ECONOMICAL DYEING OF POLYESTER -COTTON BLENDS WITH MULTIFUNCTIONAL PROPERTY BY USING CYCLODEXTRINS

The successful application of disperse dyes on P/C Blend with the help of PEG & CD bring out numerous advantages such as a Dyeing of P/C in a single stage process by using Disperse dyes

ECONOMICAL DYEING OF POLYESTER /COTTON BLENDS

CYCLODEXTRINS

The present work illustrates the beneficial effects of applying a hybrid approach which includes the treating of P/C blended material with pure PEG (M.wt.400), PEG solution containing small concentration of NaOH and third one is treatment with CD after

the later method To realise this approach, P/C blended samples were padded in the above

mentioned chemicals to wet pick up of 100% (o.w.f), and dried then subjected to saturated steam curing in the appropriate manner Then the dyeing is performed using HTHP technique The dyeing liquor was prepared using Dispersing agent, dye solution

etc.The pH of the bath was maintained at 5.5 using acetic acid Well wetted fabric was

entered in to the dye vessel and the dyeing is performed for the prescribed time under definite temperature Finally, the dyed samples were thoroughly soaped with non-ionic

detergent (3 g/l of lissapol N), rinsed and dried (for the dark shades R/C treatment was

given by using caustic and hydros each 1 g/l at 70 ºC)

PEG & CD can be effectively used to dye P/C blends using disperse dyes only

So that it can conserve time, energy, man power etc Nevertheless, CD plays in the following roles 1) To substitute surfactants in P/C processing; 2) When bound chemically with fibres, it provides hydrophilicity 3) To perform easy removal of sweat and sweat degradation products from the textiles The successful application of disperse dyes on P/C Blend with the help of PEG

& CD bring out numerous advantages such as a) Dyeing of P/C in a single stage process

by using Disperse dyes only b)Saving of water, energy, time( due to single stage process) c)Replacing of conventional surfactants & thickeners by CD (It will give low BOD & COD Value than conventional one) d)Enhancement of functional property of the P/C fabric by means of CD e)Minimizing of the effluent problem due to shortening processes, re-placing of surfactants etc f)An economical process etc

LIST OF SYMBOLS, ABBREVIATIONS or NOMENCLATURE

BIS Bureau of Indian Standards

BOD Biological Oxygen Demand

CCM Computer Colour Matching

COD β-Chemical Oxygen Demand

g/l Grammes Per Liter

M.wt Molecular Weight

NaOH Sodium Hydroxide

o.w.f On Weight of the Fabric

P/C Polyester Cotton

PEG Polyethylene Glycol

pH A measure of Acidity or Alkalinity

R/C Reduction Clearing

SHPI Sodium hypophosphite

CHAPTER 1 INTRODUCTION

The Multifunctional Auxiliaries and Energy Conservation processes are the Prime concern of the Textile Chemical processing industry Attempts to utilize CD in textile applications started in the late 1980s.This was brought about by the recognition that the inclusion complex formation capability of CD can be applied to the deodorant , aroma, antimicrobial finishes that have recently popular and in treating effluents Since then research and development of CD applications have become active, and the

possibilities of using CD in textile finishing are being explored recently in the textile industry .With the trend in the textile industry demanding high quality and new properties, the range of application of CD is expected in P/C blends dyeing In this study, for the coloration of P/C blend fabrics, so-called disperse dyes are used, which are very poorly soluble in water(0.1-10 mg/L).Without using solubility-enhancing agents(surfactants),uniform dyeing is not possible CD however can replace the surfactant, and their COD in the waste water is lower than that of the usual textile surfactants 16.

With the scarcity as well as increasing prices of fuel, it has become one of the imperative duties of the present day researchers to cut-short the processes, without sacrificing the desirable properties of the product for economy in general and conservation of energy in particular To meet the above objectiveness ,in the dyeing of P/C blends use of high boiling swelling agent like PEG can be used In conventional process P/C dyeing involves various steps, viz PET dyeing, reduction clearing, washing, drying; followed by cotton dyeing, washing, drying If unfixed dyes is not removed properly during soaping/washing treatment will lead to poor fastness properties of the dyed material Thus ,sever washing-off treatments ,reduction clearing and intermediate dyeing steps are involved in two bath P/C dyeing, which leads to more consumption of time, man-power ,energy and also declination in the productivity In this study to conserve time and energy, it is desirable to develop an economical process which can dye both the portions of the blend without altering their viz _ properties Therefore in the present investigation, an attempt can be made to dye P/C blends in a single bath with disperse dyes using high boiling swelling agent (PEG)

