Wrinkle recovery finishing on cotton by using cyclodextrin (phd report)

When treated with formaldehyde-based crosslinkers, cellulosic fabrics show improved mechanical stability, wrinkle recovery angles and durable press performance, but N-methylol treatment

ABSTRACT

BILGEN, MUSTAFA Wrinkle Recovery for Cellulosic Fabric by Means of Ionic

Crosslinking (Under the direction of Peter Hauser and Brent Smith.)

When treated with formaldehyde-based crosslinkers, cellulosic fabrics show improved mechanical stability, wrinkle recovery angles and durable press performance, but N-methylol treatment also causes fabrics to lose strength and later to release formaldehyde, a known human carcinogen We have discovered that ionic crosslinks can stabilize cellulose using high or low molecular weight ionic materials which do not release hazardous reactive chemicals, but at the same time provide improved wrinkle recovery angles as well as complete strength retention in treated goods We have varied polyelectrolyte, the ionic content of fabrics, and various features of the application procedure to optimize the results and to develop an in-depth fundamental physical and chemical understanding of the stabilization mechanism

WRINKLE RECOVERY FOR CELLULOSIC FABRIC

BY MEANS OF IONIC CROSSLINKING

TEXTILE CHEMISTRY

Raleigh

2005

APPROVED BY:

Dr Peter Hauser (Chair) Dr Brent Smith (Co-Chair)

Dr Charles Boss (Minor)

DEDICATION

This thesis is dedicated to my family and my wife, Nicole, who supported me with constant love and caring and inspired my interest in studying textile chemistry

BIOGRAPHY

Mustafa Bilgen was born in December 1, 1978 in Erdemli, Turkey He graduated from Erzurum Science High School in June 1995 He received the Bachelor of Science degree in Textile Engineering from Department of Engineering and Architecture, Uludag University, Bursa, Turkey in July 1999

After he graduated he worked as a dyeing and finishing supervisor in Akay Textile Dyeing & Finishing Company for one year before he started to help his father for taking care of the family business

He came to North Carolina State University in January 2004, to continue his education and started his master program in Textile Chemistry under the direction of Dr Brent Smith and Dr Peter Hauser

ACKNOWLEDGEMENTS

I would like to thank to the National Textile Center and North Carolina State University for their financial support I also would like to thank to my advisors, Dr Hauser and Dr Smith, for their crucial help and patience during my research and preparation of my thesis

LIST OF CONTENTS

LIST OF TABLES - viii

LIST OF FIGURES -x

1 INTRODUCTION -1

2 LITERATURE REVIEW -3

2.1 Cellulose chemistry -3

2.2 Cellulosic fabric’s nature of wrinkling -5

2.3 Durable Press finishing of cotton -6

2.3.1 Urea-Formaldehyde derivatives -7

2.3.2 Melamine-Formaldyhe derivatives -7

2.3.3 Methylol derivatives of cyclic ureas -8

2.3.4 Effects of formaldehyde based DP finishes on cellulose -9

2.4 Recent developments in non-formaldehyde DP applications - 10

2.5 Ionic crosslinking - 14

2.6 Preparation of quaternized polymers - 16

2.6.1 Chitosan and its reaction with CHTAC - 16

2.6.2 Reaction of Cellulose with CHTAC - 18

2.7 Carboxymethylation of cellulose - 20

2.8 Proposed Research - 21

3 EXPERIMENTAL PROCEDURES - 23

3.1 Test Materials - 23

3.2 Equipments - 25

3.3 Application procedures - 25

3.3.1 Pad dry cure - 25

3.3.2 Pad batch - 26

3.3.3 Exhaustion - 26

3.4 Analysis and physical property tests - 26

3.4.1 Nitrogen analysis - 27

3.4.2 FT-IR analysis - 27

3.4.3 1H- NMR analysis - 27

3.4.4 Wrinkle recovery angles - 28

3.4.5 Tensile strength - 28

3.4.6 Whiteness index - 28

3.4.7 Stiffness - 28

3.5 Reaction of cellulose with chloroacetic acid - 29

3.6 Reaction of Cellulose with CHTAC - 32

3.7 Synthesis of compounds - 35

3.7.1 Molecular weight determination of chitosan - 35

3.7.2 Depolymerization of chitosan and characterization - 37

3.7.3 Reaction of chitosan with CHTAC - 39

3.7.4 Reaction of glycerin and ethylene glycol with CHTAC - 51

3.7.5 Reaction of cellobiose and dextrose with CHTAC - 53

3.8 Preparation of fabric samples - 53

3.9 Crosslinking of carboxymethylated cellulosic fabric - 54

3.9.1 Treatment with cationic chitosan - 54

3.9.2 Treatment with cationic glycerin - 54

3.9.3 Treatment with cationic cellobiose, cationic dextrose and cationic ethylene glycol - 55

3.9.4 Treatment with calcium chloride and magnesium chloride - 55

3.10 Crosslinking of cationic cellulosic fabric - 57

3.10.1 Treatment with PCA and BTCA - 57

3.10.2 Treatment with EDTA, NTA and HEDTA - 59

3.10.3 Treatment with oxalic acid, citric acid and malic acid - 59

4 RESULTS & OBSERVATIONS AND DISCUSSION - 60

4.1 Wrinkle recovery angles of conventional durable press finished fabrics - 60

4.2 Wrinkle recovery angles of polycation treated anionic cellulosic fabrics - 60

4.2.1 Wrinkle recovery angles of cationic chitosan treated fabrics - 60

4.2.2 Application of paired t-test analysis on cationic chitosan treatments - 68

4.2.3 Wrinkle recovery angles of cationic glycerin treatments - 71

4.2.4 Wrinkle recovery angles of cationic cellobiose and cationic dextrose treated fabrics - 76

4.2.5 Wrinkle recovery angles of calcium chloride and magnesium chloride treated fabrics - 76

4.2.6 Discussion of wrinkle recovery angles for polycation treatments - 79

4.3 Wrinkle recovery angles of polyanion treated cationic cellulosic fabrics - 82

4.3.1 Wrinkle recovery angles of PCA and BTCA treated fabrics - 82

4.3.2 Wrinkle recovery angles of EDTA, NTA and HEDTA treated fabrics - 87

4.3.3 Wrinkle recovery angles of oxalic acid, citric acid and malic acid treatments 89 4.3.4 Discussion of wrinkle recovery angles for polyanion treatments - 90

