PRESENTED BY: KANTILAL B. NARKHEDE M.PHARM.1st SEMESTER DEPT. Chapter 6. In the absence of chain transfer the expression above can be written as . Solvent may terminate the growing polymer chain, leading to low molecular weight polymers 4. Gel effect. Polymerization. Looks like you’ve clipped this slide to already. Usually at least 100 monomers must be combined to make a product that has certain unique physical properties. The degree of polymerization of silk fibroin is uncertain, with DP of 300 to 3000 having been measured in different solvents. and M0 is the molecular weight of the monomer unit. Polycyclopentadiene molecules have two different kinds of double bonds for end groups and a complicated backbone of saturated fused rings. By varying the polymerization temperature, there is big effect on the rate and degree of polymerization . DP No ' N Thus, the degree of polymerization can be expressed by DP = No N0d-P) i 1-P Consider a reaction that can be pushed to 90% completion. degrees of polymerization of x and y meet their free-radical ends. large molecule or a macromolecule which essentially is a combination of many subunits Juwono Combination To give a single terminated chain of degree of polymerization x + y SEMINAR ON. Clipping is a handy way to collect important slides you want to go back to later. Learn more about polymerization. The dispersity of the polymer must be < 1.5. Polymers • To introduce the concept of a “living” polymerization. The degree of polymerization is unchanged and still described by Eq. POLYMER SCIENCE. When the temperature increases, the rate of polymerization increases, but the degree of polymerization decreases as shown in Fig. Degree of polymerization ≡ number of monomer units or structural units incorporated in polymer chain = pn 2 n u n p M M ⋅ = where M u = molecular weight (MW) of individual repeat units Can also have a—b monomers: e.g. V.S.SARAVANA MANI of Chemistry. HEAD AND ASSOCIATE PROFESSOR, Analysis of Conducting Polymer:Polypyrrole::Part 1, No public clipboards found for this slide. Polycyclopentadiene molecules have two different kinds of double bonds for end groups and a complicated backbone of saturated fused rings. Formaldehyde is a suspected carcinogen and should also be handled with gloves. Polyester (PET)- 100. The reaction mixture in line 4 of Table 2.1 is characterized by a number average degree of polymerization Nn = 10/3 = 3.3, with only 30% of the functional groups remaining. (2.25) 1 X ¯ n = K t K P [M] + K tr, M K P + K tr, S [S] K P [M] It can be seen that in cationic polymerizations, the number-average degree of polymerization is independent of initiator concentration. S. Wadhwa, The Tata Power Company Limited, Mumbai email: jwadhwa@tatapower.com Abstract - Power Transformers are the most vital components in a sub-station / Receiving station. Fibers and DP ( Degrees of Polymerisation) Nylon 6 -120. Solution polymerization | PowerPoint PPT presentation | free to view . Polymerization that occurs through the coupling of monomers using their multiple bonds is called addition polymerization. Thus, the average degree of polymerization depends on the monomer and solvent concentration and on the velocity constants of radical formation, chain termination and chain transfer. 1 ) Classification according to the relative magnitude of the initiation rate The polymerizations are divided into those with rapid initiation and those with slow initiation, according to the relative magnitude of the initiation rate with reference to the rate … It is calculated as the ratio of molecular weight of a polymer and molecular weight of the repeat unit. Nylon 6,6-200. Compared to step-growth polymerization, living chain-growth polymerization shows low PDI, predictable molecular mass and controllable … Failure of a Transformer leads to loss of Revenue besides affecting reliability of power supply to consumers. How many monomers make up each polymer (the degree of polymerization) must be related linearly to the amount of monomer you started with. 3 5. A bifunctional monomer containing two viologen moieties was designed. The difference is a … Nevertheless, polymers with degrees of polymerization determined by the ratio of the concentration of reacted monomer to the overall concentration of active species or of introduced initiator (DPn=A[M]/[I]o) have been 6 prepared with the narrow molecular weight distributions. Degree of polymerization ≡ number of monomer units or structural units incorporated in polymer chain = pn. Common synthetic fibers include: Nylon; Modacrylic; Olefin; Acrylic; … Some Condensation Polymers. 8.39) point out a very significant difference between cationic polymerization and radical polymerization. Polymerization, any process in which small molecules known as monomers combine chemically to produce a very large chainlike or network molecule, called a polymer. you dont get to decent degrees of polymerization, lets say 200, unless you have high degrees of conversion, for this example p 0.995, or a conversion of 99.5 ! When we keep adding monomers to obtain a large chain, such a process is also called as the chain growth polymerization. There are 3 mechanisms of termination: 1. Silk Fibre Structure. In step growth polymerization, X n can be related to the fractional monomer conversion as follows: (2) X n = 1 1 − p. where p is the fractional monomer conversion. Organic chemist friends of ours are happy to get reaction yields of … Let RMe be an organometalic compound such as butyl lithium (LiC 4 H 9) that initiates polymerization and M a monomer, then the individual steps can be … The number average degree of polymerization is