Chapter Notes

INTRODUCTION

Fabrics are a fundamental part of our daily lives, providing comfort, warmth, color, and style. From the moment we wake up in bedsheets to the clothes we wear and the bags we carry, fabrics are all around us, each designed for a specific purpose.

The journey from a raw material to the fabric you use involves several stages:

• Fibres: These are the basic building blocks of all fabrics. They are tiny, fine, hair-like structures.
• Yarns: When fibres are twisted together, they form a continuous thread-like structure called a yarn. You can see these if you pull a thread from a piece of cloth. Yarns can be interlaced, interlooped, or knotted to create fabrics.
• Fabrics: These are made from yarns. The final material, like a bedsheet or a T-shirt, is the fabric.

All these materials—fibres, yarns, and fabrics—are collectively known as textile products or textiles. After a fabric is made, it often undergoes a process called finishing. This can include cleaning, coloring, or other treatments to improve its appearance, feel, or durability. The final behavior of a fabric depends on the type of fibre, yarn, construction, and finish used.

FIBRE PROPERTIES

The characteristics of a fibre directly influence the properties of the final fabric. For a fibre to be useful in the textile industry, it must possess certain key properties.

• Availability and Economy: The fibre must be available in large quantities and be cost-effective to produce.
• Spinnability: This is the most crucial property, referring to the ease with which a fibre can be converted into yarn. Spinnability is a combination of several characteristics:
  • Length: How long the individual fibres are.
  • Strength: The ability to resist breaking.
  • Flexibility: The ability to bend without breaking.
  • Surface Structure: The texture of the fibre's surface, which affects how well fibres cling together.
• Consumer-Desired Properties: For user satisfaction, properties like colour, luster (shine), weight, moisture absorption, dye absorption, and elasticity are important.
• Care and Maintenance Properties: Factors like abrasion resistance (resistance to wear and tear), resistance to chemicals and heat, and resistance to biological organisms (like moths) are also vital for the user.

Classification of textile Fibres

Textile fibres can be classified in several ways, such as by their origin (natural or man-made), chemical type (cellulosic, protein), or length.

• Staple fibres: These are short-length fibres, like cotton.
• Filament fibres: These are long, continuous fibres, like silk or polyester.

Natural Fibres

Natural fibres are those that are found in nature. They are categorized into four main types:

• (a) Cellulosic fibres (from plants):
  • Seed hair: cotton, kapok
  • Bast fibres (from the stem): flax (linen), hemp, jute
  • Leaf fibres: pineapple, agave (sisal)
  • Nut husk fibres: coir (from coconut)
• (b) Protein fibres (from animals):
  • Animal hair: wool, specialty hair (goat, camel), fur
  • Animal secretion: silk
• (c) Mineral fibre: Asbestos
• (d) Natural rubber

Manufactured Fibres (also called man-made fibres)

Manufactured fibres are not found in nature and are created through industrial processes. The first manufactured fibre, Rayon, was produced in 1895.

The idea for manufactured fibres likely came from the desire to imitate silk. Scientists observed that a silkworm eats mulberry leaves (a cellulose substance), digests them, and then produces a liquid that hardens into a silk filament. This led to the idea that if a cellulose substance like wood pulp could be "digested" or processed, a silk-like fibre could be created. For this reason, rayon was often called Artificial Silk or Art Silk.

There are two main groups of manufactured fibres:

1. Those made by modifying natural non-fibrous materials (like wood pulp) into a fibrous form.
2. Those synthesized entirely from chemicals.

The basic process for creating manufactured fibres involves three steps:

1. Creating the spinning solution: The solid raw material is converted into a liquid of a specific viscosity through chemical action, heat, or dissolution.
2. Extrusion: This liquid solution is forced through a spinnerette, a small nozzle with many tiny holes, to form fine filaments.
3. Hardening and Processing: As the filaments emerge from the spinnerette, they harden. They are then collected and may be stretched for fineness or texturised to improve stretch or bulk.

Types of Manufactured Fibres:

• (a) Regenerated cellulosic fibres: Rayon (cuprammonium, viscose)
• (b) Modified cellulosic: Acetate
• (c) Protein fibres: Azlon
• (d) Non-cellulosic (synthetic) fibres: nylon, polyester, acrylic, spandex, rubber
• (e) Mineral fibres: Glass, Metallic

YARNS

Fibres are rarely used directly in consumer products, except for things like surgical cotton or stuffing for pillows. To create most fabrics, fibres must first be converted into a continuous strand, or yarn.

A yarn is a continuous strand of textile fibres or filaments suitable for knitting, weaving, or intertwining to form a fabric.