Normal dyeing of P/C blends involves the elaborated process by using appropriated class of dyes for PET and Cotton portion The proposed work aims to use Cyclodextrin (CD) and poly ethylene glycol(PEG) as a Pre-treatment to dye both polyester and cotton portion by only disperse dyes in the single stage process Nevertheless, CD can cause some Multi functional property on the dyed fabric like hydrohilicity, anti soiling etc and the generation of COD and BOD also will be low compare with sodium alginate in the conventional process 31 And use of high boiling swelling agent like PEG is desirable in P/C dyeing to develop an economical process

which can dye both the portions of the blend in a single stage with disperse dyes so that

it can conserve time, energy, man power etc1,34.As on today commercially, the blends of P/C are successively dyed by two bath process using disperse dyes and cellulosic dyes respectively Even though one bath processes have been tried using various combinations

of cellulosic dyes along with disperse dyes, none of the processes were not successful and are not practical commercially

The successful application of disperse dyes on P/C Blend with the help of PEG &

CD bring out numerous advantages such as a) Dyeing of P/C Blend in a single stage Process by using Disperse dyes only b)Saving of water, energy, time( due to single stage process) c)Replacing of conventional surfactants & thickeners by CD (It will give low BOD & COD Value than Conventional one) d)Enhancement of functional property of the P/C fabric by means of CD e)Minimizing of the effluent problem due to shortening processes, re-placing of more polluting surfactants etc f) An Economical process etc.Poly-ethylene Glycol (PEG) & Cyclodextrin (CD) can be effectively used to dye P/C blends using disperse dyes only Which can alter the nature of polyester & cellulosic fibres contained in the P/C Blends and making it viable to dye cellulosic fibre with disperse dyes along with hydrophobic PET

stable for blending with other type of fibres However, the fibres have low moisture absorption, high static built-up, high pilling tendency and are difficult to dye under practical conditions due to its compact physical structure and absence of chemical active groups etc Extensive research has been carried out on the modification of the polymer chain to overcome some of the inherent drawback of the polyester (PET) fibres.

It was reported that PET fibres desirable properties can be prepared (a) by modifying the chemical structure of the polymer during polymerization and (b) by modifying the fibre surface and the structure by treating with suitable chemical In the first method, incorporating additives during the manufacture can modify the PET fibres The modifying compounds may be mono-functional and di-functional or polymeric compounds 35 At present this type of polyester fibres are well established commercially33

In the second method surface modification of PET fibres have been achieved using various methods such as alkaline hydrolysis28graft polymerization of hydrophilic monomers14, and steaming12

Nevertheless, P/C blend enters in market because it has advantages of both PET and cellulose P/C blend has got lot of advantages from user point of view but from dyers point of view it was difficult to dye the blends And use of high boiling swelling agent like PEG is desirable in P/C dyeing to develop an economical process which can dye both the portions of the blend in a single stage with disperse dyes so that it can conserve time, energy, man power etc1,34

Three factors are mainly responsible for making PET fiber difficult to dye: (a) high-fiber crystallinity, (b) a marked hydrophobic character, and (c) an absence of chemically reactive groups in the polymer Owing to these factors, PET cannot be dyed with the same dyes that are generally employed for cellulosic, protein, nylon, or acrylic fiber Since the ester groups content of cellulose acetate and polyester fiber is nearly the same (40-45%), attempts have been made to dye polyester fiber with disperse dyes by the same method used for cellulose acetate However, it was observed that PET was not dyed

at 80-100oC This was due to a very slow rate of diffusion of disperse dyes into the compact polyester fiber

In the early years attention was directed to finding a means of improving dyeability The yield of a disperse dye on PET is limited and vastly inferior to the yield

on nylon and cellulose acetate because of the low rate of dyeing rather than the low substantivity of early disperse dyes for PET The problem is solved by using different approaches to increase the rate of dyeing.

