4.2e.2 Principles of Textiles Notes

Raw Materials for Textiles: From Fibers to Fabrics

Imagine slipping on a lightweight cotton shirt on a hot summer day. It feels soft, breathable, and comfortable against your skin. Now, think about the stretchy ease of your Lycra workout gear or the luxurious sheen of a silk scarf. These textiles, though vastly different, all begin their journey as fibers, tiny, thread-like structures that are spun into yarn and eventually transformed into fabrics. But have you ever wondered where these fibers come from and what makes them so unique? Let’s explore the fascinating world of textiles, from natural and synthetic fibers to the processes that transform them into the fabrics we use every day.

Sources and Types of Textile Fibers

Fibers, the fundamental building blocks of textiles, are classified into two main categories based on their origin:

1. Natural Fibers: Derived from plants or animals, these fibers have been used for centuries. Examples include:
   • Plant-based fibers: Cotton (from cotton plants) and linen (from flax plants).
   • Animal-based fibers: Wool (from sheep), silk (from silkworms), and alpaca (from alpacas).
2. Synthetic Fibers: Man-made and typically derived from petrochemicals, synthetic fibers are engineered for specific properties. Examples include:
   • Nylon, polyester, and Lycra.

Each type of fiber has unique properties that make it suitable for specific applications. Let’s examine these properties in more detail.

Properties of Natural Fibers

Natural fibers are valued for their comfort, breathability, and eco-friendliness. However, their properties can vary significantly depending on their source.

Wool: Warmth and Elasticity

Wool, obtained from animals like sheep, alpacas, and goats, is known for its insulating properties and natural elasticity. Its surface is covered with overlapping keratin scales, which can give wool a scratchy texture unless the fibers are ultra-fine, such as Merino wool.

• Key Properties:
• Excellent thermal insulation.
• High moisture absorption (13–18%), making it breathable.
• Naturally flame-resistant (smolders rather than burns).
• Good elasticity, providing comfort and a natural drape.

Cotton: Breathable and Versatile

Cotton, a plant-based fiber, is composed of cellulose. Its fibers are tubular with a hollow center (lumen) that collapses into twists as it dries, giving cotton its characteristic softness and breathability.

• Key Properties:
• High tensile strength ($400 \text{ MPa}$), especially when wet.
• Good moisture absorption (7–11%), making it ideal for hot climates.
• Poor resilience, meaning it is prone to wrinkling.

Silk: Strength and Luxury

Silk, produced by silkworms, is a protein fiber with a triangular cross-section. This unique structure refracts light, giving silk its lustrous sheen and smooth texture.

• Key Properties:
• High tensile strength ($500–900 \text{ MPa}$).
• Excellent drape and flexibility.
• Resistant to mildew but prone to static electricity.

Properties of Synthetic Fibers

Synthetic fibers are engineered to provide specific functionalities, often surpassing natural fibers in durability and versatility. They are typically hydrophobic (low moisture absorption) and thermoplastic (soften under heat).

Nylon: Strength and Elasticity

Nylon, a polyamide, is smooth and translucent with a circular cross-section. It is valued for its strength, elasticity, and resistance to abrasion.

• Key Properties:
• High tensile strength ($400–870 \text{ MPa}$).
• Low moisture absorption (4–4.5%).
• Thermoplastic, allowing for permanent pleats but requiring low ironing temperatures.

Polyester: Dimensional Stability

Polyester is the most widely used synthetic fiber, prized for its strength, low cost, and resistance to wear and tear.

• Key Properties: