Textile Fiber Microscopy

A Practical Approach

Ivana Markova

• Publisher: Wiley
• Year: 2019
• ISBN:
  9781119320074
• Edition: 1
• Topic: Ciencias físicas
• Subtopic: Historia y práctica de la ciencia

A groundbreaking text to the study of textile fibers that bridges the knowledge gap between fiber shape and end uses

Textile Fiber Microscopy offers an important and comprehensive guide to the study of textile fibers and contains a unique text that prioritizes a review of fibers' microstructure, macrostructure and chemical composition. The author – a noted expert in the field – details many fiber types and includes all the possible fiber shapes with a number of illustrative micrographs. The author explores a wealth of topics such as fiber end uses, fiber source and production, a history of each fiber and the sustainability of the various fibers.

The text includes a review of environmentally friendly fibers and contains information on the most current fiber science by putting the focus on fibers that have been mechanically or chemically recycled, for use in textile production. The author also offers an exploration of issues of textile waste and the lack of textile recycling that can help public policymakers with ways to inform and regulate post-industrial and post-consumer textile waste issues. This vital guide:

• Contains an accompanied micrograph for many fibers presented
• Includes information on how fiber microstructure is connected to fabric properties and how it affects the end use of fabrics
• Offers a review of the sophistication of textile fibers from a scientific point of view
• Presents a comparative textile fiber review that is appropriate for both for students, textile experts and forensic scientists

Written for students and professionals of apparel design and merchandising, and forensic scientists, Textile Fiber Microscopy presents an important review of textile fibers from a unique perspective that explores fibers' microstructure, macrostructure and chemical composition.

1
Natural Cellulosic Fibers

Cellulosic fibers are derived from one of three parts of a plant (i.e. the flower or seed, stem, or leaf) and differ based on their origins. Seed fibers are fibers that come from the flower or seed of a plant; bast fibers come from the stem of the plant. While bast fibers from different types of plants (e.g., flax or hemp) more often reveal their commonalities under a microscope, there are certain differentiable morphological characteristics that can be identified. For example, the longitudinal characteristics of linen appear as having nodes or kinks, which are similar to that of hemp's longitudinal characteristics; however, their cross‐sectional view differ as hemp has a wider lumen than linen.

Fiber morphology is the study of the structure and form of fibers and requires the utilization of microscopes to see the true characteristics of the fiber. When we view the fibers under a microscope, we see either longitudinal or cross‐sectional fiber characteristics (which will both be discussed in this book).

1.1 Seed Fibers

1.1.1 Cotton

Cotton comes from the flower of cotton plant, which is of the genus Gossypium in the mallow family Malvaceae. There are few types of the plant. Cotton is an ancient fiber as it has been used for clothing articles for thousands of years. Archeological evidence suggests that cotton was used in Pakistan more than 5000 years ago and in Mexico 3000 years ago, which makes sense because the cotton plant grows in warm climates.

Today, cotton is the most commonly used natural fabric. Its desirable properties such as comfort, absorbency, and good conductor of electricity have made it difficult to replace it with other fibers.

As already mentioned, the longitudinal characteristics of cotton fibers are ribbon‐like twists or also often called convolutions (Figure 1.1). These twists can be closer together or further apart depending first on the age of the plant and second on chemical fiber applications. The cotton fibers that come from a fully ripped bud will have twists closer together, and therefore a little bit more easy to identify under the microscope, than the cotton fibers that come from an half‐ripe bud, also called immature fibers [1], which will have twists that are further apart and therefore more difficult to identify under the microscope. When the cotton bud is unripe (immature fibers), the fibers will have very minimal twists or no twists at all. The twist starts forming after the cotton boll opens. Not all cottons have the same amount of twists/convolutions. High‐quality long staple cotton has about 300 convolutions/in., and low‐quality short staple cotton has no more than 200 convolutions/in. [2].

Figure 1.1 Longitudinal view of pima cotton fibers featuring ribbon‐like twists (2000×).

The advantage of the fiber twist is that it allows the fibers to cling together, and spinning yarns even out of short‐length fibers would not be difficult [2]. Also, twists enable cotton fabrics to be more elastic and not stiff like other cellulosic fibers such as linen fabrics. The twists also give cotton its uneven surface which in turn enables only a random skin contact, making the fabric comfortable to wear.

Another reason why these ribbon‐like twists could not be easily identified under the microscope is the chemical application called mercerization, which is “a chemical treatment applied to fibers to permanently impart a greater affinity for dyes and various chemical finishes” [3]. The fibers are immersed in a sodium hydroxide solution, which will give cotton fibers greater absorptive properties, higher degree of luster, and higher strength. Mercerization of cotton fibers will change the shape of the fibers because this chemical treatment will cause the fiber to swell, and thus, twists will be flattened out and not easily seen under the microscope (see Figure 1.2).

Figure 1.2 Physical structure of cotton fibers.

The cross‐section of cotton fibers could also vary in shape based on the maturity of the fiber. In a cotton boll, there are always some immature fibers mixed with mature ones. The mature fibers have a round cross‐sectional shape, thick cell wall, and a small lumen (also referred to as central canal). On the other hand, immature fibers do not have round cross‐section but have a U shaped cross‐section with a thin cell wall (see Figure 1.3). Immature fibers are not desirable because they are more difficult to spin into yarns and to dye [2]. Immature cotton fibers appear collapsed under the microscope. We can explain these differences in ...