The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Christopher Barnerkowollik - One of the best experts on this subject based on the ideXlab platform.
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mapping poly butyl acrylate Product distributions by mass spectrometry in a wide temperature range suppression of midchain radical side reactions
Macromolecules, 2007Co-Authors: Thomas Junkers, Thomas P Davis, Martina H Stenzel, Christopher BarnerkowollikAbstract:The Polymer Product spectra of poly(butyl acrylate), polyBA, samples obtained by full conversion bulk Polymerization in the temperature range of 60−140 °C in presence of the chain transfer agent (CTA) octylthiol is analyzed via electrospray ionization−mass spectrometry (ESI−MS) and quantitative 13C NMR. The combination of both these analytical techniques allows for very detailed information on the reaction Products associated with the formation of midchain radicals to be obtained. At 60 °C, highly uniform polyBA is generated that consists of the structure alkyl−S−(BA)n−H. With increasing temperature, several other peaks emerge that can be assigned to either conventional termination Product or to the three different β-scission Products of the so-called midchain radicals that are known to be formed in acrylate Polymerization via transfer to Polymer reactions. Because of the formation of β-scission Products that were formed by scission to either side of the radical functionality, intermolecular transfer to p...
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mapping poly butyl acrylate Product distributions by mass spectrometry in a wide temperature range suppression of midchain radical side reactions
Institute for Future Environments; Science & Engineering Faculty, 2007Co-Authors: Thomas Junkers, Thomas P Davis, Martina H Stenzel, Christopher BarnerkowollikAbstract:The Polymer Product spectra of poly(butyl acrylate), polyBA, samples obtained by full conversion bulk Polymerization in the temperature range of 60-140 °C in presence of the chain transfer agent (CTA) octylthiol is analyzed via electrospray ionization-mass spectrometry (ESI-MS) and quantitative 13C NMR. The combination of both these analytical techniques allows for very detailed information on the reaction Products associated with the formation of midchain radicals to be obtained. At 60 °C, highly uniform polyBA is generated that consists of the structure alkyl - S - (BA)n - H. With increasing temperature, several other peaks emerge that can be assigned to either conventional termination Product or to the three different β-scission Products of the so-called midchain radicals that are known to be formed in acrylate Polymerization via transfer to Polymer reactions. Because of the formation of β-scission Products that were formed by scission to either side of the radical functionality, intermolecular transfer to Polymer presumably plays an important role in the present system. For the 140 °C sample, 1.37 mol % of quaternary carbons on the Polymer backbone are identified with only a small fraction of the chains carrying an unsaturated end group. As much higher levels of branching and unsaturation are expected under the same conditions from conventional free radical Polymerization, it is concluded that the chain transfer agent is capable of suppressing the midchain radical side reactions to a large extent. © 2007 American Chemical Society.
Mladen Šercer - One of the best experts on this subject based on the ideXlab platform.
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Mathematical model for the selection of processing parameters in selective laser sintering of Polymer Products
Advances in Mechanical Engineering, 2014Co-Authors: Ana Pilipović, Igor Drstvensek, Mladen ŠercerAbstract:Additive manufacturing (AM) is increasingly applied in the development projects from the initial idea to the finished Product. The reasons are multiple, but what should be emphasised is the possibility of relatively rapid manufacturing of the Products of complicated geometry based on the computer 3D model of the Product. There are numerous limitations primarily in the number of available materials and their properties, which may be quite different from the properties of the material of the finished Product. Therefore, it is necessary to know the properties of the Product materials. In AM procedures the mechanical properties of materials are affected by the manufacturing procedure and the Production parameters. During SLS procedures it is possible to adjust various manufacturing parameters which are used to influence the improvement of various mechanical and other properties of the Products. The paper sets a new mathematical model to determine the influence of individual manufacturing parameters on the Polymer Product made by selective laser sintering. Old mathematical model is checked by statistical method with central composite plan and it is established that old mathematical model must be expanded with new parameter beam overlay ratio. Verification of new mathematical model and optimization of the processing parameters are made on SLS machine.
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Importance of Rapid Prototyping in Polymer Product Development
2013Co-Authors: Damir Godec, Pero Raos, Mladen ŠercerAbstract:In case of injection moulded parts, it must be noted that 75 % of faults in their lifetime are initiated in the process of developing and designing the parts. Moreover, in the conventional Product development process, approximately 80 % of faults generated during early phases of Product design are recognized during Production or quality control. In the later development process phases it is very difficult and costly to correct those faults. The range of possible savings of the Product development and Production is few times larger in the initial phases of Product development than later, during Product design and Production. This means, that during Product development process, it is necessary to make correct decision as soon as possible. One of possible, effective and already proven tools is application of Rapid Prototyping (RP) processes, which enable obtaining physical models in early stage of Product development. Those models can be used in order to prevent faults in Product design and function, as well as for good communication between experts involved in Product development and Production. The paper will present few examples of successful application of RP processes, and actual benefits of application of prototypes in Polymer Products development process.
