Fabrics Around Us Chapter Notes | Home Science for Class 11 - Humanities/Arts PDF Download

Introduction

• Fabrics are ubiquitous, playing a significant role in daily life by providing comfort, warmth, color, decorative style, and texture.
• Everyday activities involve interaction with fabrics, such as bedsheets, pillow covers, towels, school uniforms, and school bags, each differing in texture and purpose.
• Fabrics in homes include curtains, kitchen dusters, floor mops, and durries, varying in kind, weight, and thickness based on their intended use.
• Unraveling a fabric reveals thread-like structures called yarns, which may be interlaced at right angles (e.g., woven fabrics), interlooped (e.g., woollen cardigans or T-shirts), or knotted (e.g., nets and laces).
• Untwisting a yarn reveals fine, hair-like structures called fibres, which are the basic building blocks of fabrics.
• Fibres, yarns, and fabrics are collectively referred to as textile products or textiles.
• After fabric production, finishing processes may enhance appearance (e.g., cleaning, whitening, coloring), luster, touch, feel, or serviceability.
• A wide variety of fabrics are available, each behaving differently during use and maintenance due to factors like fibre type, yarn, fabric structure, and finishing.

Fibre Properties

• Fibre properties significantly influence the characteristics of the final fabric.
• For a fibre to be useful, it must be available in large quantities and be cost-effective.
• Spinnability is the most essential property, enabling easy conversion into yarn and fabric, determined by fibre length, strength, flexibility, and surface structure.
• Consumer satisfaction depends on properties like colour, luster, weight, moisture absorption, dye absorption, and elasticity.
• Care and maintenance are affected by properties such as abrasion resistance, resistance to chemicals, soaps, detergents, heat, and biological organisms.

Classification of Textile Fibres

• Textile fibres are classified based on origin (natural or man-made), chemical type (cellulosic, protein, or synthetic), generic types (e.g., animal hair or secretion), or trade names (e.g., polyester as Terylene or Dacron).
• Fibres can be staple (short, like cotton) or filament (long, like silk or polyester).
• Natural fibres are obtained from nature and include four types:
  • Cellulosic fibres: Seed hair (cotton, kapok), bast fibres (flax/linen, hemp, jute), leaf fibres (pineapple, agave/sisal), nut husk fibres (coir/coconut).
  • Protein fibres: Animal hair (wool, specialty hair like goat or camel, fur), animal secretion (silk).
  • Mineral fibre: Asbestos.
  • Natural rubber.
• Manufactured (man-made) fibres are created artificially, with the first, rayon, commercially produced in 1895, and most others developed in the 20th century.
• The concept of manufactured fibres stemmed from the desire to replicate silk, initially called Artificial Silk or Art Silk, by digesting cellulose to produce filaments.
• Manufactured fibres are made by modifying non-fibrous materials (e.g., cellulosic cotton waste or wood pulp) or synthesizing from chemicals.
• The production process involves converting raw materials into a spinning solution (liquid form) via chemical action, dissolution, or heat, passing it through a spinnerette (nozzle with tiny holes) to form filaments, and hardening them through coagulation.
• Filaments are collected, stretched for fineness, oriented, or texturized to enhance stretch or bulk.
• Types of manufactured fibres include:
  • Regenerated cellulosic: Rayon (cuprammonium, viscose, high-wet-modulus).
  • Modified cellulosic: Acetate (secondary acetate, triacetate).
  • Protein fibres: Azlon.
  • Non-cellulosic (synthetic): Nylon, polyester (Terylene, Terrene), acrylic (Orlon, Cashmilon), modacrylic, spandex, rubber.
  • Mineral fibres: Glass (fibreglass), metallic (Lurex).

