Abstract
In summer season polyester made garments are not comfortable to the wearer in absence of anysoftener in fabric, this happens only for the tropical countries like Bangladesh. We have seen that inhot weather polyester made garments wearer doesn’t feel comfortable. Besides cotton made garmentsgives more comfort in the same aspect to the wearer in hot condition. Due to a novel comfortcharacteristics Cotton today is the most used textile fiber in the world. It has terrific soft hand feel,good moisture absorbency & good moisture vapor transmission. On the other hand polyester is usedfor different blended fabric & home furnishing materials for its hydrophobic nature and betterdurability. The main aim of this article is to find out the possible reason of variation of comfortbetween the cotton garments and polyester garments in the tropical countries. In this paper the comfortof cotton & polyester fibers are demonstrated with respect to their dominating properties, which areaffected by some important factors. Some physiological interaction with skin and garments are alsotaken under consideration with a technical approach in this paper.
In summer season polyester made garments are not comfortable to the wearer in absence of anysoftener in fabric, this happens only for the tropical countries like Bangladesh. We have seen that inhot weather polyester made garments wearer doesn’t feel comfortable. Besides cotton made garmentsgives more comfort in the same aspect to the wearer in hot condition. Due to a novel comfortcharacteristics Cotton today is the most used textile fiber in the world. It has terrific soft hand feel,good moisture absorbency & good moisture vapor transmission. On the other hand polyester is usedfor different blended fabric & home furnishing materials for its hydrophobic nature and betterdurability. The main aim of this article is to find out the possible reason of variation of comfortbetween the cotton garments and polyester garments in the tropical countries. In this paper the comfortof cotton & polyester fibers are demonstrated with respect to their dominating properties, which areaffected by some important factors. Some physiological interaction with skin and garments are alsotaken under consideration with a technical approach in this paper.
1. Introduction
Clothing comfort is one of the most important attributes of textile materials. Comfort cannot bereliably predicted by any single lab test of a fabric or by any series of different fabric tests. Thisis because comfort is inherently subjective; it is entirely a perception in the mind of theindividual wearer and thus defies objective, quantified analysis. This perception differs person toperson, day to day, and sometimes even moment to moment.
“Generally clothing comfort is defined as absence of perceived pain or discomfort.” It is alsodefined as “Welfare, lack of pain and of nuisance.” 1
2. Cotton Fiber
Let’s have an overview on Cotton. In the sub-continent cotton based garments are vastly used inclothing. Due to its rapid moisture vapor transmission it is getting popularity day by day. Cottonfiber is mainly cellulose based fiber which contains about 94% of cellulose. Cotton is composedof pure cellulose, a naturally occurring polymer.2
Cellulose is a carbohydrate, and the molecule is a long chain of glucose (sugar) molecules.3 Itranges in length of fiber is about 10mm to 65 mm and diameter from about 11 micron to 22micron. DP of cotton is around 1000-14000. Cotton is basically a crystalline (about 70%) fiberbut small portion of amorphous region also present in the fiber.
3. Polyester Fiber
Polymers are made by a lot of little molecules together to make one long molecule, like a string ofbeads. The little molecules are called monomers and the long molecules are called polymers.According to the American Federal Trade Commission “polyester fibers are chemically composedof at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but notrestricted to substituted terephthalate units and Para substituted hydroxyl benzoate units”.5Polyester is made by reacting ethylene glycol and terephthalic acid. Polyester fabric is highlyamorphous in the molecular structure, and hydrophobic in nature, which resist water on thesurface of the fabric.
4. Variation of comforts is depending on:
4.1 Moisture Regains
Thermal comfort is depends upon the heat release from human body & moisture release is one ofthe way of heat loss, a man can release about 1200 ml perspiration/hr. in heavy activity with hisApocrine sweat glands & Eccrine sweat glands. We know that polyester fiber moisture regain isonly about 0.4% whereas cotton fiber moisture regain is 7.0-8.5% at 65% RH. If we observe thecross section of the fiber of cotton we can see convolution form of fiber where more than 70%portions are crystalline and rest of it is amorphous portions. The cotton fiber is very absorbent,owing to the countless polar –OH groups in its polymers; these attracts water molecules, whichare also polar can able to absorb water6. And the major portion of polyester is hydrophobic innature which hardly allows moisture through the fabric. We feel discomfort whenever our perspirations are on in summer through the body & if the sweat drops are begins to deposit on ourskin in order to failure of moisture regain of the garments. Cotton can absorb our perspiration &polyester hardly can do it, therefore polyester garments wearer perceives discomfort.
4.2 Moisture Vapor Transmission:
The rate at which water vapor moves through a fabric plays an important role in determining thecomfort as it influences the human perception and the cool/warmth feeling.9This process is calledmoisture vapor transmission. Cotton is a hygroscopic fiber that is it’s a hydrophilic fiber whereaspolyester is hydrophobic in nature which resists water in its surface. Moisture vapor transmissionis relevant to the nature of the fiber. Due to the hydrophilic nature of cotton it attract moist vaporin its surface and then begins to transfer the vapor though the garments. Though it is possible totransfer vapor through the pore of fabric but polyester doesn’t allow moisture on its surfacebecause of its hydrophobic nature therefore it cannot pass vapor easily through the pore of thefabric. When a fabric allows the transport of water vapor at a faster rate, it is said to be a breathable fabric. In other words, the faster a fabric breath, the better is its comfort. So we can say that cotton is more breathable fabric than polyester.
