Chemical Modification of Mango Kernel Stone Powder as a Thickener in Reactive Printing

Table of Contents

ACKNOWLEDGEMENT

ABSTRACT

LIST OF TABLES

LIST OF FIGURES

LISTS OF ABBREVIATIONS AND ACRONYMS

CHAPTER 1
INTRODUCTION
1.1 Background and Justification
1.2 Problem statement
1.3 Objectives
1.3.1 General objective
1.3.2 Specific objective
1.4 Scope of the study
1.5 Significance of the study
1.6 Benefit and Beneficiaries
1.6.1 Benefit
1.6.2 Beneficiaries

CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
2.2 Textile Printing
2.3 Chemistry of Reactive Dye
2.4 Thickeners
2.5 Screen Printing
2.6 Properties of printing paste
2.7 Starch
2.8 Mango plant
2.9 Literature gap

CHAPTER 3
MATERIALS AND METHODS
3.1 Materials
3.2 Equipment
3.3 Chemicals
3.4 Methods
3.4.1 Experimental Procedure
3.4.1.5 Determining rheological properties of powder paste

CHAPTER 4
RESULT AND DISCATIONS
4.1 Test results of important functional groups
4.2 Viscosity result Analysis.
4.2.1 Unmodified and modified thickener viscosity analysis
4.2.1 Viscosity result Analysis for unmodified thickener
4.2.2 Viscosity result Analysis for acetic acid modified thickener
4.2.3 Viscosity result Analysis for hydrogen peroxide modified thickener
4.3 Fastness properties result Analysis.
4.3.1 Washing fastness
4.3.2: Assessment of staining
4.3.3 Crock fastness
4.4 Color strength result analysis
4.4.1 Color strength result analysis for unmodified thickener
4.4.2 Color strength result analysis for 3% A.A modified thickener
4.4.3 Color strength result analysis for 4% A.A modified thickener
4.4.3 Color strength result analysis for 5% A.A modified thickener
4.4.3 Color strength result analysis for 3% H2O2 modified thickener
4.4.5 Color strength result analysis for 5% H2O2 modified thickeners
4.4.6 Color strength result analysis for 7% H2O2 modified thickeners
4.5 Whiteness index (WI) analysis (CIE)
4.5.1 Whiteness index (WI) analysis for unmodified thickeners
4.5.2 Whiteness index analysis for 3% A.A modified thickeners
4.5.3 Whiteness index analysis for 4% A.A modified thickeners
4.5.4 Whiteness index analysis for 5% A.A modified thickeners
4.5.5 Whiteness index analysis for 3% H2O2 modified thickeners
4.5.6 Whiteness index analysis for 5% H2O2 modified thickeners
4.5.5 Whiteness index analysis for 7% H2O2 modified thickeners
4.6: The moisture content of various thickeners

