Fabrics Around UsClass 11 Human Ecology and Family Sciences Part 1 NCERT Solutions
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Q1Review Questions
Name five articles of everyday use that are made from different types of fabrics.
Solution
Based on the chapter, five articles of everyday use made from different types of fabrics are:
- Bedsheets and Pillow Covers: These are fabrics we use for sleeping, providing comfort.
- Towel: A soft and absorbent fabric used after bathing.
- School Dress: A fabric of a special type designed for regular wear and durability.
- School Bag: A stiff, coarse, and strong fabric designed to bear the load of books.
- Curtains: Fabrics used in homes for decoration and to control light.
Q2Review Questions
How are textile fibres classified? Briefly discuss their characteristics.
Solution
Textile fibres can be classified based on their origin into two main categories: Natural Fibres and Manufactured Fibres.
1. Natural Fibres:
These fibres are available to us from natural sources. They are further classified based on their source:
- Cellulosic Fibres (from plants):
- Seed hair: Cotton, kapok.
- Bast fibres (from stems): Flax (linen), hemp, jute.
- Leaf fibres: Pineapple, agave (sisal).
- Nut husk fibres: Coir (coconut).
- Protein Fibres (from animals):
- Animal hair: Wool, specialty hair (goat, camel).
- Animal secretion: Silk.
- Mineral Fibre: Asbestos.
- Natural Rubber.
2. Manufactured Fibres (Man-made):
These fibres are produced through chemical processes. They can be created by modifying natural materials or synthesized entirely from chemicals.
- Regenerated Cellulosic Fibres: Made by modifying a natural cellulosic substance like wood pulp. Example: Rayon.
- Modified Cellulosic Fibres: Example: Acetate.
- Protein Fibres: Example: Azlon.
- Non-cellulosic (Synthetic) Fibres: Synthesized completely from chemicals. Examples: Nylon, polyester, acrylic, spandex.
- Mineral Fibres: Example: Glass, Metallic.
Fibres are also classified by their length:
- Staple: Short length fibres, like cotton.
- Filament: Long, continuous length fibres, like silk and polyester.
Q3Review Questions
What is a yarn? Explain different methods of yarn processing?
Solution
Yarn is a continuous strand of textile fibres, filaments, or material in a form suitable for knitting, weaving, or otherwise intertwining to form a textile fabric. It is the intermediate stage between fibre and fabric for most textiles.
The process of converting natural staple fibres into yarn is called spinning. It involves several stages:
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Cleaning: The raw natural fibres contain impurities like seeds, leaves (in cotton) or twigs and grease (in wool). This stage involves removing these impurities, sorting the fibres, and converting them into rolled sheets called laps.
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Making into a Sliver: The laps are unrolled and undergo straightening processes called carding and combing.
- Carding disentangles the fibres and lays them straight and parallel to one another.
- Combing is an additional step for finer fabrics that removes shorter fibres and finer impurities. The straightened fibres are then passed through a funnel-shaped device to form a sliver, which is a rope-like, loose mass of fibres.
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Attenuating, Drawing Out, and Twisting:
- Several slivers are combined and gradually drawn out to make them longer and finer. This process is called attenuation. If a blended yarn (e.g., cotton and wool) is required, 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 the fibres together.
- The final stage is spinning, where the strand is stretched to the required fineness, the desired amount of twist is given to it, and it is wound onto cones.
Q4Review Questions
List the processes in fabric production.
Solution
The main processes in fabric production can be categorized into two groups: making fabric directly from fibres and making fabric from yarns.
1. Fabric Production Directly from Fibres:
- Felting: Fibres are laid in the form of a matt, and adhesion is caused between them through moisture, heat, and pressure.
- Non-wovens / Bonded Fibre Fabrics: Similar to felts, fibres are laid in a matt and then bonded together chemically or mechanically.
2. Fabric Production from Yarns:
This is the most common method of fabric construction. The main processes are:
- Weaving: This is the interlacing of two sets of yarns (warp and filling) at right angles to each other on a machine called a loom. It is the oldest and most common method.
- Knitting: This is the interlooping of at least one set of yarns. It can be done by hand or machine and includes weft knitting and warp knitting.
- Braiding: This involves plaiting or interlacing three or more yarns that originate from a single location. It is used for items like shoelaces and ropes.
- Knotting: Yarns are inter-knotted by hand or machine to create open-mesh fabrics like nets.
- Lace Making: This is an intricate process that combines procedures like yarn twisting, interlooping, and knotting to create an openwork fabric with designs.
Q5Review Questions
Mention any three properties of each of the following fibres. Cotton Linen Wool Silk Rayon Nylon Acrylic
Solution
Here are three properties for each of the specified fibres, based on the chapter content:
Cotton
- It is a natural cellulosic, staple fibre of short length (1 cm to 5 cm).
- It has good moisture absorbency and also dries easily, making it very comfortable for summer use.
- The fabric made from it is dull in appearance and slightly rough to the touch.
Linen
- It is a cellulosic bast fibre obtained from the stems of the flax plant.
- The fibre is longer and finer than cotton, which makes the yarn produced from it stronger and more lustrous.
- Like cotton, it absorbs moisture readily, but it does not absorb dyes very well, so the colours are not as bright.
Wool
- It is a natural protein fibre with a natural crimp or waviness, which makes it elastic.
- It has low strength compared to other fibres but possesses good resilience and elastic recovery.
- It can absorb a large amount of water without feeling wet on the surface, providing comfort in cold and humid weather.
Silk
- It is a natural protein filament fibre, and the filaments are very long, fine, and smooth.
- It is one of the stronger natural fibres and has a relatively high lustre or sheen.
- It has good elastic recovery and moderate elongation.
Rayon
- It is a manufactured cellulosic fibre made from wood pulp.
- As a manufactured fibre, its size and shape can be controlled, so it has a uniform diameter and is clear and lustrous.
- It has properties similar to cotton but possesses lower strength and durability.
Nylon
- It is a true synthetic fibre with very good strength and abrasion resistance.
- It is a highly elastic fibre, making it suitable for 'one-size' garments like stockings.
- The filaments are usually smooth and shiny with a uniform diameter.
Acrylic
- It is a synthetic fibre that closely resembles wool and is often used as a substitute.
- Its strength is not very high, being similar to that of cotton.
- The fibres have high elongation with good elastic recovery.