Synthetic fibers produced by industrial method started in 1938.At the moment, they exist several dozen species.For all of them have in common is that the starting material are low molecular weight compounds convertible to polymers by chemical synthesis.Dissolving or melting the polymers obtained preparation is carried out of the molding or spinning solution.They are formed from solution or melt, and then have them subjected to finishing.
Species
Depending on the features that characterize the structure of macromolecules, synthetic fibers usually divided into hetero and carbon chain.The former include those derived from polymers whose macromolecules, besides carbon and other elements are present - nitrogen, sulfur, oxygen and others.These include polyester, polyurethane, polyurea and polyamide.Carbon-chain synthetic fiber characterized by the fact that the main chain of them built of carbon atoms.This group includes polyvinyl chloride, polyacrylonitrile, polyolefin, polyvinyl alcohol, and fluorine-containing.
polymers serve as the basis for hetero fibers obtained by polycondensation and the product is formed from the melt.Long carbon chain obtained by polymerization and shaping is usually from solutions, in rare cases, from the melt.You can see some one synthetic polyamide fiber, which was called siblon.
Creating and applying
a word like siblon for many is a complete stranger, but earlier on the label of clothes could be seen acronym BBM, revealing viscose high modulus fibers.Then the producers thought that this name would look nicer than siblon that could be associated with nylon and Caproni.Production of synthetic fibers of this type are made from trees, as if it did not look fabulous.
Features
siblon appeared in the early 70-ies.It is an improved viscose.In the first step, the preparation of wood pulp, it is isolated in pure form.The greatest amount of it is contained in cotton - about 98% of the cotton fiber but without that make excellent thread.Therefore, to produce wood pulp is more often used, particularly conifer where it contains 40-50%, and the rest - it is unnecessary components.They are required to get rid of in the process of production of synthetic fibers.
process of creating
synthetic fibers produced in stages.In the first step, the brewing process, during which the wood chips of all superfluous material transferred into the solution, and also produced a breakdown of long polymer chains into fragments.Of course, it's not only the cost of hot water produced by adding various reagents and other soda.Only with the addition of sulfate pulping provides a cellulose which is suitable for the production siblona, since it has less impurities.
When the pulp is already digested, it is sent to the bleaching, drying and pressing, and then moved to where it is needed - is the production of paper, cellophane, cardboard and fiber, that is the main production.What is going on with her?
Subsequent processing
If you want to receive synthetic and natural fibers, you must first prepare a dope.Cellulose is a solid which is difficult to dissolve.Therefore, it is usually converted into a water-soluble acid ester ditiougolnoy.The process of transformation in this compound is quite lengthy.First the treatment of cellulose with alkali, followed by hot pressing, to the solution thus pass unnecessary elements.After squeezing the mass of crushed and then placed in a special chamber, where it starts predsozrevanie - shortening of the cellulose molecules occur almost doubled due to oxidative degradation.Next there is a reaction of alkali cellulose with carbon disulfide to provide xanthate.This mass of orange-like dough ditiougolnoy acid ester starting material.This solution for its viscosity was named "viscose".
Further there is filtering to remove the last impurities.Dissolved air produced by the "boiling" of ether in a vacuum.All these operations lead to the fact that the xanthate becomes like a young honey - yellow and stringy.This dope is ready.
fibers obtained
solution is forced through a die.Artificial synthetic fibers not only spun in conventional manner.This operation is difficult to compare with a simple textile, it would be correct to say that it is the chemical process that allows millions of streams of liquid viscose fibers become rigid.On the territory of Russia from cellulose obtained viscose siblon.The second type fibers and a half times stronger than the first one, characterized by greater resistance to alkali, tissue from a different water absorption, a lower degree of shrinkage and crease.And the differences in the production of viscose and siblona appear in the moment of the spin bath after nozzles are just "people" synthetic fibers.
Chemistry assistance
For viscose into the bath is poured sulfuric acid.It is intended to decompose the ester so obtained pure cellulosic fiber.If you need siblona in a bath of zinc sulfate was added, providing an obstacle partially hydrolyzed ether, so the threads will contain residual xanthate.So what gives?The fibers were then subjected to stretching and forming.When polymeric fibers are xanthate residues, cellulosic polymer turns to pull the chain along the fiber axis, and not arrange them randomly, which is typical for a conventional viscose.After drawing a tow of fibers cut to a length of 2-10 mm shpatelki.After a few more procedures carried out pressing the fibers into bales.Tons of timber is sufficient to obtain 500 kg of pulp, which is produced from 400 kg of fiber siblona.Spinning the cellulose is carried out about two days.
what to do with siblonom?
In the eighties, these synthetic fibers are used as additives to cotton to yarn spun better and not torn.From siblona made substrate for artificial leather, and used it in the manufacture of products made of asbestos.Then the engineers were not interested in creating something new and needed as much fiber to realization.
And in the West in those days high modulus viscose fibers used to produce fabrics which differed cheapness and strength compared to cotton, but it absorbs moisture and breathe.Now Russia will not remain the property of the cotton regions, so siblon great expectations.Only the demand for it is not very large, since the fabric and clothing domestic production is now almost no one is buying.
polymer fibers
They are usually divided into natural, synthetic and artificial.Natural fibers are those whose formation is performed under natural conditions.They are usually classified according to origin, which determine their chemical composition on animal and vegetable.The first are composed of protein, namely carotene.This silk and wool.The latter consist of cellulose, hemicellulose and lignin.
artificial synthetic fibers are obtained by chemical processing of polymers found in nature.They accepted to acetate, rayon, alginate fiber and protein.As raw materials for their preparation are kraft or sulfite wood pulp.Release of synthetic fibers manufactured in the form of textile yarn and cord, and in the form of staple fiber which is processed together with other fibers during the manufacturing process of various fabrics.
synthetic polyamide fiber obtained from polymers derived artificially.The feedstock used in a process of polymer fibers formed from a flexible linear macromolecules or slightly branched structures having substantial mass - more than 15 000 amu and a very narrow molecular weight distribution.Depending on the type of synthetic fibers may have a high degree of strength, a significant value relative to the elongation, elasticity, resistance to multiple loads, small residual strain and quick recovery after the load is removed.That is why in addition to their use in textiles have been used as reinforcing elements during the manufacture of composites, all led to the special properties of synthetic fibers.
Conclusion
In the past few years can be seen a very steady increase in the number of achievements in the development of new polymer fibers, in particular, para-aramid, polyethylene, heat-resistant, combined, the structure of which - the core-shell, heterocyclic polymers, which include a variety ofparticles, e.g., silver or other metals.Now nylon material - this is not the top engineering, since there is now a huge number of new fibers.