CHAPTER 5
CONCLUSION AND RECOMMENDATION
5.1 CONCLUSION
5.2 RECOMENDATION

REFERENCES

Appendices

LIST OF TABLES

Table 2.1: Composition of MKSP

Table 3.1: List of chemicals

Table 3.2: Experimental design for testing

Table 4.1: Washing fastness

Table 4.2: Staining fastness results

Table 4.3: Wet rubbing fastness

Table 4.4: Dry rubbing fastness

Table 4.5: The moisture content of various thickeners

LIST OF FIGURES

Figure 2.1: Parts of mango fruit

Figure 4.1: FTIR Curves of important functional groups

Figure 4.2: Viscosity analysis for unmodified thickener

Figure 4.3: Viscosity analysis for 3% A.A modified thickeners

Figure 4.4: Viscosity analysis for 4% A.A modified thickeners

Figure 4.5: Viscosity analysis for 5% A.A modified thickeners

Figure 4.6: Viscosity analysis for 3% H2O2 modified thickeners

Figure 4.7: Viscosity analysis for 5% H2O2 modified thickeners

Figure 4.8: Viscosity analysis for 7% H2O2 modified thickeners

Figure 4.9: Color strength result analysis for unmodified thickener

Figure 4.10: Color strength result analysis for 3% A.A modified thickener

Figure 4.11: Color strength result analysis for 4% A.A modified thickener

Figure 4.12: Color strength result analysis for 5% A.A modified thickener

Figure 4.13: Color strength result analysis for 3% H2O2 modified thickeners

Figure 4.14: Color strength result analysis for 5% H2O2 modified thickeners

Figure 4.15: Color strength result analysis for 7% H2O2 modified thickeners

Figure 4.16: Whiteness index for unmodified thickeners

Figure 4.17: Whiteness index result analysis for 3% A.A modified thickeners

Figure 4.18: Whiteness index result analysis for 4% A.A modified thickeners

Figure 4.19: Whiteness index result analysis for 5% A.A modified thickeners

Figure 4.20: Whiteness index result analysis for 3% H2O2 modified thickeners

Figure 4.21: Whiteness index result analysis for 5% H2O2 modified thickeners

Figure 4.22: Whiteness index result analysis for 7% H2O2 modified thickeners

LISTS OF ABBREVIATIONS AND ACRONYMS

MKSP. Mango kernel stone powder

A.A Acetic acid

GT. Gelatinization Temperature

WI…. Whiteness Index

Un WI….Unmodified Whiteness Index

WF…. Washing Fastness

Un WF Unmodified wash fastness

WRF...Wet Rubbing Fastness

DRF….Dry Rubbing Fastness

STF…..Staining Fastness

Vsun Unmodified Viscosity

K/s…...Color strength

C …...Degree Celsius

cps …..centipoises

DSC… Differential scanning calorimeter

FITR…Fourier transform infrared spectroscopy

ACKNOWLEDGEMENT

First, I would like to thanks my almighty God for giving me strength, patience and guidance to go through this thesis work.

Secondly, I would like to express my sincere gratitude to my advisor Prof. (Dr.) Shrirang K. Chinta for his continuous support, patience, motivation, and immense knowledge. His guidance helped me in all the time of research and writing of this thesis. He consistently allowed this paper to be my own work, but steered me in the right the direction whenever he thought I needed it.

Besides my advisor, I would like to thank the rest of my thesis juries Dr. Tamrat Tesfaye, Mr. Adane Haile and Mr. Tamene Wagaw, for enlightening me the first glance of research, for their insightful comments and encouragement, as well as scientific questions which incented me to widen my idea from various perspectives.

I would also like to thanks for Kombolcha textile Share Company, Bahirdar University, Ethiopian Textile Development Institute for accepting me to do my final thesis work.

My heartfelt thanks and genuine appreciation are for Mr. Asaye Dessie for his restless support, direction, advice and patience for formatting and editing my paper work. I thank my fellow lab mates for their stimulating discussions, for sleepless nights we were working together before deadlines, and for all the fun we have had in the last one year.

Last but not the least, I would like to thank my family and parents and to my brothers and sisters for supporting me spiritually throughout writing this thesis and my life in general.

ABSTRACT

Many researchers investigated that up to 40% of the dyestuff may hydrolyzed in the dyeing and printing with reactive dye in which may be hydrolyzed dye had no affinity for the fibre and as such exhibits poor wash and rubbing fastness and also the problem of unprinted white portion arise which results in poor quality of print effect. In this investigation mango kernel stone powder (MKSP) which is abundantly available and contain starch were chemically modified from OH group to other groups like OCOCH3 and others by acetic acid (3%, 4%, and 5%) and hydrogen peroxide (3%, 5%, and 7%) to improve quality of printing. FTIR spectrum identified the presence of carboxyl and hydroxyl groups and the degree of substitution of important functional group before and after modification and more important functional group for modified thickener were achieved in case of modification with hydrogen peroxide. Particle sizes of the thickener were also studied for unmodified and modified thickeners and 90µm size was selected and used throughout this study. Moisture content of both unmodified and modified was also assessed and the results were near to each other. Viscosity of printing thickener was the biggest concern both before and after modifications as it is the heart of printing and it had significant effect when modified with hydrogen peroxide. Gelatinization temperature of thickener had no significant effect on viscosity in both unmodified and modified thickeners. Finally, Printing qualities such as colour strength, wash and rubbing fastness and whiteness index were evaluated and the modified MKSP thickener with 3% acetic acid and 7% hydrogen peroxide showed better results than unmodified and other modified thickeners.

Keywords: Cotton fabric, Mango, Modification, Thickener, Reactive printing, Characterization

CHAPTER 1

INTRODUCTION

1.1 Background and Justification

Textile printing is a method of coloration of textile fabric. It can be obtained by using dyes or pigment in the form of printing paste. This paste is viscous which provided by thickener.Successful prints depend on color, levelness, sharpness, and adequate use of dye. These all depend on the type of thickener used and the printing paste viscosity (Hosa 2016).

