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ABSTRACT

BILGEN, MUSTAFA. Wrinkle Recovery for Cellulosic Fabric by Means of Ionic Crosslinking. (Under the direction of Peter Hauser and Brent Smith.)

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WRINKLE RECOVERY FOR CELLULOSIC FABRIC BY MEANS OF IONIC CROSSLINKING

by

MUSTAFA BILGEN

A thesis submitted to the Graduate Faculty of North Carolina State University

in partial fulfillment of the requirements for the Degree of

Master of Science

TEXTILE CHEMISTRY

Raleigh 2005

APPROVED BY:

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

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DEDICATION

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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.

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ACKNOWLEDGEMENTS

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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

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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

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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

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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

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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

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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

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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

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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

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1. INTRODUCTION

The textile market has shown an interest in the demand for easy care, wrinkle-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.

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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]

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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.

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O O OH H H H H H O H O H OH O O OH H H H H H O H OH O O OH H H H H H O H OH O OH OH H H H H H O H OH n Cellulose

Figure 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

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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

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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.

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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.

2.3.2 Melamine-Formaldyhe derivatives

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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

DMDHEU

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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

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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

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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.

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COOH

COOH COOH

COOH

BTCA

Figure 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.

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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.

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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.

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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,

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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 [β-(1→ 4)-2-deoxy-D-glucopyranose], is the second most abundant natural polymer next to cellulose. Chitosan 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.

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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 H O H O H O H O O NH2 H H H H H O H O H O O NH2 H H H H H O H O H O O H NH2 H H H H H O H O H n O O N H2 H H H H H O H O H O O O

N H2

H H H H H O H O O O

N H2 H H H H H O H O O O H N H2

H H H H H O H

O N+

C H3 C H3 C H3 O H

N+ C H3

C H3 C H3 O H

N+ C H3

C H3 C H3 O H

N+ C H3

C H3 C H3 O H n Chitosan N+ CH3 CH3 CH3 Cl O H N+ CH3 CH3 CH3 O

Na O H

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

N+ CH3 CH3 CH3 O + Cationic chitosan Cl Cl Cl Cl Cl Cl Cl (EPTAC) (CHTAC)

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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.

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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 H H O H O H O H O O O H H H H H H O H O H O O O H H H H H H O H O H O O H O H H H H H H O H O H n O O O H H H H H H O H O H O O O O H H H H H H O H O O O O H H H H H H O H O O O H O H H H H H H O H

O N+

C H3

C H3

C H3 O H

N+ C H3

C H3

C H3 O H

N+ C H3

C H3

C H3 O H

N+ C H3

C H3

C H3 O H

n Cellulose

N+ C H3

C H3

C H3

O + Cationic cellulose Cl Cl Cl Cl Cl N+ C H3

C H3

C H3

C l

O H

N+ C H3

C H3

C H3

O N a O H

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

Cl Cl

(EPTAC) (CHTAC)

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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 H H H H O H O H O O O OH H H H H H O H O O O OH H H 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

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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.

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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.

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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 Name or

Group

Description Manufacturer Cotton fabric Plain weave, style 400, 102 g/m2, 44”- 45”,

78 X 76, ISO 105/F02

Testfabrics Inc Cationic

agent

3-chloro-2-hydroxypropyl trimethyl (CHTAC) ammonium chloride, 69% solution

Dow Chemical Oxidation

agent

Sodium nitrate, 97.25%,m.p. 306°C, b.p. 380°C

Acros Organics Base Sodium hydroxide, 50% aqueous solution Fisher 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

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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

di(o-hydroxyphenylacetic) acid, trisodium salt

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

154.5°C Acros Organics

Ion exchange resin

Amberlite IRA-402 (Cl- form), 200g, 1.25 meq/mL, 4.1 meq/g

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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

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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

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3.4.1 Nitrogen analysis

The nitrogen analysis was performed using a Leuco CHN analyzer. The analysis performed using EDTA as standard and 3 independent samples approximately 0.1g each.

