【Weekly Topic】Special lecture on polymer materials: “Plastics” – Learn a little every day (3) Polyvinyl chloride “Improve yourself””

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This post was last edited by tclz007 on 2013-12-9 at 19:03. Starting this month, learning activities will be carried out in the field of polymer materials; we hope that fellow enthusiasts will come to learn, offer good suggestions, engage actively in learning, and those who participate in in-depth discussions will receive substantial rewards in terms of wealth and charm~~~! To encourage everyone to come and participate in discussions more actively, as well as to study more diligently, the top ten participants each time will receive a “Motivation Reward for Active Learning.” Some people might think that it’s terrifying to spend their working days doing nothing useful, performing menial tasks without knowing what to do or what to learn, day after day, year after year, with no vision for their future We must start working hard from now on; even if we learn a little knowledge every day, it will add up over time and help us enrich ourselves. We need to set clear goals – only by filling our minds first can we enrich other aspects of our lives as well. . . . . . Just spend a short ten-odd minutes every day, and you will see the future! ! ! (Anyway, I have learned it; whether you learn it or not is up to you. Besides those experts like Hai Chuan, there are still others who know it.) . . ) Enough talk – let’s start with the basics today!! Polyvinyl chloride: Polyvinyl chloride (PVC) is one of the five most commonly used plastics. It possesses excellent properties such as corrosion resistance, electrical insulation, flame retardancy, and high mechanical strength, and it is widely used in various fields including industry, agriculture, and daily life. In particular, the high demand for PVC products in the construction industry in recent years has made it a plastic material with considerable competitiveness. The main component of PVC is polyvinyl chloride; it features bright colors, corrosion resistance, and durability. Since toxic additives such as plasticizers and anti-aging agents are used during the manufacturing process to enhance its heat resistance, toughness, and ductility, products made from PVC are generally not used for storing food or medicines. It is a synthetic material that is highly popular and widely used throughout the world today. Its global usage ranks second among various synthetic materials. According to statistics, in 1995 alone, the production of PVC in Europe was around 5 million tons, while its consumption was 5.3 million tons. In Germany, the production and consumption of PVC average 1.4 million tons. PVC is being produced and used worldwide at a growth rate of 4%. In recent years, PVC has seen particularly rapid growth in Southeast Asia, thanks to the urgent need for infrastructure development in the countries of that region. China’s PVC industry began in the 1950s; it is the second thermoplastic resin to be produced on an industrial scale after phenol-formaldehyde resin. The first PVC plant was built and put into operation at Jinxi Chemical Plant in 1958, with a production capacity of 3,000 tons per year. Since then, PVC plants have been built and put into operation across the country. To date, there are over 80 PVC resin manufacturing enterprises in China, located in 29 provinces, municipalities, and autonomous regions, with a total production capacity of 2.2 million tons per year, or 700,000 to 750,000 tons per year. PVC resin holds a pivotal position in China’s plastics industry. Meanwhile, as the largest organic chlorine-consuming product in the chlor-alkali industry, PVC plays an extremely important role in maintaining the chlorine balance within this industry. Chinese name: Polyvinyl chloride English name: Polyvinyl chloride polymer Abbreviation: PVC Glass transition temperature: 87 ℃ Melting point: 212℃ Thermal conductivity (λ): 0.16 W/m·K Coefficient of thermal expansion (α): 810-5 /K Heat capacity (c): 0.9 kJ/(kg·K) Water absorption rate (ASTM): 0.04-0.4% Polyvinyl chloride is a non-toxic, odorless white powder. It has excellent electrical insulation properties and generally does not burn; it can burn in a flame and release HCl, but it goes out on its own once removed from the flame. It is a substance with \"self-extinguishing\" and \"fire-retardant\" characteristics. It is mainly used in the production of transparent sheets, pipe fittings, gold cards, blood transfusion equipment, flexible and rigid pipes, sheets, doors and windows, profiled materials, films, electrical insulating materials, cable sheaths, and blood transfusion materials. Polyvinyl chloride has the advantages of flame retardancy (with a flame retardance value of over 40), high chemical resistance (resistant to concentrated hydrochloric acid, 90% sulfuric acid, 60% nitric acid, and 20% sodium hydroxide), good mechanical strength, and excellent electrical insulation properties. However, it has poor heat resistance; its softening point is 80°C, and it begins to decompose and change color at 130°C, with HCI being released in the process. Polyvinyl chloride is formed through the free-radical polymerization of vinyl chloride monomers, and its degree of polymerization generally ranges from 500 to 20,000. Its molecular structure is as follows: In terms of product classification, PVC belongs to the category of synthetic resins among the three major synthetic materials (synthetic resins, synthetic fibers, synthetic rubbers). It is included among the five major general-purpose resins: polyethylene PE, polyvinyl chloride PVC, polypropylene PP, polystyrene PS, and ABS resin. 