Yarns

• Fibres are not typically used directly in consumer products except in items like surgical cotton or stuffing for pillows, quilts, mattresses, and cushions.
• To create fabrics, fibres are processed into continuous strands called yarns, except in fabrics like felts or non-wovens made directly from fibres.
• Yarn is a continuous strand of textile fibres, filaments, or material suitable for knitting, weaving, or intertwining to form a textile fabric.
• Yarn processing from natural staple fibres, called spinning, involves multiple stages, with spinning as the final step.
• Historically, young unmarried girls spun fine yarns, leading to the term “spinster” for unmarried women.
• Yarn processing stages include:
  • Cleaning: Removing impurities (e.g., seeds in cotton, twigs in wool), sorting fibres, and forming laps (rolled sheets of loose fibres).
  • Making into a sliver: Unrolling laps, straightening fibres through carding (disentangling and aligning) and combing (for finer fabrics, removing short fibres and impurities), then passing through a funnel to form a sliver (rope-like mass, 2–4 cm in diameter).
  • Attenuating, drawing out, and twisting: Combining slivers for uniformity, drawing them out to become longer and finer, blending different fibres if needed (e.g., cotton-wool), attenuating in a roving machine to ¼–⅛ of original diameter with slight twisting, and final spinning to achieve desired fineness and twist, wound onto cones.
• Manufactured fibres are produced as filaments, which can form single-filament yarns, multifilament yarns (multiple filaments twisted together), or be cut into staple lengths for spinning like natural fibres, used in blends like terecot (terene-cotton) or polycot (rayon-cotton).
• Yarn terminology includes:
  • Yarn number: Indicates fineness, with higher numbers (e.g., 20, 30, 40) representing finer threads, based on the weight-to-length relationship.
  • Yarn twist: Measured as twists per inch (t.p.i.), where loosely twisted yarns are softer and lustrous, and tightly twisted yarns may show ridges (e.g., denim).
  • Yarn vs. thread: Yarn is used in fabric manufacturing, while thread is used to join fabric pieces.

Fabric Production

• Fabrics vary due to fibre content (e.g., cotton, wool) or yarn type, with different structures distinguishable by appearance.
• Most fabrics are made from yarns, but some, like felts and non-wovens (bonded fibre fabrics), are made directly from fibres by laying carded and combed fibres into a matt and causing adhesion, customizable in thickness and shape.
• Main fabric construction methods are weaving, knitting, and to a lesser extent, braiding and knotting.
• Weaving, the oldest textile art, originally used for mats and baskets, involves interlacing two sets of yarns at right angles on looms to form a compact fabric.
• Warp yarns, fitted on the loom, determine fabric length and width, held at fixed tension and spacing, while filling (weft) yarns are interlaced to form the fabric.
• The simplest weave alternates filling yarn over and under one warp yarn, reversing in the next row, with varied interlacing sequences creating designs, enhanced by dobby or jacquard attachments for figurative patterns or colored yarns.
• Extra yarns parallel to warp or filling can form loops (uncut in towels, cut in velvets/corduroy) for texture.
• In woven fabrics, warp yarns run along the lengthwise grain (selvedge), and filling yarns run along the widthwise grain (weft), with selvedges being the bound, strongest edges.
• Knitting involves interlooping at least one set of yarns, done by hand (two needles for flat fabrics, four for circular) or machines, forming loops along a needle or machine bed, with each row interlooping with the previous.
• Weft knitting, where yarn moves along the fabric width, is used for shaped articles, while warp knitting, using a set of yarns like warp yarns, produces continuous lengths suitable for cutting and stitching.
• Knitted fabrics are produced rapidly, elastic due to loops, porous for air circulation, comfortable, and ideal for fitted items like vests, underwear, socks, and sportswear.
• Braiding creates fabrics with a diagonal surface effect by plaiting three or more parallel yarns, used in shoelaces, ropes, wire insulation, and trimmings.
• Nets are open mesh fabrics with large geometric interstices, made by inter-knotting yarns by hand or machine.
• Laces are openwork fabrics with intricate designs, formed by combining yarn twisting, interloping, and knotting.

Textile Finishing

• Fabrics straight from the loom require finishing treatments to achieve market-ready appearance, texture, or behavior for specific uses.
• All market fabrics, except whites, undergo one or more finishing treatments, including color addition.
• A finish is any treatment altering a fabric’s appearance, texture, or performance, classified as durable (resistant to washing/drycleaning, e.g., dyeing) or renewable (removed by washing, e.g., starching, blueing).
• Routine finishes are essential, including:
  • Appearance changes: Cleaning (scouring, bleaching), straightening, and smoothing (calendering, tentering).
  • Texture changes: Starching, sizing, special calendering.
  • Behavior changes: Wash-and-wear, permanent press, water-repellent or waterproof, mothproof, flame-retardant or fireproof, anti-shrink (sanforisation).
• Finishing with color is critical for fabric selection in apparel or home use, using dyes that resist washing out, applied based on fibre and dye chemistry and desired effect.
• Color application stages include:
  • Fibre stage: For yarns of different colors or designed felts.
  • Yarn stage: For woven checks, stripes, or patterns.
  • Fabric stage: Most common for solid colors, batik, tie-and-dye, or printing.
• Printing, a specialized dyeing form, involves localized color application within design boundaries using tools like blocks, stencils, screens (hand tools), or roller/automatic screen printing (industrial), allowing multiple colors on a fabric.

