Introduction
Cotton is a raw material used to make yearns and threads. It is derived from a shrub plant that commonly grows in both tropical and sub-tropical areas in many parts of the world. It is commonly found in Africa, some parts of America and India (Kermit 1999, p.14). Today, India and United States are the largest producers of cotton.
The yearns or threads are used to make soft and breathable textile, the commonly used natural- fiber used for making clothing materials. Cotton is the only known of all the raw materials used for textiles because of its durability and multi-purpose use. The seeds of its planting material are usually enclosed in a protective capsule that facilitates the seed dispersal.
The most widely grown cotton species is Gossypium hirsutum , which makes up more than 90 percent of total output globally. It has its origin in Mexico where it was first grown 8,000 years ago (Lawrence 1998, p. 34). All countries in the entire world rely on cotton either directly or indirectly as a raw material for the manufacture of several textiles related materials.
It has been discovered that more consumers go for cotton-made personal items more often than those of other synthetic fibers do. In the year 1998, out of estimated 45 million tons of global fiber consumed, 20 million tons were cotton.
Cotton characteristics
Cotton is a fiber-like natural material whose origin is associated with vegetable plants. Its major component is cellulose, a carbohydrate substance found in plants. Cotton bears the characteristics of other fruits and comes from a plant commonly referred to as ‘cotton plant.’ The plant itself is among Malvacae family, which has more than 1500 species. Among the famous plants in this family are baobab and bombax trees.
The cotton plant has the ability to grow up to about ten metres high when grown in the wild but under normal circumstances it grows to the range of one to two metres in commercial farming to make picking exercise easier. The crop does well in dry tropical areas. Naturally, the plant is a perennial tree but under normal cultivation methods, it is grown as an annual shrub (Judith 1997, p.52).
It takes less than a year and only few cases have been reported where the crop takes two years. The cotton flower consists of five large petals and immediately after they fall off, capsules with thick and hard outer layers are left.
After the maturity of cotton capsules, they explode exposing the seeds along with masses of creamy-white fibers. The commonly grown cotton species of Gossypium hirsutum has narrower and lighter fibers as compared to that of Gossypium barbardense with more fibers. Despite the fact that cotton is more prevalent in tropical nations, this does not mean it cannot be grown in other geographical regions.
Cotton is extensively planted in both south and north hemisphere even though cotton is loves sunlight even though very susceptible to cold conditions. Cotton is mostly planted in third world countries. In the year 2007/08, out of 65 cotton-producing nations, 52 were third world nations, 21 of which had been categorized under the list of less developing by the United Nations.
Cotton has a significant importance in developing countries mostly in Western and Central parts of Africa- more than eight million people are dependent on cotton sector for their incomes. Cotton oil account for about 5 percent of vegetable oil consumed worldwide. The cottonseed meal is rich in protein and energy for cattle and usually taken in form of roughages (Xu & Fang 1999, p. 77).
Cotton fiber characteristics
The characteristic features exhibited by the cotton fiber make it more preferred to other fibers. The shape of the material is fairly uniform with approximate width of about 12 to 20 micrometers while its length varies between one centimeter and six centimeters. This makes it relative lighter hence the final products which include clothing materials will also be light.
One of the major uses of cotton material is the production of clothing materials and one of the significant features of a good clothing material is lightness that in most cases is determined by the density. Cotton fibers have high luster.
They have shining features and can easily reflect light (Cai 1999, p.73). This makes cotton -made clothes more comfortable to wear especially during the hot periods. They do not absorb heat that easily and therefore cotton materials become most preferred in hot regions of tropical and sub-tropical areas.
Another characteristic feature of cotton fiber can be viewed from the strength perspective. The strength of all fibers is measured in terms of grams per diner (g/d). This is described as the force required to break a bunch of fibers sandwiched between two sets of jaws. Cotton fiber has a breaking strength of between 3.0 to 6.g/d. This depends on whether the fiber is dry or wet.
Dry cotton fiber has strength of between 3g/d to 5g/d while the wet one ranges between 3.3g/d to 6g/d thus cotton is the world’s strongest fiber hence increasing the number of its possible uses and subsequently making the substitutability of the material almost impossible. Cotton fibers are resiliency (Kermit 1999, p.22). This means after a sudden disturbance, the material can easily return back to its original state.
All cotton-made items including clothing have proved this characteristic feature. Whenever a cotton-made garment is folded, crumpled, or even shrunk during washing, it eventually assumes its original shape without being subjected to ironing.