Yarn Processing

The process of converting natural staple (short) fibres into yarn is called spinning. This involves several stages:

1. Cleaning: Natural fibres contain impurities like seeds in cotton or twigs and grease in wool. These are removed, and the fibres are sorted and rolled into sheets called laps.
2. Making into a sliver: The laps are unrolled and put through straightening processes.
   • Carding: Disentangles the fibres and lays them straight and parallel, much like combing hair.
   • Combing: An additional step for finer fabrics, which removes shorter fibres and finer impurities.
   • The straightened fibres are then passed through a funnel-like device to form a sliver, which is a loose, rope-like mass of fibres.
3. Attenuating, drawing out and twisting:
   • The sliver is made longer and finer through a process called attenuation or drawing out. If a blended yarn (like cotton and wool) is needed, slivers from different fibres are combined at this stage.
   • The sliver is then taken to a roving machine, where it is further attenuated and given a slight twist to hold it together.
   • The final stage is spinning, where the strand is stretched to the desired fineness, the final amount of twist is added, and the finished yarn is wound onto cones.

Manufactured fibres are first created as long filaments. A yarn can be a single filament or a multifilament yarn (multiple filaments twisted together). These filaments can also be cut into staple lengths and then spun like natural fibres; these are called spun yarns. This is necessary for creating blended fabrics like 'terecot' (terene and cotton).

Yarn Terminology

• (a) Yarn number: This number (e.g., 20, 30, 40) on a thread reel indicates the fineness of the yarn. A higher number means a finer yarn. It represents the relationship between the weight of the fibre and the length of the yarn drawn from it.
• (b) Yarn twist: Twist is added to hold fibres together in a yarn, measured in t.p.i. (twist per inch). Loosely twisted yarns are softer and more lustrous, while tightly twisted yarns can create ridges, like in denim.
• (c) Yarn and thread: Though similar, yarn is the term used for the strands that are manufactured into fabric. Thread is the product used to sew pieces of fabric together.

FABRIC PRODUCTION

Fabrics can be produced in two main ways: directly from fibres or from yarns.

Fabrics made directly from fibres: A small group of fabrics, like felts and non-wovens (bonded fibre fabrics), are made without yarns. Fibres are laid out in a matt, and then adhesion is created between them to form a fabric sheet of any desired thickness or shape.

Fabrics made from yarns: Most fabrics are constructed from yarns using methods like weaving, knitting, braiding, or knotting.

Weaving

Weaving is the oldest method of textile production. A woven fabric is made by interlacing two sets of yarns at right angles to each other on a machine called a loom.

• Warp yarns: These are the yarns that run lengthwise and are fitted onto the loom under tension.
• Filling yarn (or weft): This is the second yarn that is interlaced over and under the warp yarns to create the fabric.
• Grain: The direction of the yarns in the fabric. The lengthwise grain is the selvedge, and the width-wise grain is the weft. The selvedges are the bound edges of the fabric and are the strongest part.

Different patterns and designs can be created by varying the sequence of interlacing. Attachments like a dobby or jacquard can create complex figurative designs. Textures like those in towels (uncut loops) or velvets (cut loops) are made by using an extra yarn that is held up as loops during weaving.

Knitting

Knitting is the process of interlooping at least one set of yarns.

• Weft knitting (or filling knitting): This is the common method done by hand with needles or on machines. A series of loops is made, and each new row is formed by interlooping with the previous row. The yarn moves along the width of the material. This method is used for articles that can be shaped during construction, like sweaters.
• Warp knitting: This is done at an industrial level on machines that have a set of yarns fitted like warp yarns on a loom. Interlooping occurs between adjacent yarns. This method produces continuous lengths of fabric that can be cut and stitched.

Braiding

Braided fabrics are made by plaiting three or more yarns, creating a diagonal surface effect. Shoelaces, ropes, and trimmings are common examples of braids.

Nets

Nets are open-mesh fabrics with large spaces between the yarns, which are made by inter-knotting them.

Laces

Lace is an openwork fabric with intricate designs formed by a combination of yarn twisting, interlooping, and knotting.

Textile Finishing

Fabric straight from the loom, known as grey goods, is often unrecognizable. All fabrics available in the market have undergone one or more finishing treatments.

A finish is any treatment applied to a fabric to change its appearance, texture, or performance for a specific use.

• Durable finishes: These do not get removed by washing or dry cleaning (e.g., dyeing).
• Renewable finishes: These need to be reapplied as they get removed during washing (e.g., starching).

Functions of Finishes:

• Change appearance: Cleaning (scouring, bleaching), straightening (calendering).
• Change textures: Starching, special calendering.
• Change behaviour: Creating wash-and-wear, water-repellent, mothproof, or flame-retardant fabrics.

(a) Finishing with colour (Dyeing): Dyes are substances that add colour to fabric in a way that it doesn't easily wash out. Colour can be applied at different stages:

• Fibre stage: For creating multi-coloured yarns.
• Yarn stage: For making woven patterns like checks and stripes.
• Fabric stage: The most common method for solid-coloured fabrics and for techniques like tie-and-dye or printing.

(b) Printing: This is a specialized form of dyeing where colour is applied to localized areas to create a design. It allows for multiple colours to be used on one fabric. Printing can be done by hand (blocks, stencils) or by machine (roller printing).