1 Building up dye molecules inside PET (azoic dyeing)

2 Opening up the fiber structure to bring down the Tg (carrier dyeing)

3 Using temperatures above 100°C [high-temperature (HT) dyeing]

4 Heating the dye and the PET in the dry state together near the softening temperature of the fiber (thermosol or thermo fixation dyeing)

5 Replacing water with an organic solvent as a dyeing medium (solvent dyeing)

Apart from the above approaches, chemical modification of PET (to impart affinity for dyes other than nonionic dyes is commercially practiced in order to get cationic dye able PET Similarly, the transfer printing process is used to colour polyester

in solid shades

The use of solvents for dyeing PET is intensively investigated in the early 1970’s Even though PET can be dyed to any depth of shade using solvents, none of the solvent dyeing methods ever reached a state of a commercial feasibility The azoic dyeing process was once used to colour PET, but with the development of disperse dyes and various dyeing methods; it has now lost its importance It is now used mainly to produce black shades

2.2 DYES FOR POLYESTER

PET is now dyed with nonionic dyes specially synthesized to suit the dyeing processes Nonionic dyes with low aqueous solubility at dyeing temperatures (100-

130oC) are the best dyes for PET The solubility of nonionic dyes in water is low such that these dyes are considered water insoluble It is essential; however, these dyes should have some solubility in the dye bath to get dyed in the aqueous bath These dyes are applied in the form of an aqueous dispersion The small aqueous solubility and the

particle size of a disperse dye plays a vital role in the rate of dissolution and the rate of adsorption of dye by PET Dispersing agents play a vital role in dyeing process Some disperse dyes are sensitive to heavy metals and form chelated compounds with calcium ions giving tonal variations Soft water is therefore used for dyeing

Disperse dyes are available in two forms-micro disperse granules or powder and liquid dyes The dispersion of a dye is spray dried to get solid granules and powders The amount of dispersing agent required to get stable dispersions can be 40-90 % and usually 60% of the dried disperse dye- powder This large proportion of a dispersing agent in the granules and powders of disperse dyes creates problems such as increasing aqueous solubility, inducing migration during drying of padded goods, lowering the exhaustion of dye bath and so on The properties expected of micro disperse -dye granules include stability, dryness, uniformity, free flowing, non-dusting, and non-hygroscopic nature, good bulk density (app.0.5 or more), and ready dispersibility Liquid dyes are dispersions with a low concentration of a dispersing agent Dispersion stability, easy miscibility, proper pH., and free flowing nature are some of the prerequisites for liquid dyes Since metering pumps can be used for liquid dyes the additions, weighing and so on not pose

no problems Liquid dyes are easy to dissolve and to use They pose none of the problems that arc associated with the granular dyes However liquid dyes are likely to dry up to settle, and to alter in concentration during storage Special precautions are required to store and handle liquid dyes Many times, disperse dyes have poor storage stability, particularly, if they are exposed to a humid atmosphere Under these conditions, the dispersion breaks into lumps Such a dye is likely to give uneven, specky dyeing The state of the dye dispersion can be easily checked by dispersing the dye in water and dropping it on filter paper If the dispersion is good, no particle will be visible on the filter paper Improvements in the physical form of the dyes improve the final color results

Chemically, the disperse dyes come from various classes Such as azo, anthraquinone Methine and diphenylamine The dyes usually have NO2, CN, OH, halogen and primary, secondary, and tertiary amines groups but they never have any polar groups which easily ionize in an aqueous bath Some of the dyes have a free

COOH group Such dyes are usually applied by printing techniques under acidic pH so that this group does not ionize substantially Free aliphatic hydroxyl groups that impart high aqueous solubility are esterified with acetic acid or a mixture of acids These dyes generally have low molecular weight which facilitates their entry and diffusion into the highly crystalline polyester fiber The higher the molecular weight of the dyes, the slower

is the diffusion in the fiber They have significant, though low vapor pressure Particularly at elevated temperatures Disperse dyes are sensitive to pH Methine dyes hydrolyze or dimerize under alkaline conditions The pH the dyebath for dyeing PET is therefore maintained on the acid side A redox buffer is usually also added to the dyebath

to avoid reduction of disperse dyes 25

The fastness properties and dyeing characteristics of disperse dyes are considered with particular reference to the subsequent treatments In the case of yam dyeing and to a lesser extent, piece dyeing, wet fastness after heat setting is important since the knitting

or coning oils on dyed goods can lead to the migration of the dye into the oil Besides the usual light and wash fastness, the sublimation fastness of disperse dyes is very important since dyes of low sublimation fastness give problems during subsequent treatments such

as resin finishing A similar high standard of fastness is required for dry and wet rubbing Migration of dye to the surface of the fiber during the heat-setting process frequently results Dyes with high sublimation fastness are therefore used for the dyeing of yarns Similarly, dyes, auxiliaries and dyeing conditions are selected to give optimum coverage

of small variations in dye affinity of textured yarns Thus; dyes used for yarn dyeing must meet the following specifications:

