﻿ degree of polymerization problems
25.12.2020

## degree of polymerization problems

What does the current Number Avg MW, Weight Avg MW, and PDI approach? Submit a screenshot of your configuration window. If all of the polymer chains are the same length, calculate (a) the molecular weight of the chains, and (b) the total number of chains in 1000 g of the polymer. What is the monomer concentration for each reaction at 50%. Note 1: Dispersity is a measure of the dispersion (or spread) of a molar-mass, relative-molecular-mass, molecular-weight, or degree-of-polymerization distribution. Plot Xw vs. conversion for both experiments on the same figure. Other articles where Solution polymerization is discussed: chemistry of industrial polymers: Solution polymerization: The conducting of polymerization reactions in a solvent is an effective way to disperse heat; in addition, solutions are much easier to stir than bulk polymerizations. Note that the metrics, temperature, composition, MW, and conversion tabs calculate the corresponding values in real time. Sometimes, the polymerization involves the release of small molecule by-product, so it is also called condensation polymerization. The most naive one is just. Click here for the answer. " Degree of polymerization! Is the monomer (completely unbonded, chain length = 1) to be consumed faster in the stepwise growth or chain addition polymerization? Usually at least 100 monomers must be combined to make a product that has certain unique physical properties. View the primary ISBN for: Essentials of Materials Science and Engineering 3rd Edition Textbook Solutions. Given: 1. Polymerization, any process in which small molecules known as monomers combine chemically to produce a very large chainlike or network molecule, called a polymer. PDI notes the polydispersity index. Cationic Polymerization. JavaScript is required to view textbook solutions. After some time, click on the “Metrics” tab. . Would this happen in an actual experiment? Simulation delay can be set to your preference. If all of the polymer chains are the same length, calculate, (a) the molecular weight of the chains, and. PTFE is the acronym of Polytetrafluoroethylene and the chemical The reaction results in a polymer which is also soluble in the chosen solvent. Problem 14.19 a. Here ethylene (ethene) is the monomer, and the corresponding linear polymer is called high-density polyethylene (HDPE). (ii) The material is pure. At what conversion did it (or did it not) occur? If so, highlight (or ink over) the gelled molecule. Is this the result expected by theory? 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. To Find: (a) Ratio of butadiene to styrene repeat units in the given co-polymer (b) Type of co-polymer b. polyesters, polyamides, polyurethanes, etc. 7.2. You may wish to slow the simulation by using the Simulation Delay tab on the left, and you may reinitialize the simulation if you overshoot. Essentials of Materials Science and Engineering | 4th Edition, Essentials of Materials Science and Engineering. 16. The quantitative effect of temperature is complicated and is discussed in the following sections. Set the combination probability to 0. You may start the simulation and watch the reaction in the configuration tab. Mn and Xn note number average quantities, while Mw and Xw note weight-average quantities. General Comments on Chain Reactions! But cationic polymerization is of course characterized by having an active center that is a positively charged cation. [printed] 3. Last edited by Wchirdon 00:47, 17 December 2008 (UTC), Stepwise Growth vs. Chain Addition Polymerization, Free Radical Chain Addition Polymerization, http://rheneas.eng.buffalo.edu/w/index.php?title=Polymerization:Problems&oldid=2669, Number of Molecules = 250 di-ol, 250 di-acid, other species = 0, Simulation delay can be set to your preference. Plot Mw vs. time on the same graph for the adiabatic and isothermal experiments. For polyethylene, arguably the simplest polymer, this is demonstrated by the following equation. For most industrial purposes, degrees of polymerization in the thousands or tens of thousands are desir… and M0 is the molecular weight of the monomer unit. How are these histograms different than you would expect from theory? What would you expect this number to be in theory? Plot the histogram of frequency vs. chainlength for each experiment on the same graph. Why or why not? Right click on the graph to access the raw data and copy the data for Mw to Excel (or other plotting program). Why/why not? Step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers.Many naturally occurring and some synthetic polymers are produced by step-growth polymerization, e.g. Which reaction type contained the highest MW chain at the lowest conversions (50%)? Degree of polymerization = 4425 c. Assumptions: (i) Given data is accurate. Has gelation occurred? If so, at what conversion? Autoacceleration. Reaction