Pub Date : 2008-04-15DOI: 10.1002/9780470692134.CH8
J. R. Leiza, J. Pinto
{"title":"Control of Polymerization Reactors","authors":"J. R. Leiza, J. Pinto","doi":"10.1002/9780470692134.CH8","DOIUrl":"https://doi.org/10.1002/9780470692134.CH8","url":null,"abstract":"","PeriodicalId":124648,"journal":{"name":"Polymer Reaction Engineering","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123628130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is known that the molecular weight distribution (MWD) formed in emulsion polymerization of ethylene can be bimodal. A simplified model is used to investigate the emulsion polymerization that involves chain transfer to polymer, aiming at finding necessary conditions to form a bimodal MWD. According to the present theoretical investigation, a bimodal MWD can be formed when the probability that the primary chain end is connected to a backbone chain, P b is larger than 0.5. The bimodality for these cases results from the limited volume effect, that is, the high molecular weight profiles are distorted by the small particle size, which is comparable to the size of the largest branched polymer molecule formed in a particle. During Interval II, the P b ‐value could be approximately equal to C p x c /[C p x c +C m (1 −x c )] in usual emulsion polymerization without using the chain transfer agents, where C p and C m are transfer constants to polymer and to monomer, respectively, and x c is the conversion at which Interval II ends, and therefore, one can predict the possibility of obtaining a bimodal MWD on the basis of these reaction parameters. On the other hand, if the experimentally obtained MWDs are bimodal even when P b < 0.5, the origin of bimodality would be attributed to other reaction mechanisms, such as the chain‐length dependent branching reactions and combination of two different MWDs formed in large and small polymer particles.
已知乙烯乳液聚合形成的分子量分布(MWD)是双峰的。采用简化模型对涉及链转移到聚合物的乳液聚合进行了研究，旨在找到形成双峰随钻的必要条件。根据目前的理论研究，当主链端与主链连接的概率P b大于0.5时，可以形成双峰MWD。这些情况下的双峰性是由有限体积效应造成的，即高分子量的轮廓被小颗粒所扭曲，小颗粒的大小与颗粒中形成的最大支化聚合物分子的大小相当。第二间隔期间,P b量价值可以约等于C x C / P (x C P C + C m(1−x C)]在没有使用的常规乳液聚合链转移剂,其中C P C m常量转移到聚合物和单体,分别和x C的转换间隔二世结束,因此,人能预测的可能性获得双峰随钻测量的基础上,这些反应参数。另一方面，当P < 0.5时，如果实验得到的MWDs是双峰的，则双峰的起源可能归因于其他反应机制，如链长依赖的分支反应和在大小聚合物颗粒中形成的两种不同MWDs的结合。
{"title":"Bimodal Molecular Weight Distribution Formed in Emulsion Polymerization with Long‐Chain Branching","authors":"H. Tobita","doi":"10.1081/PRE-120026377","DOIUrl":"https://doi.org/10.1081/PRE-120026377","url":null,"abstract":"It is known that the molecular weight distribution (MWD) formed in emulsion polymerization of ethylene can be bimodal. A simplified model is used to investigate the emulsion polymerization that involves chain transfer to polymer, aiming at finding necessary conditions to form a bimodal MWD. According to the present theoretical investigation, a bimodal MWD can be formed when the probability that the primary chain end is connected to a backbone chain, P b is larger than 0.5. The bimodality for these cases results from the limited volume effect, that is, the high molecular weight profiles are distorted by the small particle size, which is comparable to the size of the largest branched polymer molecule formed in a particle. During Interval II, the P b ‐value could be approximately equal to C p x c /[C p x c +C m (1 −x c )] in usual emulsion polymerization without using the chain transfer agents, where C p and C m are transfer constants to polymer and to monomer, respectively, and x c is the conversion at which Interval II ends, and therefore, one can predict the possibility of obtaining a bimodal MWD on the basis of these reaction parameters. On the other hand, if the experimentally obtained MWDs are bimodal even when P b < 0.5, the origin of bimodality would be attributed to other reaction mechanisms, such as the chain‐length dependent branching reactions and combination of two different MWDs formed in large and small polymer particles.","PeriodicalId":124648,"journal":{"name":"Polymer Reaction Engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126064414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Depolymerization of PET in aqueous sodium hydroxide solution was undertaken in a batch process at 90–150°C and 1 atm by varying PET particle size in the range of 50–512.5 µm. Reaction time was also varied from 10–110 min to explore effect of particle size of PET and reaction time on batch reactor performance. Particle size of PET and reaction time required were optimized. Disodium terephthalate (TPA salt) and ethylene glycol (EG) remain in liquid phase. EG was recovered by salting‐out technique. Disodium terephthalate was separated by acidification to obtain solid terephthalic acid (TPA). Produced TPA and EG were analyzed qualitatively and quantitatively. Yields of TPA and EG were almost equal to PET conversion. Depolymerization reaction rate was first order to PET concentration as well as first order to sodium hydroxide concentration. Acid value of TPA changes with reaction time. This indicates that PET molecule gets fragmented and hydrolyzes simultaneously with aqueous sodium hydroxide to produce EG and disodium terephthalate. Thermodynamics was also undertaken by determination of activation energy, Arrhenius constant, equilibrium constant, Gibbs free energy, enthalpy and entropy. Dependence of hydrolysis rate constant on reaction temperature was correlated by Arrhenius plot, which shows activation energy of 26.3 kJ/mol and Arrhenius constant of 427.2 L/min/cm2.
