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Sebastião V. Canevarolo - One of the best experts on this subject based on the ideXlab platform.
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evaluation of philips and ziegler natta high density polyethylene degradation during processing in an Internal Mixer using the chain scission and branching distribution function analysis
Polymer Degradation and Stability, 2006Co-Authors: L. A. Pinheiro, M. A. Chinelatto, Sebastião V. CanevaroloAbstract:Abstract The oxidative and thermo-mechanical degradation of HDPE was studied during processing in an Internal Mixer under two conditions: totally and partially filled chambers, which provides lower and higher concentrations of oxygen, respectively. Two types of HDPEs, Phillips and Ziegler–Natta, having different levels of terminal vinyl unsaturations were analyzed. Materials were processed at 160, 200, and 240 °C. Standard rheograms using a partially filled chamber showed that the torque is much more unstable in comparison to a totally filled chamber which provides an environment depleted of oxygen. Carbonyl and transvinylene group concentrations increased, whereas vinyl group concentration decreased with temperature and oxygen availability. Average number of chain scission and branching (ns) was calculated from MWD curves and its plotting versus functional groups' concentration showed that chain scission or branching takes place depending upon oxygen content and vinyl groups' consumption. Chain scission and branching distribution function (CSBDF) values showed that longer chains undergo chain scission easier than shorter ones due to their higher probability of entanglements. This yields macroradicals that react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the oxygen concentration, temperature, and vinyl end groups' content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than the Ziegler–Natta's type at the same processing condition.
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Evaluation of Philips and Ziegler-Natta high-density polyethylene degradation during processing in an Internal Mixer using the chain scission and branching distribution function analysis
Polymer Degradation and Stability, 2006Co-Authors: L. A. Pinheiro, M. A. Chinelatto, Sebastião V. CanevaroloAbstract:The oxidative and thermo-mechanical degradation of HDPE was studied during processing in an Internal Mixer under two conditions: totally and partially filled chambers, which provides lower and higher concentrations of oxygen, respectively. Two types of HDPEs, Phillips and Ziegler-Natta, having different levels of terminal vinyl unsaturations were analyzed. Materials were processed at 160, 200, and 240 °C. Standard rheograms using a partially filled chamber showed that the torque is much more unstable in comparison to a totally filled chamber which provides an environment depleted of oxygen. Carbonyl and transvinylene group concentrations increased, whereas vinyl group concentration decreased with temperature and oxygen availability. Average number of chain scission and branching (ns) was calculated from MWD curves and its plotting versus functional groups' concentration showed that chain scission or branching takes place depending upon oxygen content and vinyl groups' consumption. Chain scission and branching distribution function (CSBDF) values showed that longer chains undergo chain scission easier than shorter ones due to their higher probability of entanglements. This yields macroradicals that react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the oxygen concentration, temperature, and vinyl end groups' content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than the Ziegler-Natta's type at the same processing condition. © 2006 Elsevier Ltd. All rights reserved.
J. L. White - One of the best experts on this subject based on the ideXlab platform.
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Bulk Polymerization of ε-Caprolactone in an Internal Mixer and in a Twin Screw Extruder
International Polymer Processing, 2002Co-Authors: J. L. WhiteAbstract:Abstract Bulk polymerization of e-caprolactone has been carried out both in a laboratory Internal Mixer (Brabender Plasticorder) and in a modular intermeshing co-rotating twin screw extruder. Various initiators, such as titanium n-butoxide, aluminum triisopropoxide, and sodium hydride were used to polymerize e-caprolactone in an Internal Mixer. The continuous polymerization of e-caprolactone was performed using aluminum triisopropoxide under a range of processing conditions, including barrel temperature profiles, throughput, and screw speed. This polymerization was investigated for various ratios of monomer to initiator. GPC analysis demonstrated that significant quantities of oligomers were produced together with high molecular weight polymer at different reaction temperatures. H NMR detected the hydroxylation of growing chain end group for bulk polymerization at high barrel temperature. The molecular weight was reduced along the screw axis once the maximum molecular weight was obtained after the first k...