3.4.2 FT-IR analysis

FTIR analysis needs only a small sample size and it doesn’t take a long time therefore it is one of the most useful techniques in polymer characterization. All IR spectra in this work were obtained by using a Nicolet 510P FT-IR spectrophotometer. The data collection parameters were 2.0 cm-1 resolution and 64 scans. The samples were prepared as KBr pellets and were scanned against a blank KBr pellet backround. The spectra contain absorbance on the y-axis and wavelength on the x-axis.

3.4.3 1H- NMR analysis

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3.4.4 Wrinkle recovery angles

Wrinkle recovery angles were measured according to AATCC Standard Test Method 66 option 2, Wrinkle Recovery of Fabrics: Recovery Angle Method. The wrinkle recovery angles were recorded as the added total of warp and weft averages.

3.4.5 Tensile strength

The tensile strength of untreated and treated fabrics was determined with a Syntech tensile strength tester according to ASTM Test Method D5035. Cellulosic fabrics were tested only at warp direction and the breaking load (Lb) of the fabrics recorded.

3.4.6 Whiteness index

Using Spectraflush SF600X a double beam spectrophotometer, manufactured by DataColor, CIE standard illuminant D65 and 1964 10o observer the CIE Whiteness Index measurements of the cellulosic fabrics were performed according to AATCC test method 110, whiteness of textiles. Six measurements were obtained for each sample and average value was calculated and recorded.

3.4.7 Stiffness

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3.5 Reaction of cellulose with chloroacetic acid

Cellulosic fabric was treated with anionic and cationic materials to produce ionic cellulose. This approach gave us the opportunity of forming ionic crosslinks with using both cationic and anionic polyelectrolytes.

The optimum conditions for carboxymethylation of cotton using CAA and determination of carboxyl content were extracted from previous work. [4] Cotton fabric samples were soaked in 20% NaOH aqueous solution for 10 minutes at room temperature and squeezed to a wet pick up of approximately 100%. The samples were dried at 60oC for 10 minutes. Then, the alkali treated samples were steeped in aquous solutions of sodium salt of CAA with concentrations of 0, 0.5, 1, 1.5, and 2.5M, for 5 minutes and squeezed to approximately 100% wet pick up. Sodium salt of CAA was prepared with sodium carbonate. After the samples are packed in polyethylene bags and held at 70oC for 1 hour, they were washed several times with water (hot and cold), acidified with 0.2M acetic acid and washed with distilled water to adjust pH of 7. Finally, they were dried at RT for 24 hours.

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O O OH H H H H H O H O H OH O O OH H H H H H O H OH O O OH H H H H H O H OH O OH OH H H H H H O H OH n O O OH H H H H H O H O H O O O OH H H H H H O H O O O OH H H 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 Cellulose Cl O O Na Na OH

Chloroacetic acid (Sodium salt)

+

Anionic cellulose

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The carboxylic acid group content of the partially carboxymethylated cellulosic fabrics were determined. [4] Cotton fabrics were cut into small pieces, 100mL of 0.5% aqueous HCl solution prepared and fabric samples were steeped in it for 16 hours. The samples were then filtered off and washed several times with distilled water until free from HCl and having a pH of 7. Silver nitrate drop test was performed and it showed no presence of chloride. The samples were dried at 105oC for 3 hours. Accurate weight of samples (exactly 0.2g each) was soaked in 25mL of 0.05N aqueous NaOH solutions at room temperature for 4 hours. First, a blank solution (solution without any sample) was titrated with 0.05N aqueous HCl solution. Phenolphthalein pH indicator was used. The volume of HCl solution (mL) spent was recorded for the blank. Then, each of the solutions with different carboxymethylated samples was titrated in the same way as the blank. The carboxyl contents of samples were calculated as follows:

mmols carboxymethyl content per 100 grams = 100 Χ (Vblank - Vsample)HCl Χ NHCl / 0.2