Textile printing is the most adaptable methods used for introducing color and design to textile fabrics. Considered analytically, it is a process of bringing together a design idea, one or more colorants. Reactive dyes are extensively used for coloration of cellulosic fibers because of their excellent fastness which arises from covalent bond formation between dye and fiber. However, up to 40% of the dyestuff may hydrolyze in the dyeing and printing process; this hydrolyzed dye has no affinity for the fibre and as such exhibits, unprinted white portion, poor quality print effect, poor wash and rubbing fastness. Due to this multi-step ‘wash-off’ process after dyeing and printing in order to achieve high wash fastness, rubbing fastness and printing design sharpness. Wash-off and effluent treatment can also account for up to 50% of the total cost of reactive dyeing and printing which consumes significant amounts of water and energy. The mango kernel which is abundantly available and disposal become a problem but can be used in textile sizing and printing thickener (Kibria et al., 2018).

Textile Printing is to stamp or impart a pattern or design onto a textile substrate by means of coloration. It is the art or process of printing textile substrates. Fiber reactive dyes are colored organic substances, which are water-soluble. These dyes will react with cellulose under certain conditions of pH, temperature, solution, and time and it have little affinity for cotton as long as the pH is neutral or slightly acid(Weston Parkway, 2006).

Printing method requires a paste or thickening agent with special characteristics frequently referred to as the flow characteristics. Textile printing is the most universal and important method used for introducing color and design to textile fabrics. Considered analytically it is a process of bringing together a design idea, one or more colorants, and a textile substrate, using a technique for applying the colorants with some precision (Tian, 2015). In the fast-increasing biopolymers industries, starch derivatives show an important role because of its low cost, non-toxic, renewable and compatibility with many other materials for industrial applications. They are used in diverse polymer applications directly or in combination with other synthetic polymers. Starch derivatives were extremely used in food, environmental management, agriculture, pharmacy, biomedical engineering and textile. The etherification of the OH group of the starch leads to substantial alteration in the properties of starch. It evades association of the starch molecules(Agwamba et al., 2016).

As the temperature rises, the dye reacts with the hydroxyl (-OH) groups on the cotton molecule. These hydroxyl groups or radicals also exist as a component of water. The problem with this situation is since both cotton fabrics and water have these -OH groups; there can also be a reaction with the (-OH) of the water. This is called dye hydrolysis. This new molecule is still soluble but will no longer be able to react with the cotton. Hydrolysis is accelerated by alkali; the alkali is not added until the proper time. Common in printing, this is accomplished by using sodium bicarbonate, a weak alkali in the print paste (Kibria et al., 2018).

Color fastness to wash, color fastness to rubbing, strength of the finished fabric and its crease recovery properties are of paramount importance. This research is aimed towards finding the impact that mango kernel and stone thickeners execute on these properties of the printed fabrics with certain chemical modifications and study the swelling power of a starch sample as it can determines its ability to hydrate and solubilized in the presence of water and higher the swelling power; greater is the paste clarity (Kaur et al, 2004).

The present paper deals with preparation of thickening agent from mango kernel gum and investigating their suitability as thickening agent and testing its Color coordinates and color fastness towards light, washing, rubbing and perspiration(Babel, 2016).

The types of thickening agent are quite diverse. Various starch based thickening agent such as modified starch, PVA, Sodium alginates are commonly used. Alginates of different salts can be universally used in all different dye stuff but they are more expensive and the dye stuff yield is too low. Increase demand, high price, scarceness of natural thickeners stimulates the search of locally available materials(Babel et al, 2017). Common use of synthetic dyes and thickeners in textile industry will cause rapid pollution to earth and serious ecological problems in future. The best industry is one that spoils the earth the least. In the current years concern for environment has created an increasing interest in eco-friendly, biodegradable and nontoxic rational products. Starch thickeners by contrast are not only eco-friendly and sustainable, but also an effective printing additive. The purpose of this investigation was to explore novel sources of thickeners for textile surface printing with minimal environmental waste and pollution. Natural printing thickeners with some modification can exhibit better biodegradability and generally have a higher compatibility with environment. Natural thickening agents appear to be ideal choice for consumers with eco concern (Yadav, 2016).

In this research Mango kernel stone powder was chemically modified from –OH groups to other groups like -OCOCH3 etc. with the acetic acid and hydrogen peroxide. The aim of this research was to explore the production of chemically modified starch from mango kernel stone powder that can be used mainly in the printing field economically. Hence giving value to mango fruit byproduct through different routes is not only helps to reduce environmental pollution but also reduces the cost of waste disposal for juice house and processing industries.