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From an idea to the final Polymer Product
Engineering review, 2012Co-Authors: Mladen Šercer, Damir Godec, Pero RaosAbstract:Injection moulding process is one of the most important processes for the Production of Polymer parts. Effective tool for successful moulded part development is an approach of Rapid Product Development. This approach includes the application of Rapid Prototyping (RP) processes of obtaining physical models in an early stage of Product development. Rapid Product Development also includes CAE approach with powerful tools such as computer simulation of the process of injection moulding. The paper presents phases of development from an idea to the final Product in the case of a letter opener, which contains visual identity (logotype) of the Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb (FMENA).
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Application of Rapid Prototyping in Polymer Product Development - Case Studies
2010Co-Authors: Damir Godec, Ana Pilipović, Mladen ŠercerAbstract:The approach to process of development of Polymer parts with application of Rapid Prototyping (RP) processes can minimize a potential faults on the Product during Product development. The paper will present few examples of successful application of RP processes and actual benefits of application of prototypes in Polymer Product development process.
Thomas Junkers - One of the best experts on this subject based on the ideXlab platform.
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mapping poly butyl acrylate Product distributions by mass spectrometry in a wide temperature range suppression of midchain radical side reactions
Macromolecules, 2007Co-Authors: Thomas Junkers, Thomas P Davis, Martina H Stenzel, Christopher BarnerkowollikAbstract:The Polymer Product spectra of poly(butyl acrylate), polyBA, samples obtained by full conversion bulk Polymerization in the temperature range of 60−140 °C in presence of the chain transfer agent (CTA) octylthiol is analyzed via electrospray ionization−mass spectrometry (ESI−MS) and quantitative 13C NMR. The combination of both these analytical techniques allows for very detailed information on the reaction Products associated with the formation of midchain radicals to be obtained. At 60 °C, highly uniform polyBA is generated that consists of the structure alkyl−S−(BA)n−H. With increasing temperature, several other peaks emerge that can be assigned to either conventional termination Product or to the three different β-scission Products of the so-called midchain radicals that are known to be formed in acrylate Polymerization via transfer to Polymer reactions. Because of the formation of β-scission Products that were formed by scission to either side of the radical functionality, intermolecular transfer to p...
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mapping poly butyl acrylate Product distributions by mass spectrometry in a wide temperature range suppression of midchain radical side reactions
Institute for Future Environments; Science & Engineering Faculty, 2007Co-Authors: Thomas Junkers, Thomas P Davis, Martina H Stenzel, Christopher BarnerkowollikAbstract:The Polymer Product spectra of poly(butyl acrylate), polyBA, samples obtained by full conversion bulk Polymerization in the temperature range of 60-140 °C in presence of the chain transfer agent (CTA) octylthiol is analyzed via electrospray ionization-mass spectrometry (ESI-MS) and quantitative 13C NMR. The combination of both these analytical techniques allows for very detailed information on the reaction Products associated with the formation of midchain radicals to be obtained. At 60 °C, highly uniform polyBA is generated that consists of the structure alkyl - S - (BA)n - H. With increasing temperature, several other peaks emerge that can be assigned to either conventional termination Product or to the three different β-scission Products of the so-called midchain radicals that are known to be formed in acrylate Polymerization via transfer to Polymer reactions. Because of the formation of β-scission Products that were formed by scission to either side of the radical functionality, intermolecular transfer to Polymer presumably plays an important role in the present system. For the 140 °C sample, 1.37 mol % of quaternary carbons on the Polymer backbone are identified with only a small fraction of the chains carrying an unsaturated end group. As much higher levels of branching and unsaturation are expected under the same conditions from conventional free radical Polymerization, it is concluded that the chain transfer agent is capable of suppressing the midchain radical side reactions to a large extent. © 2007 American Chemical Society.