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Comparison Studies of Anionic Polymerization of Caprolactam in Different Twin Screw Extruders
International Polymer Processing, 2001Co-Authors: J. L. WhiteAbstract:Abstract There is a study on the comparison of twin screw extruders and a batch Mixer in the polymerization of caproiactam. A sodium metal initiator and 4–4'-diphenylmethane diisocyanate (MDI) as the activator were used. Our attention is given to (i) a modular intermeshing co-rotating twin screw extruder, (ii) a modular intermeshing counter-rotating twin screw extruder and (Hi) a modular tangential counter-rotating twin screw extruder. We consider the variables of screw configuration, temperature profile, screw speed, and throughput on polymer characteristics. It was found that the conversion of twin screw extruders with proper mixing segments is much higher than the Internal Mixer at low mixing times. This was seen as higher conversion in twin screw extruders than an Internal Mixer for the same mean residence time considered.
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Simulation of flow in an intermeshing Internal Mixer: Role of clearance between rotor axes and rotor flight-chamber clearance
1999Co-Authors: J. L. WhiteAbstract:A simulation of flow in intermeshing counter-rotating rotor Internal Mixers is presented. We consider flow in machines with rotor designs due to Cooke (Francis Shaw), Wiedmann and Schmid (Werner and Pfleiderer), Johnson et al. (Francis Shaw), and Tanaka and Yamada (Kobe Steel). Special attention is given to the influence of 1) changing the clearance between the rotors and 2) varying the clearance between the rotor tips and the Internal Mixer chamber wall.
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Flow visualization in an Internal Mixer using an adjustable rotor system : Comparison of double flighted and four flighted rotors
1997Co-Authors: J. L. White, L. PominiAbstract:An apparatus has been constructed which allows flow visualization measurements using an Internal Mixer with variable rotors whose designs may be readily interchanged. The use of rotors is illustrated by constructing standard two and four wing rotors and comparing their performance. Measurements of bale homogenization times, black incorporation times, torque and dump temperature are recorded.
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Simulation of flow in an Internal Mixer to evaluate rotor design : Effect of non-Newtonian behaviour
1996Co-Authors: B. Hu, J. L. WhiteAbstract:The flow in an interanl Mixer mixing chamber with separated rotors is modeled for a viscous non-newtonian fluid. The influence of rotor design on material flow fluxes in the Internal Mixer is analyzed. Rotor designs in the patent literature are critiv=cally discussed
L. A. Pinheiro - One of the best experts on this subject based on the ideXlab platform.
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evaluation of philips and ziegler natta high density polyethylene degradation during processing in an Internal Mixer using the chain scission and branching distribution function analysis
Polymer Degradation and Stability, 2006Co-Authors: L. A. Pinheiro, M. A. Chinelatto, Sebastião V. CanevaroloAbstract:Abstract The oxidative and thermo-mechanical degradation of HDPE was studied during processing in an Internal Mixer under two conditions: totally and partially filled chambers, which provides lower and higher concentrations of oxygen, respectively. Two types of HDPEs, Phillips and Ziegler–Natta, having different levels of terminal vinyl unsaturations were analyzed. Materials were processed at 160, 200, and 240 °C. Standard rheograms using a partially filled chamber showed that the torque is much more unstable in comparison to a totally filled chamber which provides an environment depleted of oxygen. Carbonyl and transvinylene group concentrations increased, whereas vinyl group concentration decreased with temperature and oxygen availability. Average number of chain scission and branching (ns) was calculated from MWD curves and its plotting versus functional groups' concentration showed that chain scission or branching takes place depending upon oxygen content and vinyl groups' consumption. Chain scission and branching distribution function (CSBDF) values showed that longer chains undergo chain scission easier than shorter ones due to their higher probability of entanglements. This yields macroradicals that react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the oxygen concentration, temperature, and vinyl end groups' content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than the Ziegler–Natta's type at the same processing condition.