The density of cotton fiber ranges between 1.54 to 1.56 g/cm3. This is slightly desirable density since the fibers can easily and conveniently be carried from one place to another. Again, the density determines how heavier or lighter a material is.
Moisture absorbency is an important characteristic feature of fiber materials. The absorbency strength is measured in terms of percentage rate. The raw conditioned cotton fiber has an absorption rate of about 8.5 percent while mercerized conditioned fiber has a range of between 8.5 to 10.3 percent.
This feature has led to higher demand of cotton materials in the manufacture of cotton wools and bandages used in hospitals to cover open wounds. So many other materials are cotton-made and preferred for this quality including baby clothes and pampers. Cotton fibers are vulnerable to acids (Lawrence 1998, p. 60). Unlike some other fibers, cotton weakens when subjected to acids.
However, similar subjection to alkali brings no harmful effects. The cotton fibers are also resistant to most organic solvents and do not dissolve easily. Prolonged exposure of cotton fibers to direct sunlight is not advisable since the material can be weakened. Another important thing to note about cotton fibers is that they cannot survive the presence of microorganisms and other insects because the fibers will be damaged.
The final characteristic feature is that prolonged exposure of cotton fibers to temperatures above 1500 C will lead to complete combustion of the fibers yet it is advisable to always maintain cotton fibers at desirable temperature rates.
Bamboo fibers
Bamboo fibers come from a bamboo plant that has a high percentage of cellulose just like cotton plant. It is usually grown in non-polluted areas for example Yunnan and Sicuan provinces of China. The production of bamboo fiber requires a green process with no pollution. Since it is cellulose, it can be 100 percent decomposed in soil by microorganisms and sunshine (Tortora & Collier 1997, p.51).
However, the process of decomposition does not cause environmental pollution. Another unique feature of bamboo fibers is their ability to breathe and their cooling effects they bring with them. This is due to the fact that the cross sections of its fiber consist of several micro-gaps and holes thus making it better for moisture absorption as well as ventilation.
Bamboo fiber can easily absorb and evaporate human sweat in a matter of seconds. It does not stick to the skin in hot summer. According to empirical studies, bamboo-made apparels are usually less than 20c the normal apparels in hot summer.
Purely bamboo-made fabrics have good wet permeability, they have the ability to transmit moisture and vapors properly, are easy to dye and have comfortable touch (soft hand). For this reason, bamboo fiber is used to make sweaters, bathing towels and suits, blankets among others. Due to its unique anti-bacteria function, bamboo fibers are most preferred in making under-cloth garments, socks and tight t-shirts (Duckett 1975, p.92).
Viscose Rayon Fiber
This is a non-synthetic fiber made from wood pulp that has been derived from a raw material rich in cellulose like cotton. Subsequently, its properties are similar to those of cotton fibers. Rayon garments are soft and comfortable to wear.
They are flexible and hang comfortably loosely when worn making them so desirable to many consumers. However, this characteristic will depend on how the fabric has been processed and the nature and amount of additives added during the processing (Mauersberger 1954, p.77).
Of all the cellulose fibers, rayon is the most absorbent. The strength of rayon reduces when it is wet. Consequently, it has more stretching and shrinking effects than cotton. Rayon is extremely inelastic. Another characteristic feature of rayon is that it is highly flammable.
Rayon led to the enactment of Flammable Fabrics Act in 1953by US’s Commerce Department. This was triggered by public concern over huge number of accidents caused by rayon fabrics. Finally, weak acids easily damage the fiber, just like any other cellulose.
Comparison of performance characteristic of Bamboo and Rayon to Cotton
Almost all the differences and similarities of the three fibers have been already directly or indirectly highlighted. From an environmental perspective, the processing of rayon unlike bamboo and cotton leads to environmental pollution as it has been observed. Rayon has been described as an eco-friendly material since its production process does not pollute environment at all.
Another difference between these fibers can be viewed from biodegradability perspective. Bamboo fibers are easily decomposed by soil microorganisms unlike rayon that resists microorganisms and insects damage thus making it non-biodegradable material (Duckett 1975, p.77).
Resiliency is another feature that distinguishes the three fibers. Cotton is more resiliency and can easily assume its original shape after shrinking or crumpling unlike rayon that can easily wrinkle. Rayon is more absorbent and elastic than both cotton and bamboo.
Cotton fibers are more luster than bamboo and rayon and thus they are the only fiber materials that reflect light. The three fiber materials have few similarities for instance all of them are cellulose fibers made from naturally occurring materials and acids can easily damage them.