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Table 3.2 Results for carboxymethylation of cellulosic fabrics (Vblank=23.8ml) Treatment CAA

concentration (M)

Sample

no Weight of sample (g)

Vsample Carboxyl content mmol/100g

None 0 0 0.243 23.5 6.24

Carboxymethylation 0.5 1 0.258 22.25 30.21

Carboxymethylation 1 2 0.256 20.7 60.73

Carboxymethylation 1.5 3 0.253 19.45 87.12

Carboxymethylation 2.5 4 0.26 17.85 114.54

3.6 Reaction of Cellulose with CHTAC

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washed with a nonionic wetting agent at boiling temperature for 10 minutes, centrifuged and dried at RT for 24 hours. Application with the last mole ratio (1.83/2.2) was repeated multiple times in order to accomplish higher degrees of cationization.

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O O OH H H H H H O H O H OH O O OH H H H H H O H OH O O OH H H H H H O H OH O OH OH H H H H H O H OH n O O OH H H H H H O H O H O O O OH H H H H H O H O O O OH H H H H H O H O O OH OH H H H H H O H

O N+

CH3 CH3 CH3 OH N+ CH3 CH3 CH3 OH N+ CH3 CH3 CH3 OH N+ CH3 CH3 CH3 OH n Cellulose N+ CH3 CH3 CH3 O

+

Cationic cellulose Cl Cl Cl Cl Cl N+ CH3 CH3 CH3 Cl OH N+ CH3 CH3 CH3 O Na OH

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

Cl Cl

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3.7 Synthesis of compounds

All the compounds synthesized in this research are given below with detailed procedures and characterization methods.

3.7.1 Molecular weight determination of chitosan

The viscosity average molecular weight (Mv) of chitosan can be determined by the Mark Houwink equation, [47] where [ή] is intrinsic viscosity determined from a Huggins plot and k and α are empirical coefficients dependent on the DD of chitosan.

[ή]=k Mvα

Wang and coworkers established the functional relationships for k and α as a function of %DD of chitosan when chitosan is dissolved in 0.2M CH3COOH/0.1M CH3COONa aqueous solution at 30oC.

k=1.64 * 10-30 * (%DD)14 α=-1.02 * 10-2 * (%DD) + 1.82

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was charged with 3mL of each solution and equilibrated to 30oC in a water bath. Three flow times were recorded at each concentration and averaged. Specific viscosity

(ήsp) were calculated according to the following equation, ήsp= (t – ts)/ ts

Where t is a sample flow time and ts is a solvent flow time. The result of viscosity measurements is reported in Table 3.3.

Table 3.3 Scheme of intrinsic viscosity measurement for the low viscosity chitosan. c (g/mL) Solvent 0.002499 0.001999 0.001499 0.000999 0.000499

time (sec) 89.75 320.56 265.19 211.99 161.8 122.47

ήsp 2.571699 1.954763 1.362006 0.802786 0.364568

ήsp/c 1029.091 977.8706 908.6095 803.5891 730.5977

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Figure 3.3 Huggins plot of ήsp/c versus c for the cationic chitosan Table 3.4 Properties of the Low Viscosity chitosan.

Chitosan %DD k α [ή] Mv

Low Viscosity

93.5 0.006400389 0.8663 658.73 6.11*105

3.7.2 Depolymerization of chitosan and characterization

The hydrolytic fragmentation of chitosan with HCl, and the oxidative fragmentation with NaNO3 and H2O2 are the possible chemical methods. [48] HCl fragmentation can be done at 65oC. Oxidative reactions take place at room temperature. The number of chain scission depended on the concentration, time and temperature of the chemical reagents. A previous work done by M. R. Kasaai showed that the rates of

y = 154254x + 658.73 R2 = 0.9867

0 200 400 600 800 1000 1200

0 0.001 0.002 0.003

Concentration (g/mL)

in

tr

in

si

c vi

s.