given by (1) DP = X n = M n M 0 The polymerization of deoxy protein was initiated by the temperature jump from 0 to 30°C, and the extent of polymerization was monitored by measuring the absorbance of turbidity at 700 nm. 1. And you want to do this on an industrial scale! One way of measurement of conversion is the degree of polymerization represented as DP or Xn. Transformer Oil and Degree of Polymerization of Solid insulation Sanjay.G.Patki, S.G.Patil, Jaspal. If you continue browsing the site, you agree to the use of cookies on this website. Looks like you’ve clipped this slide to already. • To develop expressions for the average degree of polymerization and molecular weight distribution for anionic polymerization. See our Privacy Policy and User Agreement for details. A relatively broad, calculable distribution molecular species are present throughout the course of the polymerization. 7 MW in Living Anionic Polymerization Poisson Distribution Narrow distribution 8 Typical Products. Eq. 8.45. 1 / DP 0 = (k tr /2 + k td) I 1/2 / {(k tr + k td) 1/2 k p [M]} = K T {2f C D [Cat]} 1/2 / [M] Therefore. Abstract: Degree of polymerization (DP) is thought to be a good index to determined deterioration level of insulation paper in power transformers. 1. Macromolecules 1999 , 32 (1) , 73-78. Polymerization 1. • Polymerization mainly occurs in the micelle interiors due to: • high monomer concentration • high surface/volume ratio • presence of interface for organic monomer and water-soluble initiator • During polymerization, monomer is replenished by diffusion from droplets through the solution to micelles. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Polymerization, Isobutyl Rubber Synthesis, Polyvinyl Ethers Cationic Polymerization Some differences between cationic and anionic polymerization • Rates are faster for cationic (1 or more orders of magnitude faster than anionic or free radical) • is very reactive, difficult to … • Polymerization in the aqueous phase is insignificant due to the low monomer concentration. 4- type magnitude direction of masticatory forces applied to restoration . DP is defined as the number of monomeric units in a polymer. (2.24) into the Mayo–Walling type equation gives the number-average degree of polymerization as given in Eq. Propagation proceeds through an alkoxide (anionic polymerization) or an ozonium (cationic polymerization): (1.4) (1.5) Chain transfer and complex termination steps arrest the chain propagation … See our User Agreement and Privacy Policy. A failure can cause hug revenue loss to utilities. M is the molecular weight of the polymer, DP is the degree of polymerization and the M 0 is the formula weight of the repeating unit. Therefore an alternative method has been expected. The degree of polymerisation can be defined as the frequency of repeating units present in a polymer. Note. 2. n u n. p M M. ⋅ = where M. u= molecular weight (MW) of individual repeat units. See our User Agreement and Privacy Policy. How is the Polymerization Reaction Classified? This Marginal Gap Creates An Increasingly Deteriorating Conditions For … Malaviya National Institute Of Technology Jaipur, Polymer science: preparation and uses of polymers, No public clipboards found for this slide. anionic chain polymerization, and boron trifl uoride complexes, complex aromatic salts of Lewis acids such as diaryl iodonium, triarylsulfonium, or arene diazonium for cationic chain polymerization. Further, you can calculate its degree using the steps mentioned below. In 1984, Higashimura and Sawamoto reported the first living cationic polymerization for alkyl vinyl ethers. solid having a degree of polymerization n ranging from two to greater than six. techniques Process conditions: Homogeneous polymerization: a) Bulk b) Solution 2. Heterogeneous polymerization a) Suspension b) Emulsion 1.. At an average degree of polymerization of 10, less than 1 weight percent of the monomer remains. In this paper a new method to estimate DP from load and temperature histories is … For instance, if a polymer P is made up of 5 numbers of monomers (M), then its degree of polymerisation will be 5. Introduction to Polymers 3 4. Synthetic fibers. V.S.Saravana Mani, Head& Asso.Prof, Dept. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. CONTENT: Introduction Types of Polymer Classification Polymerization Structure & Properties Crystallinity Glass Transition Temperature Pharmaceutical Applications INTRODUCTION Definition : A polymer is a large molecule … 11. Polymerization of HbS and diGEE-HbS was carried out in 1.8 M potassium phosphate buffer, pH 7.2. Many natural materials—such as proteins, cellulose and starch, and complex silicate minerals—are polymers. Ethylene + - + + Propylene - - - + 1-Butene … Also, the polymerization reactions for Nylon 6 and Spandex do not proceed by elimination of water or other small molecules. The polymerization reaction in many chemical compounds may occur through a variety of reaction mechanisms that differ in complexity because of the presence of the functional groups in the reactants as well as due to their inherent steric effects. Polymerization is the process by which monomer molecules are reacted together in a chemical reaction to form a polymer chain (or three-dimensional networks). High rates of polymerization 2. Effect of Substituents on Chain Mechanism Monomer Radical Anionic Cationic Hetero. This means that 70% of the possible reactions have already occurred, even though we are still dealing with a very low average degree of polymerization. The expressions for Rp in cationic polymerization (Eq. Degree of polymerization The Degree of polymerization (n or N) is defined as 10 the number of monomeric units in a macromolecule or polymer or oligomer molecule. CASE 2 . Emulsion polymerization BULK POLYMERIZATION The simplest method of polymerization where the reaction mixture contains only the monomer and a monomer soluble initiator. There are two basic types of polymerization, chain-reaction (or … The requirements for a separate solvent recovery step Suspension … Add 1.5 mL of … 27 Microleakage between Bacteria inside dentinal tooth and restoration tubule 28. 