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PROJECT TOPIC AND MATERIAL ON COMPARATIVE ANALYSIS OF STAIN REMOVAL METHODS USED ON COTTON FABRICS IN SOME SELECTED HOSPITALS IN NIGERIA
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ABSTRACT
Some effect of repeated laundering processes with different practical formulations of stain removal methods of blood and urine stains from 3 healthcare institutions (Ahmadu Bello University Teaching Hospital- Zaria, Aminu Kano Teaching Hospital- Kano and National Orthopedic Hospital- Kano) were carried out. Physical fabric properties such as breaking load, breaking extension, percentage shrinkage, moisture content and moisture regain as well as colour fastness were analyzed with the hospital white (bed-linen) and green theatre linen made from 100% woven cotton fabrics. Analyses of the sample after the 3rd, 6th and 9th washing cycles were investigated. The colour change in shades were evaluated from visual observation using the AATCC Evaluation Procedure 2 Gray Scale for Assessing Staining, which showed a yellowing effect on the white hospital linen (ABUTH) as a result of the continuous bleaching action on the repeated blood stained linen with a change in colour of 4 after the 9th wash. The breaking load values increased after every washing for all samples analyzed with the ABUTH hospital linen showing the highest breaking load values up to the 9th wash. The percentage shrinkage values also showed an increase in the shrinkage properties up to the 9th wash for all sample analyzed with the least shrinkage properties from the blood treated samples of the ABUTH hospital linen. The moisture content and moisture regain showed the highest percentage values with the blood treated samples of the ABUTH up to the 9th laundering. These attributes, specifically on the blood treated hospital linen from ABUTH amongst other samples analyzed showed an unequal property along the length and breadth of the fabric to a point of which the fabric stability and functionality becomes compromised thereby degrading the fabric. This study may help to improve the blood stain removal methods and fabric performances in hospital laundering.
TABLE OF CONTENTS
Title Page – – – – – – – – – i
Declaration – – – – – – – – – ii
Certification – – – – – – – – – iii
Dedication – – – – – – – – – iv
Acknowledgement – – – – – – – – v
Abstract – – – – – – – – – vi
Table of Content – – – – – – – – vii
List of Figures – – – – – – – – – xi
List of Tables – – – – – – – – – xii
CHAPTER ONE
1.0 INTRODUCTION- – – – – – – – 1
1.1 The washing process (Laundering Regime) – – – 1
1.2 Soil removal from fabrics – – – – – – 2
1.2.1 Absorbing – – – – – – – – 2
1.2.2 Washing in water – – – – – – – 2
1.2.3 Solvents – – – – – – – – 2
1.2.4 Bleaching – – – – – – – – 3
1.3 Factors affecting soil removal – – – – – 3
1.3.1 Temperature of operation – – – – – – 3
1.3.2 Duration of each step in the washing systems – – – 4
1.3.3 Concentration of liquid bath detergent in washing systems – – 4
1.4 Detergents – – – – – – – – 4
1.4.1 Types of Detergents – – – – – – – 5
1.5 Cotton (Natural Fibre)- – – – – – – 8
1.5.1 Physical and mechanical properties of cotton fabrics- Physical Properties- 8
1.5.2 Mechanical properties – – – – – – – 10
1.5.3 Tear Test – – – – – – – – 12
1.5.4 Abrasion resistance – – – – – – – 13
1.5.5 Fabric drape – – – – – – – – 14
1.6 Stains/soils – – – – – – – – 15
1.6.1 Blood – – – – – – – – – 15
1.6.2 Urine – – – – – – – – – 16
1.7 Statement of the research problem – – – – – 16
1.8 Justification of the work – – – – – – 17
1.9 Research objectives – – – – – – – 18