/

conc

ent

rat

io

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fragmentation with HCl and NaNO3 are higher than with H2O2. Also he examined the chemical structure of chitosan and of its fragments by 1H-NMR spectroscopy. The fragmentation process with H2O2 and NaNO3 did not alter the chemical structure and degree of acetylation significantly. However, in acid hydrolysis, the degree of acetylation decreased somewhat with fragmentation. The polydipersity of the fragments by the chemical methods were similar and similar to the original one. Higher values of chain scission were obtained with oxidative fragmentation with NaNO3 in shorter duration. The initial rate of hydrolysis and oxidation with NaNO3were faster than the others. Also oxidative degradation of chitosan with NaNO3 can be easily performed at room temperature and desirable fragments can be achieved in relatively shorter durations. Therefore we choose the oxidative degradation of chitosan with NaNO3.

The chitosan fragmentation is studied at 7.25 X 10-4M and 2.9 X 10-3M concentrations of NaNO3 in a filtered initial chitosan solution (1% chitosan was dissolved in 0.1M aqueous acetic acid solution). Reaction performed at room temperature with constant stirring for various times. After the reaction, chitosan is recovered from the reaction mixture as follows: The reaction mixture is neutralized with 1N NaOH to precipitate the depolymerized chitosan. The chitosan is recovered by vacuum filtration and remaining solid chitosan washed several times with distilled water to pH 7. Polymer is collected in a drying bottle and dried at 70oC overnight in an air forced oven. Final drying was done in a vacuum oven at 70oC for 24 hours.

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and the viscosity average molecular weight of depolymerized chitosan were determined by the same method used to determine the molecular weight of original chitosan but with different viscometer. The viscometer that was used is a Cannon Ubbelohde semi-micro Viscometer (size 75, No. N177, Viscometer constant = 0.00745 mm2/s2 (cSt/s)). Table 3.5 summarizes the results of depolymerization of chitosan.

Table 3.5 Intrinsic viscosity and Mv of depolymerized chitosan NaNO3

concentration (M)

Time (minutes) Intrinsic viscosity Viscosity average molecular weight

350 310.52 2.5 X 105

460 221.4 1.7 X 105

7.25 X 10-4

695 184.21 1.4 X 105

465 70.678 4.6 X 104

690 56.055 3.5 X 104

2.9 X 10-3

1410 51.045 3.2 X 104

3.7.3 Reaction of chitosan with CHTAC

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was added drop wise into slurry to adjust the pH of 10 to 11. 1L of deionized water was added to create a reaction medium to produce a better contact between quat and chitosan molecules. The slurry was constantly stirred at 60oC for 20 hours in a water bath. Then, the temperature was raised to 95oC and stirring was resumed for another 4 hours. The product was then cooled to room temperature, filtered, and pH adjusted to 7 with acetic acid. Figure 3.4 shows the possible reaction between chitosan and quat molecules.

The resulting reaction mixture was recovered by drying; the product had a high degree of cationization and was easily redissolved in water at RT. With the same procedure chitosans with molecular weight of 1.4 x 105g/mole and 3.2 x 104g/mole were also cationized.

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O O NH2 H H H H H O H O H OH O O NH2 H H H H H O H OH O O NH2 H H H H H O H OH O OH NH2 H H H H H O H OH n O O NH2 H H H H H O H O H O O O NH2 H H H H H O H O O O NH2 H H H H H O H O O OH NH2 H H H H H O H

O N+

CH3 CH3 CH3 OH N+ CH3 CH3 CH3 OH N+ CH3 CH3 CH3 OH N+ CH3 CH3 CH3 OH n Chitosan N+ CH3 CH3 CH3 Cl OH N+ CH3 CH3 CH3 O Na OH

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

N+ CH3 CH3 CH3 O

+

Cationic chitosan Cl Cl Cl Cl Cl Cl Cl (EPTAC) (CHTAC)