SOME IMPORTANT FIBRES

Cotton

Cotton is the most widely used fibre, originating from the seed pod of the cotton plant. India was the first country to grow and use cotton. The fibres are separated from the seeds in a process called ginning.

Properties:

• It is a natural, cellulosic, staple fibre, with short lengths (1-5 cm), making the fabric feel slightly rough and look dull.
• It has excellent moisture absorbency and dries easily, making it very comfortable for summer wear.
• It is versatile and available in many forms, from lightweight muslin to heavy denim.

Linen

Linen is a bast fibre obtained from the stem of the flax plant. The stems are soaked in water to rot away the soft parts (retting), after which the fibres are collected.

Properties:

• As a cellulosic fibre, its properties are similar to cotton.
• The fibres are longer and finer than cotton, making linen yarn stronger and more lustrous.
• It absorbs moisture well and is comfortable, but it doesn't absorb dyes as readily, so colours are not as bright.

Wool

Wool is a protein fibre obtained from the hair of sheep, but can also come from goats, camels, or rabbits (speciality hair fibres). The hair is removed by shearing, and the single piece of hair is called a fleece. The fibres are then sorted, scoured (cleaned of dirt and grease), and carbonised (vegetable matter removed) before spinning.

Properties:

• It has a natural crimp (waviness), which gives it elasticity and resilience (ability to spring back into shape).
• It has low strength compared to other fibres but good elastic recovery.
• The surface has scales that repel water, yet it can absorb a large amount of moisture without feeling wet, making it comfortable in cold, humid weather.

Silk

Silk is a natural filament fibre produced by silkworms. The cultivation of silkworms for silk production is called sericulture.

• Cultivated silk (mulberry silk) is produced in controlled conditions, resulting in long, smooth, lustrous fibres.
• Wild silk (tussar silk) is coarser and results in a stronger, thicker fabric.
• Spun silk is made from broken filaments that are spun like cotton.

Properties:

• It is a natural protein fibre that is very long, fine, and smooth with a high lustre.
• It is one of the stronger natural fibres, with good elastic recovery.

Rayon

Rayon is a manufactured cellulosic fibre made from wood pulp that is treated with chemicals and regenerated into fibres.

Properties:

• As a manufactured fibre, its size and shape can be controlled, resulting in a uniform and lustrous appearance.
• Being cellulosic, it shares many properties with cotton but has lower strength and durability.
• Its main advantage is that it can be made from waste materials and has a silk-like appearance.

Nylon

Nylon was the first true synthetic fibre, made entirely from chemicals. It was first used for toothbrush bristles and became famous in 1940 with nylon stockings.

Properties:

• Filaments are smooth, shiny, and uniform.
• It has very good strength and abrasion resistance, making it suitable for carpets and brushes.
• It is highly elastic, which is why it's used for 'one-size' garments like stockings.
• Commonly used for apparel, hosiery, swimsuits, and nets.

Polyester

Polyester (also known as Terylene or Terene) is another synthetic fibre widely used in textiles.

Properties:

• It has a uniform, smooth, and rod-like appearance. Its strength and length can be controlled.
• It has very low moisture absorption, making it less comfortable in hot, dry weather.
• Its most significant advantage is its excellent wrinkle resistance.
• It is very commonly blended with other fibres like cotton, wool, and rayon.

Acrylic

Acrylic is a synthetic fibre that closely resembles wool. It is often called Cashmilon and is cheaper than wool.

Properties:

• Its length, fineness, and luster can be controlled during manufacturing.
• Its strength is similar to cotton, and it has high elongation with good elastic recovery.
• It is often used as a substitute for wool in children's wear, blankets, and knitted goods.

Elastomeric fibres

These are elastic, rubber-like fibres. The natural form is rubber, while the synthetic equivalent is spandex or Lycra. They are typically blended with other fibres that have low elasticity to add stretch and comfort to fabrics.

Key Terms

• Fabrics: Materials made by weaving, knitting, or bonding yarns or fibres.
• Yarns: Continuous strands of twisted fibres used for making fabrics.
• Fibres: The basic, hair-like building blocks of yarns and fabrics.
• Textiles: A general term for fibres, yarns, or fabrics.
• Textile finishing: Treatments applied to fabrics to improve their look, feel, or performance.
• Weaving: The process of making fabric by interlacing two sets of yarns at right angles.
• Knitting: The process of making fabric by interlooping yarns.
• Cotton: A natural seed fibre from the cotton plant.
• Linen: A natural bast fibre from the flax plant.
• Wool: A natural protein fibre from the hair of sheep and other animals.
• Silk: A natural protein filament fibre produced by silkworms.
• Rayon: A manufactured fibre made from regenerated cellulose (wood pulp).
• Nylon: The first true synthetic fibre, known for its strength and elasticity.
• Polyester: A synthetic fibre known for its wrinkle resistance.
• Acrylic: A synthetic fibre that resembles wool.