1 Good dispersion properties, so that the dye is not filtered on a package of yarn that constitutes an effective filter Paste brands of disperse dyes are usually preferred for yam dyeing

2 Good stability in HT bath during dyeing (130°C/2 h)

3 Good leveling properties, at least with the addition of a surface-active agent Use

of certain carriers help in getting level dyeing of a yarn package

4 Good sublimation fastness

2.3 MECHANISM OF DYEING

The mechanism of dyeing PET with nonionic dyes under different conditions of dyeing has some common features and some significant differences HT dyeing and carrier dyeing involve dye transfer from aqueous baths, while in thermo fixation dyeing; the water in the pad liquor is completely expelled by a drying process before the dye is fixed on PET

The contribution of the PET structure to the dyeing mechanism remains the same for the three processes because the fiber does not absorb any significant amount of water and the presence or absence of water on the fibre does not play any significant role in the sorption of dye by PET The dye is adsorbed only in the amorphous regions of PET, that

is, it does not enter the crystalline regions Thus, if calculated on the basis of the amorphous content of the PET materials, the fiber saturation values of a dye on different

PET materials are similar (FIG.2.1) The percentage composition of the crystalline and

non-crystalline regions in the fiber may vary from fiber to fiber and the fiber may exhibit apparent differences in its dyeing behavior

The penetration of dyes in the PET structure is explained by the free volume theory for the low-molecular-weight compounds in an amorphous polymer The energy effects

in dyeing show abrupt changes over a very short range of temperatures at Tg

FIG.2.1 Temperature dependence of true saturation values of dyes on polyester material.

(a) Fixed in air oven: O: Fixed in metal press: (b) Saturation values were calculated for three polyesters on the basis of their amorphous content when the data on all polyesters lie on the same plot.

The concerted movements of Chain segments of polymer molecules are started at Tg

An increase temperature of above Tg, raise the frequency and amplitude of the movement

of chain segments This facilities diffusion of dye and the rate of diffusion increase with the temperature In the thermo fixation process, however, as the thermo fixation temperature increases and approaches the softening temperature of PET, there is sudden

drop in the fiber saturation value (FIG.2.1) This is attributed to the increased

crystallization of PET chains during the pre-melting stage, which lowers the amorphous content of the fiber 7

Under dyeing conditions, the rate of dye molecules on the fiber surface is always higher than the rate of diffusion into the fiber There fore, the former does not exhibit any influence on the overall rate of dyeing and the diffusion of dyes within the fiber is the rate determining step Disperse dye has a tendency to deposit on the fiber surface In the course of dyeing, this deposited dye has to be desorbed to migrate to some other part of the fiber material to get the level uniform dyeing 22 This prolongs the dyeing process

Significant surface deposition takes place only from over saturated dye bath 7 (FIG.2.2)

This is because the surface of the polyester fiber is full of C-O-C (ether) linkages that are hydrophobic, while the C==O (ester) linkages that are hydrophilic face towards the interior of the fiber

FIG.2.2 Dye on PET in HT dyeing (l30 o C/1 h).

Dye on PET in HT dyeing (l30oC/1 h) Dye: C.I Disperse Brown I (Micro disperse) Concentration: a) 0.8 g/liter (unsaturated bath): (b)) 1.6 g/liter (over saturated bath); M:L ratio 1:4000

Since dye has to diffuse through the holes and space formed by the vibrations of the chain segments of PET molecules, the shape and size of the dye molecule influences

the rate of dyeing The higher the molecular size of dye, the higher is the space required for the dye of diffuse Because of this, as the temperature increases, the effect of the size

of a dye molecule on the rate of dyeing decrease; that is, the activation energy of diffusion increases with the molecular weight of the dye The rate and extent of absorption of a dye are dedicated by the fiber structure, time and temperature of aqueous dyeing or thermo fixation 9 Disperse dyes are combined to produce mixed shades Neither the rate nor the equilibrium adsorption of dyes in mixture is influenced by the presence of the other dye 8The dyes build up on PET, independent of each other, up to their saturation values This is also the case with dyeing from an organic solvent 7

