Fibers introduction
- 1. INTRODUCTION TO FIBRES DR. RITU MADHAN
- 2. TEXTILES The word ‘textile’ comes from the Latin word ‘textilis’ and from the verb ‘texere’, which means ‘to weave’. Today the word textiles is used freely to define any product made from fibers and is applied to non- woven fabrics, knitted fabrics as well as woven fabrics. The broad definition of word textiles is applied to everyone who works with fibers or fabrics at any stage of manufacture or processing
- 4. FIBER CLASSIFICATION Natural fibers Plant Cotton Jute Linen Hemp Kapok Pina Animal Silk Wool Hair bearing animals Mineral Asbestos
- 6. Name any one natural and one synthetic fiber
- 7. FIBER PROPERTIES (PRIMARY) • Length must be greater than the diameter • Fibers less than ½ inch in length cannot be used for spinning Length to width ratio • Tenacity is the force applied to a fiber • Fibers should be durable enough to last the tension of conversion to yarn and then to fabric Tenacity
- 8. FIBER PROPERTIES Elasticity • Elasticity the ability of the material to regain original shape after being deformed by the application of force • Elasticity or elastic recovery are generally influenced by the extent of stretch, time during which material is kept in its stretched condition and time to recover Uniformity • It is essential that there should be limited variations in length and diameter between fiber to fiber or in other words the fiber should be more uniform which will ensure uniformity in the yarn as well as fabric Spinnability • Fibers must be capable of being spun into a yarn and then a fabric with sufficient strength. • For better cohesiveness i.e. they must hold themselves together to prevent slippage.
- 10. FIBER PROPERTIES (SECONDARY) • It is the ability of the fiber to bounce back or return to shape after compression, bending or similar deformation. It is important in determining the crease recovery of a fiber or fabric. Usually good elastic recovery indicates good resiliency. RESILIENCY Textile fibers in general have certain amount of moisture as an integral part of the fiber structure. ASTM defines, moisture regain as ‘the moisture in a material determined under prescribed condition and expressed as percentage of the weight of the oven dry specimen. MOISTURE REGAIN AND MOISTURE ABSORPTION
- 11. REQUIREMENTS FOR FIBER - FORMING POLYMERS • Fiber polymers should be hydrophilic i.e. they should attract water molecules. A fiber is comfortable to wear if its polymer system consists of hydrophilic polymers, and the system permits they entry of water molecules. HYDROPHILIC PROPERTIES • Fiber polymers should be chemically resistant for a reasonable length of time against the common degrading agents . Chemically resistant polymers should also not be toxic or hazardous to wear against the human skin. CHEMICAL RESISTANCE • Fiber polymers should be linear. Only linear polymers allow adequate polymer alignment to bring into effect sufficient inter - polymer forces of attraction to give a cohesive polymer and hence a useful textile fiber. LINEARITY
- 12. REQUIREMENTS FOR FIBER - FORMING POLYMERS LENGTH Fiber polymers should be long. It is found that the length of the polymers constituting the commonly used apparel fibers is in excess of 100 nanometers. Polymers of such length can be easily oriented. The longer the polymers, the more cohesive will be the fiber system and the stronger will be the fiber. ORIENTATION Fiber polymers should be capable of being oriented. This means that the polymers are or con be arranged or aligned into more or less parallel order in the direction of the longitudinal axis of the fiber or filament. FORMATION OF HIGH MELTING- POINT POLYMERS SYSTEMS A fiber consisting of this system tends to have adequate heat resistance to enable it to stand the various heat systems of textile finishing. A fiber’s melting point needs to be above 225°C if it is useful for textile manufacture and apparel use
- 13. Which is the most important property for a textile fiber?
- 14. Fiber Length, since short fibers cannot be twisted to form a yarn and in turn fabric!
- 15. POLYMERIZATION Textile fibers like most substances are made up of molecules. Fiber molecules are called polymer. The unit of a polymer is called monomer. At the molecular level the polymer is extremely long and linear, whereas a monomer is very small. Monomers are usually reactive chemically whereas polymers tend to be unreactive. This is illustrated by chemical reaction called polymerization, which causes the monomers to joint from end to end. The length of the polymers is most important. All fibers both man made and natural have long too extremely long polymers Measuring the length of a polymer is a complicated if not impossible task. Estimates of the length of a polymer can be obtained by determining the degree of polymerization. This is often abbreviated as DP. A polymer is often described a having a back bone consisting of the atoms, which are bonded to each other in a linear configuration and are responsible for the length of the polymer.
- 16. POLYMERIZATION Addition polymerization • The monomers add or join end to end without liberating any by- product. Addition polymerization is composed of 3 distinct steps: • Initiation • Propagation • Termination • The process is initiated through the presence of activated molecule introduced into the system. Condensation polymerization • The monomers join end to end and liberate a by-product. This by-product is usually a simple compound- generally water - but it may alternatively be hydrogen chloride or ammonia depending upon the specific monomers involved. • This polymerization is expressed as: • n X M → Mn + (n-1)A • Where, n - no. of monomers reacting together. • M - Monomer • A - Simple molecule
- 17. MOLECULAR ARRANGEMENT • When the molecules are highly oriented, they are parallel to each other and to the longitudinal axis of the fiber. Molecules may exhibit low degree of variation associated with a good fiber strength and low elongation. Low orientation tends to reverse properties. Oriented • In contrast to orientation, crystalline arrangement indicates that the molecules are parallel to each other but not to the fiber axis. Crystalline • When molecules have no systematic arrangement, they may lie far from each other, criss-cross, or in other irregular ways. The extent of amorphous area varies widely from slight disorder to extremely amorphous arrangement depending upon the fiber and the location within the fiber. Amorphous