1.10 Scope of study- – – – – – – – 18
CHAPTER TWO
2.0 LITERATURE REVIEW – – – – – – 19
CHAPTER THREE 3.0 MATERIALS AND METHODS – – – – – 21
3.1 Materials – – – – – – – – 21 3.1.1 Chemicals – — – – – – – – 21
3.1.2 Apparatus and Equipment – – – – – – 21
3.2 Methods – – – – – – – – 22 3.2.1 Laundering Regime 1 – – – – – – – 22
3.2.2 Stain Removal Methods – – – – – – 22
3.2.3 Laundering Regime 2 – – – – – – – 23
3.3 Determination of Fabric Properties – – – – 23
3.4 Determination of Moisture Content & Moisture Regain (Physical Properties) – – – – – – – 24
3.5 Determination of Percentage Shrinkage (Physical Properties) – – – – – – – 24
3.6 Determination of Standard Fastness – – – – 25
CHAPTER FOUR
4.0 RESULTS AND DISCUSSION – – – – – 26
4.1 Effects of washing cycles on breaking strength- Hospital linen – 26
4.2 Effects of washing cycles on breaking extension- Hospital linen – 31
4.3 Effects of washing cycles on breaking strength- Green theatre linen- 35
4.4 Effects of washing cycles on breaking extension- Green theatre linen 39
4.5 Effects of moisture content and moisture regain on hospital linen 43
4.6 Effects of moisture content and moisture regain on green theatre linen 46
4.7 Effects of percentage shrinkage on hospital linen – – – 49
4.8 Effects of percentage shrinkage on green theatre linen – – 50
CHAPTER FIVE
5.0 CONCLUSION AND SUMMARY – – – – – 59
5.1 Recommendation – – – – – – – – 62
REFERENCES – – – – – – – – – 63
APPENDICES- – – – – – – – – 66
LIST OF FIGURES
Fig. 3.3.1: Effect of 3rd wash of hospital dry and wet linen on breaking load – – 26
Fig. 3.3.2: Effect of 6th wash of hospital dry and wet linen on breaking load- – 27
Fig, 3.3.3: Effect of 9th wash of hospital dry and wet linen on breaking load – – 28
Fig. 3.3.4: Effect of 3rd wash of hospital dry and wet linen on breaking extension – 31
Fig. 3.3.5: Effect of 6th wash of hospital dry and wet linen on breaking extension – 32
Fig. 3.3.6: Effect of 9th wash hospital dry and wet linen on breaking extension – 33
Fig. 3.3.7: Effect of 3rd wash of theatre dry and wet linen on breaking load – – 35
Fig. 3.3.8: Effect of 6th wash of theatre dry and wet linen on breaking load – – 36
Fig. 3.3.9: Effect of 9th wash of theatre dry and wet linen on breaking load – – 37
Fig. 3.3.10: Effect of 3rd wash of green theatre dry and wet linen on breaking extension 39
Fig. 3.3.11: Effect of 6th wash of green theatre dry and wet linen on breaking extension 40
Fig. 3.3.12: Effect of 9th wash of green theatre dry and wet linen on breaking extension 41
Fig. 3.4.1: Effect of moisture content and moisture regain for 3rd wash of hospital linen on percentage of moisture – – – – – – – 43
Fig. 3.4.2: Effect of moisture content and moisture regain for 6th wash of hospital linen on percentage of moisture – – – – – – – 44
Fig. 3.4.3: Effect of moisture content and moisture regain for 9th wash of hospital linen on percentage of moisture – – – – – – – 45
Fig. 3.4.4: Effect of moisture content and moisture regain of green theatre linen – 46
Fig. 3.5.1: Effect of treated and untreated hospital linen on percentage shrinkage – 49
Fig. 3.5.2: Effect of treated and untreated green theatre linen on percentage shrinkage- 50
LIST OF TABLES
Table 3.3.1: Breaking load test for 3rd wash (dry sample) – hospital linen – – 66
Table 3.3.2: Breaking load test for 3rd wash (wet sample) – hospital linen – – 67
Table 3.3.3: Breaking load test for control sample (dry and wet sample) – hospital linen- 68
Table 3.3.4: Breaking load test for 6th wash (dry sample) –hospital linen – – 69
Table 3.3.5: Breaking load test for 6th wash (wet sample) – hospital linen – – 70