2.4 HT Dyeing

The mechanism of dyeing PET with nonionic dyes in an aqueous dispersion has been investigated by many workers Earlier investigation shows that dyeing involves the attraction of positively charged particles of suspended dye to negatively charged fiber surfaces to build up a surface layer of dye particles Subsequently, the solid dye dissolves

in the fiber to form a solid solution This mechanism, which was first suggested for

dyeing cellulose acetate with disperse dyes by Kartaschoff 17 is now rejected It is now established that dyeing takes place in a saturated solution of dye in an aqueous bath the suspended particles in dispersion form a reservoir of dye that replenishes the solution as the dye molecules are removed from the dye bath by the fiber The dye in solution is assumed to be in a monomeric form even though experimental difficulties prevent any conclusive proof from being obtained on the monomolecular state of dye in solution Disperse dyes have definite water solubility The solubility of a dye in the bath increases with temperature

Dyeing takes place in three simultaneous steps: (a) dissolution of dye particles in the bath to give a dye solution, (b) adsorption of the dissolved dye from solution on to the fiber surface, and (c) diffusion of adsorbed dye from the fiber surface to the interior of the fiber substance

2.5 COTTON:

Cotton is a linear cellulosic polymer The repeating unit in the cotton polymer is Cellobiose, which consists of two glucose units Cotton consists of about 5,000 – 10,000 cellobiose units, that is, its degree of polymerization is about 5,000 – 10,000 It is a very long, linear polymer, about 5,000 nanometer in length and about 0.8 nanometer thick The cotton fibres are amongst the finest in common use Such very fine fibres permit the manufacture of fine, lightweight cotton fabrics and garments, etc, Cotton is a very fine fibre with little variation in fibre diameter The fibre length to breadth ratio of cotton ranges from about 6000: 1

The most important chemical group in the cotton polymer is the hydroxyl (or) –

OH group These are also present as methylol groups (or) CH2OH Their polarity gives raise to hydrogen bonds between –OH groups of adjacent cotton polymers Vander Wall’s forces also occur but compared with the hydrogen bonds, the van der wall’s forces are of little significance

Cotton is a crystalline fibre Its polymer system is about 65 –70 % crystalline and about 30 – 35 % amorphous Therefore, the cotton polymers are well oriented and probably no further apart than 0.5 nanometer, in the crystalline regions This is the maximum distance across which hydrogen bonds can form between polymers Hydrogen bonds are the dominant and most important force of attraction present in the polymer system of cotton For this reason, van der wall’s forces, which are also present, have little relevance

2.6 MECHANISM OF DYEING

2.6.1 The internal surface of fibers and its importance

The natural fibers (i.e.,) the cellulosic and protein fibers have exceedingly large internal surfaces, which are the walls of the channels between the bundles of long chain

molecules composing the fibre The number of such channels is immense, of the order of ten million in the cross section (e.g.,) cotton or a wool fibre, and the total surface of their walls is of the order of 100 m2/g, (or) five acres per lb This is about one thousand times

as large as the outer surface of the fibre

When the fiber is wetted, water rapidly penetrates and swells a large proportion of these channels Dyes in solution are then able to diffuse into the channels (or) pores

They can however, enter only a relatively small proportion of the total internal space, because the remainder is in pores too small to admit a dye molecule Many of the synthetic polymer fibers have much less internal surface than the natural fibres, but the dyes used with such fibers are able to penetrate between the fibre molecules even though water cannot always do so

Dyes are surface active substances, (i.e.,) when dissolved in water their molecules tend to concentrate more closely together at a surface than in the body of the solution The surface can be between the solutions and either air (or) a fibre The first action in any dyeing operation is therefore the concentration of dye molecules that as much of the internal surface of the fibre as they can reach The concentration so produced is however not usually sufficient to give a usefully deep coloration to the fibre and for such coloration other factors must be brought into play

These are the chemical forces, which can operate between a dye molecule, and a fibre molecule, which are classified below, and also those between the dye molecules themselves, which can cause their association into larger units