M. Soroush - One of the best experts on this subject based on the ideXlab platform.
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Product quality improvement in a high-temperature free-radical Polymerization reactor
Proceedings of the 2003 American Control Conference 2003., 2003Co-Authors: Congling Quan, M. Soroush, Michael C. GradyAbstract:In response to the strict environmental regulations on volatile organic solvents in paints and coatings, high-temperature solution Polymerization has increasingly been used to manufacture low-molecular-weight, acrylic Polymer resins for automotive coatings. Free-radical Polymerization of acrylate and methacrylate monomers at high-temperatures (140-200 /spl deg/C) involves a number of side reactions that have a marked effect on the quality of the Polymer Product. These reactions are not significant at low temperatures. We have studied kinetics of liquid-phase, high-temperature, free-radical, n-butyl acrylate (nBA), Polymerization reactions, leading to the development of a mathematical model for the Polymerization. The model is capable of predicting the Polymer molecular weight distribution and several functionality indices very accurately. For a semi-batch nBA Polymerization reactor, a multi-objective optimization problem is solved to calculate optimal feed (initiator, solvent and monomer) flow-rate and reactor temperature profiles. These profiles minimize total amount of initiator fed to the reactor, polydispersity index of the final Product, and batch time (t/sub f/), subject to (a) the reactor dynamics, (b) a monomer conversion of above 0.99 at t/sub f/, and (c) a Polymer weight-average molecular weight of 8,000 at t/sub f/. The results show that high-quality Polymers can be produced at lower operating costs by minimizing initiator usage and batch time.
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Multi-rate control of a Polymerization reactor: a comparative study
Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999Co-Authors: N. Zambare, M. Soroush, B.a. OgunnaikeAbstract:A comparative study of multi-rate control of a jacketed styrene Polymerization reactor is presented. A multi-rate nonlinear control system is used to regulate the weight-average molecular weight of the Polymer Product and temperature in the reactor, by manipulating the flow rate of an initiator feed stream and the rate of heat input to the reactor jacket. The multi-rate control system consists of a multi-rate nonlinear state estimator, a mixed error and state-feedback controller. The state estimator provides continuous estimates of state variables of the process from: 1) frequent measurements of the reactor temperature, the jacket temperature and the reacting-mixture density, and 2) infrequent and delayed measurements of the leading moments of the molecular weight distribution of the dead Polymer chains. The infrequent and delayed measurements have sampling periods of three hours and measurement delays of one hour. The performance of the multi-rate nonlinear control system is shown and compared with those of a multi-rate, PI, parallel cascade control system and a multi-rate, PI, completely decentralized control system.
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Multi-rate nonlinear state estimation in a Polymerization reactor
Proceedings of the 1998 American Control Conference. ACC (IEEE Cat. No.98CH36207), 1998Co-Authors: S. Tatiraju, M. Soroush, B.a. OgunnaikeAbstract:A new multi-rate nonlinear observer design method is presented. It can use a nonlinear process model in the estimator design directly, without any linear approximation. The multi-rate nonlinear state observer is easy to design and implement and is computationally efficient. The implementation and performance of the observer design method are shown by a Polymerization reactor in which free-radical solution Polymerization of styrene takes place. The initiator concentration and the three leading moments of the molecular weight distribution (MWD) of the Polymer Product are estimated continuously from: 1) the frequent measurements of the reactor temperature, jacket temperature and the reacting-mixture density; and 2) the infrequent and delayed measurements of the leading moments of the MWD.
B.a. Ogunnaike - One of the best experts on this subject based on the ideXlab platform.
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Multi-rate control of a Polymerization reactor: a comparative study
Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999Co-Authors: N. Zambare, M. Soroush, B.a. OgunnaikeAbstract:A comparative study of multi-rate control of a jacketed styrene Polymerization reactor is presented. A multi-rate nonlinear control system is used to regulate the weight-average molecular weight of the Polymer Product and temperature in the reactor, by manipulating the flow rate of an initiator feed stream and the rate of heat input to the reactor jacket. The multi-rate control system consists of a multi-rate nonlinear state estimator, a mixed error and state-feedback controller. The state estimator provides continuous estimates of state variables of the process from: 1) frequent measurements of the reactor temperature, the jacket temperature and the reacting-mixture density, and 2) infrequent and delayed measurements of the leading moments of the molecular weight distribution of the dead Polymer chains. The infrequent and delayed measurements have sampling periods of three hours and measurement delays of one hour. The performance of the multi-rate nonlinear control system is shown and compared with those of a multi-rate, PI, parallel cascade control system and a multi-rate, PI, completely decentralized control system.
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Multi-rate nonlinear state estimation in a Polymerization reactor
Proceedings of the 1998 American Control Conference. ACC (IEEE Cat. No.98CH36207), 1998Co-Authors: S. Tatiraju, M. Soroush, B.a. OgunnaikeAbstract:A new multi-rate nonlinear observer design method is presented. It can use a nonlinear process model in the estimator design directly, without any linear approximation. The multi-rate nonlinear state observer is easy to design and implement and is computationally efficient. The implementation and performance of the observer design method are shown by a Polymerization reactor in which free-radical solution Polymerization of styrene takes place. The initiator concentration and the three leading moments of the molecular weight distribution (MWD) of the Polymer Product are estimated continuously from: 1) the frequent measurements of the reactor temperature, jacket temperature and the reacting-mixture density; and 2) the infrequent and delayed measurements of the leading moments of the MWD.