4.4 Strength data - 92

4.4.1 Tensile strength of conventional durable press finished fabric - 92

4.4.2 Strength data of polycation treated anionic cellulosic fabrics - 93

4.4.3 Strength data of polyanion treated cationic cellulosic fabrics - 96

4.4.4 Discussion of strength data of untreated and treated fabrics - 98

4.5 CIE whiteness index data -101

4.5.1 CIE whiteness index of conventional durable press treated fabric -101

4.5.2 CIE whiteness index of polycation treated anionic cellulosic fabrics -102

4.5.3 CIE whiteness index of polyanion treated cationic cellulosic fabrics -104

4.5.4 Discussion of whiteness index of untreated and treated fabrics -106

4.6 Stiffness data -108

4.6.1 Stiffness of conventional durable press treated fabrics -109

4.6.2 Stiffness data of polycation treated anionic cellulosic fabrics -109

4.6.3 Stiffness data of polyanion treated cationic cellulosic fabrics -111

5 CONCLUSIONS -116

6 RECOMMENDATIONS FOR FUTURE WORK -118

7 LIST OF REFERENCES -121

8 APPENDIX -126

8.1 Wrinkle recovery angles -126

8.2 Breaking strength -133

8.3 CIE whiteness index -137

8.4 Stiffness -141

8.5 Nitrogen analysis -145

LIST OF TABLES

Table 3.2 Results for carboxymethylation of cellulosic fabrics - 32

Table 3.3 Scheme of intrinsic viscosity measurement for the low viscosity chitosan - 36

Table 3.4 Properties of the Low Viscosity chitosan. - 37

Table 3.5 The intrinsic viscosity and Mv of depolymerized chitosans - 39

Table 4.1 Paired t-test results for dry wrinkle recovery angles of cationic chitosan treated fabrics - 69

Table 4.2 Paired t-test results for wet wrinkle recovery angles of cationic chitosan treated fabrics - 70

Table 4.3 Paired t-test results for dry/wet wrinkle recovery angles of Ca++ and Mg++ treated fabrics - 79

Table 4.4 Paired t-test results for dry/wet wrinkle recovery angles of PCA and BTCA treated fabrics - 87

Table A.1 Dry and wet wrinkle recovery angles for molecular weight of 3.2 x 104g/mole cationic chitosan treated fabrics -126

Table A.2 Dry and wet wrinkle recovery angles for molecular weight of 1.4 x 105g/mole cationic chitosan treated fabrics -127

Table A.3 Dry and wet wrinkle recovery angles for molecular weight of 6.11 x 105g/mole cationic chitosan treated fabrics -127

Table A.4 Dry and wet wrinkle recovery angles for molecular weight of 1.4 x 105g/mole cationic chitosan treated fabrics by exhaustion method -128

Table A.5 Dry and wet wrinkle recovery angles for cationic glycerin treated fabrics 128

Table A.6 Dry and wet wrinkle recovery angles for cationic glycerin treated fabrics by exhaustion method -129

Table A.7 Dry and wet wrinkle recovery angles for cationic cellobiose and cationic dextrose treated fabrics -129

Table A.8 Dry and wet wrinkle recovery angles for calcium chloride and magnesium chloride treated fabrics -130

Table A.9 Dry and wet wrinkle recovery angles for PCA treated fabrics -130

Table A.10 Dry and wet wrinkle recovery angles for BTCA treated fabrics -131

Table A.11 Dry and wet wrinkle recovery angles for EDTA treated fabrics -131

Table A.12 Dry and wet wrinkle recovery angles for NTA treated fabrics -132

Table A.13 Dry and wet wrinkle recovery angles for HEDTA treated fabrics -132

Table A.14 Dry and wet wrinkle recovery angles for oxalic, malic and citric acid treated fabrics -133

Table A.15 Breaking strength data for molecular weight of 3.2 x 104g/mole cationic chitosan treated fabrics -134

Table A.16 Breaking strength data for molecular weight of 1.4 x 105g/mole cationic chitosan treated fabrics -134

Table A.17 Breaking strength data for molecular weight of 6.11 x 105g/mole cationic chitosan treated fabrics -135 Table A.18 Breaking strength data for cationic glycerin treated fabrics -135 Table A.19 Breaking strength data for calcium chloride and magnesium chloride treated fabrics -136 Table A.20 Breaking strength data for PCA treated fabrics -136 Table A.21 Breaking strength data for BTCA treated fabrics -137 Table A.22 Whiteness index data for molecular weight of 3.2 x 104g/mole cationic

chitosan treated fabrics -138 Table A.23 Whiteness index data for molecular weight of 1.4 x 105g/mole cationic

chitosan treated fabrics -138 Table A.24 Whiteness index data for molecular weight of 6.11 x 105g/mole cationic chitosan treated fabrics -139 Table A.25 Whiteness index data for CG treated fabrics -139 Table A.26 Whiteness index data for calcium and magnesium chloride treated fabrics -140 Table A.27 Whiteness index data for PCA treated fabrics -140 Table A.28 Whiteness index data for BTCA treated fabrics -141 Table A.29 Stiffness data for molecular weight of 3.2 x 104g/mole cationic chitosan treated fabrics -142 Table A.30 Stiffness data for molecular weight of 1.4 x 105g/mole cationic chitosan treated fabrics -142 Table A.31 Stiffness data for molecular weight of 6.11 x 105g/mole cationic chitosan treated fabrics -143 Table A.32 Stiffness data for cationic glycerin treated fabrics -143 Table A.33 Stiffness data for calcium chloride and magnesium chloride treated fabrics 144 Table A.34 Stiffness data for PCA treated fabrics -144 Table A.35 Stiffness data for BTCA treated fabrics -145 Table A.36 Nitrogen analysis data for molecular weight of 3.2 x 104g/mole cationic

chitosan treated fabrics -146 Table A.37 Nitrogen analysis data for molecular weight of 1.4 x 105g/mole cationic

chitosan treated fabrics -146 Table A.38 Nitrogen analysis data for molecular weight of 6.11 x 104g/mole cationic chitosan treated fabrics -147 Table A.39 Nitrogen analysis data for cationic glycerin treated fabrics -147