2.6.2 Chemical Forces Responsible For Dyeing

Broadly, four main chemical effects are subsequently responsible for the substantively of the dye for the fibre They are,

1 Hydrogen Bond

2 Non Polar or Wander Walls force

3 Electrostatic or ionic forces and

4 Covalent Bonds

These seldom act in isolation; usually at least two operate in any dyeing process Additionally, the so called ‘hydrophobic bond’ may be involved

2.7 Cyclodextrins:

Cyclodextrins are crystalline, water soluble, cyclic, non-reducing, oligosaccharides built up from six, seven, or eight glucopyranose units Cyclodextrins have long been known as products, which are able to form inclusion complexes They used to be, however, no more than scientific curiosities due to their limited availability and high price As a result of intensive research and advances in enzyme technology, cyclodextrins and their chemically modified derivatives are now available commercially, generating a new technology: the packaging on molecular level They have circular, conical configuration, where the height is about 800 pm and the inner diameter of the

cavity is from 500-800pm (vogtle, 1991; weber, 1987).

FIG.2.3 Structure and dimensions of CD

CD is a cyclic polymer of alpha-D-glucopyranose The common cyclodextrins used in chromatography are the alpha-, beta- and gamma-cyclodextrins which have been

shown to contain 6 (cyclo-hexamylose), 7 (cyclo-heptamylose) and 8 (cyclo-octamylose) glucose units, respectively These cyclic, chiral, torus shaped macromolecules contain the D(+)-glucose residues bonded through a-(1- 4)glycosidic linkages.

The most stable three dimension molecular configuration takes the form of a toroid with the upper (larger) & lower (smaller) opening of the toroid presenting secondary and primary hydroxyl groups respectively to the solvent environment The interior of the toroid is hydrophobic as a result of the electron rich environment provided

in large part by glucosidic oxygen atom

FIG.2.4 Cyclic shaped CD

It is the interplay of atomic (Vander walls), thermodynamic (hydrogen bonding), and solvent (hydrophobic) forces that accounts for the stable complexes that may be formed with the chemical substances which in the polar environment of the CD cavity The complex exists in an equilibrium depended upon the concentration of the CD, the guest chemical and water

FIG 2.5 Torus shaped CD

Once the molecular has entered the cavity, the “goodness of fit”, as determined by the weaker interactions taking place in the cavity, will make the final contribution to the association component of the equilibrium process These week forces can create selective interaction similar to those of enzymes.

from glucopyranose units linked by α ( 1,4)-glycosidic bonds (frendenberg, 1948;

vogtie, 1991) CD can be obtained by enzymatic degradation of starch In this process

compounds with 6-12 glucopyranose units per ring are produced Depending on enzymes and how the reaction is controlled the main product is, α, β or γ, cyclodextrine (6, 7 & 8

glucopyranose units respectively) β- CD is the most commercial interesting of the three

natural CD because of the easy production, availability, cavity diameter and price It is

most widely used and presents at least 95% of all produced and consumed CD (Szejtli,

1994), the inner diameter of β-CD cavity is from 600-680 pm (Szejtli, 1996; Jozwiakowski, 1985) and can accommodate aromatic compounds such as volatile

molecules and pharmaceutical compounds New concept for modification of textile substrate is based on the permanent fixation of super molecular compounds, such as CD

on the material surface and thus imparts new functionality to the fabric(Knittel,2003).In

such a way that treated substrates will be important for medical and hygienic textiles for

garment and home textiles( Buschmann,1990) From the structure of β-CD it is evident

that it can not form direct co-valent bond with textile fibres.Polycarboxylic acids like 1,2,3,4 BTCA are well Non-Formaldehyde Cross Linking Agent, which can react with

OH group of PEG & Cellulose and form stable ester bonds (Lewis, 1997; Yang, 1991;

Martel,2002).

Molecules, or functional groups of molecules being less hydrophilic than water, can be included in the cyclodextrin cavity in the presence of water, if their molecular dimensions correspond to those of the cyclodextrin cavity The formed inclusion complexes are relatively stable and rapidly separate from the solution in crystalline form One, two or three CD molecules contain one or more entrapped guest molecules This is the essence of molecular encapsulation, the packaging on molecular level Molecules of poorly soluble drugs, rapidly deteriorating flavors, volatile fragrances, toxic pesticides or dangerous explosives, even gases can be encapsulated The capsules of molecular size are the cyclodextrins Almost all applications of cyclodextrins involve complexation In many cases complexes are separated in more or less pure form and utilized as crystalline substances (drug and flavor complexes) while in other cases the complexation process is only a transient state, and becomes apparent through the final result(CD-catalysis, separation of mixtures.)