2.5 Degree of Polymerization The degree of polymerization (DP or Xn) is defined as the number of monomer units in the polymer. Concerning: Molecular Weight Rate (kinetics) Heat effects (thermodynamics) Bulk polymerization The. Several Nevertheless, the polymer clearly forms by a step-growth process. Radical polymerization shows a half-order dependence of Rp on Ri, while cationic polymerizations show a first-order dependence of Rp on Ri. the degree of polymerization 2. The polymerization is reversible and, on strong heating, the polymer reverts to cyclopentadiene. The degree of polymerization is the number of mono meric units in a macromolecule or polymer molecule . CASE 1 ; Mono-disperse Polystyrene Gel Permeation Chromatography (GPC) standard. The quantitative effect of temperature is complicated and is discussed in the following sections. Degree of Polymerization. Number average DP and weight average DP are the two main types used for measuring the DP. Degree of polymerization. Cotton- 4000-10,000. It can cause non availability of transformers for long hours. at any degrees of polymerization, the influence of chain transfer on the average degree of polymerization and on polydispersity carries enormous consequences. Its for First year BE/BTech Anna University Students CY6151- Engg.Chemistry-I I Unit Polymers. In practical conditon, using this method is complicated and expensive due to the necessity of disasembling the transformer. Phenol is a toxic substance and can cause serious burns. The degree of polymerization can be calculated by using the following relationship if a molecular weight of a polymer molecule is known. It is calculated as the ratio of molecular weight of a polymer and molecular weight of the repeat unit. Ex: calculate the degree of polymerization of a sample of polyethylene [ (CH 2-CH 2) n], which has a molecular … The degree of polymerization, DP is the original number of molecules divided by the remaining number of molecules and approaches a number equal to the original number of molecules as N approaches one. 1 / DP = 1 / DP 0 + C M + C S [S] / [M] The amount of chain … Thus, the proportion of termination to propagation increases substantially with increasing free Example PMMA ADVANTAGE Advantage of the high concentration of monomer result in 1. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The … Introduction to Polymers 1 2. The polymer is formed by polymerization of monomers with double or triple … High degree of polymerization 3. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. A key characteristic … This is known as solution polymerization. 1. The polymerization is obtained with a broad molecular weight distribution due to the high viscosity and lack of good heat transfer. a—a + b—b → a—c—b +d. moles of P*; P: number-average degree of polymerization of the polymer obtained at reaction time t; f([l), g (tm) and u (tn) increase with increasing tl, tm and tn. Often anionic polymerization involves living polymerizations, which allows control of structure and composition. Very high molecular weights are obtained. M- concentration of all anions in the system M concentration of the monomer C concentration of the initiator n the number of anions that an initiator molecule produces. Chemical Composition of Silk Fiber, Cotton Fiber & Wool Fiber. This is the primary feature of polymer that describes its physical properties as well. M= (DP) M 0. Initiation, propagation, and termination reactions have different rates and mechanisms. solid having a degree of polymerization n ranging from two to greater than six. General Comments on Chain Reactions! POLYMERS Introduction to Polymers 2 3. You can change your ad preferences anytime. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. On the other hand, in chain-growth polymerization, the monomer consumed steadily but the degree of polymerization could be increased very quickly after chain initiation. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The degree of polymerization (DP or Xn) is defined as the number of monomer units in the polymer. Mobility is reduced and this can affect termination events, so the rate of reaction is increased 3. The difference in Tg and Tm between the first polyester (completely aliphatic) and the two nylon polyamides (5th & 6th entries) shows the effect of intra-chain hydrogen … Polymers and Polymerizations Polymers are macromolecules built up by the linking together of large numbers of much smaller molecules. If you continue browsing the site, you agree to the use of cookies on this website. Furthermore, propagation is a first order reaction while termination is second order. For example, if a—a is a diacid and b—b is a diol: from diacid from diol. Low M high M Not all chains in a polymer are of the same length i.e., there is a distribution of molecular weights 15 x i = number fraction of chains in size range i i i n M x M w i = weight fraction of chains in size range i M i = mean (middle) molecular weight of size range i Number-average molecular weight i i w M w M Weight-average molecular weight Degree of Polymerization, DP DP = average number of repeat …