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3.7.3.1 Characterization of cationic chitosan by conductometric titration method The amount of substitution on chitosan was obtained. Reaction between chitosan and quat was done under alkali conditions, therefore it was expected that the product could have some OH- ions as counter ions of quaternary ammonium salts. The OH- ions must be exchanged to Cl- ions for characterization of degree of substitution (DS) by conductometric titration. For this procedure, an ion-exchange column was prepared. [49] Ion-exchange resin (Amberlite IRA-402 (Cl- form), 200g, 1.25 meq/mL, 4.1 meq/g) was stirred in 1L of 12%(with volume) NaOH solution for 16 hours, filtered over a glass filter and thoroughly washed with distilled water until neutral. The resin was stirred in 1L of 3M HCl solution for 3 hours and washed with deionized water until pH of 7. This fresh ion exchange resin was charged into a 500mL burette.

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the dried cationic chitosan was dissolved in 100mL of deionized water and conductometrically titrated with 0.017N AgNO3 solution. Titration was conducted at a constant temperature (23.5oC). The titration curve for cationic chitosan is shown in Figure 3.5.

360 400 440 480 520

0 4 8 12 16 20 24 28 32

Volume of silver nitrate (mL)

Conductivity (uS/cm)

Figure 3.5 Conductometric titration curve of cationic chitosan

The amount of silver nitrate used at the bending point (22.3mL) equals to the amount of Cl- ions on the cationic chitosan derivative. 1mL of 0.017N AgNO3 is equal to 1mg NaCl, therefore 0.1g of the cationic chitosan contains 3.81588 X 10-4 moles of Cl- ions. The percentage degree of substitution was calculated by the equation below:

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Where MW is the molecular weight of each repeating unit of the cationic chitosan when the DS is 1 (314.89 g/mol), NCl- is the number of moles of Cl- ions in the cationic chitosan (2.6523 Χ 10-4), and m is the mass of cationic chitosan sample in grams (0.1344g). Finally the DS of cationic chitosan was calculated as 89%.

3.7.3.2 Characterization of cationic chitosan by FTIR analysis

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Table 3.6 Major IR functional group frequencies relevant to chitin and chitosan [46] Frequencies Intensity Functional group Assignment

3420-3250 s Alcohol –OH OH stretch (solid & liquid)

3460-3280 m Primary amine –NH2 NH stretch; broad band, may have some structures

350-3050 vs Ammonium, NH4+ NH stretch; broad band 3200-3000 v br Amino acid –NH3 NH3+ antisym stretch 2990-2850 m-s Aliphatic alkyl CH antisym stretch

2830-2810 m Primary amine –NH2 CH stretch

2750-2350 m-s, br Amine hydrohalides - NH3+

NH3+ stretch, several peaks

1680-1630 vs Secondary amide C=O Carbonyl stretch (Amide I) 1650-1580 m-s Primary amine –NH2 NH2 deformation

1610-1560 vs Carboxylic acid slat –COO- COO- antisym stretch 1565-1475 vs Secondary amide –NH- NH deformation (Amide II) 1440-1260 m-s, br Alcohol C-OH in plane bend

1430-1390 s Ammonium, NH4+ NH2 deformation ; sharp peak 1400-1310 s Carboxylic acid salts –

COO

-COO- sym stretch; broad band

1310-1250 m Trans amide linkage C-N stretch (Amide III) 1240-1070 s-vs Ether –C-O-C C-O-C stretch; antisym stretch 1200-1015 s-vs Alcohol –C-O-H C-O stretch

1150-1070 vs Aliphatic ethers C-O-C antisym stretch 1120-1030 s Primary aliphatic amine

C-NH2

C-N stretch

860-760 vs- br Primary aliphatic R-NH2 NH2 wag

680-620 s Alcohol –C-O-H C-O-H bend

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The peaks (1646 cm-1 and 1599 cm-1) shown in Figure 3.6 respond to C=O of secondary amide and NH2 of primary amine groups. [46]

0.0 0.2 0.4 0.6 0.8 1.0 1.2

500 1000

1500 2000

2500 3000

3500 4000

Wavenumbers (cm-1)

