Drawing and Morphology of Textile Fiber

On drawing and orientation, the synthetic fibers become smaller in diameter and additional crystalline, and imperfections within the fiber morphology are improved somewhat. Side-by-side bicomponent or biconstituent fibers on drawing become wavy and bulky.

Fig: Aspects of Internal Fiber Morphology

In natural fibers, the orientation of the molecules among the fiber is determined by the biological source throughout the expansion and maturity method of the fiber.

The form and structure of polymer molecules in relevance each other among the fiber can depend upon the relative alignment of the molecules in relationship to 1 another. Those areas wherever the polymer chains are closely aligned and packed along are crystalline areas inside the fiber, wherever as those areas where there's basically no molecular alignment are mentioned as amorphous areas. Dyes and finishes will penetrate the amorphous portion of the fiber, however not the ordered crystalline portion.

A number of theories exist regarding the arrangement of crystal-line and amorphous areas inside a fiber. Individual crystalline areas during a fiber are usually mentioned as micro fibrils. Micro fibrils will associate into larger crystalline teams, which are known as fibrils or micelles. Micro fibrils are 30-100 A (10-to meters) long, whereas fibrils and micelles are typically 200-600 A long. This compares to the individual molecular chains, that vary from three hundred to 1,500 A long and that are typically a part of each crystalline and amorphous areas of the polymer and, therefore, give continuity and association of the varied crystalline and amorphous areas among the fiber. Variety of theories are developed to clarify the interconnection of crystalline and amorphous areas within the fiber and embrace such ideas as fringed micelles or fringed fibrils, molecular chain folding, and extended chain ideas. The amorphous areas among a fiber are going to be comparatively loosely packed and related to each other, and areas or voids can seem because of discontinuities inside the structure. Figure outlines the assorted aspects of internal fiber morphology with regard to polymer chains.

The forces that keep crystalline areas along among a fiber embrace chemical bonds (covalent, ionic) as well as secondary bonds (hydrogen bonds, Vander Waals forces, dipole-dipole interactions). Valence bonds result from sharing of electrons between atoms, like found in carbon-carbon, carbon-oxygen, and carbon-nitrogen bonding, among organic com-pounds. Valency bonds connexion adjacent polymer chains are remarked as cross links. Ionic bonding happens once molecules present or settle for electrons from each other, as once a metal salt reacts with acid aspect chains on a polymer among a fiber. Chemical bonds are a lot of stronger than secondary bonds formed between polymer chains, however the full associative force between polymer chains may be massive since a really sizable amount of such bonds could occur between adjacent polymer chains. Hydrogen bonds are the strongest of the secondary bonds and occur between electro positive hydrogen atoms and electro negative atoms like oxygen, nitrogen, and halogens on opposing polymer chains. Nylon, protein, and cellulosic fibers are capable of intensive hydrogen bonding. Van der Waals interactions between polymer chains occur once clouds of electrons from every chain are available in shut proximity, thereby promoting a little force between chains. The additional extended the cloud of electrons, the stronger the van der Waals interactions are going to be. Covalently bonded materials can show some uneven distribution of electron density over the molecule because of the differing electro negativity of the atoms and electron distribution over the molecule to make dipoles. Dipoles on adjacent polymer chains of opposite charge and shut proximity are interested in one another and promote secondary bonding. Once an artificial fiber is stretched or drawn, the molecules in most cases can orient themselves in crystalline areas parallel to the fiber axis, though crystalline areas in some chain-folded polymers like polypropylene may be aligned vertically to the fiber axis. The degree of crystallinity is going to be affected by the full forces available for chain interaction, the gap between parallel chains, and therefore the similarity and uniformity of adjacent chains. The structure and arrangement of individual polymer chains additionally affects the morphology of the fiber. Also, cistrans configurations or optical isomers of polymers will have terribly totally different physical and chemical properties.