1.2 Problem statement

Today reactive dyes play a major role in cotton printing due to its low cost and simplicity, but have a drawback of hydrolysis due to which tinting of unprinted portion takes place, which result poor wash and rubbing fastness. Up to 40% of the dyestuff maybe hydrolyzed in the dyeing and printing process; this hydrolyzed dye has no affinity for the fibre and as such exhibits poor washing and rubbing fastness. Wash-off and subsequent effluent treatment can account for up to 50% of the total cost of reactive dyeing and printing which consumes significant amounts of water and energy. For a sustainable chemistry and engineering perspective, consumption of water and energy, effluent generation and treatment are arguably the biggest issues in textile dyeing and printing.

The mango kernel stones powder (MKSP) which is abundantly available and its disposal become a problem was used in textile sizing and printing. However, there were a problem of hydrolysis if it is applied without any chemical modification this may be due to the fact that the MKSP contain 65%-73% starch constitution which contain higher amount of OH group when it is studied under FITR testing instrument and the number of these OH groups can create the hydrolysis problem with reactive dyes during printing and results poor print effects.

In this research Mango kernel stone powder was chemically modified from –OH groups to other groups like acetyl and carboxyl (-OCOCH3) groups. with the acetic acid and hydrogen peroxide.

The aim of this research was to explore the production of chemically modified starch from mango kernel stone powder that can be used mainly in the printing field economically.

Natural thickening agents have better biodegradability and higher compatibility with environment. Hence giving value to mango fruit byproduct through different routes is not only helps to reduce environmental pollution but also reduces the cost of waste disposal for juice house and processing industries.

1.3 Objectives

1.3.1 General objective

- Chemical modification of mango kernel stone powder (MKSP) as a thickener in reactive printing

1.3.2 Specific objective

- To minimize the problem of reaction of thickener with reactive dye and water in printing.
- To improve sharpness of mark, levelness, hand and efficient use of dye.
- To minimize cost of thickeners
- To minimize environmental pollution by chemically modifying MKSP (waste) generated from mango fruit into valuable printing thickeners.

1.4 Scope of the study

The scope of this study was covering not only the collection of mango seed as a byproduct and conversion of an indigenous resource into some useful material but also, chemical modification of indigenous material, and its characterization and application area.

1.5 Significance of the study

This study is significant enough not only to convert an indigenous waste resource into some useful product but also, it can identify the chemical modification of indigenous material for efficient use of a byproduct as the main study. In this study the physicochemical characterization of mango kernel was clearly identified and the applications of characterized product have been studied. It is also significant enough to give enough information how to utilize the byproduct with chemical modification and simplify the problem within indigenous materials.

1.6 Benefit and Beneficiaries

1.6.1 Benefit

- It can reduce effluent generated from reactive dyes due to hydrolysis, unfixed dyes, staining during printing and improve quality of the printed product if the modified material is introduced more in printing paste in the form of thickener.
- Safe consumption of water for washing of staining part, hydrolyzed and unfixed dyes during printing with reactive dyes.
- Increase awareness about the realization that the intermediates and chemical used in synthetic dyes (i.e. reactive dyes) being toxic and hazardous to human health as well as to the environment if hydrolysis unfixed dye and staining are not controlled.
- Safe the environment from heavy pollution by utilization of mango seed kernel into useful product and save disposal cost of by product and minimize the problem of unprinted portion and staining of printed fabric since there is a minimization in reaction of reactive dyes with thickener as well as water.

1.6.2 Beneficiaries

From project many textile factories, mango juice house and all surrounding communities will be benefited as huge amount of waste, heavy pollution, problem of printed fabric and water consumption will be rectified as well as clear procedures for conversion, chemical modification and characterizations of indigenous material is carried out as a result this research will be clear guide lines for many researchers and students for further modifications and characterizations on this research.

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

Reactive dyes are extensively used for coloration of cellulosic fibers because of their excellent fastness which arises from covalent bond formation between dye and fiber. However, up to 40% of the dyestuff may hydrolyze in the dyeing and printing process; this hydrolyzed dye has no affinity for the fiber and as such exhibits, unprinted white portion, poor quality print effect, poor wash and rubbing fastness. Due to this multi-step ‘wash-off’ process after dyeing and printing in order to achieve high wash fastness, rubbing fastness and printing design sharpness. Wash-off and effluent treatment can also account for up to 50% of the total cost of reactive dyeing and printing which consumes significant amounts of water and energy.

The mango kernel which is abundantly available and disposal become a problem but can be used in textile sizing and printing thickener. From the literature cited about mango kernel and stone indicates the use of this powder as it is for printing is not suitable due to the presence of more hydroxyl groups in its chemical structure which can react with hydroxyl groups of both cotton and reactive dyes the problem mentioned will be occurred. However, if mango kernel is chemically modified from -OH groups to other group like -OCOCH3 and other functional groups. Problem mentioned will be settled by using organic modification of starch in MKSP.

