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وزارت علوم و تحقیقات و فناوری
مؤسسۀ آموزش عالی جهاد دانشگاهی استان یزد
دانشکدۀ هنر اردکان
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علوم الیاف
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جناب آقای عبقری
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نرگس توسلی
«862381018»
زمستان 87
What is Cotton?
Cotton is a natural fiber harvested from the cotton plant. Cotton is one of the oldest fibers under human cultivation, with traces of cotton over 7,000 years old recovered from archaeological sites. Cotton is also one of the most used natural fibers in existence today, with consumers from all classes and nations wearing and using cotton in a variety of applications. Thousands of acres globally are devoted to the production of cotton, whether it be new world cotton, with longer, smoother fibers, or the shorter and coarser old world varieties.
Cotton is in the mallow family and produces delicate, lovely flowers. Other members of the mallow family include hollyhocks and hibiscus, used to brighten gardens all over the world. The cotton fiber forms around the seeds of the cotton plant and is designed to help carry the seeds long distances on the wind so that the plant can distribute itself. Early humans realized that the soft, fluffy fibers might be suitable for textile use and began to breed the plant, selecting for fluffy, easily spun varieties.
After harvesting, cotton must be combed to remove the seeds. This used to be a laborious process until the invention of the cotton gin, which quickly separates the seeds from the fiber and combs them for spinning. While a single cotton fiber is not terribly strong, when multiple curling fibers are straightened and twisted together, they form a strong, smooth thread that can be knitted or woven, as well as dyed.
Cotton is somewhat flammable, especially lighter cottons that hold a lot of air. Some cotton is chemically treated to reduce flammability. Many cottons are also blended with other natural fibers, such as linen, for particular properties, or to add texture and strength to the fiber. Cotton can be woven or knitted. It can also be turned into flannel, corduroy, muslin, and a variety of other fabrics used so universally that the American Cotton Council uses “the fabric of our lives” as a tag line.
Cotton also carries environmental controversy, particularly in the developing world, where dangerous pesticides are heavily employed. Cotton is subject to infestation, and therefore many growers heavily douse the plant in pesticides that are harmful to human and animal health, as well as herbicides to eliminate competition for resources. A number of producers also genetically modify the plant, which many outside the industry view as a questionable practice. Cotton also has very large water requirements, which may place stress on nations with limited water resources. In the late 20th century, there was a push for organic, sustainable cotton grown and harvested without the use of pesticides and human exploitation. This cotton is significantly more expensive than conventionally farmed cotton, however, and may not be practical for most consumers.
What is Pima Cotton?
Pima cotton is a type of cotton grown primarily in the United State's Southwest. It is considered to be one of the superior blends of cotton, and is extremely durable and absorbent. Pima cotton is named after the Pima Native Americans who first cultivated the plant in the US, but its origins date back to its cultivation in Peru.
Pima cotton bears some similarity to many forms of Egyptian cotton, which is frequently used in towels and sheets. In other words, a piece of Egyptian cotton has a much more extensive weave than other types of cotton. Towels made from Egyptian cotton are particularly desirable because they are very soft and help absorb water from the body quickly.
Since Egyptian cotton was so desirable, the US decided to try growing a type of it in the Southwest, which is a somewhat similar climate to Egypt. The resultant cotton was a mix of Egyptian and other types of cotton. Pima cotton is a little shorter than Egyptian cotton but still yields a thread that can be woven multiple times into a piece of fabric to create a dense, soft fabric.
Pima cotton has long threads similar to Egyptian cotton, which made it an ideal type for development in the US. Cultivation of this form of cotton became especially popular in the early 20th century. Length of threads make it a desirable choice for many products since it can be woven into soft dense fabric.
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