Absorbance

1646 1599

Figure 3.6 FTIR spectrum of deacetylated chitosan

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0.0 0.2 0.4 0.6 0.8 1.0 1.2

500 1000

1500 2000

2500 3000

3500 4000

Wavenumbers (cm-1)

Absorbance

1479

Figure 3.7 FTIR spectrum of cationic chitosan

3.7.3.3 1H-NMR spectrums of deacetylated and cationized chitosan

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In order to characterize the O-substitute chitosan the N-substituted chitosan was used as reference, because the N-substituted chitosan has only quaternary ammonium salts on the NH2 site of chitosan, which proven by Kim et. al. [39] The O-substituted chitosan spectra, the bottom spectra in Figure 3.9, showed a strong peak at 3.21 ppm and the spectra of N-substituted chitosan, the top spectra in Figure 3.9, also showed a similar peak at 3.19 ppm. Both of these peaks come from the CH3 groups of the quaternary ammonium salt. Unlike the chitosan spectra both of the cationized chitosan spectra didn’t show a clear separation of peaks. We believe that it is due to introducing a complex ammonium salt group into the chitosan’s structure. Therefore both spectra didn’t give us the opportunity of calculating the degree of substitution by using the intensities of the peaks. It is clearly seen from the peaks that the spectrum of N-substituted chitosan is different than O-substituted chitosan.

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3.7.4 Reaction of glycerin and ethylene glycol with CHTAC

Reaction of alcohols with quat can be performed at mild temperatures and using high mole ratios. Glycerin was cationized using the following method: 1156g (4 moles) from CHTAC was charged into a 2L beaker, 228mL of 50%NaOH solution was added dropwise to adjust pH of the CHTAC 10 to 11 and 46.05g (0.5 moles) from glycerin was added into highly alkaline CHTAC solution. Note that glycerin to CHTAC mole ratio was 1:8. The mixture was stirred 10 minutes at RT, transferred into a preheated water bath and stirred at 60oC for 20 hours. A viscose and yellowish mixture was collected at the end. The resulting reaction product was cooled off to room temperature, filtered, and pH adjusted to 7 with acetic acid. The reaction of glycerin with CHTAC is shown in Figure 3.10.

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Glycerin N+ CH3 CH3 CH3 Cl OH N+ CH3 CH3 CH3 O Na OH

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

N+ CH3 CH3 CH3 O

+

Cationic Glycerin Cl Cl Cl (EPTAC) (CHTAC) O H O H OH O O O N+ CH3 C H3 CH3 O H N+ CH3 CH3 OH N+ CH3 CH3 OH CH3 C H3 Cl Cl Cl

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3.7.5 Reaction of cellobiose and dextrose with CHTAC

The similarity of the molecular structure of cellobiose, dextrose and chitosan we used the cationization method of chitosan for reaction of CHTAC with both cellobiose and dextrose. The procedure was as follows: 50g (0.18 moles) from CHTAC solution was charged into a 250mL beaker and pH adjusted to 10-11 with 10mL of NaOH solution and followed by adding 15.5g (0.045 moles) from cellobiose into highly alkaline quat solution. The mixture stirred for 10 minutes at room temperature and transferred into a preheated water bath. The mixture stirred at 60oC for 20 hours. Then the temperature raised to 95oC and stirring continued for another 4 hours. Finally the reaction mixture was cooled off to room temperature and pH adjusted to 7 with acetic acid.

With the same procedure dextrose was also cationized. For this procedure 90g (0.32 mole) from CHTAC solution was charged into a 250 mL beaker and pH adjusted to 10-11 with 90mL of NaOH. Followed by adding 15g (0.08 mole) from dextrose into the quat solution. The reaction performed using the same method described for cellobiose.