LIST OF FIGURES

Figure 2.1 Molecular structure of a cellulose polymer chain -4

Figure 2.2 Crystalline and amorphous structure of cellulose -4

Figure 2.3 Molecular structure of DMDHEU -8

Figure 2.4 Molecular structure of BTCA - 12

Figure 2.5 Reaction of chitosan with CHTAC in alkaline conditions - 17

Figure 2.6 Reaction of cellulose with CHTAC in alkaline conditions - 19

Figure 2.7 Molecular structure of carboxymethyl cellulose - 20

Figure 3.1 Reactions of cellulose with CAA that impart an anionic character - 30

Figure 3.2 Reactions of cellulose with CHTAC that impart a cationic character - 34

Figure 3.3 Huggins plot of ήsp/c versus c for the cationic chitosan - 37

Figure 3.4 Reaction of chitosan with CHTAC - 41

Figure 3.5 Conductometric titration curve of cationic chitosan - 43

Figure 3.6 FTIR spectrum of deacetylated chitosan - 46

Figure 3.7 FTIR spectrum of cationic chitosan - 47

Figure 3.8 1H-NMR spectrum of deacetylated chitosan - 48

Figure 3.9 1H-NMR spectrum of O-substituted and N-substituted cationic chitosan - 50

Figure 3.10 Reaction of glycerin with CHTAC - 52

Figure 3.11 Crosslinked anionic cellulose with calcium - 56

Figure 3.12 Crosslinked cationic cellulose with BTCA - 58

Figure 4.1 Effect of carboxyl content and concentration on dry wrinkle recovery angles of cationic chitosan treated fabrics - 62

Figure 4.2 Effect of carboxyl content and concentration on wet wrinkle recovery angles of cationic chitosan treated fabrics - 62

Figure 4.3 Effect of carboxyl content and concentration on %Nitrogen content of cationic chitosan treated fabrics - 64

Figure 4.4 The relationship between %Nitrogen content of the fabrics and dry/wet wrinkle recovery angles - 65

Figure 4.5 Effect of molecular weight of chitosan and concentration on dry wrinkle recovery angles of cationic chitosan treated fabrics - 67

Figure 4.6 Effect of molecular weight of chitosan and concentration on wet wrinkle recovery angles of cationic chitosan treated fabrics - 67

Figure 4.7 Effect of carboxyl content and concentration on dry wrinkle recovery angles of cationic glycerin treated fabrics - 72

Figure 4.8 Effect of carboxyl content and concentration on wet wrinkle recovery angles of cationic glycerin treated fabrics - 72

Figure 4.9 Effect of carboxyl content and concentration on %Nitrogen content of cationic glycerin treated fabrics - 74

Figure 4.10 The relationship between %Nitrogen content of the fabrics and dry/wet wrinkle recovery angles - 75

Figure 4.11 Effect of carboxyl content on dry wrinkle recovery angles of calcium and magnesium treated fabrics - 77 Figure 4.12 Effect of carboxyl content on wet wrinkle recovery angles of calcium and magnesium treated fabrics - 78 Figure 4.13 Effect of %Nitrogen fixed and concentration on dry wrinkle recovery angles

of PCA treated fabrics - 83 Figure 4.14 Effect of %Nitrogen fixed and concentration on wet wrinkle recovery angles

of PCA treated fabrics - 84 Figure 4.15 Effect of %Nitrogen fixed and concentration on dry wrinkle recovery angles

of BTCA treated fabrics - 85 Figure 4.16 Effect of% Nitrogen fixed and concentration on wet wrinkle recovery angles

of BTCA treated fabrics - 86 Figure 4.17 Effect of %Nitrogen fixed and concentration on dry wrinkle recovery angles

of EDTA treated fabrics - 88 Figure 4.18 Effect of %Nitrogen fixed and concentration on wet wrinkle recovery angles

of EDTA treated fabrics - 89 Figure 4.19 Effect of treatment on dry wrinkle recovery angles - 91 Figure 4.20 Effect of treatment on wet wrinkle recovery angles - 92 Figure 4.21 Effect of carboxyl content and concentration on breaking strength of the cationic chitosan (molecular weight of 1.4 x 105g/mole) treated fabrics - 94 Figure 4.22 Effect of carboxyl content and concentration on breaking strength of the cationic glycerin treated fabrics - 95 Figure 4.23 Effect of carboxyl content and concentration on breaking strength of the calcium and magnesium treated fabrics - 95 Figure 4.24 Effect of %Nitrogen content and concentration on breaking strength of the PCA treated fabrics - 97 Figure 4.25 Effect of %Nitrogen content and concentration on breaking strength of the BTCA treated fabrics - 97 Figure 4.26 Effect of treatment on breaking strength - 99 Figure 4.27 Correlation between wet wrinkle recovery angles of cationic chitosan

(molecular weight of 1.4 x 105g/mole) treatment and tensile strength -100 Figure 4.28 Correlation between wet wrinkle recovery angles of PCA treatment and tensile strength -101 Figure 4.29 Effect of carboxyl content and concentration on whiteness index of the

cationic chitosan (molecular weight of 1.4 x 105g/mole) treated fabrics -103 Figure 4.30 Effect of carboxyl content and concentration on whiteness index of the

cationic glycerin treated fabrics -103 Figure 4.31 Effect of carboxyl content and concentration on whiteness index of the

calcium chloride and magnesium chloride treated fabrics -104 Figure 4.32 Effect of %Nitrogen fixed and concentration on whiteness index of the PCA treated fabrics -105

Figure 4.33 Effect of %Nitrogen fixed and concentration on whiteness index of the BTCA treated fabrics -106 Figure 4.34 Effect of treatment on whiteness index -108 Figure 4.35 Effect of carboxyl content and concentration on stiffness of the cationic chitosan (molecular weight of 1.4 x 105g/mole) treated fabrics -110 Figure 4.36 Effect of carboxyl content and concentration on stiffness of the cationic glycerin treated fabrics -110 Figure 4.37 Effect of carboxyl content and concentration on stiffness of the calcium chloride and magnesium chloride treated fabrics -111 Figure 4.38 Effect of %Nitrogen fixed and concentration on stiffness of the PCA treated fabrics -112 Figure 4.39 Effect of %Nitrogen fixed and concentration on stiffness of the BTCA treated fabrics -113 Figure 4.40 Effect of treatment on stiffness -115