Table 3.3:6: Breaking load test for 9th wash (dry sample) – hospital linen – – 71
Table 3.3.7: Breaking load test for 9th wash (wet sample) – hospital linen – – 72
Table 3.3.8: Breaking load test for 3rd wash (dry sample) – green theatre linen- – 73
Table 3.3.9: Breaking load test for 3rd wash (wet sample) – green theatre linen- – 74
Table 3.3.10: Breaking load test for control sample (dry & wet samples) – green theatre linen – – – – – – – – – 75
Table 3.3.11: Breaking load test for 6th wash (dry sample) – green theatre linen – 76
Table 3.3.12: Breaking load test for 6th wash (wet sample) – green theatre linen – 77
Table 3.3.13: Breaking load test for 9th wash (dry sample) – green theatre linen – 78
Table 3.3.14: Breaking load test for 9th wash (wet sample) – green theatre linen – 79
Table 3.4.1: Moisture content and moisture regain for hospital linen at different washing cycles – – – – – – – – – 79
Table 3.4.2: Moisture content and moisture regain for green theatre linen at different washing cycles – – – – – – – – 83
Table 3.6.1: Colour fastness result I.S.O (1) of the 3rd, 6th and 9th washings for hospital linen and theatre linens – – – – – – – 52
CHAPTER ONE
1.0 INTRODUCTION
Removal of stains from clothes is necessary for proper care of the clothes and to increase the lifespan of the fabric. Healthcare linen can be subjected to a huge range of staining, including food, blood, urine, sweat and other body excretions so the laundry‟s success in producing clean, stain-free linen is a testimony to the effectiveness of the applied washing regimes (Ian, 2010).
1.1 The Washing Process (Laundering Regime)
The washing or cleaning process in a typical detersive system usually consists of the following sequence of operations (Omole, 1994);
I. The soiled substrate (fabric) is immersed or otherwise introduced into a large excess of the bath liquor. Sufficient liquor is used to provide a thick layer over the whole surface of the substrate. During this stage, air is displaced from the soil and substrate i.e. they become wetted by the bath.
II. The system is subjected to mechanical agitation, for example, rubbing or shaking, this provides shearing action which aids in separating soils and other dirt‟s from the substrate and dispersing them in the bath.
III. The fouled bath, carrying the removed soil and dirt is drained, wiped, squeezed or otherwise removed from the substrate.
IV. The substrate is rinsed free of the remaining fouled bath. This rinsing step can be quite important in determining the final cleanliness of the substrate.
V. The clean substrate is dried or otherwise brought to the desired finished state.
1.2 Soil Removal from Fabrics
All soils on fabrics should be treated gently as hard rubbing or wrong application of cleaning fluid can ruin the cloth. If the cause of the soil and the type of fabric on which it has occurred are known, it is more likely to be able to remove the soil successfully without damaging the fabric (Peter, 1993).
There are four basic methods of soil removing from fabric:
i. Absorbing
ii. Washing in water
iii. Use of solvents
iv. Bleaching
1.2.1 Absorbing
This is used to deal with wet soils spilled on the fabric and also to get rid of greasy particles on fur and other fabrics that cannot be washed. Typical absorbents are salts (absorbs urine and fruit-juice soil from carpets etc.) and French chalk or talcum (absorb grit and dirt from fur etc.).
1.2.2 Washing in water
Soil must be removed immediately with cold water; hot water should be avoided (i.e. cause soil to be more strongly held onto the fabric). The whole fabric is soaked in soap solution for washing.
