Fiber Classification

• Natural fibers: vegetable or plant fibers, animal fibers, and mineral fibers
• Man-made fibers: inorganic fibers, regenerated fibers, and synthetic fibers

Man-made fibers

Trivia: Man-made fibers belong to the category of fibers that includes inorganic, regenerated, and synthetic fibers. These fibers are created by humans using various chemical processes. They are widely used in the textile industry for their versatility and durability. Some common examples of man-made fibers include polyester, nylon, and acrylic.

Chemical Structure of Fibers

• Natural fibers: Polymerized by nature, composed of cellulose or polypeptides.
• Synthetic fibers: Polymerized via addition or condensation, composed of polyesters, polyamides, or polyolefins.
• Intra-polymer bonding: Holds atoms together in fiber polymers.

Chemical Bonds in Fibers

• Covalent bonds: chemically stable and un-reactive
• Amide or peptide groups: present in nylon, silk, wool, etc.
• Benzene rings: provide thermal and chemical stability
• Ether linkages: found in cellulose and polyesters
• Ester groups: undergo alkaline hydrolysis
• Nitrile groups: present in acrylic and modacrylic fibers
• Hydroxyl groups: responsible for moisture absorption

Types of Bonding in Polymer Fibers

• Hydrogen bonding: Occurs in polyamides, aramids, and cellulose fibers. Bond energy: 20.9 kJ.
• Van der Waals forces: Weak inter-polymer forces formed between atoms along adjacent polymers. Bond energy: 8.4 kJ.
• Salt linkages: Formed between carboxyl radical and positively charged amino group. Bond energy: 54.4 kJ.
• Cross-links: Present in PAN, Nylon 6,6, PET, and Kevlar fibers.