Lecture 45 polymerization techniques there are four types of polymerization techniques. Polymers usually are prepared by two different types of polymerization reactionsaddition and condensation. Mass polymerization in this type of polymerization the monomer is taken in liquid. For reasons that will become obvious, the terms stepgrowth and chain polymerizations.
It is used for most stepgrowth polymers and many types of chaingrowth polymers. Ppt polymerization powerpoint presentation free to view. Techniques of polymerization in engineering chemistry. In the case of chaingrowth reactions, which are generally exothermic, the heat evolved may cause the reaction to become too vigorous. Bulk polymerizationpolymer chemistryengineering chemistry. Cationic polymerization is less efficient than freeradical polymerization due to the caustic nature of cationproducing reagents. This ppt is related to the techniques utilized for polymerization process.
In this procedure, a monomer is dissolved in a nonreactive solvent that contains a catalyst the reaction results in a polymer which is also soluble in the chosen solvent. Four polymerization techniques bulk,solution,suspension and emulsion free download as pdf file. Effect of amide frequency on the melting points of ab type. Converting monomer to long chain polymer is the final step in the polymer manufacturing sequence. We report a new grafting to technique for the functionalization of silica particles with anionically produced polymers. Polymerization mainly occurs in the micelle interiors due to. During polymerization, smaller molecules, called monomers or building blocks, are chemically combined to create larger molecules or a macromolecule. But in condensation polymerization, any molecule can react with any other. This is the type of polymerization in which the molecules of a similar monomer or different monomer add up together on a large scale to form a polymer. Addition polymerization the key feature of addition polymerization is that monomers add to one another in such a way that the polymeric product contains all the atoms of the starting monomers. Controlled synthesis of polymer brushes by living free. Following its generation, the initiating free radical adds nonradical monomer units, thereby growing the polymer chain. The chemical reaction in which high molecular mass molecules are formed from monomers is known as polymerization.
Four polymerization techniques bulk,solution,suspension. Emulsion polymerization mechanism emulsion polymerization is a free radical polymerization protocol occurs in three distinct steps. To outline polymerization techniques and describe approaches to reducing viscosity and improving thermal. For emulsion polymerization or polymerization in an aqueous system, a watersoluble initiator like k 2. Pdf bulk and solution polymerization are two very important. These two types of polymerization both create high molecular mass molecules from monomers through a chemical reaction. In this type, multimers resulting from straight polymerization coupled together in blocks. Site of polymerization radicals are produced in the aqueous phase at approximately 10 radicalscm3sec. Tg and tm versus molecular weight mn or mw assuming a semicrystalline polymer most are. Molecular weight distribution mwd in equilibrium step condensation polymerizations.
Comparison of common polymerization methods stepgrowth chaingrowth anionic growth method cons. Dec 16, 2009 we report a new grafting to technique for the functionalization of silica particles with anionically produced polymers. Solution polymerization is a method of industrial polymerization. The preparation of a wide variety of unique polymer brush structures can be accomplished by living free radical polymerization of vinyl monomers from surfacetethered alkoxyamines or from tethered. New polymerization techniques and synthetic methodologies advances in polymer science 155 biswas, m. This pdf gives a basic idea on general polymerization techniques. Polymerisation techniques polymerisation techniques used in the production of some commercial polymers. Synthesis of polymersilica hybrid nanoparticles using.
Polymerisation techniques polymerisation techniques used in the. Bulk polymerization or mass polymerization is carried out by adding a soluble initiator to a pure monomer in liquid state. Lecture notes synthesis of polymers chemical engineering. Polymers products that are commonly referred to as plastics by the general public are known to chemists as polymers. Bulk polymerization is carried out in the absence of any solvent or dispersant and is thus the simplest in terms of formulation. In literature, there were studies related to the polymerization methods on the cytotoxicity of dental composites suggesting that there were no statistically significant differences between polymerization methods. Stepgrowth polymerization is the other main method to make polymers. To outline polymerization techniques and describe approaches to reducing viscosity and improving thermal control that involve dispersion of the monomer in. In addition polymerization, the monomers add to one another in such a way that the polymer contains all the atoms of the starting monomers. It is thought to account for dhp for vac and vc being lower than for acrylic and styrenic monomers. Polymerization, in polymer chemistry, is the process of reacting monomer molecules together in a chemical. Telechelic oligomers and novel architectures using coupling techniques. Four polymerization techniques bulk,solution,suspension and. For reducing the disadvantages of bulk polymerization, the process can be carried out in a solution.
Viscosity increases dramatically during conversion 2 types quiescent bulk polymerization eg. Somegeneralfeatures ofliving polymerizations living polymerization techniques give the. Polymer polymerisation technique polyamides polycarbonates polyethylene terephthalates polysulphides polyethylene low density polyethylene high density polymethyl methacrylate polypropylene polystyrene polyvinyl acetate. Ethylene molecules are joined together in long chains. The number on the curves indicate the specific nylon. Jul 30, 2017 the chemical reaction in which high molecular mass molecules are formed from monomers is known as polymerization. There are two basic types of polymerization, chainreaction or addition and stepreaction or condensation polymerization. There are two general types of polymerization reactions, both with many variations. If the desired polymerization occurs at or below 20 c, then special, lowtemperature freeradical initiators need to be used. Pdf various heterogeneous polymerization techniques such as suspension. Classification of polymerization reaction addition and. In addition polymerization monomers only join at the active site of the chain. Once the reaction starts, heating is stopped as the reaction is exothermic.