1.2.3 Solvents
Solvents are used to remove soils caused by grease or oil. Many solvents can be employed and the most common ones being used are trichloroethane (sold as spot remover under various trade names), carbon tetrachloride, (white spirit, Acetone, acetic
acid, white vinegar, oxalic acid, lemon juice or 50% solution of citric or tartaric acid, fat, margarine or butter) used to soften tar or oil.
1.2.4 Bleaching
Two types of bleaches are employed in dirt removal. They are oxidizing and reducing bleaches. Oxidizing bleaches are the ones which destroy dirt‟s by oxidation, while reducing of bleaches destroy dirt‟s by reduction. Examples of oxidizing bleaches are hydrogen peroxide and chlorine bleach (usually containing sodium hypochlorite). While example of reducing bleaches is sulphurdioxide; bleaches of this type are mainly used by laundries and dry-cleaners (Peter, 1993).
1.3 Factors affecting Soil Removal
Before considering practical washing systems (which are usually quite complex and difficult to resolve), it is helpful to outline the various factors which determine the degree of soil removal, and also to see how soil is removed in various simplified model washing system (Perdue, 1970). These factors are:
i. Temperature of operation.
ii. Duration of each step in the washing system.
iii. Type of degree of mechanical action used.
iv. Concentration of liquid bath detergents in the washing systems.
1.3.1 Temperature of Operation
Practical washing with materials shows that at high temperature of washing at long cycle‟s causes excessively hard wrinkles and reduces the crease shedding properties. Some experiments carried out showed that the effect of temperature on various types of fabrics at a particular concentration of soap and detergent was done keeping concentration and time constant. E.g. Increase in temperature increases the degree of mobility of the soap particles thus increasing the chances of breaking up the dirt‟s or soils (Perdue,1970).
1.3.2 Duration of Each Step in the Washing Systems
This is the time taken for the soil to be released from the fabric at a particular concentration of soap and detergent solution, Keeping temperature and concentration constants.
1.3.3 Concentration of Liquid Bath Detergent in Washing Systems
This is the percentage of detergents used to remove soil on each of the soil fabrics by varying the concentration and keeping time of washing and temperature of washing constants. The importance of concentration determination or detergency is that, it helps to know the exact quantity of detergents to be used in washing processes, when the quantities of the fabrics are known (Perdue, 1970).
1.4 Detergents
A detergent is a cleansing agent which exerts cleansing action on a material by helping the water to soak into the material quickly to make washing easier. The dirt is divided into little particles by the detergent and this can be more easily washed out of the material. The detergent also keeps the dirt suspended in the water and prevents it from settling on the fabric again. Any material which exerts a cleansing action is referred to as a detergent; thus water alone or indeed a solvent such as perchloroethylene can be called a detergent. Soap is the product of the reaction between caustic soda and a fat by a process known as „saponification‟ while synthetic detergents are manufactured from organic chemicals, most of which come from petroleum sources.
1.4.1 Types of Detergents
There are different groups in which detergents can be classified, namely anionic detergents, cationic detergents, non-ionic detergents, synthetic or soapless detergents. The most important thing is to be able to select a suitable detergent for a particular purpose because if the wrong detergent is used for a particular fabric, it could damage it, ruin the colours or not clean it efficiently.
1.4.1.1 Anionic Detergents
The most common detergent/surfactants are the alkyl sulphates and the aryl alkyl sulphates. Alkyl sulphate is one of the first soapless detergent. These compounds possess many desirable features. They are approximately neutral in aqueous solutions; they lather and clean in alkaline, neutral in acid solutions. Most importantly, these anionic surfactants do not form scum in hard water because calcium and magnesium alkyl sulphates are soluble in water. The alkyl sulphonates ionize in a manner similar to soap and to the alkyl sulphates (Mittal, 1978). The molecule ionizes thus:
Anion
Surfactants of this type are almost biodegradable (that is broken up by the bacteria present in rivers and in the sewage works treatment) and are known as „soft‟ detergents; this is advantage because detergents that are for washing should be soft and at least 90% biodegradable (Mittal, 1978).