1 INTRODUCTION

The textile market has shown an interest in the demand for easy care, resistant for cellulosic fabrics over the years Untreated cellulose has poor recovery, because cellulose is stabilized by hydrogen bonds within and between cellulose chains Moisture between the polymer chains can invade the cellulose structure and can temporarily release the stabilizing hydrogen bonds and hydrogen bonds in cellulose experience frequent breaking and reforming when extended and newly formed hydrogen bonds tend to hold cellulose chain segments in new positions when external stress is released Preventing wrinkling of cellulosic fabric can be accomplished by the crosslinking of polymer chains, thus making intermolecular bonds between chains that water cannot release In a typical durable-press (DP) treatment, some hydrogen bonds are replaced with covalent bonds between the finishing agent and the fiber elements Because covalent bonds are much stronger than hydrogen bonds, they can resist higher external stress Hence, treated cellulose has a higher initial modulus and better elastic recovery After the external force is released, the energy stored in the strained covalent bonds provides the driving force to return chain segments back to their original positions

wrinkle-Formaldehyde-based cellulose crosslinking was a very important textile chemical breakthrough of the 1930's, and is still the basis for a vast array of modern finished cotton products today N-methylol crosslinkers have the biggest use in durable press finishing They give fabrics crease resistance, shrinkage control, anti-curl, and durable press, but

they also impart strength loss and release formaldehyde, a known human carcinogen [1] Today’s textile industry has for a long time been searching for durable press finishes that can give same results as formaldehyde based finishes, but cause less strength loss and no formaldehyde release For example, polycarboxylic acids and citric acid have been used with varying degrees of success [2, 3]

We have developed multiple methods of forming ionic crosslinks to give wrinkle effects to cellulosic fabric [4] These includes, (1) treatment of cellulose with an anionic material and reacting with a polycation, (2) treatment of cellulose with a cationic material and then application of a polyanion, (3) treatment of cellulose with a precondensate of an ionic reactive material and a polyelectrolyte of the opposite charge The performance of crosslinkers can be measured by dry and wet wrinkle recovery angle (WRA) Dry WRA is important for outerwear clothing to help resist dry wrinkling during wearing, but wet WRA is more important for bedding which is almost never ironed and must resist wrinkling during laundering We observed simultaneous enhancements of both wet and dry WRA as well as significant strength gain and excellent washing durability Polyelectrolytes are strongly bond and thus do not desorb during laundering The chemicals are common industrial reactants and do not have unusual safety or environmental issues Processes use existing equipment and no high temperature curing is necessary In addition, ionic crosslinks may have other important advantages, such as antimicrobial activity and enhanced dyeability

non-2 LITERATURE REVIEW

2.1 Cellulose chemistry

We can only understand chemical as well as physical properties of cellulose by the knowledge of both chemical nature of the cellulose molecules and their structural and morphological arrangement in the solid, mostly fibrous, state For example reactivity of the functional sites in the cellulose molecules and structural characteristics of polymers such as; inter- and intramolecular interactions, and size of crystallites and fibrils These structural characteristics of the cellulosic polymers influence the physico-mechanical properties utilized in the textile industry The largest part of the cellulosic polymers used for textile substrates comes from cotton

Cotton is a soft fiber that grows around the seeds of the cotton plant The fiber is most often spun into thread and used to make a soft, breathable textile Cotton is a valuable crop because only about 10% of the raw weight is lost in processing [5] Once traces of wax, protein, etc are removed, the remainder is a natural polymer of pure cellulose This cellulose is arranged in a way that gives cotton unique properties of strength, durability, and absorbency After scouring and bleaching, cotton is 99% pure cellulose [6] Cellulose is a macromolecule made up of anhydroglucose units united by 1,

4, oxygen bridges as shown in Figure 2.1 The anhydroglucose units are linked together as beta-cellobiose; therefore, anhydro-beta-cellobiose is the repeating unit of the polymer chain The number of these repeat units that are linked together to form the cellulose polymer is referred to as the degree of polymerization and is between 1000 and 15000 [7]

O O OH

H

O H

OH

O O OH

H H H

O H

OH

O

OH OH H H

H

H

H O

H

OH n

CelluloseFigure 2.1 Molecular structure of a cellulose polymer chain

The cellulose chains within the cotton fibers tend to be held in place by hydrogen bonding These hydrogen bonds occur between the hydroxyl groups of adjacent molecules and are more prevalent between the parallel, closely packed molecules in the crystalline areas of the fiber as shown in Figure 2.2 [8]

Figure 2.2 Crystalline and amorphous structure of cellulose

The chemical characters of the cellulose molecules are determined by the sensitivity of the three-hydroxyl groups, one primary and two secondary, in each repeating cellobiose unit of cellulose, which are chemically reactive groups These groups can

as esterification and etherification or in the application of dyes and finishes for crosslinking The hydroxyl groups also serve as principal sorption sites for water molecules Directly sorbed water is firmly chemisorbed on the cellulosic hydroxyl groups

by hydrogen bonding [8] Of particular interest in the case of cellulosic fibers is the response of their strength to variations in moisture content Generally, in the case of regenerated and derivative cellulosic fibers, strength decreases with increasing moisture content In contrast, the strength of cotton generally increases with increased moisture The contrast seen between the fibers in their response to moisture is explained in terms of intermolecular hydrogen bonding between cellulose chains and their degree of crystallinity [8]

2.2 Cellulosic fabric’s nature of wrinkling

The textile market has shown an interest in the demand for easy care, resistant for cellulosic fabrics over the years Improvements in crease angle recovery property are obtained by chemical treatments, which improve the ability of fibers to maintain configurations in which they are treated [9] Untreated cellulose has poor recovery, because hydrogen bonds in cellulose experience frequent breaking and reforming when extended, and newly formed hydrogen bonds tend to hold cellulose chain segments in new positions when external stress is released In a typical durable-press treatment, some hydrogen bonds are replaced with covalent bonds between the finishing agent and the fiber elements Because covalent bonds are much stronger than hydrogen bonds, they can resist higher external stress Hence, treated cellulose has a higher initial

wrinkle-modulus and better elastic recovery After the external force is released, the energy stored

in the strained covalent bonds provides the driving force to return chain segments back to their original positions However, chemical treatment on cellulose also causes the loss of mechanical properties [10] The classical explanation to this problem is that traditional crosslinks are too rigid to allow cellulose chain segments to move

