Lecture slides Silk Fiber and its properties

Basic Introduction to Slik Fiber, Properties and uses

1. Silk Fiber Lecture 2 Textile Basics Dr. Rehan Abbasi

2. Introduction Silk is an animal fiber and it is also called protein fiber. Silk is only natural fiber which is found in filament form. Silk is produced by insects. Fibroin is the main chemical components of silk. The best- known silk is obtained from the cocoons of the larvae of the mulberry silkworm .

3. Introduction The shimmering appearance of silk is due to the triangular prism-like structure of the silk fiber, which allows silk cloth to refract incoming light at different angles, thus producing different colors.

4. Introduction Silk production was originated by the Chinese , who kept it as a closely guarded secret, approximately 5,000 years ago & silk continues to hold a certain prestige as a luxury fiber. Silk is produced by the caterpillars belonging to the genus Bombyx and are commonly referred to as silkworms.

5. Microscopic view Smooth surface, Structureless, triangular shaped transparent rod (Wild silk/Tussah silk – broader fiber with fine, longitudinal lines passing across filament) . Triangular shape with rounded corners (Tussah silk flat wedge or spindle-shaped

6. Properties of Silk Fibers Composition : The silk fiber is chiefly composed of 80% of fibroin, which is protein in nature and 20% of sericin, which is otherwise called as silk gum. Resilience : Silk fabrics retain their shape and have moderate resistance to wrinkling. Fabrics that are made from short – staple spun silk have less resilience.

7. Properties of Silk Fibers Strength : Silk as a fiber, has good tensile strength , which allows it to withstand great pulling pressure. Silk is the strongest natural fiber and has moderate abrasion resistance . The strength of the thrown yarns is mainly due to the continuous length of the fiber. Spun silk yarn though strong is weaker than thrown silk filament yarns.

8. Properties of Silk Fibers Drapability : Silk has a liability and suppleness that, aided by its elasticity and resilience, gives it excellent drapability. Heat Conductivity : Silk is a protein fibre and is a non-conductor of heat similar to that of wool. This makes silk suitable for winter apparel .

9. Properties of Silk Fibers Absorbency : Silk fabrics being protein in nature have good absorbency. The absorptive capacity of the silk fabric makes comfortable apparel even for warmer atmosphere. Fabrics made from silk are comfortable in the summer and warm in the winter.

10. Properties of Silk Fibers Absorbency (cont…) : Silk fibre can generally absorb about 11% of its weight in moisture, but the range varies from 10% to as much as 30%. This property is also a major factor in silk’s ability to be printed and dyed easily.

11. Properties of Silk Fibers Cleanliness and Wash Ability: Silk fabric does not attract dirt because of its smooth surface. The dirt, which gathers can be easily removed by washing or dry cleaning. It is often recommended for the silk garments to be dry-cleaned. Silk fabrics should always be washed with a mild soap and strong agitation in washing machine should be avoided.

12. Properties of Silk Fibers Cleanliness and Wash Ability (cont…): Silk water – spot easily, but subsequent washing or dry cleaning will restore the appearance of the fabric.

13. Properties of Silk Fibers Shrinkage: Silk fabrics are subjected only to normal shrinkage which can be restored by ironing. Crepe effect fabrics shrink considerably in washing, but careful ironing with a moderately hot iron will restore the fabric to its original size.

14. Properties of Silk Fibers Effect of Heat: Silk is sensitive to heat and begins to decompose at 330°F (165°C). The silk fabrics thus have to be ironed when damp. Effect of Light: Silk fabric weakens on exposure to sunlight. Raw silks are more resistant to light than degummed silk.

15. Properties of Silk Fibers Resistance to Mildew: Silks will not mildew unless left for sometime in a damp state or under the extreme conditions of tropical dampness. Resistance to Insects: Silk may be attacked by the larvae or cloth moths or carpet beetles.

16. Properties of Silk Fibers Affinity for Dyes: Silk has good absorbency and thus has good affinity for dyes. Dyed silk is colourfast under most conditions, but its resistance to light is unsatisfactory.

17. Properties of Silk Fibers Resistance to Perspiration: Perspiration and sunlight weakens and yellows silk fabrics. The silk itself deteriorates and the colour is affected causing staining. Garments worn next to the skin should be washed or otherwise cleaned after each wearing.

18. Properties of Silk Fibers Reaction to Alkalis: Silk is not as sensitive as wool to alkalis, but it can be damaged if the concentration and the temperature are high. A mild soap or detergent in lukewarm water is thus advisable.

19. Uses of Silk Fiber Silk is mainly used in the manufacture of clothing such as dresses, ties, shirts, trousers, pajamas, underwear and folk costumes. It is also used in skiing garments because of its ability to keep body warmth contained and because it is lightweight.

20. Uses of Silk Fiber Silk is also used to make silk comforter or duvets which are lightweight and hypoallergenic. It is also used as fabric for upholstery, curtains, rugs and bedding such as sheets .

21. Class Assignment Due date Thursday 18th Oct 2018 Marks 4 out of 25 (sessional) Choose one fiber (either natural or man-made) of your choice and present its brief history, general characteristics and uses in terms of textiles in 10 min. PS: The topic must be unique from other fellows.

22. Thank you