The Chemistry of Textile Fibres: From Raw Materials to Modern Applications

Jan 03, 2025 Viewd 23

The Chemistry of Textile Fibres: From Molecular Structures to Modern Applications

The textile industry is deeply rooted in chemistry, where the molecular structures and polymerisation processes behind fibres shape their properties, applications, and market viability. From natural cellulose and protein-based fibres to petrochemical-derived synthetics, each type of fibre carries a unique chemical signature that influences its performance. This article delves into the detailed chemistry of textile fibres, exploring their synthesis, transformation processes, technical challenges, and the companies leading innovation in this field.

1. The Role of Chemistry in Textile Fibre Properties

Textile fibres are complex structures where chemical composition directly determines physical properties such as tensile strength, elasticity, dye affinity, and thermal resistance. These fibres are classified into three major categories:

  1. Natural Fibres: Derived from plant cellulose or animal proteins.
  2. Synthetic Fibres: Polymers created through petrochemical processes.
  3. Regenerated Fibres: Chemically modified natural polymers, often cellulose-based.

The polymeric nature of these fibres, characterised by high molecular weights and long chains of repeating units, is the fundamental reason for their ability to form durable and flexible fabrics.

2. Chemical Composition and Synthesis of Textile Fibres

Natural Fibres

Cotton:

  • Chemical Basis: Composed of 99% cellulose (C₆H₁₀O₅)n, a linear polysaccharide with β-1,4 glycosidic linkages. The hydroxyl groups (-OH) along the polymer chains allow hydrogen bonding, imparting strength and water absorption properties.
  • Processing Chemistry: Includes mercerisation, where fibres are treated with sodium hydroxide (NaOH) to enhance dye uptake and tensile strength.
  • Applications: Soft, breathable fabrics for casual wear, home textiles, and medical bandages.

Wool:

  • Chemical Basis: A keratin protein polymer composed of amino acids, primarily cysteine, which forms disulfide bonds (-S-S-) providing strength and elasticity.
  • Processing Chemistry: Wool scouring removes lanolin and impurities, while treatments such as bleaching use hydrogen peroxide (H₂O₂) for colour improvement.
  • Applications: Insulating clothing, carpets, and industrial padding materials.

Synthetic Fibres

Polyester (Polyethylene Terephthalate - PET):

  • Chemical Basis: Formed through esterification and polycondensation of terephthalic acid (TPA) and ethylene glycol (EG). The ester functional group (-COO-) provides hydrophobicity, while the aromatic ring contributes to rigidity.
  • Manufacturing Process: The reaction occurs at 250–280°C under vacuum to achieve high molecular weight. Melt spinning produces fibres, which are drawn to orient polymer chains for strength.
  • Applications: Sportswear, industrial fabrics, automotive interiors, and fashion blends.

Nylon (Polyamide 6,6):

  • Chemical Basis: Synthesised from hexamethylenediamine (HMD) and adipic acid, forming amide linkages (-CO-NH-) through condensation polymerisation.
  • Manufacturing Process: Polymerisation occurs at 260°C, producing a high-viscosity nylon salt that is extruded and cooled.
  • Applications: Elastic garments like hosiery, durable industrial fabrics, and automotive parts.

Polypropylene (PP):

  • Chemical Basis: Formed via Ziegler-Natta polymerisation of propylene monomers (CH₂=CH-CH₃). Its hydrophobic nature and crystalline structure offer high strength.
  • Applications: Geotextiles, filtration systems, and agricultural fabrics due to chemical resistance and lightweight properties.

Regenerated Fibres

Rayon (Viscose):

  • Chemical Basis: Regenerated cellulose, chemically treated to enhance solubility and processing.
  • Manufacturing Process: Cellulose reacts with sodium hydroxide (alkalisation) and carbon disulphide (CS₂) to form cellulose xanthate. Dissolution in NaOH solution creates viscose, extruded into a sulfuric acid bath to regenerate cellulose fibres.
  • Applications: Drapery, apparel, and upholstery with a silk-like appearance.

3. Technical Challenges and Limits in Fibre Production

Raw Material Purity:

Impurities in raw materials, such as lignin in cellulose or trace metals in synthetics, can disrupt polymerisation and degrade mechanical properties.

Energy-Intensive Processes:

High temperatures (250–300°C) and pressures required for polymerisation increase energy costs and environmental impact, especially in synthetic fibre production.

Hydrophobicity vs. Dyeability:

Synthetics like polypropylene resist moisture and dyes, requiring surface treatments like plasma modification or addition of compatibilisers during polymerisation.

Biodegradability:

Natural fibres like wool and cotton decompose readily, but synthetics persist in the environment, leading to waste management challenges. Recent innovations focus on developing biodegradable polyesters using aliphatic chains instead of aromatic structures.

4. Fibre Transformation and Recycling

While transforming one fibre type to another is chemically complex, advancements in recycling processes address environmental concerns.

  • Chemical Recycling of PET: Hydrolysis or glycolysis depolymerises PET into TPA and EG, which can be repolymerised to create new fibres.
  • Mechanical Recycling: Melting and re-extrusion of PET or nylon retains polymer structure but reduces quality over cycles.
  • Challenges: Recycling requires energy-intensive purification and sorting processes to ensure fibre integrity.

5. Market Dynamics and Leading Innovators

Global Market Trends:

The global textile fibres market, valued at USD 42.92 billion in 2022, is projected to grow to USD 62.45 billion by 2030, driven by demand for sustainable materials and advanced functionality.

Key Companies and Innovations:

  1. Indorama Ventures (Thailand): Specialises in recycled polyester, using advanced chemical recycling techniques to enhance sustainability.
  2. Toray Industries (Japan): Known for high-performance fibres like carbon and aramid, focusing on aerospace and industrial applications.
  3. DuPont (USA): Pioneered nylon and Kevlar, with strengths in protective and industrial textiles.
  4. Lenzing Group (Austria): Innovators of Tencel, eco-friendly regenerated fibres with closed-loop production processes.
  5. BASF (Germany): Develops biodegradable polymers and blends for sustainable textiles.

6. Conclusion

The chemistry of textile fibres forms the foundation for their properties and applications, from apparel to technical fabrics. Innovations in fibre synthesis and recycling are critical for addressing environmental challenges while meeting industry demands for high-performance materials. With companies at the forefront of sustainable and advanced fibre development, the textile industry is set to evolve, blending chemistry and technology to redefine modern fabrics.