1.4.1.2 Cationic Detergents
These materials are cation active that is to say that they ionize or dissociate, they do not hydrolyze and can be used effectively in hard water.
Ionization of this type of compound takes place as follows:
They have disinfecting powers and are sometimes used, especially in hospital launderettes for disinfecting articles which cannot be subjected to high temperatures (Mittal, 1978). Due to this, they are added to the final rinse of the washing process.
Another possible application for cationic substances in the laundry is as textile softening agents. „Softening‟ in this context refers to the effect of producing a more bulky fabric with a softer handle than one, which has not been so treated. When used as softening agent the cationic substances are again added to the final rinse of the washing process, but in this case there is no need of restriction on the type of detergent used in the washes (Mittal, 1978).
1.4.1.3 Non Ionic Detergent
As the name implies these material do not ionize and therefore are extremely stable under any condition likely to be encountered in laundry processing, making them good wetting and emulsifying agents for stain removal processes (Barry, 1998).
1.4.1.4 Synthetic or Soap Less Detergents
During the Second World War when there was a shortage of oils and fats in Great Britain a considerable amount of work was done on the production of synthetic detergent compounds. It was at this time these new detergents came into use in package domestic washing powders and as a result the general public became aware of the word detergent (Barry, 1998).
Unfortunately, modern advertisement with its somewhat outrageous claim has resulted in the public believing that what package detergent provides is the magical answer to successful washing of all types of textile materials. This often produces disastrous result, which sometimes land in the hands of the professional launderer. Worse still, the launderer is expected to work this „magic‟ on wholly suitable textile materials.
Soapless detergents do not react with minerals in hard water. They are formulated with such ingredients as surfactants, which suspend dirt particles with reduced suds, builders, which prevent scum formation.
1.4.1.5 Surface Active Agent
These are compounds which when dissolved in water; in a very small amount considerably reduce the surface tension of water with respect to air or other substances. They are sometimes called surfactants. They have an organic body made of long molecular chains, which confer, to its nature. At the end of the body is a hydrophilic head. It includes soluble detergent in liquid medium, dispersing agents, foaming agents in penetrating agent and emulsifying agent (Encyclopedia, 1990)
(a) Dispersing agents: increase the stability of the dispersion of one liquid in another.
(b) Emulsifying agent: increase the stability of dispersion of two immiscible liquid phases.
(c) Foaming agents: increase the stability of suspension of gas bubbles in a liquid medium.
(d) Penetrating agents: increase the penetration of liquid medium into porous materials.
(e) Wetting agents: increase the spreading of a liquid medium on the surface (Mittal, 1978).
1.5 Cotton (Natural Fibre)
Cotton is the most versatile and the most used textile fibres. It is the cheapest natural fibres used in clothing applications. Cotton is attached to the seed of certain plant of genius „Gossypium‟. Cellulose regardless of source has been shown to consist of carbon (44.4%), hydrogen (6.2%), and oxygen (49.4%) which corresponds to an empirical formular of (C₆H₁₂O₅)n thus, classifying it as a carbohydrate (Peter, 1993). Investigations have shown that hydrolysis of cellulose gives high yield of the sugar D-glucose [1] the yield of glucose varying with the conditions of hydrolysis. The long linear chain of cellulose permits the (-OH) group on each hydro glucose to interact with the hydroxyl group of adjacent chains through hydrogen bonding and van der waal attractions. These strong intermolecular forces between chains, coupled with the high linearity of the molecule, account for the crystalline nature of cellulose fibre. All cellulosic fibre are hydrophilic (water attracting) in character, they crease badly when washed except when treated with crease resist finish (Peter, 1993)
1.5.1 Physical and Mechanical Properties of Cotton Fabrics- Physical Properties
1.5.1.1 Fabric Thickness
It might be expected that the thickness of a fabric is one of its basic properties giving information on its warmth heaviness or stiffness in use. In practice, thickness measurement is rarely used as they are very sensitive to pressure used in the measurement. Instead fabric weight per unit area is used commercially as an indicator of thickness.