2.2 Textile Printing

Textile printing can be best described as the art and science of decorating a fabric with a colorful pattern or design. Textile printing may be briefly described as the art of dyeing or coloration of localized areas on cloth or yarn so that a design is produced in one or more colours on a white or coloured ground or in short as ‘localized dyeing’. The main objective of printing is to produce coloured design with one or more colours with sharp boundaries on textile materials without spreading of the dye beyond the boundaries of the design where a thickener is an important ingredient of the paste (Chinta S. K.* & Chavan S. V. D., 2012). It is ‘localized dyeing’ where confined portions of fabric are colored. In textile printing, color is applied in the form of thick paste and dye is present in the concentrated form. Printing can be classified either by methods of printing or styles of printing. Way of printing is a means of transferring a design to a textile substrate. The various methods of printing are block printing, stencil printing, hand screen printing, automatic flat-bed screen printing, rotary screen printing, roller printing and transfer printing. Style of printing describes the means of application of the dye to the material. Direct style, resist style and discharge style are the main styles of printing (Sparks & Kissell, 2013).

Mango kernel and stone gum has been taped to explore as a source of natural thickener for sustainable development. The present paper deals with preparation of thickening agent from mango kernel gum and investigating their suitability as thickening agent and testing its Color coordinates and color fastness towards light, washing, rubbing and perspiration (Babel, 2016)

Printing method requires a paste or thickening agent with special characteristics frequently referred to as the flow characteristics. Textile printing is the most universal and important method used for introducing color and design to textile fabrics. Considered analytically it is a process of bringing together a design idea, one or more colorants, and a textile substrate, using a technique for applying the colorants with some precision (Tian, 2015)

Cotton fabric is the most commonly printed substrate, and reactive dyes are the most commonly used dyes in cotton printing. The relatively high cost and limited supply of natural thickeners has spurred efforts to find alternatives. There are many variables that might be examined, but generally a printer is looking for a paste that is simple to prepare, stable, prints level and sharp, minimizes the use of dye and auxiliaries, and easy to remove (Madhu & Patel, 2016).

Common use of synthetic dyes and thickeners in textile industry will cause rapid pollution to earth and serious ecological problems in future. The best industry is one that spoils the earth the least. In the current years concern for environment has created an increasing interest in eco-friendly, biodegradable and nontoxic rational products. Natural printing thickeners with some modification can exhibit better biodegradability and generally have a higher compatibility with environment. Natural thickening agents appear to be ideal choice for consumers with eco concern (Yadav, 2016).

In recent eras, synthetic coloration of textiles is the alarming issue around the world because of ecological imbalance as well as a future threat for human being. It was noted that approximately 250-350 kg water consumed to process per kg cotton fabric. Additionally, unexhausted synthetic dyes and hazard chemicals produces about 4-37% waste water with huge amount of pollutants(Roy et al., 2018).

2.3 Chemistry of Reactive Dye

The major classes of dyes for cellulose fibers are the reactive dyes, as they have good washing fastness, bright shades and very flexible batch. As the name indicates, the reactive dyes bind to the fiber under alkaline conditions but, hydroxyl ions of water also react with the reactive group of the dye, generating hydrolyzed dye and decreasing the efficiency of the fixation process. This hydrolyzed dye has to be removed after dyeing and printing thorough washing to safeguard good washing fastness and this process is vital for the final quality of the dyeing and printing. Approximately half the cost of reactive dyeing and printing may be credited to the washing stage and the treatment of the consequent effluent (Gheorghe Asachi, 2017).

2.4 Thickeners

Thickeners are viscous pastes used for textile printing usually consist of either solutions of high molecular weight polymers or emulsions of immiscible liquids. The chemicals used belong to various chemical classes. Unbranched polymers give viscous solutions at low concentrations but the viscosity falls with increasing shear. Branched chain polymers require higher concentrations to give the required viscosity but are less sensitive to shear (Kibria et al., 2018).

The thickener used in printing should have following functional properties and requirements. Stability of thickener to keeping should be good, it should have certain physico-chemical properties like viscosity, flow property, ability to wet and adhere to the surface, it must be compatible with other print paste ingredients and should not have affinity for the dyes, the thickener film should dry properly on the fabric to prevent spreading of the Colour by capillary action beyond the boundaries of the design at the end of the process, its removal from the fabric should be easy, it should be available in abundance and cheaper. Efforts are being made to find out a cheaper conventional gums amongst various natural seed powders capable of being used as thickeners (Chinta S.K.* & Chavan S. V. D., 2012). The types of thickening agent are quite diverse. Various starch based thickening agent such as modified starch, PVA, Sodium alginates are commonly used. Alginates of different salts can be universally used in all different dye stuff but they are more expensive and the dye stuff yield is too low. Increase demand, high price, scarceness of natural thickeners stimulates the search of locally available materials (Babel et al, 2017).