3.8 Preparation of fabric samples

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3.9 Crosslinking of carboxymethylated cellulosic fabric

Untreated fabric having a carboxymethyl content of 6.2mmol/100g and carboxymethylated cellulosic fabrics with anionic contents of 30.2, 60.7, 87.1, and 114.5mmole/100g, were treated with cationized chitosan, cationized glycerine, calcium chloride, magnesium chloride, cationized ethylene glycol, cationized dextrose and cationized D-cellobiose. All of these treatments are given below.

3.9.1 Treatment with cationic chitosan

Crosslinking with cationic chitosan was studied using dry-cure, cold pad-batch and exhaustion procedures. Fabrics with five different anionic levels were used. The procedure was same for different molecular weight of cationized chitosans. For pad dry cure and pad batch application 400mL of blank (0%) and three different concentrations of polyelectrolyte, 1, 3, and 6 % with weight, solutions were prepared. Cationic chitosan dissolved in deionized water at pH of 7. For exhaustion method 400mL of 6% with weight cationic chitosan solution and 1:15 bath ratio was used.

3.9.2 Treatment with cationic glycerin

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temperature rose to 95oC with a 2oC/minute grade and hold for 90 minutes and followed by hot and cold washing of the samples and drying at room temperature for 24 hours.

3.9.3 Treatment with cationic cellobiose, cationic dextrose and cationic ethylene glycol These treatments were studied as a prescreening study in order to identify if the polyelectrolytes can impart crease angle recovery to anionic cellulosic fabric. Treatments with cationic cellobiose, cationic dextrose, and cationic ethylene glycol were studied using anionic cellulosic fabrics with two different carboxyl content, 30.2 and 60.7mmole/100g. The concentrations of cationic crosslinkers were 6% with weight of the bath. All treatments were applied using the pad dry cure procedure and followed by washing and drying as described previously.

3.9.4 Treatment with calcium chloride and magnesium chloride

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O O OH H H H H H OH O H O O O OH H H H H H O H O O O OH H H H H H OH O O OH OH H H H H H O H O O O O O O O O O Ca O O OH H H H H H O H OH O O O OH H H H H H OH O O O OH H H H H H O H O O O H OH H H H H H OH O O O O O O O O O

Ca++

+ +

Anionic cellulose chain Anionic cellulose chain

Divalent calcium ion Divalent calcium ion

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3.10 Crosslinking of cationic cellulosic fabric

Various polyelectrolytes were used. Polyanion types were PCA, BTCA, EDTA, NTA, HEDTA, oxalic acid, citric acid, and malic acid. The approach was to form ionic crosslinks between cationic cellulose chains by reacting them with a polyanion. All of these crosslinkers improved crease angle recovery of cotton with varying degrees of success, but we accomplished higher WRA with PCA and BTCA treatments.

3.10.1 Treatment with PCA and BTCA

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O O OH H H H H H OH O H O O O OH H H H H H O H O O O OH H H H H H OH O O OH OH H H H H H O H O

N+ CH3 CH3 C H3 O H N CH3 CH3 C H3 O H

N+ CH3 CH3 C H3

O H

N CH3 C H3 C H3 O H O O OH H H H H H O H OH O O O OH H H H H H OH O O O OH H H H H H O H O O O H OH H H H H H OH O N+ C H3 CH3 CH3 OH N C H3 CH

3 CH3 OH N+ C H3 CH3 CH3 OH N C H3 CH3 CH3 OH COO COO COO COO Cl Cl Cl Cl - -+ + + +

Cationic cellulose chain Cationic cellulose chain BTCA

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3.10.2 Treatment with EDTA, NTA and HEDTA

Treatments were studied using five different %N fixed fabrics and three different concentrations, 1%, 3%, and 6% with weight of the solution, of HEDTA, NTA, and EDTA solutions. The pH of the solutions was adjusted to 7 with acetic acid. The pad dry cure application procedure was used. The treated fabrics were washed and dried as described above.

3.10.3 Treatment with oxalic acid, citric acid and malic acid

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4. RESULTS & OBSERVATIONS AND DISCUSSION

In this section the results of the physical property measurements of the untreated and treated fabrics are represented using figures. A detailed discussion for each property is also stated.

