The no of repeating units or monomer units in the chain of a polymer is called degree of polymerization dp. Polymer polymerisation technique polyamides polycarbonates polyethylene terephthalates polysulphides polyethylene low density polyethylene high density polymethyl methacrylate polypropylene polystyrene polyvinyl acetate. Cannot be used for polymers whose glass transition temperature is less than the polymerization temperature, or else aggregation will occur. Polymerization degrees, molecular weights and protein. To emphasize the importance of stabilization of the charged reactive center on the growing chain. Unlike condensation polymers, the repeating unit of an addition polymer has the same composition as the monomer. The degree of polymerization and its distribution are important indicators of product quality. Download fulltext pdf influence of the degree of polymerization of oligogalacturonates and of esterification pattern of pectin on their recognition by monoclonal antibodies. Ethylene molecules are joined together in long chains. A degree of polymerization is a key characteristic of polymers that determine physical properties of polymer materials.
Chapter two, stepgrowth polymerization, version of 1505 80 by line 5, the reaction has reached 80% completion and the number average value of the degree of polymerization nn is 5. Guaranteed to have a long shelf life, the handbook of radical polymerization promises to be an indispensable resource for chemists, chemical engineers, material scientists, and graduate students in the field, as well as a valuable addition to industrial, academic, and government libraries. Apr 27, 2018 a degree of polymerization is a key characteristic of polymers that determine physical properties of polymer materials. The two differences between emulsion and suspension polymerization are. Polymers are large molecules that consist of repeating structural monomer units. This number will be equal to the one in the definition stated above if the repeating unit is the residue of a single monomer. But in condensation polymerization, any molecule can react with any other. A stepgrowth polymerization is a stepwise reaction between bifunctional or multifunctional monomers in which a highmolecularweight polymer is formed after a large number of steps. The weightaverage degree of polymerization is a weighted mean of the degrees of polymerization, weighted by the weight fractions or the overall weight of the molecules of the species.
What is the relationship between viscosity and degree of. Symmetric diblock copolymers degree of polymerization classe. Degree of polymerization estimation of insulation papers. The degree is calculated by dividing the corresponding average molecular weight between the weights of monomer unit m0 with the formula of the polymer, calculated as explained in the next section. Architecture of polymers linear or branched quenched disorder average number of units in the chain. Handbook of radical polymerization wiley online library. Within a sample of paper, not all the cellulose molecules have the same degree of polymerization so that the mean value measured by viscometric methods is not. The method used more recently, called the indirect method, estimates the. The polymerization is initiated by the formation of radicalic monomer molecules. High impact polystyrene hips acrylonitrile butadiene styrene absaaaaaaaaaa. The degree of polymerization, or dp, is the number of monomeric units in a macromolecule or. The interflavan bonds break and the extender units react to form the phloroglucinol adduct. Although we have considered this slowly evolving polymer in terms of the extent of reaction, another question starts to be worrisome. Principles of polymerization, fourth edition presents the classic text on polymer synthesis, fully updated to reflect todays state of the art.
Syllabus synthesis of polymers chemical engineering mit. Polymerization yields finely divided, stable latexes and dispersions to be used directly in coatings, paints, and adhesives. Pdf technological application of maltodextrins according. Microstructure depends on method of polymerization. These polymerization techniques generate many important commodity polymers where their broad range of molecular weight distribution gives rise to important physical properties. What is degree of polymerization the term degree of polymerization is defined as the number of repeating units in a polymer molecule. Polymerization kinetics step growth slow can use statistical methods as well as kinetics to describe mol. Introduction polystyrene ps, figure 1 is an allpurpose resin used in a variety of fields. And the molecular weight, m, is just mm dp where m is the molecular weight of monomer polymer properties depend on average dp. Chemical engineering 160260 polymer science and engineering lecture 6 mechanism and kinetics of free radical chain polymerization january 29, 2001. The reason why such high molecular weight is necessary is believed to be as follows. Technological application of maltodextrins according to the degree of polymerization article pdf available in molecules 2012. In addition polymerization, the monomers add to one another in such a way that the polymer contains all the atoms of the starting monomers. The polymerization conforms to the fixed shape of the reaction vessel when solidification occurs.
