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Purification and Polymerization of Polymers Chemical fibers are manufactured from polymers. This high polymer can be directly taken from nature, or it can be obtained by artificial synthesis of low molecular substances.
Regenerated fibers are made from natural polymers by chemical methods. It is basically the same chemical composition as the original polymer. Natural polymers, require purification to remove impurities.
For example, the high polymer of viscose fiber is cellulose, which is purified from cellulose raw materials such as wool, wood, reed, bagasse, etc., and made into pulp, and then the pulp is used to make fibers.
The high polymer of synthetic fiber is obtained by chemical polyaddition or polycondensation using low molecular compounds obtained from coal, petroleum, natural gas, agricultural and sideline products, etc. as raw materials. Finally, the synthetic fiber is obtained by processing the high polymer.
The melt method is to heat the fiber-forming polymer above the melting point to form a melt. It is suitable for polymers whose decomposition point is higher than the melting point.
Or if the decomposition point of the fiber-forming polymer is lower than the melting point, the melting method must be used, which is to dissolve the fiber-forming polymer into a spinning fluid with a certain viscosity with an appropriate solvent.
In actual industrial production, there are two main methods for preparing spinning melt: one is to directly send the high polymer melt obtained by polymerization to spinning, which is called direct spinning.
The other is to make the polymer melt obtained by polymerization into "chips" by casting, dicing, and other processes, and then remelting it on a spinning machine into a melt and spinning, this method is called chip spinning.
According to the different properties of fiber-forming polymers, the spinning methods of chemical fibers mainly include melt spinning and melt spinning. In addition, there are special or unconventional spinning methods.
Among them, according to the different solidification methods, the melt spinning method is divided into wet spinning and dry spinning. In the production of chemical fibers, most of them are produced by melt spinning, followed by wet spinning, and only a few are produced by dry or other unconventional spinning methods.
The pre-crystallized and dried fiber-forming polymer chips are added from the polymer hopper, and the screw extruder is heated by the user in stages according to the requirements successively melts, mixes, measures, and extrudes. The elbow is fed into the melt metering pump.
The melt is quantitatively extruded from the small holes of the spinneret through the metering pump in the spinning box to form a thin stream of melt.
After the melt stream is used, it cools, solidifies, and forms primary fibers at a lower temperature and in a cooling air-blowing environment.
The primary fibers are then oiled and networked and wound into a tube.
The coiled filament is then subjected to subsequent secondary forming processes such as stretching and heat setting to obtain a suitable finished fiber.
The melt spinning process usually has a relatively simple production process and high production speed and does not require a solvent recovery process in production. The quality of the final product can be controlled, and most importantly, there is no environmental pollution.
But there are also some disadvantages, such as the knowledge of this method and the use of thermoplastic fibers, and due to the relatively high solidification rate, the structure of the fibers may be a bit poor. Also because the input heat is very high, you need to control the temperature accurately, and you need to maintain the machine regularly.
Anytester(Heifei) Co. Ltd is a professional company specializing in the research, design, and manufacture of laboratory equipment, with more than 40 years of production experience, our products are sold to more than 50 countries. And we have more than ten years of overseas service experience and various certifications.
If you are interested in information on other textile fields, you can browse our other article for more help:
Introduction-of-the-Spinning-Technological-Process