Besides fibres, a fabric encloses a large amount of air, which among other things, is responsible for its good thermal insulation properties. When a fabric is compressed, the space between the fibers is decreased until they eventually come into contact with one another. The stages in the deformation of a fabric have been identified (Matsudaira and Qin, 1995). Firstly, the individual fibers protruding from the surface are compressed. The resistance to compression in this region comes from the bending of the fibres. Secondly, contact is made with the surface of the yarn, at which point the inter-yarn and/or inter-fiber friction provides the resistance to compression until the fibres are all in contact with one another. In the third stage the resistance is provided by the lateral compression of fibers themselves.
1.5.1.2 Fabric Shrinkage
The product of textile manufacture, whether yarn or fabric, is stable only to moderate degree. The instability may manifest itself in shrinkage or in extensibility, and may assume such properties that garments become unsuitable for further use as soon as they are laundered or dry-cleaned, and sometimes even during wear.
1.5.1.3 Fabric Handle
Fabric uses can be roughly divided into industrial, household and apparel. Fabric for industrial use can be chosen on straight forward performance characteristics such as tensile strength, extension and resistance to environmental attack. However, fabrics intended for clothing such as cotton fabrics have less emphasis placed on their technical specification and more on their appearance and handling characteristic such as luster, smoothness or roughness, stiffness and draping quality. „Handle‟, the term given to properties assessed by touch or feel depends upon subjective assessment of a fabric by a person. Terms such as smooth, rough, stiff or limp depends strongly on the type of fabric being assessed, for instance the smoothness of a worsted suiting is different in nature from that of these properties. Attempt has been made over the years to devise the objective tests to measure some or all of the factors that make up handle. Fabric stiffness and drape were some of the earliest properties to be measured objectively (Pierce, 1980).
1.5.2 Mechanical Properties
1.5.2.1 Breaking Strength
This is the maximum tensile force extending a test piece to breaking point. The force at which a specimen breaks is directly proportional to its cross sectional area, therefore when comparing the strength of different fibres, yarns and fabrics, allowance has to be made for this (Morten and Hearle, 1993).
1.5.2.2 Stress
Stress is a way of expressing the force on a material in a way that allows for the effect of the cross sectional area of the specimen on the force needed to break it.
In the case of textile materials, the cross sectional area can only be easily measured in the case of fibres with circular cross section. The cross section of yarns and fabrics contain an unknown amount of space as well as fibres so that in these cases the cross sectional area is not clearly defined. Therefore stress is only used in limited number of application involving fibers.
1.5.2.3 Specific (Mass) Stress
Specific stress is a more useful measurement of stress in the case of yarns as their cross-sectional area is not known. The linear density of the yarns is used instead of the cross sectional area as a measure of yarn thickness. This allows the strength of yarns of different linear densities to be compared.
1.5.2.4 Breaking Length
Breaking length is an older measure of tenacity and is defined as theoretical length of a specimen of yarn whose weight would exert a force sufficient to break the specimen. It is usually measured in kilometers.
1.5.2.5 Elongation
Elongation is the increase in length of the specimen from its starting length expressed in units of length. The distance that a material will extend under a given force is proportional to its original length; therefore elongation is usually quoted as strain or percentage extension. The elongation at maximum force is the value some often quoted (Morten and Hearle, 1993), (McIntyre and Daniels, 1995).
1.5.2.6 Strain
The elongation that a specimen undergoes is proportional to its initial length. As a fraction of the original length.
1.5.2.7 Extension Percentage
This measure is the strain expressed as a percentage rather than a fraction.
Breaking fraction is the extension percentage at breaking point.
After care treatment such as laundering affects the breaking strength of cotton fabric in the fabrics are relaxed as a result of the mechanical application of laundering. Therefore, elongation at break or break elongation increase with increase in cotton fabric laundering.