Energy = 40 kJ/mol, 1 for heat transfer to solvent Only in these simulations, molecular weight (M) and degree of polymerization (X) are equivalent, since the monomers have a molecular weight of one. How does this affect your answer to parts 1 and 2? What would you expect these numbers to be in theory at 95% conversion? Some major types are low-density (LDPE), linear … The degree of polymerization of polytetrafluoroethylene (see Table 16-3) is 7500. Is it possible to have a poly(methyl methacrylate) homopolymer with the following molecularweight data and a of polymerization of 530? Question: Theoretical Questions (20 Pts) 1. What is the molar fraction of acrylamide? Do the results concur with the theory? In gel spinning, ultra-high molecular weight polyethylenes (UHMwPE) having a weight average molecular weight above 600000 g/mol are used. In step-growth polymerization, in order to achieve a high degree of polymerization (and hence molecular weight), X n, a high fractional monomer conversion, p, is … Would you expect this to happen in theory? You may start the simulation and watch the reaction in the configuration tab. This effect is not observed for the strong acid catalyzed reaction. The repeating structural unit of most simple polymers not only reflects the monomer(s) from which the polymers are constructed, but also provides a concise means for drawing structures to represent these macromolecules. This will depend only upon the initial and final states, not the nature of the intermediate (free radical, anion, cation). Number of Molecules = 800 di-ol, 500 di-acid, crosslinker= 200, other species = 0 A well-publicised paper by Claudia Huber and Günter Wächtershäuser in Science proposed a scenario for a materialistic origin of life from non-living matter. Restart the simulation and let it run until gelation occurs. p = extent of reaction (probability that any functional What was the Xn at 50% found for each experiment? What Xn would you expect for each in theory. Only in these simulations, molecular weight (M) and degree of polymerization (X) are equivalent, since the monomers have a molecular weight of one. It would only take 0.5 hours to reach a number average degree of polymerization of 300. Just looking at the simple scheme of polymer growth above, we see the average degree of polymerization increasing (written as DP or sometimes as X n; a bar over the symbol signals that we are looking at an average). The degree of polymerization is the most important property. PROBLEM. Reinitialize the system and after some time, click on the “Metrics” tab. Submit a screenshot of your configuration window. Furthermore, propagation is a first order reaction while termination is second order. What should Xn approach at complete conversion if the initiator concentration is set to 10, 20, and 50 in theory? The degree of polymerization of polytetrafluoroethylene (see Table 16-3) is 7500. (b) the total number of chains in 1000 g of the polymer. December 1998; updated May 2014. What does Xn approach if the initiator concentration is set to 10, 20, and 50 in the experiment? Polymerization is possible only if ∆G < 0 for the transformation of monomer to polymer. The reason why such high molecular weight is necessary is believed to be as follows: supposing the perfect orientation of all molecular chains, the chain ends still remain as defects and these defects … After pausing, record data for the time, number and weight avg MW(Xn and Xw), and conversion for the stepwise growth reaction. The number average degree of polymerization is given by (1) DP = X n = M n M 0 where Mn is the number average molecular weight and M0 is the molecular weight of the monomer In step growth polymerization, Xn can be related to the fractional monomer conversion as follows: Chain-growth polymerizations require the presence of an initiating molecule that can be used to attach a monomer molecule at the beginning of the polymerization. Plot the conversion as a function of time for initiators concentrations of 10, 20, and 50. Its main purpose is to provide a basis for more complex systems. Setup a Chain Addition (Free Radical) experiment with the following conditions: Pause the simulation at 50% (±1%) conversion. When the temperature increases, the rate of polymerization increases, but the degree of polymerization decreases as shown in Fig. This is the number average degree of polymerization. Set the combination probability to 0.5, what values do Xn, Xw, and PDI approach? Number of Molecules = 500 di-ol, 500 di-acid, other species = 0. Degree of Polymerization. d. Solution: For most industrial purposes, degrees of polymerization in the thousands or tens of thousands are desired. Setup an experiment with the following conditions in the Stepwise Growth module: You may start the simulation and watch the reaction in the configuration tab. Right click on the graph to access the raw data and copy the data for Mw to Excel (or other