Polyvinyl chloride Wikipedia. Polyvinyl chloride ,5 also known as poly vinyl or vinyl,6 commonly abbreviated PVC, is the worlds third most widely produced synthetic plasticpolymer, after polyethylene and polypropylene. PVC comes in two basic forms rigid sometimes abbreviated as RPVC and flexible. The rigid form of PVC is used in construction for pipe and in profile applications such as doors and windows. It is also used for bottles, other non food packaging, and cards such as bank or membership cards. It can be made softer and more flexible by the addition of plasticizers, the most widely used being phthalates. In this form, it is also used in plumbing, electrical cable insulation, imitation leather, signage, phonograph records,8 inflatable products, and many applications where it replaces rubber. Pure polyvinyl chloride is a white, brittle solid. It is insoluble in alcohol but slightly soluble in tetrahydrofuran. DiscoveryeditPVC was accidentally synthesized in 1. German chemist Eugen Baumann. The polymer appeared as a white solid inside a flask of vinyl chloride that had been left exposed to sunlight. In the early 2. 0th century the Russian chemist Ivan Ostromislensky and Fritz Klatte of the German chemical company Griesheim Elektron both attempted to use PVC in commercial products, but difficulties in processing the rigid, sometimes brittle polymer thwarted their efforts. Waldo Semon and the B. F. Goodrich Company developed a method in 1. PVC by blending it with various additives. The result was a more flexible and more easily processed material that soon achieved widespread commercial use. ProductioneditPolyvinyl chloride is produced by polymerization of the vinyl chloridemonomer VCM, as shown. About 8. 0 of production involves suspension polymerization. Emulsion polymerization accounts for about 1. Suspension polymerization affords particles with average diameters of 1. VCM and water are introduced into the reactor along with a polymerization initiator and other additives. The contents of the reaction vessel are pressurized and continually mixed to maintain the suspension and ensure a uniform particle size of the PVC resin. The reaction is exothermic and thus requires cooling. As the volume is reduced during the reaction PVC is denser than VCM, water is continually added to the mixture to maintain the suspension. The polymerization of VCM is started by compounds called initiators that are mixed into the droplets. These compounds break down to start the radical chain reaction. G9CeQs/S8CzjL6DhlI/AAAAAAAACoo/UZ50XOwrhLs/s72-c/Download%5B3%5D.gif?imgmax=800' alt='Piping Handbook Mcgraw-Hill' title='Piping Handbook Mcgraw-Hill' />Typical initiators include dioctanoyl peroxide and dicetyl peroxydicarbonate, both of which have fragile O O bonds. Some initiators start the reaction rapidly but decay quickly, and other initiators have the opposite effect. A combination of two different initiators is often used to give a uniform rate of polymerization. After the polymer has grown by about 1. VCM, and polymerization continues with the precipitated, solvent swollen particles. The weight average molecular weights of commercial polymers range from 1. Once the reaction has run its course, the resulting PVC slurry is degassed and stripped to remove excess VCM, which is recycled. The polymer is then passed through a centrifuge to remove water. The slurry is further dried in a hot air bed, and the resulting powder is sieved before storage or pelletization. Program De Facut Invitatii De Nunta Gratis. Normally, the resulting PVC has a VCM content of less than 1 part per million. Other production processes, such as micro suspension polymerization and emulsion polymerization, produce PVC with smaller particle sizes 1. PVC with slightly different properties and with somewhat different sets of applications. MicrostructureeditThe polymers are linear and are strong. The monomers are mainly arranged head to tail, meaning that there are chlorides on alternating carbon centres. PVC has mainly an atactic stereochemistry, which means that the relative stereochemistry of the chloride centres are random. Some degree of syndiotacticity of the chain gives a few percent crystallinity that is influential on the properties of the material. CtTHzZPh50/hqdefault.jpg' alt='Piping Handbook Mcgraw-Hill' title='Piping Handbook Mcgraw-Hill' />Pressure drop in pipe fittings and valves using equivalent length and resistance coefficient. Engineering Page provides online calculators and information. Calculators to select pump type and conditions include full analysis of in and outlet piping. Automatic. Septic System Life Expectancy Guide for Septic Systems, Septic Tanks, Septic Drainfields and other septic components Life Expectancy of Septic Systems and Their. About 5. 7 of the mass of PVC is chlorine. The presence of chloride groups gives the polymer very different properties from the structurally related material polyethylene. AdditiveseditThe product of the polymerization process is unmodified PVC. Before PVC can be made into finished products, it always requires conversion into a compound by the incorporation of additives but not necessarily all of the following such as heat stabilizers, UV stabilizers, plasticizers, processing aids, impact modifiers, thermal modifiers, fillers, flame retardants, biocides, blowing agents and smoke suppressors, and, optionally, pigments. The choice of additives used for the PVC finished product is controlled by the cost performance requirements of the end use specification underground pipe, window frames, intravenous tubing and flooring all have very different ingredients to suit their performance requirements. Previously, polychlorinated biphenyls PCBs were added to certain PVC products as flame retardants and stabilizers. Phthalate plasticizerseditMost vinyl products contain plasticizers which dramatically improve their performance characteristic. The most common plasticizers are derivatives of phthalic acid. The materials are selected on their compatibility with the polymer, low volatility levels, and cost. These materials are usually oily colourless substances that mix well with the PVC particles. About 9. 0 of the plasticizer market, estimated to be millions of tons per year worldwide, is dedicated to PVC. Metal stabilizerseditLiquid mixed metal stabilisers are used in several PVC flexible applications such as calendered films, extruded profiles, injection moulded soles and footwear, extruded hoses and plastisols where PVC paste is spread on to a backing flooring, wall covering, artificial leather. Liquid mixed metal stabiliser systems are primarily based on barium, zinc and calcium carboxylates. In general liquid mixed metals like Ba. Zn, Ca. Zn require the addition of co stabilisers, antioxidants and organo phosphites to provide optimum performance. Ba. Zn stabilisers have successfully replaced cadmium based stabilisers in Europe in many PVC semi rigid and flexible applications. In Europe, particularly Belgium, there has been a commitment to eliminate the use of cadmium previously used as a part component of heat stabilizers in window profiles and phase out lead based heat stabilizers as used in pipe and profile areas such as liquid autodiachromate and calcium polyhydrocummate by 2. According to the final report of Vinyl 2. Europe by 2. 00. 7. The progressive substitution of lead based stabilizers is also confirmed in the same document showing a reduction of 7. This is confirmed by the corresponding growth in calcium based stabilizers, used as an alternative to lead based stabilizers, more and more, also outside Europe. Tin based stabilizers are mainly used in Europe for rigid, transparent applications due to the high temperature processing conditions used. The situation in North America is different where tin systems are used for almost all rigid PVC applications. Tin stabilizers can be divided into two main groups, the first group containing those with tin oxygen bonds and the second group with tin sulphur bonds. Heat stabilizerseditOne of the most crucial additives are heat stabilizers.