New and expanded coverage in the fourth edition includes. Aug 31, 2016 polymerization is the process of converting the single units monomers to linked monomers called polymers poly many by chemical reactions. For a homopolymer, there is only one type of monomeric unit and the numberaverage degree of polymerization is given by, where m n is the numberaverage molecular weight and m 0 is the molecular weight of. View enhanced pdf access article on wiley online library html view download pdf for offline viewing. The degree of polymerization is the most important property. Yet the practical applications of polymers are only increasing. Metallocene and postmetallocene polymerization catalysts living polymerizations radical, cationic, anionic. The traditional method of determining the dp, called the direct method, requires actual paper samples and is therefore intrusive and costly. The relation between molecular weight and viscosity is defined according to. Polymerization degrees, molecular weights and proteinbinding affinities of condensed tannin fractions from a leucaena leucocephala hybrid mookiah saminathan 1, hui yin tan 2, chin chin sieo 1,3, norhani abdullah 3,4, clemente michael vui ling wong 5, emilia abdulmalek 6 and yin wan ho 1, 1. Introduction term polymer comes from greek polymeros consisting of many parts and means large molecule made up of repeating simple molecules mers or monomers that have low molecular weight. The new edition of a classic text and reference the large chains of molecules known as polymers are currently used in everything from wash and wear clothing to rubber tires to protective enamels and paints.
Solution polymerization is a method of industrial polymerization. The reaction results in a polymer which is also soluble in the chosen solvent. Other forms of chain growth polymerization include cationic addition polymerization and anionic addition polymerization. A free powerpoint ppt presentation displayed as a flash slide show on id. The technique is the most studied and utilized of the controlledliving radical polymerization techniques since a large number of monomers. 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.
Astm d4243 16 standard test method for measurement of. In some cases, this term is used to express the number of monomer units in an average polymer molecule. The two major types of polymerization are addition polymerization and condensation. The degree of polymerization of the sio or po network structures weakened with increasing slag basicity and feo content, while promoted with increasing p. The difference between the two terms is explained in more detail in section 7. Symmetric diblock copolymers degree of polymerization detlef smilgies, chess. Stiile colorado state university, fort collins, co 80523 as illustrated in the articles on chain polymerization, a chaingrowth polymerization is one in which each polymer chain, after being started by a free radical initiator, a cationic catalyst or an anionic catalyst, grows rapidly, producing a high molecular weight polymer. Post polymerization or how to make a graft copolymer examples. Proanthocyanidins are incubated with phloroglucinol in acidic ethanol. Chemical engineering 160260 polymer science and engineering lecture 6 mechanism and kinetics of.
These reactions control the degree of polymerization and the rate of branching of the polymers. Thus, we are discussing the degree of polymerization \ \overlinedp \ and the polymerization rate of step polymerization using these two polymers as examples. There are two general types of polymerization reactions. The term degree of polymerization is also used in some contexts in the polymer literature to mean the number of monomer residues in an average polymer molecule. The degree of polymerization is the number of mono meric units in a macromolecule or polymer molecule. If we divided, the molecular weight of polymer by the molecular weight of monomer, then we can get the degree of polymerization. Pdf principles of polymerization 4th ed by odian minh. Polymerization definition is a chemical reaction in which two or more molecules combine to form larger molecules that contain repeating structural units.
The dextrose equivalent gives an indication of the average degree of polymerisation dp for starch sugars, it is another word for gelatine. To develop expressions for the average degree of polymerization and molecular weight distribution for anionic polymerization. The test ensures the coatings maximise their full quality potential at the optimum degree of polymerisation. Relationship between degree of polymerization and optical and.
The degree of polymerization can be calculated from equation 17 since the volume of the reaction can be assumed to be constant. In this procedure, a monomer is dissolved in a nonreactive solvent that contains a catalyst. In this study a new light source, based on a metalhalide. Reaction at the interfaces15 2010 aalborg universitet. Somegeneralfeatures ofliving polymerizations living polymerization techniques give the. Drugs are found in the form of droplets distributed in an aqueous phase. One structure factor that greatly influences the physical properties of ps is molecular weight. Find materials for this course in the pages linked along the left. Obviously, the polydispersity index could be calculated with the average degree of polymerization as. The degree of polymerization a polymeric molecule c 2 h 4 n n is termed the degree of polymerization dp the extended length l ext l ext ml sin109. Pdf technological application of maltodextrins according to. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation. It is typically determined by measurements of rayleigh light scattering by the polymer. Degree of polymerization an overview sciencedirect topics.
The interflavan bonds break and the extender units react to form the phloroglucinol. Polymers are formed by linking monomers through chemical reactioncalled polymerization. Emulsion polymerization is characterized by the use of an aqueous phase. Use of ftraman spectroscopy to determine the degree of. Determination of the degree of polymerization of oligosaccharides.
Well over 100 billion pounds of polymer are produced each year, and it is expected that this. The two repeat units in this copolymer are acrylonitrile and butadiene. How to calculate the degree of polymerization sciencing. Polymerization definition of polymerization by merriamwebster. In practice, efflux times greater than 350 s should be avoided as reproducible results will be difficult to obtain.