Up to quite recently cyclodextrins have been considered exclusively as “empty” capsules of molecular size Recent studies revealed such a broad versatility in their application, that they can be considered as a new group of industrial basic materials CDs are besides being “molecular capsules”, reagents in analytical chemistry and diagnostics, raw materials for the production of derivatives and polymers, biologically active substances, etc

Research Objective of this Project:

To dye P/C in single stage process by using Disperse dyes

To save water, energy, time due to single stage process

To replace the surfactant & alginate by CD to face BOD, COD Problem

To enhance the functional property of the P/C fabric

To minimize effluent problem due to shortening processes

EXPERIMENTAL METHODOLOGY

Fabric: 67:33 Polyester: Cotton Knitted Sample

Yarn: 67:33 and 50:50 Polyester: Cotton Blended Samples

Dye stuff: Yellow C4G H/C

N.Blue 3G 200%

Scarlet BR

Special Auxiliaries: β-Cyclodextrin

Polyethylene glycol with m.w 400

BTCA Sodium Hypophosphite And all other chemicals are in laboratory reagent grade

METHODS:

Scouring and Bleaching:

The samples were scoured and bleached by the Combined Process at 80 ºC for 45 min., with a solution containing 2 gpl Non-Ionic Detergent, 2 % Hydrogen Peroxide and

2 % sodium carbonate etc, Washed with Hot Water, Cold Water, Squeezed and Air

Dried

Chemical Treatments:

Table

Methods Treatment

U Untreated

A Samples Treated with PEG then steaming at 160º C for 2 min Finally the

samples were thoroughly washed with tap water and air dried

B Samples Treated with a mixture of PEG and Sodium hydroxide solution

(95.5%/4.5% w/w) to wet pick-up of 100 % expression then steaming at 160º C for 2 min.Finally the samples were thoroughly washed with tap water and air dried

C Samples Treated with a mixture of PEG and Sodium hydroxide solution

(95.5%/4.5% w/w) to wet pick-up of 100 % expression then steaming at 160º C for 2 min ; treated with CD in different concentration(10,15,20,30,35gpl) along with BTCA-0.6% ,Catalyst-SHPI-0.6% etc then Curing at 170º C for 2 min Finally the samples were thoroughly washed with cold water and hot water, air dried

Dyeing:

All the dyeing was performed using HTHP Dyeing technique The pH of the liquor was maintained at 5.5 using acetic acid Well wetted fabric was entered in to the vessel with the disperse dyes-x%, dispersing agent-0.5% etc at room temperature and then the temperature is gradually raised to 130ºC and work for 30-40 min Finally, all the dyed samples were thoroughly rinsed, soaped with 3 gpl Lissapol N(Non-ionic detergent)

at boil for 10 min, washed and air dried

CHAPTER – 42.3 Testing and Analysis:

2.3.1 Determination of degradation of PET:

Carboxylic content of treated samples (A, B & C) was analyzed according to a reported method10.This tests is useful to determine the degradation effect of PET causes

by alkaline and steaming, However the staining test can also carried out with Basic dyes (Basic Blue 9 for 0.5%(o.w.f); Temp 85ºC, Time, 60 min; MLR 1:100) to find qualitatively through colour strength determination by CCM

2.3.2 Dye Exhaustion percentage:

The dye uptake was evaluated by visible spectroscopy from calibration curve of concentration versus absorption of the individual dye at its wavelength of maximum absorption using shimadzu spectrophotometer Dye exhaustion percent expressed as E%,

it was calculated as a difference between the dye concentration before and after dyeing i.e

E %=( Cb-Ca/Cb) x 100 - (2.1)

Where, E-Exhaustion percentage

Cb-The Dye concentration before dyeing

Ca- The Dye concentration after dyeing

2.3.3 Evaluation of K/S Value:

Colour strength (K/S Value) of the dyed sample was measured on Data Spectra flash SF 600 Sectrophotometer.These values are computer calculated from reflectance data according to kubelka-munk equation2

K/S= (1-R) ² / 2R - (2.2)