Polyester fibers
Polyester fibers are made from polyester material that is among the polymer’s category. Polyester consists of naturally occurring chemicals that include cutin found in leaf cuticles and synthetics. Natural polyesters can be decomposed while synthetic ones cannot. Polyester fabrics are resistant to wrinkles (Rodriguez 1996, p.76).
They always retain their original shape even after being wrinkled and hence their clothes can be worn without necessarily ironing them. Another characteristic feature is its durability. Unlike other synthetic fibers, polyester fabrics can last for long. They also have the ability to retain their colours for long periods. That is clothes made from polyester do not fade easily due to frequent washing or exposure to too much direct light.
Polyesters are thermoplastics and their exposure to too much heat may lead to change in their shape. They burn at high temperatures, shrink away from flames, and put themselves off after ignition. Polyester fibers are characterized by high tenacity. In addition, they have low water absorption ability unlike other industrial fibers.
Polyester fabrics are easily washable and therefore suitable for making children clothes that are vulnerable to dirt. Polyester fabrics also dry faster and they do not remain wet for long after washing.
They are resistant to most chemicals including acids and alkalis hence they are not easily damaged upon exposure to these two. Therefore, this type of fiber is most suitable to use while making pillowcases, bed sheets, curtains, carpets among others (Ogorkiwicz 1970, p.112).
Nylon fiber
Nylon is a light synthetic material with high tenacity. It is manufactured through polymerization of an amine chemical mixed with an acid chloride. One characteristic feature of nylon is that it is very strong and highly elastic (Gresp & Luciana 1981, p.67). It can stretch to considerable strengths unlike polyester fibers. Washing of polyester fibers has been described as one of the easiest.
It requires little attention and dirt does not stick to the material very easily. Nylon clothes dries faster when washed even during cold weather. Resiliency is another characteristic of nylon fabrics. They do assume their original shape after being shrunk or crumpled.
Because of these characteristics, nylon is widely used to make track pants and shorts, swimming costumes, windbreakers, stockings among others. The luster of nylon varies; it can be either lustrous or dull (Chung Hee & YunKyung 2004, p.248). When nylon fabrics are exposed to too much heat, they melt instead of burning.
Nylon fabrics are very transparent under infrared light and allow light to pass through easily. Finally, nylon fibers are non-biodegradable and resist any attacks by micro-organisms and many other chemicals. They do not decompose.
Acrylic fibers
Acrylic is an artificial fiber made through dry and wet spinning processes. Acrylic fibers are heavy with high bulk exhibiting the features of wool. It is an excellent heat retainer and light responsive. Acrylic fibers are not resiliency and therefore they do not retain their shape easily when disturbed but their fabrics are wrinkle resistant. In addition, acrylic fibers are durable and can last for long (Bat & Salusso 2003, p.150).
They have also quick drying characteristics and dry faster when washed. One disadvantage of acrylic is that it does not insulate the wearer against heat loss. Acrylic materials are usually perceived as cheap due to their typical lower pricing than other natural counterparts are.
Acrylic fabrics are machine washable and therefore suitable for making baby clothes that require frequent washing. Acrylic is a non-biodegradable material since it is resistant to microorganisms, chemicals and resists deterioration when subjected to sunlight (Gordon 1968, p.122).
Comparison of performance characteristics of Nylon, Acrylic to Polyester
The three synthetic fibers mentioned above have a number of differences as well as similarities. All the three synthetic materials are non-biodegradable and do not undergo decomposition. Thus, the three of them poses a potential threat to environment and can lead to environmental pollution. In addition, they are characterized by durability and they tend to last longer.
The three materials resist any exposure to many chemicals including acids and bases. The three fiber materials dry faster after washing and therefore they are more recommended in cold and humid environments.
One of the differences among them is that acrylic fibers are not resistant to wrinkles like nylon and polyester though their fabrics tend to resist wrinkles (Kadolph & Langford 1998, p.77). Polyester unlike nylon and acrylic has the ability to retain colour for a long period without fading.
Conclusion
From the above discussion, it is evident that the natural fibers (cotton, bamboo and rayon) possess good characteristic features than artificial ones (polyester, nylon and acrylic). Almost all artificial synthetic fibers are non-biodegradable and therefore lead to environmental pollution (Tortora & Collier 1997, p.49).
Natural fibers usually decompose to manure and acids and other chemicals affect them. Any pollution caused by textile industry can be largely attributed to artificial fibers and incase there are any natural fibers involved, their contribution to pollution is very minimal.
List of References
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