Bulk polymerization, which may also be referred to as mass polymerization, involves a monomer and an initiator as the main components, without a solvent. A polymer is a macromolecule which consists of small molecular units that are repeated over and over again to form a long chain. In gel spinning, ultrahigh molecular weight polyethylenes uhmwpe having a weight average molecular weight above 600000 gmol are used. Ppt polymeric materials powerpoint presentation free. It is a chain reaction consisting of a sequence of three steps, initiation, propagation and termination. Chapter 10 polymeric materials 101 introduction to polymers polymers many parts plastics advantages wide range of properties. A newer method of polymerization similar to free radical, but allowing more control involves the zieglernatta catalyst, especially with respect to polymer branching. The real challenge concerns the dissipation of the heat produced by polymerization.
Rate of mechanochemical activation of spiropyran as a function of a numberaverage molecular weight, and b degree of polymerization. These molecules add successively many monomer molecules, so. The viscometer size is selected to give efflux times of over 100 s, but less than 800 s. The suspension polymerization is similar to the bulk one, but the polymerization process occurs at lower temperatures. Since the monomers usually differ in size, this means that. The determination is made by measuring the intrinsic viscosity of a solution of the paper in an appropriate solvent.
Heat released by the reaction is absorbed by the solvent, and so the reaction rate is reduced. As the degree of polymerization increases, the molecular weight will increase and consequently, the viscosity increase. Step growth polymerization and condensation polymerization are two different concepts, not always identical. To use the ftraman spectroscopy for evaluation the degree of polymerization of dental composite as a result of photo curing with a new light source in comparison to the conventional halogen light. The degree of polymerization, or dp, is the number of monomeric units in a macromolecule or polymer or oligomer molecule for a homopolymer, there is only one type of monomeric unit and the numberaverage degree of polymerization is given by. Sep 18, 2019 the degree of polymerization is the number of mono meric units in a macromolecule or polymer molecule. Principles of polymerization, 4th edition polymer science. The degree of polymerization, or dp, is usually defined as the number of monomeric units in a macromolecule or polymer or oligomer molecule. Atom transfer radical polymerization atrp has proven to be a powerful technique to obtain polymers with narrow polydispersities and controlled molecular weight. Polymerization is the process of forming larger macromolecules from simpler subunits known as monomers. The reaction mechanisms, kinetics of polyesters and polyamides have been thoroughly studied. The degree of polymerization dp may be defined as the average number of base units per molecule if the molecules are composed of regularly repeating units, or as the average number.
Chemical engineering 160260 polymer science and engineering. Controlled radical polymerization guide sigmaaldrich. Let us do a comparative analysis of the two types of polymerization to understand them better. Below we learn some of the scientific principles involved in the production and processing of these fossil fuel derived materials known as polymers. In this study, 9,9bis42hydroxyethoxy phenyl fluorene bpef homo polymer was selected. Degree of polymerization engineering chemistry tech glads. In practical conditon, using this method is complicated and expensive due to the necessity of disasembling the transformer. In addition to the conversion of the functional groups, the degree of poly merization, and the number average molecular weight we are interested in the distribution. In fact polyurethane polymerizes with addition polymerization because its polymerization produces no small molecules, but its reaction mechanism corresponds to a stepgrowth polymerization.
Degree of polymerization dp is thought to be a good index to determined deterioration level of insulation paper in power transformers. Highperformance technical machines such as electrical motors require accurate and comprehensive quality control of the ideal curing of insulating materials during the manufacturing process. What is the degree of polymerization of polyethylene hw 400000. Dsc measurements of polystyrene the effects of molecular weight on glass transition 1. Polymerisation techniques polymerisation techniques used in the production of some commercial polymers. Degree of polymerization major reference works wiley. Free radical polymerization is one of the most common processes used to produce vinylic polymers. Hence a symmetric diblock copolymer consists of two coupled chains filling the same volume. Chaingrowth polymerization has been successfully performed for many decades through conventional free radical, anionic, or cationic polymerization. The phase behavior and the microstructure of block copolymers depends on the volume taken up by each block. The chemical reaction in which high molecular mass molecules are formed from monomers is known as polymerization. For example, polyethylene is composed of repeating units ch 2ch 2 n where n is an integer number that indicates the degree of.
In addition polymerization monomers only join at the active site of the chain. All rate data collapse onto a single linear regression when plotted against degree of polymerization, independent of the composition or side chain constitution of the individual polymers. In this study, 9,9bis4 2hydroxyethoxy phenyl fluorene bpef homo polymer was selected. Predication of life of transformer insulation by developing relationship between degree of polymerization and 2 furfural dipak mehta, prof. Polymers products that are commonly referred to as plastics by the general public are known to chemists as polymers.