2.3 Durable Press finishing of cotton

Durable press is shaping a garment and then treating it in such a way that after wearing and washing it will return to its pre-set shape In order to produce non-wrinkle cellulosic fabrics the durable press finishing has been developed

The original process for the production of crease resistant fabrics was developed in 1928 [11] DP finishes have been marketed ever since Durable press is accomplished by resin treatments The main purpose of resin treatments is to overcome a serious drawback of cellulosic fabrics, for example their ease of wrinkling, which requires ironing after washing [12] Ideally, a DP finished fabric will wash and dry to a completely smooth state The usual method of production of crease resistant fabric consists of padding fabric trough a crosslinking agent along with a catalyst and other additives, drying at 100-110oC followed by curing at 155-175oC for 2-3 minutes [13] The resulting fabric has the ability

of recovering from creases both when fabric is wet and dry The selection of crossslinking agents for DP finishing is important There are a large number of cross linker available Some of the most common reagents are urea-formaldehyde derivatives, melamine-

formaldehyde derivatives and methylol derivatives All of these reagents used for DP of cellulosic fabric with varying degrees of success

2.3.1 Urea-Formaldehyde derivatives

The first widely used crosslinking agent for DP finishing was urea-formaldehyde adducts These products are mostly prepared at the finishing plant; also precondensate are available in the market The treatment of fabrics with urea-formaldehyde resin involves padding the fabric through precondensate and an acid catalyst, drying, curing and washing The advantages of urea-formaldehyde resins are the low cost and high efficiency The disadvantages are poor stability of the agent, poor durability and imparting chlorine retention to the fabric The chlorine retention is due to the presence of the –NH groups which react with chlorine from the bleach or laundry bath [14, 15, 16] The reaction of –NH groups and chlorine produces hydrochloric acid and it is a strong acid that causes tendering and yellowing of cellulose

2.3.3 Methylol derivatives of cyclic ureas

These compounds are also referred to as fiber reactants, because they only react with the cellulose instead of themselves As a result insoluble resin on the surface of the fabric is absent hence the finished fabric have a softer hand The members of this group are:

(a) Dimethylol ethylene urea (DMEU) has high reaction efficiency and low price [19] It can produce high wrinkle recovery angles at low add-ons The finish with DMEU is sensitive to acids and can be destroyed by acid treatment during laundering (b) Dimethylol propylene urea (DMPU) is suitable for white goods, since it does not produce yellowing on heating [20] Another advantage of it is that not giving any odor But the finish is not susceptible to chlorine retention damage It is more expensive than others in the group (c) Dimethylol dihydroxy ethylene urea (DMDHEU) as shown in Figure 2.3 It

is the most commonly used DP finish agent and gives excellent crease angle recovery [21, 22]

N N

O

OH O

H

OH O

H DMDHEUFigure 2.3 Molecular structure of DMDHEU

It shows some chlorine retention therefore it is not recommended for white goods It does not effect the lightness of the dyes hence it is dominating the colored garments durable press finishing

2.3.4 Effects of formaldehyde based DP finishes on cellulose

Formaldehyde-based N-methylol reagents are the most common DP reagents But these reagents produce losses in tensile strength of cotton due to depolymerization of cellulose chains Cellulose depolymerization occurs with a polycarboxylic acid or a Lewis acid, which are catalysts for formaldehyde based resins As a result they cause a high degree of depolymerization A direct correlation between tensile strength loss of the treated cotton and the molecular weight of cellulose was found [23] Severe tensile strength loss is a major disadvantage of DP finished cotton fabrics, and it continues to be the major obstacle for DP applications Most of the studies of mechanical strength of durable press finished cotton fabrics in the past have focused on changes in the gross properties of cotton fabrics, such as tensile strength and abrasion resistance Another disadvantage of N-methylol reagents is later formaldehyde release In recent years there have been extensive efforts to find non-formaldehyde alternatives due to increasing concern with health risks associated with formaldehyde On the other hand, the final textile products not only have to be eco-friendly, but also have to be produced by clean technologies Crosslinking of cellulose with N-methylol crosslinking agents to impart wrinkle-resistance, shrink proofing, and smooth drying properties by virtue of chemical reaction with cellulosic hydroxyl groups to form covalent crosslinks in the interior of

cellulosic fibers have successfully been done However, at the present time, presence of formaldehyde in the finished product, working atmosphere, as well as in wastewater streams is considered as highly objectionable due to the mutagenic activity of various aldehydes, including formaldehyde [24]

2.4 Recent developments in non-formaldehyde DP applications

Extensive research has attempted to develop nonformaldehyde crosslinking agents

to replace N-methylol compounds that release formaldehyde during production and storage, which is proven to be carcinogenic [25] Durable press finishing, used to overcome wrinkling problems in cotton fabric for some years, involves chemical crosslinking agents that covalently crosslink with hydroxyl groups of adjacent cellulose polymer chains within cotton fibers This crosslinking not only results in the fabric's wrinkle resistance, but also in discoloration and impairment of fabric strength and of other mechanical properties The early chemical agents used for crosslinking with cellulose were mostly formaldehyde and formaldehyde derivatives, which can form ether bonds with cellulose DMDHEU is the most widely used crosslinking agent because it provides good durable press properties at a lower cost and an acceptable level of detrimental effects

on fabric strength and whiteness compared to other N-methylol agents However, fabric treated with DMDHEU tends to release formaldehyde vapors during processing, storage, and consumer use Because formaldehyde is toxic to human beings, several attempts have been made to replace it with formaldehyde-free crosslinking agents

Several polycarboxylic acids have served as durable press agents Carboxylic groups in polycarboxylic acids are able to form ester bonds with hydroxyl groups in cellulose The main advantages of polycarboxylic acids are that they are formaldehyde-free, do not have a bad odor, and produce a very soft fabric hand BTCA (1.2,3,4-butcnetetracarboxylic acid) is the most effective polycarboxylic acid for use as a durable press agent as shown in Figure 2.4 In the presence of sodium hypophosphite monohydrate

as catalyst, BTCA provides almost the same level of durable press performance and finish durability with laundering as the conventional DMDHEU reactant, but its high cost may

be an obstacle to a mill's decision to use it as a replacement for the conventional durable press reactant As with DMDHEU, fabrics treated with polycarboxylic acids generally lose their strength, [26] probably due to excess crosslinking with cellulose chains This may be tackled by using long-chain polycarboxylic acids, which can be obtained through copolymerization of two unsaturated polycarboxylic acids