4.3 Static Electricity:
The comfort is also depends upon fiber mechanical properties, Since static electricity is thecollection of electrically charged particles on the surface of a material, various materials have atendency of either giving up electrons and becoming positive (+) in charge or attracting electronsand becoming negative (−) in charge.7 Where cotton is the neutral in static charge. 7 Neutral instatic charge means it does not react with other matters when it is rubbed with other materials onthe other hand polyester is negatively charged when it is rubbed with other surface.8 It meanspolyester is highly sensitive to static electricity. Besides human dry skin & hair is chargedpositively whenever it rubbed with other materials like polyester. Due to this static electricitypolyester clothes is remain cling next to skin, which is a great cause of discomfort. And thereremain a small gap between garments and skin which trap hot air into it, as polyester is a less airpermeable fiber, therefore discomfort is perceived by wearer. And when dry skin getting moist itbegins to release charge then static electricity may decrease.
4.4 Microstructural Difference
Under microscope, the cotton looks like a twisted ribbon or a collapsed and twisted tube. Thistwisted property of cotton is called convolutions. The convolutions give cotton an uneven surface,which increase inter-fiber friction and enables fine cotton yarns of adequate strength to be spun.And the cross section shape is oval not circular like polyester fiber. For this reason the contactbetween cotton garments & skin is higher, therefore though a small amount of air is trap in thisgap but as the air permeability is possible through cotton, trapped air is capable to transmit troughcotton.10 On the other hand if we see the cross section of polyester fiber there we get very circulareven shaped cross section so there should be more pores in the fabric structure of polyester & thepore retain air into them; therefore having more distance to the skin. Where also some air istrapped but not released easily to the environment, which air is getting body temperature and retain heat, as well as creates discomfort to the wearer.
4.5 Sensorial Comfort
Sensorial comfort means the effect of fabric properties on human sense. Our sense working by anervous system based upon neuron. A neuroendocronic gland called hypothalamus is responsiblefor the heat mechanism of body and can send any signal created on skin to the neuron. Thecontact between the skin and the inner clothing layer determines the subjective perception ofclothing comfort, especially at high skin humidity. Strong friction between skin and clothingresults in greater displacement of the skin during body movements, and thus leads to a higherdegree of discomfort.11 When polyester fabric is get friction with skin some sort of sound isproduced which may be a cause of feeling discomfort to wear polyester garments, whereascotton is smoothly gentle fabric regarding this aspect. Besides, polyester has a great disadvantagethat has a chance of polyester allergy, where cotton is less hazardous from this point of view.12Apart from these polyester fabrics can make some discomfort on skin likes itchy, tickling, harshfeelings & causes polyester rash etc.12
Sensorial comfort means the effect of fabric properties on human sense. Our sense working by anervous system based upon neuron. A neuroendocronic gland called hypothalamus is responsiblefor the heat mechanism of body and can send any signal created on skin to the neuron. Thecontact between the skin and the inner clothing layer determines the subjective perception ofclothing comfort, especially at high skin humidity. Strong friction between skin and clothingresults in greater displacement of the skin during body movements, and thus leads to a higherdegree of discomfort.11 When polyester fabric is get friction with skin some sort of sound isproduced which may be a cause of feeling discomfort to wear polyester garments, whereascotton is smoothly gentle fabric regarding this aspect. Besides, polyester has a great disadvantagethat has a chance of polyester allergy, where cotton is less hazardous from this point of view.12Apart from these polyester fabrics can make some discomfort on skin likes itchy, tickling, harshfeelings & causes polyester rash etc.12
4.6 Aesthetics:
Fabric aesthetics also gives a psychological comfort to the wearer. In case of cotton it is much softer than the polyester whereas polyester is harsh in hand feel .In hot weather cotton givesrough touch whenever it comes contact with skin, polyester is less compressible than cotton. Incase of abrasion cotton does not introduce any charge where polyester introduces a negativecharge, which makes some sort of discomfort to the wearer. Polyester fabric also gives a rough &tough noise if is it friction with different body parts.
5. Conclusion
Cotton is widely used fiber which has a terrific acceptance to the textile market & also to thecustomer, Cotton is obviously better in warm condition in terms of comfort, but polyester is alsoa most popular fiber to produce better clothes for technical purposes, fancy fabric & furnishingpurposes. Besides by applying softener and additives to polyester fabric it will become verypopular for the casual clothing like cotton fabric.
References
1 http://www.woodheadpublishing.com/en/basket.aspx
2 Textile fiber to fabric
3 www.worldformolecules.com/materials cotton .htm
4 http://schwarzt.eng.euburn.edu/polyester/glossary.htm#denier
5 http://oecotextiles.files.wordpress.com/2011/09/art-polyprocess3.jpg
6 J.E.BOOTH- Textile testing & quality control
7 http://www.schoolforchampions.com/science/static-materials
8 http.www.siliconfareast.com/htm. tribo science.htm
9 Indian journal of Fiber & Textile research vol-37, June.2012p.p151-152
10 http://scwartz.eng.monomer
11 Oecotextiles.wordpress.com/2011/2012/10/13,polyester and our health
12 www.ehow.com/facts-6031197-allergies.polyester.html
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