1. General soft PVC products: Can be extruded into hoses, cables, wires, etc., using an extruder ； By using injection molding machines in combination with various molds, plastic sandals, shoe soles, slippers, toys, automotive parts, and more can be manufactured. 　2. PVC film: PVC is mixed with additives and plasticized, and then transformed into transparent or colored films of a specified thickness using a three-roller or four-roller calendering machine. Films produced in this way are known as calendered films. Packing bags, raincoats, tablecloths, curtains, inflatable toys, etc. can also be made through cutting and heat-sealing. Wide transparent films can be used for greenhouses, plastic sheds, and mulch films. Biaxially stretched films, due to their thermal shrinkage property, can be used for shrink packaging. 　3.PVC-coated products: Artificial leather with a substrate is made by applying PVC paste to fabric or paper and then plasticizing it at temperatures above 100 degrees Celsius. It is also possible to first calender PVC with additives into a film, and then bond it to a substrate. Substrate-free artificial leather is directly rolled into a soft sheet of a certain thickness using a calender, after which patterns are pressed onto it. Artificial leather can be used to make suitcases, handbags, book covers, sofa cushions and car seats, as well as floor coverings for use as flooring in buildings. 　4. PVC foam products: When soft PVC is mixed, an appropriate amount of blowing agent is added to create sheets, which are then foamed into foam plastics. These can be used to make foam slippers, sandals, insoles, as well as shock-absorbing packaging materials. It can also be used with extruders to produce low-foam rigid PVC sheets and profiles, which can serve as a substitute for wood; it is a new type of building material. 　5.PVC transparent sheet: PVC to which impact modifiers and organotin stabilizers are added, and which is then turned into a transparent sheet through mixing, plasticizing, and calendering. Utilizing thermoforming, thin-walled transparent containers can be made or used for vacuum form packaging; it is an excellent material for packaging and decoration – such as for mooncake packaging boxes. 　6. PVC paste resin: PVC is dispersed in a liquid plasticizer to cause it to swell and become plasticized, thus forming a plasticized sol. Emulsions or microsuspended resins are commonly used; stabilizers, fillers, colorants, etc., are also added. After thorough mixing and defoaming, a PVC paste is prepared, which is then used to manufacture various products through processes such as coating, impregnation, casting, or spin-coating. Such as hangers, tool handles, Christmas trees, etc. 　7. PVC rigid boards and sheets: Stabilizers, lubricants, and fillers are added to PVC; after mixing, it can be extruded using an extruder to produce rigid pipes, shaped pipes, and corrugated pipes of various diameters, which are used as sewer pipes, drinking water pipes, electrical conduit, or stair handrails. By overlapping the rolled sheets and hot-pressing them, rigid sheets of various thicknesses can be produced. The sheets can be cut into the desired shapes, and then welded together using PVC electrodes and hot air to create various chemically resistant tanks, ducts, and containers. 　8. Other PVC doors and windows are assembled from rigid, custom-shaped materials. In some markets where **they already share the door and window space with wooden doors, windows, and aluminum windows ； Wood-like materials, steel substitute building materials (northern regions, coastal areas) ； Special Lecture Series on Hollow Containers – Special Lectures on Polymer Materials: “Plastics”. Learn a little every day (6): Polystyrene. “Improve yourself”: http://bbs.hcbbs.com/thread-1257966-1-1.html Special Lectures on Polymer Materials: “Plastics”. Learn a little every day (5): Polystyrene. “Improve yourself”: http://bbs.hcbbs.com/thread-1257435-1-1.html Special Lectures on Polymer Materials: “Plastics”. Learn a little every day (4): ABS plastic. “Improve yourself”: http://bbs.hcbbs.com/thread-1257228-1-1.html Special Lectures on Polymer Materials: “Plastics”. Learn a little every day (3): Polyvinyl chloride. “Improve yourself”: http://bbs.hcbbs.com/thread-1256914-1-1.html Special Lectures on Polymer Materials: “Plastics”. Learn a little every day (2): Polyethylene. “Improve yourself”: http://bbs.hcbbs.com/thread-1256622-1-1.html Special Lectures on Polymer Materials: “Plastics”. Learn a little every day (1): Engineering plastics. “Improve yourself”: http://bbs.hcbbs.com/thread-1256345-1-1.html Everyone is welcome to listen. I’m already broadcasting; I hope those who, like me, want to gain knowledge every day will listen. Let’s learn together every day and discuss~~! 【Special Lecture】Special lecture on polymer materials: “Plastics”; continuously being updated. http://bbs.hcbbs.com/thread-1256917-1-1.html