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Evaluation of Philips and Ziegler-Natta high-density polyethylene degradation during processing in an Internal Mixer using the chain scission and branching distribution function analysis
Polymer Degradation and Stability, 2006Co-Authors: L. A. Pinheiro, M. A. Chinelatto, Sebastião V. CanevaroloAbstract:The oxidative and thermo-mechanical degradation of HDPE was studied during processing in an Internal Mixer under two conditions: totally and partially filled chambers, which provides lower and higher concentrations of oxygen, respectively. Two types of HDPEs, Phillips and Ziegler-Natta, having different levels of terminal vinyl unsaturations were analyzed. Materials were processed at 160, 200, and 240 °C. Standard rheograms using a partially filled chamber showed that the torque is much more unstable in comparison to a totally filled chamber which provides an environment depleted of oxygen. Carbonyl and transvinylene group concentrations increased, whereas vinyl group concentration decreased with temperature and oxygen availability. Average number of chain scission and branching (ns) was calculated from MWD curves and its plotting versus functional groups' concentration showed that chain scission or branching takes place depending upon oxygen content and vinyl groups' consumption. Chain scission and branching distribution function (CSBDF) values showed that longer chains undergo chain scission easier than shorter ones due to their higher probability of entanglements. This yields macroradicals that react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the oxygen concentration, temperature, and vinyl end groups' content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than the Ziegler-Natta's type at the same processing condition. © 2006 Elsevier Ltd. All rights reserved.
James L. White - One of the best experts on this subject based on the ideXlab platform.
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Continuous polymerization of ω-lauryl lactam in an intermeshing corotating twin-screw extruder
Journal of Applied Polymer Science, 2020Co-Authors: James L. WhiteAbstract:This article describes the synthesis of poly(ω-lauryl lactam) by a reactive extrusion process. Anionic ring-opening polymerization was performed in an intermeshing corotating twin-screw extruder. We investigated the evolution of conversion of ω-lauryl lactam as a function of reaction time, screw speeds, different feed rates, and different screw configurations along the screw axis in a twin-screw extruder. For comparison with continuous polymerization in a twin-screw extruder, we studied polymerization in an Internal Mixer, which was considered a batch reactor. We found the final conversion of ω-lauryl lactam made in a twin-screw extruder was higher than in an Internal Mixer. Higher molecular weights are found at lower screw speeds and feed rates. Melt viscosities and mechanical properties of the polymers were measured. Residence time, molecular weights, and shear mixing have the main effect on the mechanical properties of products. The twin-screw extruder performance was interpreted in terms of commercial software. It was found that twin-screw extruder reaction rate was higher than those in the batch reactor and increased locally with screw speed and feed rate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1605–1620, 2005
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maleic anhydride modification of polyolefin in an Internal Mixer and a twin screw extruder experiment and kinetic model
Polymer Engineering and Science, 2001Co-Authors: James L. WhiteAbstract:There has been little effort. to quantitatively understand graft copolymerization in batch and continuous Mixers. Little information exists on the evolution of grafting reactions with respect to residence time in an Internal Mixer or along the screw axis in a twin-screw extruder. In this study, maleic anhydride was grafted onto polypropylene in both an Internal Mixer and a twin screw extruder. The influence of residence time on degree of grafting in an Internal Mixer and a twin screw extruder was studied through measuring reaction yields with respect to reaction time in the Internal Mixer as well as along the screw axis in the extruder. The dependence of the degree of grafting with monomer and peroxide concentration was determined. A free radical kinetic model of the process was developed and compared to experiment. Kinetic parameters were determined.
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Maleic anhydride modification of polyolefin in an Internal Mixer and a twin‐screw extruder: Experiment and kinetic model
Polymer Engineering and Science, 2001Co-Authors: James L. WhiteAbstract:There has been little effort. to quantitatively understand graft copolymerization in batch and continuous Mixers. Little information exists on the evolution of grafting reactions with respect to residence time in an Internal Mixer or along the screw axis in a twin-screw extruder. In this study, maleic anhydride was grafted onto polypropylene in both an Internal Mixer and a twin screw extruder. The influence of residence time on degree of grafting in an Internal Mixer and a twin screw extruder was studied through measuring reaction yields with respect to reaction time in the Internal Mixer as well as along the screw axis in the extruder. The dependence of the degree of grafting with monomer and peroxide concentration was determined. A free radical kinetic model of the process was developed and compared to experiment. Kinetic parameters were determined.
