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Sven Sangerlaub - One of the best experts on this subject based on the ideXlab platform.
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recycling of blends made of polypropylene and an iron based oxygen scavenger influence of multiple extrusions on the Polymer Stability and the oxygen absorption capacity
Polymer Degradation and Stability, 2015Co-Authors: Daniel Schlemmer, Markus Lehner, Sven SangerlaubAbstract:Abstract An often used oxygen scavenger is a blend of iron powder and additives dispersed in a Polymer carrier matrix. It is applied as an additive for separate layers of multilayer film structures which are produced by coextrusion. Not much is known about the influence of multiple extrusions, for example during recycling processes, of these materials on Polymer properties, film properties and process Stability. Therefore the aim of this study was to assess these issues. The focus was on polypropylene because it is a common blend partner for iron-based oxygen scavenger additives. Pure polypropylene and blends of polypropylene with approximately 20 wt.-% iron-based oxygen scavenger additive (SHELFPLUS ® O 2 2710) were extruded up to ten times at two temperature profiles (T1: 160–230 °C; T2: 210–300 °C). Polymer degradation was evaluated by different means of measurement: MFR, DSC, colorimetry, IR-spectroscopy and oxygen absorption. The results indicate that polypropylene and polypropylene with dispersed oxygen scavenger degrade by the impact of extrusion which can be seen by increased MFR and crystallinity and color changes. Furthermore the iron particles did undergo changes regarding color and oxygen scavenging capacity. The absorption capacity at 23 °C was reduced by one third from 39 to 48 mg oxygen per one gram scavenger additive after one extrusion to 26–35 mg oxygen per one gram scavenger additive after 9 and 10 extrusion cycles, respectively. Overall the iron based oxygen scavenger has a lower impact on degradation than the temperature and the number of extrusions.
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Recycling of blends made of polypropylene and an iron-based oxygen scavenger – Influence of multiple extrusions on the Polymer Stability and the oxygen absorption capacity
Polymer Degradation and Stability, 2015Co-Authors: Markus Lehner, Daniel Schlemmer, Sven SangerlaubAbstract:Abstract An often used oxygen scavenger is a blend of iron powder and additives dispersed in a Polymer carrier matrix. It is applied as an additive for separate layers of multilayer film structures which are produced by coextrusion. Not much is known about the influence of multiple extrusions, for example during recycling processes, of these materials on Polymer properties, film properties and process Stability. Therefore the aim of this study was to assess these issues. The focus was on polypropylene because it is a common blend partner for iron-based oxygen scavenger additives. Pure polypropylene and blends of polypropylene with approximately 20 wt.-% iron-based oxygen scavenger additive (SHELFPLUS ® O 2 2710) were extruded up to ten times at two temperature profiles (T1: 160–230 °C; T2: 210–300 °C). Polymer degradation was evaluated by different means of measurement: MFR, DSC, colorimetry, IR-spectroscopy and oxygen absorption. The results indicate that polypropylene and polypropylene with dispersed oxygen scavenger degrade by the impact of extrusion which can be seen by increased MFR and crystallinity and color changes. Furthermore the iron particles did undergo changes regarding color and oxygen scavenging capacity. The absorption capacity at 23 °C was reduced by one third from 39 to 48 mg oxygen per one gram scavenger additive after one extrusion to 26–35 mg oxygen per one gram scavenger additive after 9 and 10 extrusion cycles, respectively. Overall the iron based oxygen scavenger has a lower impact on degradation than the temperature and the number of extrusions.
Jan Sedláček - One of the best experts on this subject based on the ideXlab platform.