1.5.3 Tear Test
A fabric tears when it is snagged by a sharp object and the immediate small puncture is converted into a long rip by what may be very small extra effort.
Measuring Tear Strength: The fabric property usually measured is the force required to propagate an existing tear and not the force required to initiate a tear as this usually requires a cutting of thread. As part of the preparation of the fabrics specimens, a cut is made in them and then the force required to extend the cut is measured. This is conveniently carried out by gripping the two halves of the cut in a standard tensile tester. The various tear test carried out in this manner differ mainly in geometry of the specimen. The simplest is the rip test where a cut is made down the centre of a strip of fabric and the two tails pulled apart by a tensile tester.
1.5.4 Abrasion Resistance
Fabric abrasion has been defined as a simply rubbing action (Booth, 1968).It is an aspect of wear and rubbing away of the components fibres and yarns of the fabric.
Hamburger (1994) states that abrasion is a series of repeated stress application, usually caused by forces of a relatively low order of magnitude, which occur many times during the life span of the material. The ability of a material to absorb energy repeatedly by means of low load deformation and recovery is related to abrasion resistance.
1.5.4.1 Factors Affecting Abrasions Resistance
The evidence concerning the various factors that influence, the abrasion resistance of fabrics is contradictory. This is because experiment has been carried out under widely different conditions in particular using different modes of abrasion. The results are not comparable and often opposing results have been reported. The factors that have been found to affect abrasion include the following (Galbraith, 1975), (Birds, 1984). Fiber Type:
It is thought that the ability of a fiber to withstand repeated distortion is the key to its abrasion resistance. Therefore high elongation, elastic recovery and work of rapture are considered to be more important factors for a good degree of abrasion resistance in fibre. Nylon is generally considered to have the best abrasion resistance. Cotton has a moderate abrasion resistance.
Fiber properties:
One of the results of abrasion is the gradual removal of fibres from the yarns. Therefore factors that affect the cohesion of yarns will influence their abrasion resistance. Longer fibres incorporated into a fabric confer better abrasion resistance than short fibers because they are harder to remove from the yarns. For the same reason filament yarns are more abrasion resistant than staple yarns from the same fibre. Fabric Structure:
The crimp of the yarn in the fabric affects whether the warp or the weft is abraded the most, Fabrics with crimp evenly distributed between warp and weft give the best wear because the damage is spread evenly between them. If one set of yarns is predominately on the surface then this will wear most; this effect can be used to protect the load-bearing yarns. Yarn twist:
There has been found to be an optimum amount of twist in a yarn to give the best abrasion resistance. At low-twist factors fibers can easily be removed from the yarn so that it is gradually reduced in diameter. At high twist level, fibres are held more tightly but the yarn is stiffer so it is unable to flatten or distort under pressure when being abraded. It is this ability to distort that enables the yarn to resist abrasion.
1.5.5 Fabric Drape
Drape is the term used to describe the way a fabric hangs under its own weight. It has an important bearing on how good a garment looks in use. The draping qualities required from a fabric will differ completely depending on its end use; therefore a given value for drape cannot be classified as either good or bad. Knitted fabrics are relatively floppy and garment made from them will tend to follow the body contours. Woven fabrics are relatively stiff when compared with knitted fabrics so they are used in tailored clothing where the fabrics hang away from the body and disguise its contour. Measurement of fabric drape is meant to assess its ability to hang in graceful curves.
In drape test, the specimen deforms with multi-directional curvature and consequently the results are dependent to a certain amount upon the sheer properties of the fabric. The results are mainly dependent however, on the bending stiffness of the fabric (BS 5058). In crusick drape test, a circular specimen is held to its area.A value known as the drape coefficient, F, is determined by:
100%
The higher the drape coefficient, the stiffer is the fabric.