4.1 Wrinkle recovery angles of conventional durable press finished fabrics

In order to compare the wrinkle recovery angles of ionic crosslinked fabrics the crease angle recovery test was performed on the DMDHEU treated cellulosic fabric. The dry/wet wrinkle recovery angles were 276/266 degrees respectively.

4.2 Wrinkle recovery angles of polycation treated anionic cellulosic fabrics

Wrinkle recovery angle data are presented for polycation treated anionic fabrics. Carboxyl content on the cellulosic fabrics is given on the x-axis while dry/wet wrinkle recovery angles are given on the y-axis.

4.2.1 Wrinkle recovery angles of cationic chitosan treated fabrics

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120 160 200 240

0 30 60 90 120

Carboxyl content (mmol/100g)

Dry wrinkle recovery angles

(degrees)

0% 1%CC 3%CC 6%CC

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

120 160 200 240 280

0 30 60 90 120

Carboxyl content (mmol/100g)

Wet wrinkle recovery angles

(degrees)

0% 1%CC 3%CC 6%CC

(76)
(77)

higher nitrogen fixation than the 1% treatment. The maximum nitrogen fixation was 0.54% and was obtained with the application of 6% cationic chitosan on the fabric containing 114.5 mmol/100g carboxyl content.

0.20 0.30 0.40 0.50 0.60

0 30 60 90 120

Carboxyl content (mmol/100g)

%Nitrogen content

0% 1%CC 3%CC 6%CC

Figure 4.3 Effect of carboxyl content and concentration on %Nitrogen content of cationic

chitosan treated fabrics

(78)

angles. The dry wrinkle recovery angle data of the treated fabrics did not show a good correlation with the % nitrogen content, as most of the ionic crosslinks were formed while the fabric was wet. Increases in % nitrogen content led to increases in wet crease angle recovery for treated fabrics. As previously mentioned, the nitrogen content of the fabrics is proportional with the number of the ionic crosslinks, therefore fabrics having greater nitrogen contents are expected to produce higher wrinkle recovery angles than others. The data obtained with cationic chitosan treatments indicated that fabrics with greater nitrogen contents also produced higher crease angle recovery.

R2 = 0.7391

180 200 220 240 260 280

0.2 0.3 0.4 0.5 0.6

%Nitrogen content

Wrinkle recovery angles (degrees)

Wet WRA Dry WRA

(79)

Several laundry washings were applied to the cationic chitosan treated fabrics using a commercial detergent, Tide, and % nitrogen content of the fabric were tested. The % nitrogen content was initially 0.67%, after one laundry washing it was 0.68% and was 0.59% after five laundry washings and 0.40% after ten laundry washings.

The anionic cellulosic fabrics were treated with three different molecular weights of cationic chitosan. Regardless of molecular weight of the polycation, significant increases in both dry and wet wrinkle recovery angles were observed, but the results show that wet wrinkle recovery angles are higher than dry wrinkle recovery angles. The effects of different molecular weights of cationic chitosan and carboxyl content of the fabrics on wrinkle recovery angles are compared in Figures 4.5 and 4.6. These figures are produced from the data obtained with 6% cationic chitosan concentration.

(80)

160 200 240

0 30 60 90 120

Carboxyl content (mmol/100g)

Dry wrinkle recovery angles

(degrees)

611000g/mo l

140000g/mo l

32000g/mol

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

150 200 250

0 30 60 90 120

Carboxyl content (mmol/100g)

Wet wrinkle recovery angles

(degrees)

611000g/mo l

140000g/mo l

32000g/mol

Figure

Figure 2.3 Molecular structure of DMDHEU
Figure 3.4 Reaction of chitosan with CHTAC
Figure 4.2 Effect of carboxyl content and concentration on wet wrinkle recovery angles of  cationic chitosan treated fabrics
Figure 4.3 Effect of carboxyl content and concentration on %Nitrogen content of cationic chitosan treated fabrics
+7

References

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