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New Fluorene-Based CoPolymers Containing Oxadiazole Pendant Groups: Synthesis, Characterization, and Polymer Stability
Journal of Polymer Science Part A: Polymer Chemistry, 2009Co-Authors: Dmitrij Bondarev, Jiří Vohlídal, Jiří Zedník, Klára Podhájecká, Jan SedláčekAbstract:A series of fluorene-based coPolymers containing hole blocking/electron transporting diphenyloxadiazole units were synthesized by means of Suzuki-Miyaura coupling of selected aromatic dibromo- and diboronato- derivatives catalyzed with a Pd(PPh3)4 catalyst. All of the coPolymers with various composition of main-chain units were characterized by SEC chromatography, NMR, UV–vis, fluorescence and IR spectroscopy, and DSC. The emission Stability of fluorene coPolymers was improved by the replacement of alkyl groups on the C-9 carbon of fluorene with aryl groups or by the incorporation of anthracene units into the coPolymer main chain. A comparison of luminescence properties of pristine and annealed thin layers of studied coPolymers was performed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4532–4546, 2009
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Poly(p-iodophenylacetylene): synthesis, characterization, Polymer Stability and photoelectrical properties
Polymer, 1997Co-Authors: Jiří Vohlídal, Jan Sedláček, Marta Pacovská, Olivier Lavastre, Pierre H. Dixneuf, Hynek Balcar, Jiří PflegerAbstract:Abstract New functional acetylene, 1-ethynyl-4-iodobenzene, ( p -iodophenylacetylene) was prepared, characterized (i.r., n.m.r., u.v. and mass spectra) and transformed into high-molecular-weight Polymers. Various WOCl 4 -based and MoCl 5 -based catalysts were used in the Polymerization, the former leading to the red soluble and the latter to dark red insoluble poly( p -iodophenylacetylene) (PIPA), respectively. Both types of PIPA are non-crystalline and they differ in the configurational structure which, however, could not be assigned with certainty. A too high molecular weight and/or cross-linking is suggested as a reason of insolubility of PIPA prepared on Mo-based catalysts. The soluble PIPA was found to degrade autoxidatively in tetrahydrofuran solution at room temperature obeying the kinetic laws of Polymer random degradation. The determined value of the rate constant of degradation, 2.6 × 10 −6 min −1 , is slightly higher than that found for unsubstituted poly(phenylacetylene) (PPA), under the same conditions. PIPA was found to possess a higher photo-conductivity than PPA at low and moderate electric fields. The Onsager model offers an adequate explanation for the measured dependence of the photogeneration efficiency of the applied electric field assuming the Gaussian distribution of the radii of charge-transfer states.
Jiří Vohlídal - One of the best experts on this subject based on the ideXlab platform.
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New Fluorene-Based CoPolymers Containing Oxadiazole Pendant Groups: Synthesis, Characterization, and Polymer Stability
Journal of Polymer Science Part A: Polymer Chemistry, 2009Co-Authors: Dmitrij Bondarev, Jiří Vohlídal, Jiří Zedník, Klára Podhájecká, Jan SedláčekAbstract:A series of fluorene-based coPolymers containing hole blocking/electron transporting diphenyloxadiazole units were synthesized by means of Suzuki-Miyaura coupling of selected aromatic dibromo- and diboronato- derivatives catalyzed with a Pd(PPh3)4 catalyst. All of the coPolymers with various composition of main-chain units were characterized by SEC chromatography, NMR, UV–vis, fluorescence and IR spectroscopy, and DSC. The emission Stability of fluorene coPolymers was improved by the replacement of alkyl groups on the C-9 carbon of fluorene with aryl groups or by the incorporation of anthracene units into the coPolymer main chain. A comparison of luminescence properties of pristine and annealed thin layers of studied coPolymers was performed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4532–4546, 2009
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Poly(p-iodophenylacetylene): synthesis, characterization, Polymer Stability and photoelectrical properties
Polymer, 1997Co-Authors: Jiří Vohlídal, Jan Sedláček, Marta Pacovská, Olivier Lavastre, Pierre H. Dixneuf, Hynek Balcar, Jiří PflegerAbstract:Abstract New functional acetylene, 1-ethynyl-4-iodobenzene, ( p -iodophenylacetylene) was prepared, characterized (i.r., n.m.r., u.v. and mass spectra) and transformed into high-molecular-weight Polymers. Various WOCl 4 -based and MoCl 5 -based catalysts were used in the Polymerization, the former leading to the red soluble and the latter to dark red insoluble poly( p -iodophenylacetylene) (PIPA), respectively. Both types of PIPA are non-crystalline and they differ in the configurational structure which, however, could not be assigned with certainty. A too high molecular weight and/or cross-linking is suggested as a reason of insolubility of PIPA prepared on Mo-based catalysts. The soluble PIPA was found to degrade autoxidatively in tetrahydrofuran solution at room temperature obeying the kinetic laws of Polymer random degradation. The determined value of the rate constant of degradation, 2.6 × 10 −6 min −1 , is slightly higher than that found for unsubstituted poly(phenylacetylene) (PPA), under the same conditions. PIPA was found to possess a higher photo-conductivity than PPA at low and moderate electric fields. The Onsager model offers an adequate explanation for the measured dependence of the photogeneration efficiency of the applied electric field assuming the Gaussian distribution of the radii of charge-transfer states.
Markus Lehner - One of the best experts on this subject based on the ideXlab platform.