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Styrene grafting onto a polyolefin in an Internal Mixer and a twin-screw extruder: Experiment and kinetic model
Polymer Engineering and Science, 2001Co-Authors: James L. WhiteAbstract:There has been relatively little effort to quantitatively understand graft copolymerizaution in either batch Mixers or twin-screw extruders. Most efforts have concentrated on grafting maleic anhydride, which does not homopolymerize. In this paper we consider grafting with styrene, which may homopolymerize as well as graft. The influence of residence time on degree of grafting in an Internal Mixer and a twin-screw extruder were studied by measuring reaction yields with respect to reaction time in a Mixer and along the screw axis in a twin-screw extruder. The degree of grafting increased with initial monomer and peroxide concentration. Grafting reactions with three different peroxides were also investigated. The degree of styrene grafting in an Internal Mixer is slightly higher than that in a twin-screw extruder. The rate of reaction along the screw axis in terms of residence time seems higher than for the batch Mixer. The melt viscosity dropped dramatically with addition of peroxide. A kinetic scheme is proposed and the experimental results are critically compared with it.
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Simulation of Flow in an Intermeshing Internal Mixer and Comparison of Rotor Designs
Rubber Chemistry and Technology, 1996Co-Authors: James L. WhiteAbstract:Abstract This paper describes a simulation of flow in various intermeshing rotor Internal Mixer designs. The rotor designs studied were obtained from the patent literature and presentations of the major intermeshing rotor machinery Mixer manufactures. The results of the simulation are compared to those for rotors of commercial separated rotor Mixers. We seek to compare intermeshing and separated rotor Mixers by contrasting estimated rates of mixing per unit total mixing chamber volume. Intermeshing rotors are generally predicted to perform better. This indicates they will mix more material despite smaller available Internal Mixer volume.
M. A. Chinelatto - One of the best experts on this subject based on the ideXlab platform.
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evaluation of philips and ziegler natta high density polyethylene degradation during processing in an Internal Mixer using the chain scission and branching distribution function analysis
Polymer Degradation and Stability, 2006Co-Authors: L. A. Pinheiro, M. A. Chinelatto, Sebastião V. CanevaroloAbstract:Abstract The oxidative and thermo-mechanical degradation of HDPE was studied during processing in an Internal Mixer under two conditions: totally and partially filled chambers, which provides lower and higher concentrations of oxygen, respectively. Two types of HDPEs, Phillips and Ziegler–Natta, having different levels of terminal vinyl unsaturations were analyzed. Materials were processed at 160, 200, and 240 °C. Standard rheograms using a partially filled chamber showed that the torque is much more unstable in comparison to a totally filled chamber which provides an environment depleted of oxygen. Carbonyl and transvinylene group concentrations increased, whereas vinyl group concentration decreased with temperature and oxygen availability. Average number of chain scission and branching (ns) was calculated from MWD curves and its plotting versus functional groups' concentration showed that chain scission or branching takes place depending upon oxygen content and vinyl groups' consumption. Chain scission and branching distribution function (CSBDF) values showed that longer chains undergo chain scission easier than shorter ones due to their higher probability of entanglements. This yields macroradicals that react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the oxygen concentration, temperature, and vinyl end groups' content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than the Ziegler–Natta's type at the same processing condition.
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Evaluation of Philips and Ziegler-Natta high-density polyethylene degradation during processing in an Internal Mixer using the chain scission and branching distribution function analysis
Polymer Degradation and Stability, 2006Co-Authors: L. A. Pinheiro, M. A. Chinelatto, Sebastião V. CanevaroloAbstract:The oxidative and thermo-mechanical degradation of HDPE was studied during processing in an Internal Mixer under two conditions: totally and partially filled chambers, which provides lower and higher concentrations of oxygen, respectively. Two types of HDPEs, Phillips and Ziegler-Natta, having different levels of terminal vinyl unsaturations were analyzed. Materials were processed at 160, 200, and 240 °C. Standard rheograms using a partially filled chamber showed that the torque is much more unstable in comparison to a totally filled chamber which provides an environment depleted of oxygen. Carbonyl and transvinylene group concentrations increased, whereas vinyl group concentration decreased with temperature and oxygen availability. Average number of chain scission and branching (ns) was calculated from MWD curves and its plotting versus functional groups' concentration showed that chain scission or branching takes place depending upon oxygen content and vinyl groups' consumption. Chain scission and branching distribution function (CSBDF) values showed that longer chains undergo chain scission easier than shorter ones due to their higher probability of entanglements. This yields macroradicals that react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the oxygen concentration, temperature, and vinyl end groups' content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than the Ziegler-Natta's type at the same processing condition. © 2006 Elsevier Ltd. All rights reserved.