{"title":"Chemical Recycling, Kinetics, and Thermodynamics of Alkaline Depolymerization of Waste Poly (Ethylene Terephthalate) (PET)","authors":"S. Mishra, A. Goje","doi":"10.1081/PRE-120026382","DOIUrl":"https://doi.org/10.1081/PRE-120026382","url":null,"abstract":"Depolymerization of PET in aqueous sodium hydroxide solution was undertaken in a batch process at 90–150°C and 1 atm by varying PET particle size in the range of 50–512.5 µm. Reaction time was also varied from 10–110 min to explore effect of particle size of PET and reaction time on batch reactor performance. Particle size of PET and reaction time required were optimized. Disodium terephthalate (TPA salt) and ethylene glycol (EG) remain in liquid phase. EG was recovered by salting‐out technique. Disodium terephthalate was separated by acidification to obtain solid terephthalic acid (TPA). Produced TPA and EG were analyzed qualitatively and quantitatively. Yields of TPA and EG were almost equal to PET conversion. Depolymerization reaction rate was first order to PET concentration as well as first order to sodium hydroxide concentration. Acid value of TPA changes with reaction time. This indicates that PET molecule gets fragmented and hydrolyzes simultaneously with aqueous sodium hydroxide to produce EG and disodium terephthalate. Thermodynamics was also undertaken by determination of activation energy, Arrhenius constant, equilibrium constant, Gibbs free energy, enthalpy and entropy. Dependence of hydrolysis rate constant on reaction temperature was correlated by Arrhenius plot, which shows activation energy of 26.3 kJ/mol and Arrhenius constant of 427.2 L/min/cm2.","PeriodicalId":124648,"journal":{"name":"Polymer Reaction Engineering","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123328369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Zubitur, P. Armitage, S. Ben Amor, J. R. Leiza, J. Asua
A mathematical model for free‐radically initiated semi‐continuous emulsion polymerizations of a multimonomer system containing vinylic, divinylic and acidic monomers in the presence of chain transfer agent (CTA) was deleloped. In addition to the more traditional aspects of emulsion polymerization, the model takes into account both the presence of water‐soluble monomers and the formation of gel due to the polymerization of a divinylic monomer in the presence of CTA. The outputs of the model are the time evolution of monomers conversions, copolymer composition, molecular weight of the sol polymer and gel fraction.
{"title":"Mathematical Modeling of Multimonomer (Vinylic, Divinylic, Acidic) Emulsion Copolymerization Systems","authors":"M. Zubitur, P. Armitage, S. Ben Amor, J. R. Leiza, J. Asua","doi":"10.1081/PRE-120026368","DOIUrl":"https://doi.org/10.1081/PRE-120026368","url":null,"abstract":"A mathematical model for free‐radically initiated semi‐continuous emulsion polymerizations of a multimonomer system containing vinylic, divinylic and acidic monomers in the presence of chain transfer agent (CTA) was deleloped. In addition to the more traditional aspects of emulsion polymerization, the model takes into account both the presence of water‐soluble monomers and the formation of gel due to the polymerization of a divinylic monomer in the presence of CTA. The outputs of the model are the time evolution of monomers conversions, copolymer composition, molecular weight of the sol polymer and gel fraction.","PeriodicalId":124648,"journal":{"name":"Polymer Reaction Engineering","volume":"82 Suppl 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131950242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sophia Parouti, Olga Kammona, C. Kiparissides, J. Bousquet
In the present study a comprehensive experimental investigation on the batch and semi‐batch emulsion terpolymerization of methyl methacrylate/butyl acrylate/acrylic acid (MMA/BuA/AA) is reported. Batch experiments were carried out in a fully automated pilot‐scale reactor system to analyze the effect of polymerization temperature, anionic surfactant and initiator concentrations on the polymerization rate, average particle size, copolymer composition and glass transition temperature of the polymer. In addition, a series of semi‐batch experiments were performed under monomer starved conditions to assess the effect of seven process variables, (e.g., concentrations of anionic, nonionic surfactants and initiator, polymerization temperature, agitation rate, impeller type and addition time of initiator/pre‐emulsion mixture) on the polymerization rate, average particle size, copolymer composition, glass transition temperature and MWD of the polymer.
{"title":"A Comprehensive Experimental Investigation of the Methyl Methacrylate/Butyl Acrylate/Acrylic Acid Emulsion Terpolymerization","authors":"Sophia Parouti, Olga Kammona, C. Kiparissides, J. Bousquet","doi":"10.1081/PRE-120026375","DOIUrl":"https://doi.org/10.1081/PRE-120026375","url":null,"abstract":"In the present study a comprehensive experimental investigation on the batch and semi‐batch emulsion terpolymerization of methyl methacrylate/butyl acrylate/acrylic acid (MMA/BuA/AA) is reported. Batch experiments were carried out in a fully automated pilot‐scale reactor system to analyze the effect of polymerization temperature, anionic surfactant and initiator concentrations on the polymerization rate, average particle size, copolymer composition and glass transition temperature of the polymer. In addition, a series of semi‐batch experiments were performed under monomer starved conditions to assess the effect of seven process variables, (e.g., concentrations of anionic, nonionic surfactants and initiator, polymerization temperature, agitation rate, impeller type and addition time of initiator/pre‐emulsion mixture) on the polymerization rate, average particle size, copolymer composition, glass transition temperature and MWD of the polymer.","PeriodicalId":124648,"journal":{"name":"Polymer Reaction Engineering","volume":"7 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113965105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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