BTCA satisfies many desirable requirements such as durability to laundering and durable press performance Crosslinking of cellulose molecules with BTCA increases fabric wrinkle resistance at the expense of mechanical strength [27]

COOH

COOH

COOH BTCAFigure 2.4 Molecular structure of BTCA

Severe tensile strength loss diminishes the durability of finished cotton garments The factors involved in strength loss of cotton fabric treated with BTCA include acid catalyzed degradation of cellulose molecules and their crosslinking The common catalysts for polycarboxylic acids are phosphorous-containing compounds, although their use has disadvantages such as high cost, strength loss and raises some environmental concerns In order to decrease strength retention other catalysts have been proposed; among these is boric acid, [28] which was added to increase strength of the treated fabrics With this treatment, durable press properties were similar to those obtained with sodium hypophosphite; moreover the mechanical resistance improved

A previous study [29] indicated that cellulosic fabric treated with a copolymer made with maleic and acrylic acids possesses the same level of wrinkle resistance as with BTCA, while tensile strength retention improves slightly Another disadvantage of polycarboxylic acid finishing is yellowing of the treated fabric It is proposed that the use

of a copolymer between acrylic and maleic acids as a durable press finishing agent can improve crease angle recovery for cotton fabric [29] However, the copolymer treatment

Chitosan citrate has been evaluated as non-formaldehyde durable press finish to produce wrinkle-resistance and antimicrobial properties for cotton fabrics [30] The carboxylic groups in the chitosan citrate structure were used as active sites for its fixation onto cotton fabrics The fixation of the chitosan citrate on the cotton fabric was done by the padding of chitosan citrate solution onto cotton fabrics followed by a dry - cure process The factors affecting the fixation processes were systematically studied The antimicrobial activity and the performance properties of the treated fabrics, including tensile strength, wrinkle recovery, wash fastness and whiteness index, were evaluated The finished fabric shows adequate wrinkle resistance, sufficient whiteness, high tensile strength and more reduction rate of bacteria as compared to untreated cotton fabric

A non-polluting system of applying an easy-care finish to cotton fabrics has been proposed [31] The new formulation is based on an aqueous system of BTCA-chitosan-sodium hypophosphite and was applied by the traditional pad-dry-cure method to an Egyptian poplin The variables studied were the concentrations of BTCA and chitosan, the time and temperature of polymerisation The study also included a comparison with other traditional or recommended systems The treated fabric was tested for crease recovery angle, resistance to traction, elongation to breakage, rigidity, wetability, whiteness, nitrogen content and dyeability It was concluded that the new formulation gave comparable if not better results than the traditional treatments

2.5 Ionic crosslinking

Ionic crosslinking has been used in the polymer industry for various applications

It is an alternative to covalent crosslinks It is well known that the thermal resistance, durability, abrasion resistance, chemical resistance, etc., of a polymer are improved by crosslinking For example, acrylic copolymer sizes have been used for improving the weaving properties of polyester filament warps [32] Acrylic sizes produce good abrasion resistance, high strength, good adhesion and easy removability But when exposed to high humidity many of the acrylics absorb water and cause blocking on the beam In order to improve the stability of acrylic sizes divalent cations are used for reduction of the moisture regain Calcium and magnesium ions were used [32] for reducing the water sensitivity of sizes These cations form ionic crosslinks between the polymer chains and stabilize the structure against moisture Also these crosslinks improved the strength properties of the polymer film

The copolymer of propylene and maleic anhydride is also crosslinked by ionic bonding It is considered that the ionic crosslinking by maleic anhydride groups is possible by using not only of magnesium hydroxide but also of other metal compounds Magnesium 12-hydroxy stearate, zinc oxide, and zinc sulfide were chosen for ionic crosslinking Accordingly, by changing the kind and content of the metal compounds, the viscosity can be freely controlled Considering also other rheological characteristics, these ionically crosslinked compounds are assumed to show ideal flow processabilities except for the extrudate appearance [33,34]

A series of siloxane-based liquid-crystalline elastomers were synthesized by using ionic crosslinking agents containing sulfonic acid groups The ions aggregated in domains forces the siloxane chains to fold and form an irregular lamellar structure Ionic aggregates and liquid crystalline segments may be dispersed among each other to form multiple blocks with increasing ionic crosslinking content [35]

In a previous work [36] a vulcanized carboxylated nitrile rubber compound was prepared using a mixed crosslinking system employing a mixture of zinc peroxide and sulphur accelerators as vulcanizing agents to produce ionic and covalent structures Because of the existence of carboxyl groups in the polymeric chain, crosslinked polymers

of ionic nature can be obtained when a bivalent metal oxide, such as zinc oxide, is used as

a crosslinking agent Ionic vulcanized compounds with properties equal to or better than those produced using sulphur accelerators can also be obtained in the same way using metal peroxides

Polyurethanes are a versatile class of materials; their end applications dictate the structure and morphology during synthesis From the prepolymer stage through chain extension and in the required cases of final crosslinking, there are many ways to influence the final characteristics of the polyurethanes Crosslinked networks are obtained through ionic crosslinking and the different approaches produce cationic, anionic and Zwitter ionic polyurethanes These networks find a variety of applications as coatings, adhesives,

shoe soles, and vibration damping materials [37]

2.6 Preparation of quaternized polymers

Conversion to quaternary ammonium salts gives products whose degree of ionization is pH-independent Such polymers can be prepared by reaction of polymers with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHTAC)

2.6.1 Chitosan and its reaction with CHTAC

Chitosan is the deacetylated form of chitin, poly glucopyranose], is the second most abundant natural polymer next to cellulose Chitosan

