Structure of Cotton Fiber

In this article, we are going to describe about the structure of cotton fiber, the composition of cotton fiber. Let's check the description from below for more information.

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Introduction

Cotton is obtained from a plant, and it is classified as a natural, cellulose, seed, mono-cellular, staple fiber. Cotton is the most important natural textile fiber, as well as cellulose textile fiber, in the world, used to produce apparel, home furnishings, and industrial products.

Composition of Typical Cotton Fibers

Component	Main Location	Relative Amount (%)
Cellulose	Secondary Wall	86.8
Oil and Waxes	Cuticle	0.7
Pectin	Primary Wall	1
Carbohydrate	Primary Wall	0.5
Proteins	Lumen	1.2
Salts	Lumen	1
Water		6.8
Others		2

Specification of Cotton Fiber

• Length: 1 cm to 6.5 cm
• Diameter: 11 micrometers to 22 micrometers
• Length, width ratio: 6000:1 to 350:1
• Convolution: Sixty per cm
• Specific gravity: 1.52
• Color: Generally white, maybe creamy or brown.
• Strength tenacity: At dry = 3.0-5.0 g/; at wet = 3.3-6.0 g/d
• Light reflection: Low luster, dull appearance
• Dimensional stability: Medium
• Elasticity: Low breaking extension 5% to 7%
• Moisture regain: 8.5%
• Resiliency: Low
• Abrasion resistance: Medium

The Micro Structure or Morphological Diagram of Cotton Fiber

The cotton fiber is made up of a cuticle, primary wall, secondary wall, and lumen. The cotton fiber is a single plant cell.

Structure of Cotton Fiber

Cuticle

• The cuticle is the very outside layer or skin of the cotton fiber.
• It is composed of a waxy layer only a few molecules thick.
• This way layer protects the rest of the fiber against chemical and other degrading agents.

Primary Cell Wall

• This is immediately underneath the cuticle and is about 200 nm thick.
• It is composed of very fine threads of cellulose, called fibrils, which are about 20 nm thick.
• The fibrils are at about 70% of the fiber axis. This spiraling imparts strength to the primary cell wall and hence to the fiber.

Secondary Cell Wall

• Beneath the primary cell wall, the secondary cell wall lies, which forms the bulk of the fiber.
• Its fibrils are about 10 nm thick and of undefined length.
• Near the primary cell wall, the fibrils of the secondary wall spiral at about 20° to 30° to the fiber axis. This spiral angle widens to about 20° to 45° for the fibrillar layers nearer the lumen.

Lumen

• The hollow canal, running the length of the fiber, is called the lumen.
• Its walls are the innermost, concentric layers of spirals of the secondary cell wall.
• It was full of cell sap, which was composed of a dilute, aqueous solution of proteins, sugars, minerals, and cell waste products.
• Further, as the sap evaporated, the pressure inside the fiber became less than the atmospheric pressure on the outside. This caused the fiber to collapse inward, resulting in the characteristic kidney-shaped cross-section of the cotton fiber.