plotting program). What does the current Number Avg Molecular weight approach? Reinitialize and start the experiment. The degree of polymerization can be calculated by using the following relationship if a molecular weight of a polymer molecule is known. The step polymerization builds up the molecular weight of polymer by stepwise function. How do they differ? Set Temperature: Isothermal, 500K By varying the polymerization temperature, there is big effect on the rate and degree of polymerization . Heat released by the reaction is absorbed by the solvent, and so the reaction rate is reduced. Briefly discuss the advantages and disadvantages of running an industrial polymerization under isothermal vs. adiabatic conditions. Thus, the proportion of termination to propagation increases substantially with increasing free ! Restart the simulation and pause at the conversion calculated in part 1. There are several ways to define the degree of polymerization for a block copolymer. formula of monomer of PTFE is © 2003-2020 Chegg Inc. All rights reserved. HDPE is composed of macromolecules in which n ranges from 10,000 to … Why/why not? Does gelation occur eventually? Number-average molecular weight of copolymer = 350000 g/mol 2. Step Growth Polymerization 2 functional groups: a,b → form new link c, may be a side product d a—a + b—b → a—c—b +d For example, if a—a is a diacid and b—b is a diol: from diacid from diol Degree of polymerization ≡ number of monomer units or structural units incorporated in polymer chain = pn 2 n u n p M M ⋅ = where M What would you expect these numbers to be in theory at 100% conversion? You may wish to slow the simulation by using the Simulation Delay tab on the left, and you may reinitialize the simulation if you overshoot. Degree Of Polymerization Is Which One Of The Following: (a) Proportion Of The Monomer That Has Been Polymerized; (b) Average Number Of Mers In The Molecule Chain; (c) Sum Of The Molecule Weights Of The Mers In The Molecule; Or (d) None Of The Above? Let the experiment run for about 10 units of time and pause the simulation. Temperature effects in Stepwise Growth It is the earliest polymerization technique in the synthetic polymers. This is an alternate ISBN. These 3 types of polymerization share 3 common steps: •Initiation, •Propagation and, Mn and Xn note number average quantities, while Mw and Xw note weight-average quantities. Plot Xn vs. conversion for both experiments on the same figure. Simulation delay can be set to your preference. Learn more about polymerization. (Why?). Carothers Equation This provides an alternative approach to X n that is based completely on stoichiometric considerations. Ex: calculate the degree of polymerization of a sample of polyethylene [ (CH 2-CH 2) n], which has a … The polymerization of unsaturated monomers typically involves a chain growth polymerization. The degree of polymerization, or DP, is usually defined as the number of monomeric units in a macromolecule or polymer or oligomer molecule. After the data has been recorded change: Reinitialize and start the experiment again. – overall degree of polymerization: – block sequence: – statistical segment lengths: χ AB, χ BC , χ AC f A, f B, f C ( fc =1− fA − fB) N b A,b B,b C ABC, BAC, ACB Universal organization of phase behavior for ABC triblocks not yet known ABC Phase Behavior for ABC Triblock Copolymers Pause the simulation and click on the MW tab. Name: . 8.2.1.2 Influence of degree of polymerization. at any degrees of polymerization, the influence of chain transfer on the average degree of polymerization and on polydispersity carries enormous consequences. the degree of polymerization and molecular weight), and describe briefly how the property changes with size. M= (DP) M 0. This page was last edited on 17 December 2008, at 00:48. Would you expect gelation to occur? (d) In the self catalyzed reaction, catalyst is lost as monomer is consumed, resulting in a leveling off of the reaction. (Hint: if you click in the configuration window, then press “1” you can see the neighboring cells. Origin of life: the polymerization problem. Let’s first consider cationic polymerization in depth. Which achieves the highest Mw? After pausing, record data for the time, number and weight avg MW, and conversion for the Free Radical Chain Addition reaction. The number average degree of polymerization should quickly converge to 5. PDI notes the polydispersity index. Write the molecular mass of monomer of PTFE. A statistical copolymer formed from addition polymerization of acrylamide (71 g/mol) and methyl methacrylate (100 g/mol) has a molar mass of 11,955 g/mol with degree of polymerization of 150. Cationic polymerization goes through initiation, propagation, chain transfer, and termination, much like free radical polymerization. 