[β-(1→4)-2-deoxy-D-is a linear copolymer composed mainly β-(1→4)-2-amino-2-deoxy-D-glucopyranose and partially β-(1→4)-2-acetamido-2-deoxy-D-glucopyranose residues [38] Chitosan can be dissolved in diluted acids by being protonated to soluble polyammonium salt Hydroxyl and amino groups of chitosan can react with epoxides by a ring opening reaction in either present of a base or neutral conditions These reactions were performed previously [4, 39] Kim at al performed the reaction between chitosan and CHTAC at neutral conditions They proved by FTIR and H1-NMR that the product they produced had a degree of substitution larger than 60% and substitutions formed at NH2 sites Because the hydroxyl groups of chitosan are not sufficiently nucleophilic under neutral conditions, N-substituted cationic chitosan can be obtained under neutral conditions

On the other hand; in alkali conditions the hydroxyl groups of chitosan are nucleophilic therefore reaction of chitosan and CHTAC produce O-substituted cationic chitosan Hasem at al performed the reaction under highly alkaline (pH=11-12) conditions

neutral conditions Both of the products have cationic properties and can be used as a cationic polyelectrolyte to form ionic crosslinks and anti-microbial finish for cellulosic fabrics [30, 40] Figure 2.5 shows the reaction of chitosan with CHTAC in alkaline conditions

O O

NH2

H H H

H

O H

O H

O O

NH2

H H H

O H

O H

O

O H

NH2H H

H

H

H O

H

O H n

H

O H

O

O O

N H2

H H H

O H

O

O

O H

N H2H H

H

H

H O

Figure 2.5 Reaction of chitosan with CHTAC in alkaline conditions

2.6.2 Reaction of Cellulose with CHTAC

The cationization of cellulose with using CHTAC has been previously studied [41,42,43] The process basicly takes place in two stages From practical point this occurs

in a single process Sodium hydroxide (NaOH) is the base catalyst The cationic character

of cellulose is independent from pH In the first stage the epoxide form of CHTAC formed

in the presence of NaOH In the second stage this epoxide reacts with a hydroxyl group in the cellulose

The reaction efficiency for cationization of cellulose is low due to hydrolysis reaction of CHTAC Hydrolyzed CHTAC is no longer reactive therefore the efficiency is less than perfect There are many ways to perform the reaction for example, pad-batch, pad-steam, exhaust, and pad-dry-cure methods [42] All of these procedures give different values of efficiency The pad-batch process is consist of padding the fabric through a mixture of NaOH and CHTAC solution at room temperature and followed by holding at room temperature for 24 hours The exhaustion procedure was studied at 75oC for 90 minutes The mole ratio of NaOH and CHTAC varied Also different solvent systems were experimented such as; water, acetone, ethanol, isopropanol, and methanol The highest cationization level was obtained with acetone The pad-steam application was consist of padding the fabric through the mixture of CHTAC and NaOH and steaming at

100oC for 30 minutes The pad-dry-cure method investigated at using different drying and curing times and temperatures The mole ratio of NaOH and CHTAC was also varied The best conditions for this application was after padding the fabrics drying at 35oC for 5

10% substitution, pad-batch and pad steam methods are more efficient, and they produced about 25% substitution The pad-dry-cure methods give fixations around 85% The efficiencies for all the methods decreased when increasing in concentration of CHTAC The optimum mole ratio was determined as 1.8 or greater [42]

O O

O H

H H H

O

O H

O O

O H

H H H

H

H O

O H n

O

O

O O

O H

H H H

O O

O

O H

O H H H H

H

H O

N a O H

3 -chloro- 2 -hydroxypropyl trimethyl ammonium chloride Epoxypropyl trimethyl ammonium chloride

(EPTAC) (CHTAC)

Figure 2.6 Reaction of cellulose with CHTAC in alkaline conditions

2.7 Carboxymethylation of cellulose

Carboxymethylcellulose (CMC) is a derivative of cellulose that can be formed by its reaction with alkali and chloroacetic acid The CMC structure is based on the β-(1→4)-D-glucopyranose polymer of cellulose as shown in Figure 2.7 Different preparations may have different degrees of substitution [44] CMC molecules are somewhat shorter, on average, than native cellulose with uneven derivatization giving areas of high and low substitution This substitution is mostly 6-O-linked, followed in order of importance by 2-

O, 2,6-di-O- then 3-O-, 3,6-di-O-, 2,3-di-O- lastly 2,3,6-tri-O-.linked It appears that the substitution process is a slightly cooperative (within residues) rather than random process giving slightly higher than expected unsubstituted and trisubstituted areas

O O OH

H

O H

O

O O OH

H H H

O H

O

O

OH OH H H

H

H

H O

H

O

O O

O O

O O

O O n

Figure 2.7 Molecular structure of carboxymethyl cellulose

CMC molecules are most extended (rod-like) at low concentrations but at higher concentrations the molecules overlap and coil up The average chain length and degree of substitution are of great importance At low pH, CMC may form cross-links through

Cellulosic fabrics can react with several materials, which impart an anionic

character to it, for example, chloroacetic acid (CAA) and chlorosulfonic acid [4] and

sodium, 4-(4,6-dichloro-1,3,5-triazinylamino)-benzenesulfonate [45]

In a perivious study [4] carboxymethylation process was experimented first padding the cellulosic fabric through sodium hydroxide solution, which opens the struchture of cellulose, drying at a mild temperature and then padding through chloroacetic acid solution and holding the fabric in a plastic bag at 70oC for 1 hour

2.8 Proposed Research

Today’s textile industry has for a long time been searching for durable press finishes that can give the same advantages as formaldehyde based finishes, but cause less strength loss and no formaldehyde release

We have developed multiple methods of forming ionic crosslinks to give wrinkle effects to cellulosic fabric These include, (1) treatment of cellulose with an anionic material and reacting with a polycation, (2) treatment of cellulose with a cationic material and then application of a polyanion, (3) treatment of cellulose with a precondensate of an ionic reactive material and a polyelectrolyte of the opposite charge Methods 1 and 2, which we studied in this research, involve a pretreatment step for the cellulosic fabric, but the third method is very similar to commercial DP applications The performance of crosslinkers can be measured by dry and wet wrinkle recovery angle (WRA) Dry WRA is important for outerwear clothing to help resist dry wrinkling during use, but wet WRA is more important for bedding which is almost never ironed and must

non-resist wrinkling during laundering We observed simultaneous enhancements of both wet and dry WRA In addition, ionic crosslinks may have other important advantages, such as antimicrobial activity and enhanced dyeability