Some Important Fibres

• Widely used for apparel and home textiles, cotton was first grown and used in India, which remains a major cotton-producing region.
• Obtained from the seed pod of the cotton plant, where seeds have numerous hairs attached, collected after the pod bursts and separated by ginning, sent as bales for spinning.
• Properties: Natural cellulosic staple fibre, short (1–5 cm), resulting in dull, slightly rough yarn/fabric, heavier than most fibres; good moisture absorbency and quick drying, comfortable for summer; available in various weights, fineness, structures, and finishes (e.g., muslin, cambric, poplin, denim, sheeting, furnishing).

Linen

• A bast fibre from flax plant stems, obtained through retting (steeping to rot soft parts) and separating woody parts.
• Properties: Cellulosic, similar to cotton but longer and finer, producing stronger, more lustrous yarn; readily absorbs moisture, comfortable but poor dye absorption, resulting in less vibrant colors; less common than cotton due to limited cultivation and longer processing.

Jute and Hemp- Bast fibres like linen, coarser and less flexible, used for ropes, gunny bags, and similar products.

Wool

• Obtained from sheep hair or specialty hair (goats, rabbits, camels), with different breeds providing varied hair types, sheared once or twice yearly to form fleece.
• Processing involves sorting, scouring (removing dirt, grease, perspiration), and carbonisation (removing vegetable matter) before spinning.
• Properties: Natural protein fibre, varying in length (4–40 cm) and coarseness, with natural crimp for elasticity and elongation; lower strength but good resilience and elastic recovery; surface scales repel water, but high water absorption internally, comfortable in humid/cold climates; blended with cotton, rayon, or polyester for improved care/maintenance.

Silk

• A natural filament fibre from silkworm secretions, with cultivated (mulberry) silk producing smooth, long, fine, lustrous fibres, and wild (tussar) silk producing coarser, stronger, shorter fibres.
• Sericulture ensures high-quality silk, reeled from cocoons without spinning, or spun like cotton for broken filaments (spun silk).
• Discovered accidentally in China, kept secret for over 2000 years until around 500 A.D.
• Properties: Natural protein fibre, off-white to cream (wild silk brownish), long, fine, smooth, lustrous, with natural gum for crisp texture; strong with good elastic recovery and moderate elongation.

Rayon

• A manufactured cellulosic fibre made from chemically treated wood pulp, regenerated into fibres.
• Properties: Controlled size and shape, uniform diameter, clear, lustrous; similar to cotton but less strong and durable; reprocessed from waste, resembling silk in appearance.

Nylon

• The first true synthetic fibre, introduced in 1940 for socks and stockings, later used in various fabrics.
• Properties: Smooth, shiny filaments with uniform diameter; high strength and abrasion resistance, suitable for brushes, carpets; highly elastic, used in one-size garments like stockings; used in apparel, socks, undergarments, swimsuits, gloves, nets, sarees, hosiery, lingerie, and blends.

Polyester

• A synthetic fibre (Terylene, Terene) with uniform diameter, smooth, rod-like, partially transparent, lustrous appearance, customizable in strength, length, and diameter.
• Properties: Low moisture regain, less comfortable in hot/dry summers; excellent wrinkle resistance, commonly blended with rayon, cotton, wool, or spun silk.

Acrylic

• A synthetic fibre resembling wool (Cashmilon), cheaper than wool, with controlled length, diameter, fineness, crimp, and luster.
• Properties: Strength similar to cotton, high elongation, good elastic recovery; used in children’s wear, apparel, blankets, and knitted goods as a wool substitute.

Elastomeric Fibres- Elastic, rubber-like fibres, including natural rubber and synthetic spandex (Lycra), typically blended with less elastic fibres for stretch.