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recycling of blends made of polypropylene and an iron based oxygen scavenger influence of multiple extrusions on the Polymer Stability and the oxygen absorption capacity
Polymer Degradation and Stability, 2015Co-Authors: Daniel Schlemmer, Markus Lehner, Sven SangerlaubAbstract:Abstract An often used oxygen scavenger is a blend of iron powder and additives dispersed in a Polymer carrier matrix. It is applied as an additive for separate layers of multilayer film structures which are produced by coextrusion. Not much is known about the influence of multiple extrusions, for example during recycling processes, of these materials on Polymer properties, film properties and process Stability. Therefore the aim of this study was to assess these issues. The focus was on polypropylene because it is a common blend partner for iron-based oxygen scavenger additives. Pure polypropylene and blends of polypropylene with approximately 20 wt.-% iron-based oxygen scavenger additive (SHELFPLUS ® O 2 2710) were extruded up to ten times at two temperature profiles (T1: 160–230 °C; T2: 210–300 °C). Polymer degradation was evaluated by different means of measurement: MFR, DSC, colorimetry, IR-spectroscopy and oxygen absorption. The results indicate that polypropylene and polypropylene with dispersed oxygen scavenger degrade by the impact of extrusion which can be seen by increased MFR and crystallinity and color changes. Furthermore the iron particles did undergo changes regarding color and oxygen scavenging capacity. The absorption capacity at 23 °C was reduced by one third from 39 to 48 mg oxygen per one gram scavenger additive after one extrusion to 26–35 mg oxygen per one gram scavenger additive after 9 and 10 extrusion cycles, respectively. Overall the iron based oxygen scavenger has a lower impact on degradation than the temperature and the number of extrusions.
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Recycling of blends made of polypropylene and an iron-based oxygen scavenger – Influence of multiple extrusions on the Polymer Stability and the oxygen absorption capacity
Polymer Degradation and Stability, 2015Co-Authors: Markus Lehner, Daniel Schlemmer, Sven SangerlaubAbstract:Abstract An often used oxygen scavenger is a blend of iron powder and additives dispersed in a Polymer carrier matrix. It is applied as an additive for separate layers of multilayer film structures which are produced by coextrusion. Not much is known about the influence of multiple extrusions, for example during recycling processes, of these materials on Polymer properties, film properties and process Stability. Therefore the aim of this study was to assess these issues. The focus was on polypropylene because it is a common blend partner for iron-based oxygen scavenger additives. Pure polypropylene and blends of polypropylene with approximately 20 wt.-% iron-based oxygen scavenger additive (SHELFPLUS ® O 2 2710) were extruded up to ten times at two temperature profiles (T1: 160–230 °C; T2: 210–300 °C). Polymer degradation was evaluated by different means of measurement: MFR, DSC, colorimetry, IR-spectroscopy and oxygen absorption. The results indicate that polypropylene and polypropylene with dispersed oxygen scavenger degrade by the impact of extrusion which can be seen by increased MFR and crystallinity and color changes. Furthermore the iron particles did undergo changes regarding color and oxygen scavenging capacity. The absorption capacity at 23 °C was reduced by one third from 39 to 48 mg oxygen per one gram scavenger additive after one extrusion to 26–35 mg oxygen per one gram scavenger additive after 9 and 10 extrusion cycles, respectively. Overall the iron based oxygen scavenger has a lower impact on degradation than the temperature and the number of extrusions.
J.c. Gubulin - One of the best experts on this subject based on the ideXlab platform.
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A factorial-design study of the variables affecting the electrochemical reduction of Cr(VI) at polyaniline-modified electrodes
Chemical Engineering Journal, 2005Co-Authors: Luís A.m. Ruotolo, J.c. GubulinAbstract:Abstract An electrochemical process using reticulated vitreous carbon-supported polyaniline cathodes is proposed to reduce toxic hexavalent chromium, which is present in industrial wastewater. The effect of five variables was simultaneously studied: (1) flow velocity; (2) current density; (3) electrode thickness; (4) electrode porosity and (5) Cr(VI) concentration. Due to the number of variables, a Box–Behnken factorial-design was chosen in order to reduce the number of experiments required. The current efficiency, energy consumption and space–time yield were the variables evaluated. The process was also analyzed in terms of the Polymer Stability and the overpotential distribution inside the porous electrode.
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Reduction of hexavalent chromium using polyaniline films. Effect of film thickness, potential and flow velocity on the reaction rate and Polymer Stability
Journal of Applied Electrochemistry, 2003Co-Authors: L.a.m. Ruotolo, J.c. GubulinAbstract:Reduction of very toxic hexavalent chromium (Cr(VI)) to its trivalent state (Cr(III)) is necessary to facilitate the treatment of wastewater by precipitation or adsorption. The present study proposes the use of thin films of polyaniline on a conducting substrate for this purpose. The reduction rate of hexavalent chromium and the degree of degradation of the polyaniline film were studied as a function of the solution flow velocity, applied potential and film thickness. The reduction rate was significantly affected by the flow velocity, while the film thickness was observed to have little effect. The potential had no effect on the reduction rate within the range studied. The current efficiency was 100% in all experiments and no significant degradation of polyaniline was observed.