1.6 Stains / Soils
1.6.1 Blood
Blood is the red fluid that oozes out of the body when sustained with a cut or deep injury. The composition of the blood is quite complex. Blood is composed of straw-coloured liquid called plasma which contains suspended cells. The different specialized cells found in blood are; Red blood cells, White blood cells and Platelets. Approximately 90% of plasma is water-blood`s solvent with the rest composed of dissolved substance, primary proteins (e.g albumin, globulin and fibrogen). Plasma typically accounts for 55% by volume of blood and of the remaining 45% the greatest contribution is from the red blood cells (Membranes, 2011).
1.6.2 Urine
Urine is composed mostly of water and organic wastes as well as some salt. The composition of urine can vary according to diet, time of the day, and diseases. In one measure the make-up of urine is 95% water and 5% solid. In terms of organic wastes (per 1,500 ml), urine containing 30g of urea, 1-2g each of ceratinine and ammonia, and 1g of uric acid. In terms of salt or ions, 25g per 1,500 ml of urine contain the positive ions of sodium, potassium, magnesium and calcium, as well as the negative ions of chlorine, sulphate and phosphate (Answer.com, 2011).
1.7 Statement of the Research Problem
“Removing stains can sometimes seem like a complex algebra problem”. A Hospital‟s textile or linen will often become soiled with blood and other organic stains and the longer the blood stains are left; the more difficult it will be to remove them. Ordinarily, when someone gets blood on their clothing at home, they will usually sluice it or rinse off before it dries. In a hospital, blood soiled fabrics would rarely be sluiced immediately and the stain may not be treated until it reaches the laundry which may be several days later. By this time the blood would have dried onto and into the fabric and will no longer respond to normal wash. This means that launderers need to resort to more drastic measures if they are going to remove the blood successfully and return the item to the user in a stain free condition. Blood which is one of the prominent coloured stains on hospital linen is highly contagious and most proteins will set permanently if washed at high temperature at any stage as the higher temperature will “cook” the protein and make it difficult if not impossible to remove. Blood albumin and organic iron sometimes produce stain that are never completely removed, but only lightened.
Effect of urine in this case is predominantly on the bed linen. Urine discolours cotton white sheet and cotton blend fabrics. Urine stains are especially visible on white fabrics. Hot and warm water cause coagulation in the fibres of the material, making the stain more difficult to washout. Ammonia is also a common cleaning agent, which also happens to occur naturally in urine. However, when chlorine from bleach mixes with ammonia, it can create a noxious gas (mustard gas). This research work intends to study the cleaning processes of these organic stains and the effect of the methods on the properties of hospital textile linen.
1.8 Justification of the work
Procuring hospital textile linen by the hospital management may be capital intensive and uneconomical, if the linens are poorly managed. From this research study, assessing the characteristic changes in the performance of each fabric properties from the various stain removal methods may help to define the quality of the fabrics after some use. Hence, from the results obtained and where minimal effects occur on the fabric, a more sustainable method of upholding hospital spotted linen can be developed enabling a valuable fabric care handling with minimal damage.
1.9 Research Objectives
The aims and objectives of the research are;
1. To investigate the effect of laundering regime of three healthcares tertiary Hospitals with respect to their methods of organic stain removal for blood and urine.
2. To determine the effects of these procedures on the properties of cotton fabric.
3. To suggest improved method of stain removal with minimal degrading effects on the fabric properties.
1.10 Scope of Study
The mechanical and physical properties of the samples (theatre outfits and bed linen) used in this work were studied before and after laundering. The three tertiary healthcare institutions are; Ahmadu Bello University Teaching Hospital-Zaria. Aminu Kano Teaching Hospital-Kano, and The National Orthopedic Hospital-Kano.
This research was limited to the use of the fabric properties of each hospital, the available detergents and chemical components (reagents) used in each case, the laundering regime practiced in each hospital. This research also limits its study only on blood and urine amongst other organic stains. A standard drying method (Tumble drying) and drying time was considered for all washings.
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