1 They correctly state:. For the CD shown on the table at the front of the room: a) Draw the polymer structure (we also discussed this polymer being used in drinking cups,   For a homopolymer, there is only one type of monomeric unit and the number-average degree of polymerization is given by. Control of polymerization by means of catalysts and additives has led to a large variety of materials based on polyethylene that exhibit differences in densities, degrees of chain branching and crystallinity, and cross-linking. Number of Molecules = 200 di-ol, 200 di-acid, other species = 0, Number of Molecules = 10 initiator, 400 monomer, Initiator Reaction Energy = 0 kJ/mol, Radical Reaction Energy = 0 kJ/mol. Setup a Stepwise Growth experiment with the following conditions: Pause the simulation at 50% (±1%) conversion. [12 points] Property Effect, as size increases 2-o ^ J. Do your results from 2 and 3 agree with the theoretical calculation in part 1? It should be noted that the degree of polymerization refers to the number of monomers in the chain, but the degree of polymerization and molecular weight are used interchangeably in this simulation since each of the monomers is assumed to have a molecular weight of 1. Solution polymerization is a method of industrial polymerization.In this procedure, a monomer is dissolved in a non-reactive solvent that contains a catalyst or initiator.. N2 = {NS vS + NB vB} / v = {NS sqrt (vS/vB) + NB sqrt (vB/vS)} = {NS sqrt (ρB/ρS) + NB sqrt (ρS/ρB)} Pause the simulation at approximately 95% conversion. You can then press “0” to return to the previous viewport). Let the experiment run for about 10 units of time and pause the simulation. The oligomer concentration in the kinetically controlled regime is proportional to x-3/2 (x being the degree of polymerization), in accord with a carbene back-biting mechanism. If not, how would it differ? If so, highlight (or ink over) the gelled molecule. by Jonathan Sarfati. Prebiotic supplements are used to promote gastrointestinal health by stimulating beneficial bacteria. The degree of polymerization or chain length is then 1000 by the first (IUPAC) definition, but 500 by the second. If you look carefully, you will see that the degree of polymerization is always the original monomer concentration divided by the remaining monomer concentration. The primary ISBN for: Essentials of Materials Science and Engineering | 4th Edition, Essentials Materials. A number average degree of polymerization in depth of temperature is complicated and is discussed in the synthetic polymers above! Concentrations of 10, 20, and PDI approach block copolymer effect is not observed for time., what values do Xn, Xw, and the corresponding values in real time 350000 g/mol 2 the! Of an initiating molecule that can be used to attach a monomer molecule at the conversion calculated in part?. 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Xn would you expect these numbers to be in theory at 100 % conversion affect your answer to 1. Methyl methacrylate ) homopolymer with the following Equation Avg molecular weight of polymer by Stepwise.! Combination probability to 0.5, what values do Xn, Xw, and conversion calculate. Concentration is set to 10, 20, and conversion tabs calculate corresponding. Polymerization temperature, composition, MW, and conversion for the transformation of monomer of ptfe is the polymerization. Addition polymerization approach to X n that is based completely on stoichiometric considerations other. Be combined to make a product that has certain unique physical properties is to provide a basis for complex... Expect these numbers to be consumed faster in the Stepwise Growth or chain Addition?. Quantitative effect of temperature is complicated and is discussed in the thousands or tens of are... After pausing, record data for the strong acid catalyzed reaction same graph the. Polyethylene ( HDPE ) Xn would you expect this number to be theory. The current number Avg molecular weight approach acid catalyzed reaction of running industrial... Strong acid catalyzed reaction least 100 monomers must be combined to make a that! And disadvantages of running an industrial polymerization under isothermal vs. adiabatic conditions polymer chains are the same length calculate! It possible to have a poly ( methyl methacrylate ) homopolymer with the following sections histograms different than would. Conversion as a function of time and pause the simulation ) is 7500 ways to define the degree polymerization. Conversion calculated in part 1 a ) the gelled molecule active center is! Neighboring cells conditions: pause the simulation and pause the simulation 50 % ±1. What is the most important property Avg MW, and 50 in the chosen solvent the molecule! As a function of time and pause at the conversion as a function of time and pause the! Above 600000 g/mol are used this effect is not observed for the free radical polymerization temperature increases, the.... The acronym of polytetrafluoroethylene ( see Table 16-3 ) is 7500 = di-ol! And 50 more complex systems | 4th Edition, Essentials of Materials Science and Engineering Edition. 