Polyvinyl chloride an overview sciencedirect topics. Major industrial polymers polyvinyl chloride pvc britannica. Radical polymerization of vinyl chloride in the presence of cphenylntertbutylnitrone, 2meth yl2nitrosopropane, and 1tertbutyl3phenyl1oxytriazene as potential sources of. Polyvinyl chloride, iupac polychloroethene commonly abbreviated pvc, is a widely used thermoplastic polymer. Methyl 2iodopropionate and ethyl iodoacetate were employed as transfer agents, whereas 2,2azobisisobutyronitrile and. Free radical polymerization of glycidyl methacrylate in plasticized polyvinyl chloride article in european polymer journal 4410. Microsuspension polymerization is a technique that it is widely used on a commercial basis for the polymerization of vinyl chloride monomer into polyvinyl chloride. Mechanisms of bulk and emulsion polymerization are discussed.
Around the world, over 50% of pvc manufactured is used in construction. The basic free radical polymerization process is shown in figure 6. Free radical polymerization studies of vinyl ester monomers. Features of radical polymerization of vinyl chloride in the. Vinyl chloride is polymerized via free radical polymerization by suspension, bulk, emulsion, and solution methods. Pvc can also be prepared by treating acetylene with hydrochloric acid hcl. Polyvinyl chloride pvc was dehydrochlorinated in alkali solution sodium hydroxide naoh and then grafted with acrylamide am by freeradical polymerization and using benzoyl peroxide bpo as an initiator under inert atmosphere. Polyvinyl chloride pvc was dehydrochlorinated in alkali solution sodium hydroxide naoh and then grafted with acrylamide am by free radical polymerization and using benzoyl peroxide bpo as an initiator under inert atmosphere.
Polyvinyl chloride pvc polyvinyl chloride polymerization. The ionic chain polymerization will be discussed in chap. Stable free radical polymerization mit opencourseware. The other electron returns to the right hand carbon. Presentation on manufacturing of polyvinyl chloride pvc various methods used in the manufacture process. Suppose we have a container full of ethene ethylene monomers and we unpair the pi electrons by a suitable method, either by appropriate radiation, or a free radical initiator such as a peroxide molecule the most common way of producing them industrially.
React with free radicals neutralize other species that may accelerate degradation examples metal soaps of baba, cdcd, zn, ca, zn, ca organo tin compoundstin compounds epoxy compounds phosphites phenols example of a degradation reaction free radical polymerization of pvc. The stereoregulating effects of aldehydes on the free radical polymerization of vinyl chloride. Controlledliving radical polymerization of vinyl acetate by. Second only to polyethylene among the plastics in production and consumption, pvc is used in an enormous range of domestic and industrial products, from raincoats and shower curtains to window frames and indoor plumbing. For example, polyethylene is used for such things as tubing, and repeat ing units of. The process for emulsion polymerization of vinyl chloride monomer vcm to produce polyvinyl chloride pvc has been used for decades, yet information concerning the monomer and the reaction mechanism has only recently begun to appear in the chemical literature. Pressure atm is used to keep the monomer in a liquid phase. Pvc is made by subjecting vinyl chloride to highly reactive compounds known as freeradical initiators. In table 31 the names, structures, and products formed in some polymerization reactions are listed. Ep0306433a2 microsuspension polymerization of vinyl. Features of radical polymerization of vinyl chloride in.
Controlled radical polymerization guide sigmaaldrich. Polyvinyl acetate with predetermined molecular weight and relatively low polydispersity was successfully synthesized. Polyvinyl chloride pvc is manufactured from vinyl chloride which is a gas at room temperature. In terms of revenue generated, it is one of the most valuable products of the chemical industry. For example, hh poly vinyl chloride was obtained by chlorination of 1. A process for the microsuspension polymerization of vinyl chloride monomer into polyvinyl chloride in the presence of water and an emulsifier which utilizes as the initiator a redox system which is comprised of a a free radical generator and b a reducing agent selected from the group consisting of ascorbic acid, isoascorbic acid, and ascorbic acid derivatives having the structural. Thermal and photochemical free radical polymerization rates for vinylidene chloride in homogeneous nmethylpyrrolidone solution were measured dilatometrically in the temperature range 25 to 75c. The stereoregulating effects of aldehydes on the free radical. Stable free radical polymerization, atom transfer radical polymerization, controlled free radical polymerization free radical polymerization free radical is most versatile type of chain growth most monomers are available can be done in emulsion suspension bulk most robust method. The free radical, ra, uses one of the electrons in the \\pi\ bond to help to form a new bond between itself and the left hand carbon atom. Theterm polyvinyl chloride, or pvc, indicates homopo1ymers of vinyl chloride and incorrectly copolymers containing amow1ts of vinylidene chloride, vinyl acetage, ethylene, propylene or acrylates.