When we keep adding monomers to obtain a large chain, such a process is also. Anshuman shrivastava, in introduction to plastics engineering, 2018. There are two general types of polymerization reactions. Graphenebased electrochemical sensors for biomolecules, 2019. Anna university engineering chemistry1 cy6151 notes unit1 polymer chemistry polymerization techniques bulk polymerization. Various azotype initiators can be chosen to satisfy the decomposition temperature requirement. With chainreaction polymerization, there are three steps that takes two chemicals. Techniques of polymerization in engineering chemistry tech. Polymerization in the aqueous phase is insignificant due to the low monomer concentration. Radical polymerization steric factors appear to be dominant in determining dhp and dsp. Heat released by the reaction is absorbed by the solvent, and so the reaction rate is reduced.
The polymerization reaction kinetics of benzoxazine resins is described in this chapter. In this lesson, learn about the process of polymerization. Simplest of the techniques requiring only monomer and monomersoluble initiator, and. Polymerization reactions can be classified into two or three basic types. There are two basic types of polymerization, chainreaction or addition and step. Freeradical polymerization frp is a method of polymerization by which a polymer forms by the successive addition of freeradical building blocks. Emulsion polymerization this technique suits well for addition. Carothers, a great and tragic figure in the history of polymer science, suggested that most polymers could be classified into two broad categories, condensation or addition. Influence of initiator types and emulsion polymerization techniques to particle size of copolymerization styrenebutyl acrylatemethyl methacrylate. Moreover, the viscosity of the reaction mixture is reduced. Polymerization techniques bulk polymerization solution polymerization.
Polymerization is usually highly favourable in thermodynamic terms, mainly on energetic grounds because ordering molecules into linked chains is a process where the entropy is decreased. Polymerization is of two types, condensation polymerization and addition polymerization. The fattyacid soap forms aggregates of 50 100 soap molecules. New polymerization techniques and synthetic methodologies advances in polymer science 155. The use of a living free radical process permits the molecular weight and polydispersity of the covalently attached polymer chains to be. The resonance energy lost in converting monomer to polymer is of secondary importance for most common mono mers. Ppt polymerization powerpoint presentation free to. The base year considered for the study is 2019, and the market size is. One is the chain growth reaction, which can be differentiated into radical, cationic, anionic, and coordinative polymerization. Aug 23, 2015 anna university engineering chemistry1 cy6151 notes unit1 polymer chemistry polymerization techniques bulk polymerization. Well over 100 billion pounds of polymer are produced each year, and it is expected that this. Different polymerization techniques are applied to obtain polymers with unique properties suitable for various applications.
In addition polymerization all of the atoms of the monomer molecules become part of the polymer. Polymerization reactions proceed via either cationic or freeradical mechanisms. Free radicals can be formed by a number of different mechanisms, usually involving separate initiator molecules. The process of converting a monomer or a mixture of monomers into a polymer. A polymer is a macromolecule which consists of small molecular units that are repeated over and over again to form a long chain. Suspension polymerization it is used only in free radical type processes the. Chemical engineering 160260 polymer science and engineering. When we keep adding monomers to obtain a large chain, such a process is also called as the chain growth polymerization. In polymer chemistry, polymerization is a process of reacting monomer molecules. There are two types of polymerization known as stepreaction polymerization or condensation and chainreaction polymerization.
Syllabus synthesis of polymers chemical engineering. Polymer polymerisation technique polyamides polycarbonates polyethylene terephthalates polysulphides polyethylene low density polyethylene high density polymethyl methacrylate. This class presents the most common synthetic methods used in polymerization, the basic differences in the kinetics of these methods, the final endproducts obtained, and the synthetic processing techniques that might be used for various applications. The polymerization is obtained with a broad molecular weight distribution due to the high viscosity and lack of good heat transfer. Polyester and nylon are some of the most common examples of this type. In the first step the silica nanoparticles were modified with multifunctional chlorosilanes. Bulk polymerization or mass polymerization is carried out by adding a soluble initiator to pure monomer in liquid state.
Chemical engineering 160260 polymer science and engineering lecture. Chakravarty university college of technology, osmania university, hyderabad email. New polymerization techniques and synthetic methodologies. Polymerization is a reaction process in which two or more monomers are bonded chemically to form large polymer chains or threedimensional networks. Hundreds of such macromolecules collectively form a polymer. The reaction is initiated by heating or exposure to radiation. An example of alkene polymerization, in which each styrene monomers double bond reforms as a single bond plus a bond to another styrene monomer. The homogeneous polymerization techniques involve pure monomer or homogeneous. Let us do a comparative analysis of the two types of polymerization to understand them better. Explore the two major types, common polymers, and some of the chemistry involved with this biologically and commercially important. In this article, we are going to discuss condensation type of polymerization.
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