Cellulose can react with several materials, which impart an anionic character to it, such as chloroacetic acid (CAA) On the other hand, cellulose can also react with cationic materials that impart cationic character to it, for instance 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHTAC) Our work is based on Methods 1 and 2, the first consisting of the reaction of cellulose with CAA, which producing partially carboxymethylated cellulose, followed by a treatment with a polycation, such as, cationized chitosan, cationized glycerine, cationized ethylene glycol, cationized dextrose

or cationized D-celobiose We also observed WRA improvements with divalent cations such as Ca++ and Mg++ Method 2 consists of the reaction of cellulose with CHTAC to produce cationic cellulose, followed by the application of polyanion, such as, polycarboxylic acids (PCA), 1,2,3,4-butanetetracarboxylic acid (BTCA), ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid, trisodium salt, monohydrate (NTA), ethylenediamine di(o-hydroxyphenylacetic acid (HEDTA), oxalic acid, citric acid,

or malic acid

Both methods gave promising results with excellent washing durability Polyelectrolytes are strongly bond and thus do not desorb during washing These chemicals are common industrial reactants and there is also no unusual safety or environmental issues No high temperature curing is necessary The processes utilize

3 EXPERIMENTAL PROCEDURES

The materials, equipments and experimental procedures used in this study are

described in this section The fabric is characterized, and the chemicals are identified their

manufacturers and chemical names The equipment is described, and manufacturers are

named Also the synthesis of experimental products and their application are presented

The test procedures are listed, and detailed descriptions can be found in the appropriate

references

3.1 Test Materials

The materials that used in this project are given in the table below including

names, brief descriptions and manufacturers

Table 3.1 Test materials and chemicals

Calcium chloride dehydrate, 77-80% CaCl2 Fisher Chemicals Salts

Magnesium chloride hexahydrate, 99%

MgCl2

Fisher Chemicals Ethylene glycol dimethyl ether 99+%, b.p 84

oC -86oC

Fisher Chemicals Alcohols

Glycerol, 99+%, b.p 290°C Fisher Chemicals

Table 3.1 Test materials and chemicals continued CROSSLINK RB 105, Aqueous solution of polycarboxylic acids BioLab Water Additives CROSSLINK RB 120, 1,2,3,4-

Butanetetracarboxylic acid

BioLab Water Additives

HEDTA, Ethylenediamine hydroxyphenylacetic) acid, trisodium salt

di(o-Lynx Chemical Group, LLC

NTA, Nitrilotriacetic acid, trisodium salt monohydrate, 92-94% aqueous solution Hampshire Chemical Corporation Polyanions

EDTA, Ethylenediaminetetraacetic acid, tetrasodium salt, 39% aqueous solution

BASF Corporation

Chitosan, medium viscosity with nominal degree of deacetylation of 91.5% Vanson HaloSource, Inc Dextrose, D-(+)-Glucose, anhydrous Acros organics

Polysaccharides Cellobiose, D (+)-Cellobiose, 98% ,m.p

239°C

Acros Organics

Monochloro acetic acid, 99 + % Aldrich Chemical

Company, Inc

Oxalic acid anhydrous 98%, m.p 189°C Acros Organics

DL-Malic acid 99%, m.p 130°C to 132°C Acros Organics Acids

Citric acid anhydrous 99%, m.p 153°C to

3.2 Equipments

Stirring was performed using a Fisher Hot Plate A Fisher Scientific Co model 600-pH meter was equipped with a standard combination pH electrode Intrinsic viscosity and viscosity average molecular weight determinations and cationization reactions were performed in a water bath with an electrical temperature controller and a heavy-duty stirrer Application of finishes and ionic materials were performed using a 14-inch Laboratory padding machine manufactured by Werner Mathis AG Fabrics were dried and cured, to their original dimensions on 7 X 12 inch metal pin frames, in a forced air oven manufactured by Werner Mathis AG

3.3 Application procedures

The ionic crosslinkers were applied to untreated and ionic cellulosic fabrics by using three kinds of procedure The procedures are given below

3.3.1 Pad dry cure

Approximately 7 X 12 inch fabric samples were used The fabrics dipped into the various concentrations of aqueous polyelectrolyte solutions, followed by squeezing to a wet pick up of approximately 100% Then the wet fabric samples were pinned to the original 7 X 12 inch dimensions, dried at 85oC for 5 minutes and cured at 140oC for 1.5 minutes Finally the treated samples were washed using 2g/L nonionic wetting agent at

100oC for 10 minutes, rinsed with hot and cold water, centrifuged and dried at room temperature for 24 hours

3.3.2 Pad batch

The same size samples as in pad dry cure application were used The fabrics were padded through the ionic crosslinker solutions and squeezed to a wet pick up of approximately 100% Then the wet fabrics put into plastic bags, sealed and hold for 18 hours at room temperature Followed by washing and drying the treated samples as described above

3.3.3 Exhaustion

The samples were put into 500mL glass beaker Ionic crosslinker solution was charged into the beaker The bath ratio of fabric weight to weight of the bath was 1:15 Then the beakers were located into a water bath and temperature raised to 95oC with a rate

of approximately 2oC/minutes and hold for 1 hour The solution was stirred using an electrical stirrer Finally the samples were washed and dried as described previously

3.4 Analysis and physical property tests

Including nitrogen, Fourier Transform Infrared Spectroscopy (FTIR), and Nuclear Magnetic Resonance (NMR) were performed Physical properties of untreated and treated cellulosic fabrics including wrinkle recovery angles; tensile strength, stiffness and whiteness index were also tested The precise procedures are given below

3.4.3 1 H- NMR analysis

Nuclear Magnetic Resonance spectroscopy is a powerful technique for determining the structure of simple inorganic to complex biochemical compounds [46] The usefulness of this technique in chemistry can be attributed to the very detailed information obtained by NMR For example in IR spectroscopy the spectroscopic features are correlate with groups of atoms but in NMR spectroscopy the features correlates with the individual atoms Therefore much more detailed information can be obtained The 1H-NMR analysis was performed using GE NMR 300Ω (300 MHz) spectrometer at room temperature and sodium 3-(trimethylsilyl) propane sulfonate was used as an internal reference