodother is by solvent extraction method
 In the commercial point of view alkaline method isIn the commercial point of view alkaline method is
cheap and preferred, whereas quality point of viewcheap and preferred, whereas quality point of view
solvent extraction method (solvents are costly) issolvent extraction method (solvents are costly) is
preferred. Alkalies are highly sensitive on wool andpreferred. Alkalies are highly sensitive on wool and
possibility of damage is also high, but by solventpossibility of damage is also high, but by solvent
extraction method the damage on wool is nil.extraction method the damage on wool is nil.

14. ……continuedcontinued
 Carbonization is applied on original wool fibresCarbonization is applied on original wool fibres
to remove the vegetable matters by treating withto remove the vegetable matters by treating with
dilute sulphuric acid followed by drying. By thisdilute sulphuric acid followed by drying. By this
the vegetable matters are converted to carbonthe vegetable matters are converted to carbon
contents and charred to ash which is washedcontents and charred to ash which is washed
away. This process is called carbonization.away. This process is called carbonization.
 Degreasing and carbonization removes almostDegreasing and carbonization removes almost
all the natural impurities present in the woolall the natural impurities present in the wool
fibre substratesfibre substrates

15. …….continued.continued
 Other possible pretreatments on wool fibreOther possible pretreatments on wool fibre
substrates are Non-felting, Decatizing, Potting ,substrates are Non-felting, Decatizing, Potting ,
etcetc
 Non felting is the process carried out on woolNon felting is the process carried out on wool
fibres to give partial scale removal so thatfibres to give partial scale removal so that
chemicals entry in the wool polymer is easychemicals entry in the wool polymer is easy
 Decatizing and potting are similar treatments inDecatizing and potting are similar treatments in
acidic medium to improve the characters ofacidic medium to improve the characters of
wool for some special applicationswool for some special applications

16. TH
AN
K
YO
U!
TH
AN
K
YO
U!