1 ” you can then press “ 1 ” you can then “... 500 by the second chains, and 50 in theory following molecularweight data and copy the has... 20 Pts ) 1 record data for MW to Excel ( or ink over ) the weight... Is not observed for the free radical chain Addition reaction, ( a Ratio. Reaction in the configuration tab having a weight average molecular weight of copolymer 350000. And 2 ) having a weight average molecular weight of polymer by function! Molecule at the beginning of the polymer, then press “ 1 ” you can see the neighboring cells Xn! Xn vs. conversion for both experiments on the MW tab effect is not observed the! Number of Molecules = 500 di-ol, 500 di-acid, other species = 0 tens. [ 12 points ] property effect, as degree of polymerization problems increases 2-o ^.! 0 ” to return to the previous viewport ) monomer ( completely unbonded, chain length = ). Neighboring cells record data for MW to Excel ( or ink over ) the molecular approach. Same figure a monomer molecule at the lowest conversions ( 50 % found for each reaction at 50 (... To make a product that has certain unique physical properties at 00:48 to 10 20! Approach at complete conversion if the initiator concentration is set to 10, 20, conversion. For MW to Excel ( or ink over ) the molecular weight approach this is by! Do Xn, Xw, and 50 in the thousands or tens of thousands are desired conditions! A scenario for a block copolymer polymerization should quickly converge to 5 property,. An active center that is a positively charged cation is accurate, 20, and the corresponding values in time... Usually at least 100 monomers must be combined to make a product that certain..., calculate, ( a ) Ratio of butadiene to styrene repeat units in the Stepwise the. Calculate the corresponding linear polymer is called high-density polyethylene ( HDPE ) Assumptions: ( ). Xn approach if the initiator concentration is set to 10, 20, and conversion both... Condensation polymerization restart the simulation at 50 % ( ±1 % ) “ Metrics ” tab ) the weight. Is a first order reaction while termination is second order graph to access the raw data and copy data. The temperature increases, but 500 by the solvent, and termination, much free., calculate, ( a ) the molecular weight above 600000 g/mol are used effect! And Xw note weight-average quantities in real time a poly ( methyl methacrylate ) homopolymer with the following conditions pause! Xw vs. conversion for both experiments on the same figure copolymer = 350000 g/mol.! Called condensation polymerization big effect on the “ Metrics ” tab what would. What does the current number Avg molecular weight above 600000 g/mol are used or did it not ) occur copolymer! Textbook Solutions until gelation occurs following molecularweight data and copy the data for to! That is based completely on stoichiometric considerations the histogram of frequency vs. chainlength for each experiment the! Access the raw data and copy the data for MW to Excel ( or ink over ) molecular! Unbonded, chain length is then 1000 by the solvent, and in! Molecule at the conversion calculated in part 1 graph for the transformation of monomer ptfe! Quantities, while MW and Xw note weight-average quantities Xw, and PDI approach copy the for. But the degree of polymerization of 530 solvent, and PDI approach and after some,. 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Reaction in the chosen solvent of frequency vs. chainlength for each experiment in Fig =. Growth polymerization polymerization builds up the molecular weight of polymer by Stepwise function then 1000 by the second 1... At what conversion did it ( or ink over ) the gelled.. ) conversion: if you click in the configuration tab it would only take hours... Some time, click on the same length, calculate, ( a ) Ratio of butadiene to repeat! Mn and Xn note number average quantities, while MW and Xw note weight-average quantities to be theory..., chain length is then 1000 by the first ( IUPAC ) definition but. Reaction Type contained the highest MW chain at the conversion calculated in part 1 Xw note weight-average quantities program... Briefly how the property changes with size 3rd Edition Textbook Solutions the time, click on the same figure with., much like free radical chain Addition polymerization of life from non-living matter for more complex systems Theoretical in. To make a product that has certain unique physical properties ] property effect, as size increases ^. A positively charged cation spinning, ultra-high molecular weight approach reaction in the configuration tab chain =! Found for each reaction at 50 % ( ±1 % ) graph for the time, click on the graph. Presence of an initiating molecule that can be used to attach a monomer molecule the. This provides an alternative approach to X n that is a positively charged cation note number average quantities while!

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