The synthetic thickening agents are generally extremely high molecular weight polymers capable of developing a very high viscosity at a reasonably low concentration. However, the paste or thickening agents are difficult to dispose it and it creates sedimentation in the water during its waste disposal (Kaur et al, 2004). Textile processing generates huge quantities of waste and pollution and this is true also in textile printing. Pollution in textile printing is caused by emissions of hydrocarbons, ammonia and other volatile organic matter. Synthetic polymer thickeners induce pollution in the environment in the form of these harmful emissions and toxic waste materials which cannot be degraded and assimilated into the environmental(Sparks & Kissell, 2013). Starch thickeners by contrast are not only eco-friendly and sustainable, but also an effective printing additive. The purpose of this investigation was to explore novel sources of thickeners for textile surface printing with minimal environmental waste and pollution.

2.5 Screen Printing

Screen printing is a traditional and versatile printing method which consists of a synthetic fiber or metal gauze stretched taut over a frame. Parts of the gauze have the holes blocked off (no-printing area) and the printing paste is forced through the open printing areas by a rubber or metal blade, called a squeegee, and on to the fabric beneath. In hand screen printing the fabric is immobilized to the printing table, which is enclosed with a resilient felt, wax cloth or rubber material(Sparks & Kissell, 2013)

2.6 Properties of printing paste

The mechanism of dye fixation on fabric is the same in both dyeing and printing. But the dyes that are used in a print paste should have a high solubility because the amount of water in the print paste is severely limited and at the fixation stage, the dye must be re-dissolved in a small volume of condensed steam. The specifics of print paste formulation depend on the fiber content of the fabric, the colorant system used, the fixation method used and to some extent, the type of printing machine employed(Sparks & Kissell, 2013). However, the typical ingredients found in most paste formulations include the following: dyes or pigments, thickeners, sequestering agents, dispersing or suspending agents (surfactants), water-retaining agents (humectants), defoamers, catalysts, and hand modifiers.

2.7 Starch

Starch is naturally occurring material, a plentifully available and low-cost poly hydroxyl biopolymer. Due to these advantageous properties, there has been investigation for studying such a biodegradable material (Yatnatti & Vijayalakshmi, 2018). Chemical modification involves the coupling of functional groups into the starch chain via hydroxyl moieties, resulting in marked development in physicochemical properties of starch. Such modification of native granular starches profoundly changes their conformational behavior. Chemical modification is proposed to simplify intra and inter macromolecular bonds at random locations in the starch granule for their stabilization (Okunlola & Akingbala, 2013).

The behavior of chemically modified starch depends on starch source, reactant concentration, pH, reaction time, the present of catalyst, type of substituent, degree of substitution (DS), and the distribution of the substituent in the starch molecule. In plants, starch is found in a semi-crystalline granular form that has a complex organization and structure(Sparks & Kissell, 2013). Modification decreased the water solubility of films because the modifiers (acetic anhydride and citric acid) act as a barrier against the diffusion of the water to films. Low water uptake in the modified starch films can be explained in terms of changes in molecular structure of the starch (Ikhtiyarova, 2018).A cross-link network is formed in the starch molecules when hydroxyl group (OH) is replaced with acetyl and carboxyl groups, which inhibit the absorption of water as these groups are less hydrophilic than the OH group (Tawakaltu et al., 2015).

2.8 Mango plant

Mango (Mangifera indica) is a fleshy stone fruit belonging to the genus Mangifera, consisting of numerous tropical fruiting trees in the flowering plant family Anacardiaceae.The mango tree is commonly cultivated in many tropical and subtropical regions, and it can grow up to 15-20m high, and also its trunk can reach a diameter of 1.5m. The fruit is oval; round, heart shaped, kidney- shaped with varying sizes and bears one seed. It measures an average of 8-20cm by 7-12cm.The seed can be hairy or fibrous. The ripe fruit varies in size and color. There are several cultivars, which are variously yellow, orange red, or green(Hassan et al., 2013).

From mango handling, high amounts of by products are generated and their discarding represents a problem that is governed by universal law. In consequence, finding new conceivable application area to feat these wastes for the production of high-value products have extended increasing awareness. There is a recognition that mango seed (kernel and seed coat) had protein contents of 5.09 and 6.12%; moisture, 3.58 and 5.11%; crude fat, 18.67 and 11.33%; mineral ash, 2.65 and 1.98%; fibre, 5.47 and 2.02% while the carbohydrate was 64.24 and 72.24% respectively(Tesfaye, 2017).

