Properties of Textile Fibers: Chemical and Physical Structure
Reading Assignment 1
Collier and Tortora, Understanding Textiles, Chapters 2 and 3, Appendix
C
Objectives
After you have completed this lesson you should be able to:
§ Define a fiber and identify the performance properties necessary
for specified uses
§ Distinguish between the classifications of natural and manufactured
fibers.
§ Differentiate between a fiber's generic name and a trademark
name
§ Identify and explain the requirements of the Textile Fiber Products
Identification Act (TFPIA)
§ Identify and analyze the different categories of fiber properties
as they relate to the performance and/or behavior or a textile product.
§ Analyze the scientific concepts necessary to the understanding
of textile molecular structure, polymerization, and polymer arrangement
(internal structure).
Discussion
Consumers and professionals working with textile materials select a textile product for a particular end use, taking into consideration the performance expected of the product as well as the cost. The cost of the selected product will be determined by the different steps used in the manufacturing and the value-added components of the product.
Fibers are the basic unit that make up the majority of textile products used for wearing apparel, interior textile products, and industrial uses. The textile fibers exist in nature (cotton and wool for example) or are created in a laboratory (rayon and polyester for example). Natural and manufactured fibers are divided into categories (see Figure 2.1, page 30).
Properties of textile fibers are divided into physical, mechanical,
chemical, and environmental properties.
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Self-help Exercise 1
Do not submit for grading
1. To understand how fibers, yarns, and fabric structure interrelate,
unravel fabric sample 1 as follows: pull out a yarn from both directions,
unravel the yarns, untwist the yarn into fiber.
2. Visit a local department store and inspect the labels on textile
products to determine the following: fiber content and percentage
used, trademark name, and country of origin.
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Lesson 2
Natural Fibers: Cellulosic and Protein Fibers
Reading Assignment 2
Collier and Tortora, Understanding Textiles, Chapters 3 and 4.
Objectives
After you have completed the lesson, you should be able to:
§ Identify and analyze the chemical structures and properties
of cellulosic and protein fibers as to end use performance
§ Analyze cellulosic and protein fabric samples for fiber characteristics
§ Explain the Wool Products Labeling Act
Discussion
Natural cellulosic fibers are derived from a variety of plant sources. The parts of the plant from which the fiber comes are classified as: seed hair fibers, bast fibers, and leaf fibers. Cellulosic fibers The chemical composition of these fibers is mostly cellulose. The most common cellulosic fibers are cotton and flax (see Table 3.1, page 66).
Cotton comes from the seed of the cotton plant; the cotton fibers
are separated from the cotton seeds and processed for use as a textile
fiber. Flax is a stem or bast fiber . Bast fibers required
extensive processing to remove the fibers from the woody stem. The
term linen refers to fabric made from flax fiber.
Cellulosic fibers have the following properties:
Low resilience
Burn readily and completely
Hydrophilic (absorb moisture readily)
Shrink in presence of heat and moisture
Support growth of mold and mildew
Damaged by some insects, especially silverfish
Protein fibers are naturally occurring animal products and are
obtained from two sources: animal hair (wool and specialty protein
fibers) and animal secretions (silk). All protein fibers contain
the chemical elements carbond, hydrogen, oxygen, and nitrogen.
Wool also contains sulfur. Because of their chemical composition,
wool and silk fibers have some of the same properties:
Good absorbency
Good resilience
Damaged by acids, alkalis, sunlight
Difficult to ignite but have distinctive odor when burned
Damaged by carpet beetles, moths (wool)
Wool fiber is obtained from the sheep by shearing and pulling. Shearing removes the fleece from the live animal; pulling removes the wool from the hides of slaughtered animals. The protein in wool is keratin. All products containing wool fiber are covered under the Wool Products Labeling Act, passed in 1939 and amended in 1984.
The natural protein fiber silk is the only natural filament fiber.
It is formed from the excretions of the silkworm. The protein in
silk is fibroin. Sericulture is the production of cultivated silk
under controlled conditions; sometimes silk is produced in the wild; this
silk is called Tussah.
Burning a small sample of a fabric may help to distinguish its
general fiber category. The odor and appearance of the fabric during
and after burning, and the appearance of the residue may put it into a
general category such as cellulosic, protein or manufactured.
Manufactured Fibers: Regenerated Cellulosic, Inorganic and Carbon Fibers
Reading Assignment 3
Collier and Tortora, Understanding Textiles, Chapters 6 and 12
Objectives
After you have completed this lesson you should be able to
§ Describe the processes used in manufacturing fibers
§ Explain the concept of cellulose regeneration and chemical modification
of cellulose in the formation of rayon, acetate, and lyocell.
§ Identify the properties of rayon, acetate, and lyocell.
Discussion
Whether the synthetic polymer is chemically synthesized or regenerated from naturally occurring polymers, the fiber-forming polymer must be produced in a physical for suitable for use in the construction of textile products. The basic process for forming manufactured fibers involves converting the synthetic polymer into a liquid form, either by dissolving the polymer in a suitable solvent or by melting the polymer and then forcing the liquid through a spinneret.
Rayon, the first manufactured fiber, was produced form plant materials in an attempt to duplicate the fiber produced by the silkworm. This manufactured fiber, produced by chemical digestion of cellulose was first called "artificial silk". In 1024, the name rayon was given to this regenerated cellulose fiber. Properties of rayon have been similar to cotton, with the exception of strength - rayon is weak, particularly when wet. Developments in rayon have made it a fiber with increased strength and durability.
A new generic fiber lyocell with structure and properties similar but superior to rayon has been developed with the tradename Tencelâ.
Cellulose acetate, a chemical derivative of cellulose, was used during World War I as a coating for fabric wings of airplanes. After the war, researchers were able to convert cellulose acetate into a fiber with high luster and excellent draping qualities. Acetate is the name given to the fiber. Acetate has properties similar to rayon but since it has much less cellulose, it is thermoplastic (softens and melts in the presence of heat).
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