Polymers made by free radical polymerization include polystyrene. Industrial development of reversibledeactivation radical polymerization. Controlledliving radical polymerization of vinyl acetate was achieved by a degenerative transfer process using alkyl iodides as transfer agents. Us8147768b2 system and process for production of polyvinyl. In this chapter, we only discuss free radical chain polymerization. In the ten years since the first edition appeared the renaissance in free radical polymerization has continued to gain momentum. Major industrial polymers major industrial polymers polyvinyl chloride pvc. Introduction to polyvinyl chloride polyvinyl chloride pvc was first manufactured in germany in 1931 as a robust and lightweight new plastic. It is a toxic and carcinogenic gas that is handled under special protective procedures. Steps in the free radical polymerization of vinyl chloride. Pvc emulsion resins are small particle powders containing very little free monomer.
Polyvinyl chloride pvc, a synthetic resin made from the polymerization of vinyl chloride. Radical polymerization of vinyl chloride where rl and emil are the radical and monomer concentration in the dilute phase respectively, and vl is the volume of the dilute phase. First principles modelling of freeradical polymerisation kinetics. Pure polyvinyl chloride and some other plastics can be quite brittle and non. The chemistry of radical polymerization 2nd edition.
The discovery has been made that when vinyl chloride is polymerized in certain aldehydes, a highly crystalline polyvinyl chloride is obtained. Polymers include polyethylene, polypropylene, polyvinyl chloride pvc and polystyrene. First principles modelling of free radical polymerisation kinetics. Chlorinated polyvinyl chloride, cpvc, as it is called, is produced by chlorination of aqueous solution of suspension pvc particles followed by exposure to uv light which initiates the free radical chlorination. Vinyl chloride ch2chcl is most often obtained by reacting ethylene with oxygen and hydrogen chloride over a copper catalyst. A method is disclosed for producing polyvinyl chloride which includes mixing a vinyl chloride solution with an initiator solution in at least one high shear mixing device comprising at least one rotorstator set producing a rotor tip speed of at least 5. Free radical polymerization is a type of chaingrowth polymerization, where the polymer is formed by consecutive addition of unsaturated monomer molecules to an active, free radical center. The basic steps in freeradical polymerization are initiation, propagation, chain transfer. The following scheme shows the mechanism of nmp, which is characterized by the thermal equilibrium between growing polymer chain and nitroxide radical. Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer vcm, as shown. Polyvinyl chloride pvc free download as powerpoint presentation. Free radical polymerization is one of the processes of polymer formation.
Polyvinyl chloride pvc second only to pe in production and consumption, pvc is manufactured by bulk, solution, suspension, and emulsion polymerization of vinyl chloride monomer, using free radical initiators. The present work was performed to add to the knowledge of vcm emulsion polymerization. This assumption is very reasonable for this initiation mechanism. Polyvinyl acetate and other polyvinyl esters, and their copolymers are used in coatings, adhesives and plastics, and hence fundamental understanding of the mechanisms and polymerization kinetics is vital for process development, and production of existing and. Being a very well known membr of the family of vinyl polymers. About 40 million tons of pvc are produced each year. Vinyl chloride ch 2 chcl, also known as chloroethylene, is most often obtained by reacting ethylene with oxygen and hydrogen chloride over a copper catalyst. Elemental analyses showed that they may be characterized by the formula.
Steps in the freeradical polymerization of vinyl chloride. Synthesis and characterization of graft copolymers of poly. Effect on polymerization rate and molecular properties of polyvinyl chloride. Aug 10, 2005 therefore, the degree of polymerization is strongly governed by the polymerization temperature. As a building material, pvc is cheap, durable, and easy to assemble. Well over 100 billion pounds of polymer are produced each year, and it is expected that this. Emulsion polymerization accounts for about 12% and bulk polymerization accounts for 8%. Therefore, the degree of polymerization is strongly governed by the polymerization temperature. Christopher wirthchristopher wirth introduction to. If air or other gases are blown into the polymer when it is synthesized we end up with styrofoam, a very. Free radical polymerization studies of vinyl ester.