Mango seed is a single flat oblong seed that can be fibrous or hairy on the surface, depending on the cultivar. It contains a tenacious coat enclosing the kernel. The seed content of different varieties of mangoes ranges from 9% to 23% of the fruit weight and the kernel content of the seed ranges from 45.7% to 72.8% (Kittiphoom, 2012).

Huge quantities of mango seed by-products are produced by the food industry raises serious economic, management and environmental problem besides being a great defeat of valuable materials (Elgindy, 2017).

Abbildung in dieser Leseprobe nicht enthalten

Figure 2.1: Parts of mango fruit

Table 2.1: Composition of MKSP

Abbildung in dieser Leseprobe nicht enthalten

Table 2.1: above indicate that mango kernel and stone is used for thickener due to a greater number of carbohydrates constituent which is the sources of starches. However, it is clearly sited in the literature using this thickener without modification with reactive dyes results the reaction of dyes with thickeners this is due to the thickener and reactive dyes contain a greater number of hydroxyl groups. Concerning the reaction of the above-mentioned reagents with starch, part of hydroxyl groups on anhydro-glucose units is substituted with acetyl groups and, consequently, esters (starch acetates) are formed. The number of acetyl groups incorporated into the starch molecule is dependent on the reactant concentration, pH, reaction time, and presence of catalysts.

2.9 Literature gap

Most of the studies in recent years have focused on analyzing starch extracted from mango seed kernel and stone and most studies were in context of application in food sciences and only small bodies of literature dealing with textile-related end uses were available within no any chemical modification. The methods of extraction of starch and modification from these sources were not customized to the mango kernel and stone unique properties. These chemically modified mango kernel stone have never been studied in the context of application as a textile print paste thickener which makes this study unique in its approach.

The goal of the investigation is to modify chemically extracted starch from mango seed kernel followed by characterization of the extracted starch by using physicochemical techniques. The characterization of starch was further knowledge on the degree of compatibility of the starch with other print paste auxiliaries and aids the choice of modification of the starch molecule to increase the compatibility. Upon the completion of characterization of extracted starch granules, the next step is to use the extracted and chemically modified starch as a thickener in a conventional print paste recipe. The resultant print quality was analyzed for its performance on the basis of crock fastness, bending length, washing fastness and depth of the color. This study enables the new sources of chemically modified starch to be used in a commercially high value end use and will help production of these grains more profitable thus benefitting farmers and industries in Ethiopia and other states.

CHAPTER 3

MATERIALS AND METHODS

3.1 Materials

In this research 100% cotton fabric, Mango kernel stone powder and polyester bolting cloth were used.

3.2 Equipment

The following Equipments were used to carry out this investigation; Weighing balance, viscometer (BTRA viscosity cup), Beaker, thermometer, PH meter, Sample printing table, manual silk screen, Rubbers squeeze, oven dryer, steamer, Mac gregor color eye 850 Spectrophotometer, Laundro meter and Crock meter and FITR instrument.

3.3 Chemicals

The chemicals given in the table below were used to carry out the investigation.

Table 3.1: List of chemicals

Abbildung in dieser Leseprobe nicht enthalten

3.4 Methods

3.4.1 Experimental Procedure

3.4.1.1 Mango collection

Mango seeds as a byproduct were obtained from the mango juice house and Borkena River found in Kombolcha city administration to get mango kernel powder (MKSP) from its kernels and stone parts.

3.4.1.2 Mango kernel stone powder preparation (MKSP)

After mango were obtained, then it was sliced by stainless steel knife, washed and wet grinded with 0.25 ml sodium hydrosulphite to prevent oxidation problem, filtered and settled down, dried and shacked by lower speed of juice pulpier to obtain solid particle size at my home.

3.4.1.3 Investigation of particle size

The particle sizes were investigated through re grinding the solid particle size obtained above by using mechanical seed grinding machine and fine powder were obtained with 0.1, 0.5, 90, 125, 355, 425 micrometer (µm) by using cieve analyzer at BahirDar university chemical engineering department found in southern parts of Ethiopia. 90 µm particle sizes was selected for the investigation due to 0.1 and 0.5 µm particle sizes were insufficient in amount and the reset were coarser and create a problem during screen printing as they block the mesh of the screen.

3.4.1.4 Identification of functional groups

After the required particle size above, identification of functional groups for both chemically modified and unmodified mango kernel stone powder (MKSP) were carried out by using FITR testing instrument and the data was recorded and later on analyzed.

