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.
Like all the textile fibers, silk has its own physical and chemical properties which are required to know for better processing in spinning, weaving, knitting, dyeing, printing as well as finishing. Here, I have written about physical and chemical properties of silk fiber.
Physical Properties of Silk: There have a lot of physical properties of silk. Followings are the physical properties of silk:
- Color: The color of silk fiber could be yellow, brown, green or grey.
- Tensile Strength: Cotton is a strong fiber. It has a tenacity of 3.5 – 5 gm/den. The strength is greatly affected by moisture; the wet strength of silk is 75 – 85%, which is higher than dry strength.
- Elongation at break: 20 -25% at break.
- Elastic Recovery: Not so good.
- Specific Gravity: Specific gravity is 1.25 to 1.34.
- Moisture Regain (MR %): Standard moisture regain is 11% but can absorb up to 35%.
- Effect of Heat: Silk will withstand at higher temperatures than wool. It will remain unaffected for prolonged periods at 1400C. Silk decomposes at 1750C.
- Effect of Sun Light: Sun light tends to encourage the decomposition of silk by atmospheric oxygen.
- Luster: Bright.
Chemical Properties of Silk: Chemical properties of the silk fiber are given below:
- Effect of Acids: The Fibroin of silk can be decomposed by strong acids into its constitute amino acids. In moderate concentration, acids cause a contraction in silk. Dilute acids do not attack silk under mild conditions.
- Effects of Alkalis: Silk is less readily damaged by alkalis than wool. Weak alkalis such as soap, borax and ammonia cause little appreciable damage. Silk dissolves in solutions of concentrated caustic alkalis.
- Effect of Organic Solvent: Silk is insoluble in the dry-cleaning solvents in common use.
- Effects of Insects: Insect does not affect silk.
- Effect of Mildew: Silk is affected by mildew slightly.
I think above physical and chemical properties will help us to be careful about the processing of silk in the different stages of processing from spinning to garments making. Day by day the use of silk products is increasing rapidly.
Spinning is the first steps of textile product processing. The process of making yarns from the textile fiber is called spinning. There are various types of spinning methods for producing various types of yarn. If we notice, we will see that the cotton fibers are converted into carded yarn, combed yarn and rotor yarn. For producing this three types of cotton yarn, spinning methods also different.
Types of Spinning Process: Spinning process is varying depending on the fiber types which we want to process. There are different methods of spinning for yarn preparation. Such as-
- Ring Spinning
- Rotor Spinning
- Friction Spinning
- Self Twist Spinning
- Electro-Static Spinning
- Vortex Spinning
- Air Jet Spinning
- Twist Less Spinning
- Wet Spinning
- Dry Spinning
- Melt Spinning
- Bi-Component Spinning
- Film Splitting Reaction Spinning
- For Integrated Multi-Component Yarns:
- Integrated Composite Spinning
- Cover Spun
- Selfil Yarn Spinning
- Acro dynamic Spinning
By the spinning process; various counted yarns are produces. Spinning frames are set for producing specific counted yarn.
In textile arena; textile fiber is the raw materials to produce various types of textile finished products. A fiber that can be spun into yarn or processed into textile such as a woven fabric, knit fabric, lace, felt, non-woven etc by means of an appropriate interlacing method is called as textile fiber.
A textile fiber should have at least 5 mm length then it will be spin able and it must be supple, flexible and strong enough. Other properties like elasticity, fineness, uniformity, durability, luster, and crimp should have a textile fiber more or less.
Classification of Textile Fiber: There are various types of fiber are found in the market but all have not same characteristics. The characteristics of the fiber differ depending on the source from where it is produced. Generally textile fibers are classified into main two types they are-Natural fiber And Synthetic fiber or manmade fiber or artificial fiber. Now I like to present the classification of textile fiber as below.
Natural Fiber: Natural fiber is that which is produced naturally. The source of origin could be vegetable, animal and mineral origin.
- Bast Fibers (Jute, Flax, Ramie)
- Leaf Fibers (Sisal, manila)
- Seed and Fruits Fibers (cotton, coir)
- Wool and Hair Fiber
- Silk and other Filaments
Synthetic Fibers/Manmade Fibers/Artificial Fibers: Synthetic fibers are produced by the polymerization of various monomers. It is made by the man for this reason, it is so called.
- Cellulose Ester
- Polyvinyl Derivatives ( PVA, PTFE, Polyvinylidene dinitrite, Polystyrene etc)
- Polyurethanes (Elastomer)
Above textile fibers are processed by different methods. All textile fibers contain their own characteristics. We can identify the fiber type by different testing procedure. Also we should know the physical and chemical properties of different fibers.