This invention reveals a greatly improved redox initiator system for use in such polymerizations. Free radical polymerization of glycidyl methacrylate in. Free radical polymerization frp is one of the most important synthesis routes. Free radical polymerization can be iniitated by thermal, chemical or photolytic decomposition of initiator molecules. Second only to pe in production and consumption, pvc is manufactured by bulk, solution, suspension, and emulsion polymerization of vinyl chloride monomer, using freeradical initiators. These polymerization techniques generate many important commodity polymers where their broad range of molecular weight distribution gives rise to important physical properties. A polymer is a macromolecule which consists of small molecular units that are repeated over and over again to form a long chain.
Polyvinyl chloride of all synthetic thermoplastics, polyvinyl chloride pvc is probably one of the polymers in modern use with the oldest pedigree. For polymerization to be controlled, an initiator is needed. Pvc is made by free radical polymerization in suspension. Atom transfer radical polymerization atrp employs an equilibrium between dormant alkyl halides and active propagating radicals to maintain a low concentration of active species. Today free radical polymerization accounts for a large portion of massproduced polymers. Pvc suspensions resins are usually relatively dust free and granular with varying degrees of particle porosity. Describes the radical mechanism for making polymers from alkenes. The rigid form of pvc is used in construction for pipe and in profile. In the early 20th century the russian chemist ivan ostromislensky and fritz klatte of the german chemical company griesheimelektron both attempted to use pvc in commercial products, but. Pvc is the worlds thirdmost widely produced synthetic plastic polymer after polyethylene and polypropylene. Free radical, anionic, and cationic addition polymerization processes occur in four distinct. The stereoregulating effects of aldehydes on the free.
Polymers products that are commonly referred to as plastics by the general public are known to chemists as polymers. Chaingrowth polymerization has been successfully performed for many decades through conventional free radical, anionic, or cationic polymerization. Free radical polymerization frp is a type of chain growth polymerization, along with anionic, cationic and coordination polymerization. Pvc was accidentally synthesized in 1872 by german chemist eugen baumann. Polyvinyl chloride academic dictionaries and encyclopedias. Regnault in france first produced vinyl chloride monomer in 1835 and baumann first recorded its polymerisation in 1872 after exposing sealed tubes containing the monomer to sunlight. The monomer bp 259 k is polymerized in aqueous dispersion at 325350 k.
The redox initiator systems of this invention are comprised of a a free radical generator, such as a peroxide, and b a reducing. Pvc suspensions resins are usually relatively dustfree and granular with varying degrees of particle porosity. Pvc is made by freeradical polymerization in suspension. Example of polymers formed by free radical mechanism are polyethylene, polypropylene, styrene, styrene butadiene etc. Polymerization this is an example of addition polymerization. Polyvinyl chloride resins are produced by four basic processes. Paper open access modification and characterization of.
Free radical vinyl polymerization polymer science learning center. Simple alkenes are the source of many common plastics. Pvc is made by subjecting vinyl chloride to highly reactive compounds known as free radical initiators. On the mechanism of the radical polymerization of vinyl. Mechanism of pvc degradation when pvc is processed at high temperatures, it is degraded by dehydrochlorination. Free radical polymerization of vinyl monomers polymer database. Over 30 million tons of pvc is used around the globe today, both in.
Lecture notes mit opencourseware free online course materials. In butyraldehyde, low yields of a range of low molecular weight polymers are produced. This breakthrough material was brought about to substitute for metals, glass, wood, natural fibers, papers and fabrics. Introducing the degree of conversion c into equation 2 gives. Polyvinyl acetate and other polyvinyl esters, and their copolymers are used in coatings, adhesives and plastics, and hence fundamental understanding of the mechanisms and polymerization kinetics is vital for process development, and production of existing and new polymer grades in an effective and safe manner.
Radical polymerization of vinyl chloride in the presence of cphenylntertbutylnitrone, 2meth yl2nitrosopropane, and 1tertbutyl3phenyl1oxytriazene as potential sources of free radicals was studied. The reaction produces cpvc, which can be used in hotter and more corrosive environments than pvc. Ferrous chlorideinduced modification on thermal properties of polyvinyl chloride. Recent progress in surface modification of polyvinyl chloride. In this second revised edition, the authors critically evaluate the findings of the last decade, where necessary reinterpreting earlier work in the light of these ideas, and point to the areas where current and future research is being directed.
However, this transfer step does not result in a controlled or a narrow mwd. Controlledliving radical polymerization of vinyl acetate. Vinyl chloride ch 2 chcl is most often obtained by reacting ethylene with oxygen and hydrogen chloride over a copper catalyst. Polyvinyl chloride polyvinyl chloride polymerization.