3.4.1.5 Determining rheological properties of powder paste

The viscosity of starch samples and the internal structural bonding was determined by rheological analysis of starch solutions. Unmodified and modified starch solutions of 5%, 6% and 7% concentration were prepared by adding distilled water and the solutions were then cooked in a water bath for 15 min at 65°C, 75°C and 85°C with constant stirring to avoid lump formation. The gelatinized starch samples were then allowed to cool down and a BTRA viscosity cup was used to determine the apparent viscosity in centi poise at a uniformly stirring at room temperature (°C) after cooling.

3.4.1.6 Experimental design

Mini tab of Taguchi and ANOVAs one-way design were used to decide the number of runs, level of design and number of factors and achieve optimum tests and the significance of all tested samples. In this research the level of design were 3 (9 runs) and the number of factors were 2 (MKSP concentration and gelatinization temperature).

Table 3.2: Experimental design for testing

Abbildung in dieser Leseprobe nicht enthalten

3.4.1.7 Preparation of MKSP paste

Pastes of MKSP with 5%, 6% and 7% concentration were prepared by sprinkling the powder in 10 ml water with continuous mechanical stirring and soaking for 10 min. After 10 min the pastes were taken in beaker and heated at temperature of 65oC, 75oC and 85oC for 10 minutes with continuous mechanical stirring to get homogeneous paste on temperature and time adjustable stove. After 10 min each paste were taken into beaker containing 3% shade reactive dye, 2gm urea, 3gm sodium carbonate, 0.5 ml wetting agent and 0.25 ml sequestering agent and continuously stirred for 5 min to get uniform printing pastes. After uniform printing pastes were prepared, then full bleached plain fabric was printed and dried at 90oCfor 5 min, steamed at 102oC for 10 min in steamer and taken for one cold wash followed by two hot wash and one cold wash and dried at 90oC for 5 min in mini drier.

3.4.1.8 Chemical modification of mango kernel stone powder (MKSP)

Following three thickeners were prepared by using 5gm, 6gm and 7gm Mango Kernel Stone powder.

MKSP + Acetic Acid: 3%, 4% and 5% acetic acid were added to 5gm, 6gm and 7gm MKSP with continuous stirring and allowed to dry at atmospheric temperature in order to prevent evaporation of acid from the powder and then immediately taken to FTIR to identify functional groups.

MKSP + Hydrogen peroxide: 3%, 5% and 7% Hydrogen peroxide were added to 5gm, 6gm and 7gm MKSP with continuous stirring and allowed to dry at atmospheric temperature in order to prevent evaporation of Hydrogen peroxide from the powder and then immediately taken to FTIR instrument to identify functional groups.

Preparation of pastes and printing with modified MKSP

3.4.1.9 Preparation of pastes from acetic acid modified MKSP

Pastes of modified MKSP with acetic acid (5%, 6% and 7%) concentration were prepared from each modified powder by sprinkling in 10 ml and heated to a temperature of 65 oC,75oC and85oC for 10 minutes with continuous stirred to get homogeneous paste of all modified mango kernel stone powder on temperature and time adjustable stove. After 10 min the pastes were taken in to beaker containing 3% shade reactive dye, 2gm urea, 3gm sodium carbonate, 0.5 ml wetting agent, 0.25 ml sequestering agent and stirred for 5 min to get uniform printing pastes. After uniform printing pastes were prepared, then full bleached plain fabric was printed and dried at 90oC for 5 min, steamed at 102 oC for 10 min in steamer and taken for two hot wash followed by one cold wash and dried at 90oC for 5 min in mini drier.

3.4.1.10 Preparation of pastes from hydrogen peroxide modified MKSP

Pastes of modified MKSP hydrogen peroxide (5gm, 6gm and 7gm) concentration were prepared from each modified powder by sprinkling in 10 ml and heated at temperature of 65oC, 75oC and 85oC for 10 minutes with continuous stirring to get homogeneous paste of all modified Mango kernel stone powder on temperature and time adjustable stove.

After 10 min the pastes were taken in to beaker containing 3% shade reactive dye, 2gm urea, 3gm sodium carbonate, 0.5 ml wetting agent, 0.25 ml sequestering agent and stirred for 5 min to get uniform printing pastes. After uniform printing pastes were prepared, then full bleached plain fabric was printed and dried at 90oC for 5 min, steamed at 102 oC for 10 min in steamer and taken for one cold wash followed by two hot wash and one cold wash and dried at 90 oC for 3 min in mini drier.

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