The Experts below are selected from a list of 40035 Experts worldwide ranked by ideXlab platform
Kurt Pricer - One of the best experts on this subject based on the ideXlab platform.
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ethylene oxide s role as a Reactive Agent during sterilization effects of polymer composition and device architecture
Journal of Biomedical Materials Research Part B, 2013Co-Authors: Edward Phillip, Sanjeeva N Murthy, Durgadas Bolikal, Pallassana Narayanan, Joachim Kohn, Linda Lavelle, Stanko Bodnar, Kurt PricerAbstract:Sterilization conditions need to be optimized to effectively neutralize the bioburden while using short exposure times for minimizing the changes in chemical composition, material properties and device architecture. Towards this goal, effects of ethylene oxide (EtO) exposure parameters such as time, temperature, humidity, and EtO concentration on the polymer properties were investigated by monitoring the changes in composition, and the morphology of different types of structures in a family of poly(ethylene glycol) (PEG)-containing tyrosine-derived polycarbonates. EtO was found to esterify the carboxyl groups present in the desaminotyrosyl-tyrosine groups. Sterilization under conditions more severe than those normally used reduced the glass transition temperature (Tg) and the molecular weight of the polymers, and the presence of PEG in the polymer enhanced this effect. Furthermore, electron micrographs showed that EtO sterilization cycle conditions, even those considered “mild,” were found to damage the fragile structures such as those found in electrospun mats and porous scaffolds. Our study shows that the presence of EtO-susceptible groups, fusible architecture, and surface morphology should be taken into account in choosing the appropriate EtO sterilization conditions. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
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ethylene oxide s role as a Reactive Agent during sterilization effects of polymer composition and device architecture
Journal of Biomedical Materials Research Part B, 2013Co-Authors: Edward Phillip, Sanjeeva N Murthy, Durgadas Bolikal, Pallassana Narayanan, Joachim Kohn, Linda Lavelle, Stanko Bodnar, Kurt PricerAbstract:Sterilization conditions need to be optimized to effectively neutralize the bioburden while using short exposure times for minimizing the changes in chemical composition, material properties and device architecture. Towards this goal, effects of ethylene oxide (EtO) exposure parameters such as time, temperature, humidity, and EtO concentration on the polymer properties were investigated by monitoring the changes in composition, and the morphology of different types of structures in a family of poly(ethylene glycol) (PEG)-containing tyrosine-derived polycarbonates. EtO was found to esterify the carboxyl groups present in the desaminotyrosyl-tyrosine groups. Sterilization under conditions more severe than those normally used reduced the glass transition temperature (Tg) and the molecular weight of the polymers, and the presence of PEG in the polymer enhanced this effect. Furthermore, electron micrographs showed that EtO sterilization cycle conditions, even those considered "mild," were found to damage the fragile structures such as those found in electrospun mats and porous scaffolds. Our study shows that the presence of EtO-susceptible groups, fusible architecture, and surface morphology should be taken into account in choosing the appropriate EtO sterilization conditions.
Jonathan Cailloux - One of the best experts on this subject based on the ideXlab platform.
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sheets of branched poly lactic acid obtained by one step Reactive extrusion calendering process physical aging and fracture behavior
Journal of Materials Science, 2014Co-Authors: Jonathan Cailloux, O O Santana, Edgar Francourquiza, Jordi J Bou, F Carrasco, Ll M MaspochAbstract:The architectural modifications of a linear poly(D,L-Lactide) acid (PD,L-LA) commercial grade were induced by a one-step Reactive extrusion–calendering process using a styrene-glycidyl acrylate copolymer as Reactive Agent. The melt degradation was counteracted by chain extension and branching reactions, leading to a stabilization of the melt properties and an increase in the molecular weight. For such modified samples [poly(lactic acid) (PLA)-Reactive extrusion (REX)], the rate of physical aging at 30 °C was investigated during 1 week in order to simulate industrial storage conditions. Fracture behavior of “de-aged” and “controlled aged” (1 week) samples was investigated using the essential work of fracture (EWF) methodology and the critical tip opening displacement at the crack propagation onset, respectively. These analyses were complemented by digital image correlation analysis and inspection of the fractured surfaces by scanning electronic microscopy. As a result of the architectural modifications, the entanglement network density was increased. Those accounted for a slight decrease in the physical aging rate. Under uniaxial loading, aged Reactive extrusion (REX) samples exhibited multiple crazing, leading to a slight increase in strain at break. Nevertheless, as a result of a similar dynamic environment of the entangled polymer coils, de-aged REX samples disclosed similar mechanical properties as compared to their neat counterparts. Regarding de-aged samples, the EWF analysis revealed no changes in the work required for the onset of crack propagation. However, the energy consumed up to the onset of crack propagation of aged PLA-REX samples decreased due to an apparently decreased network extensibility, promoting a premature craze–crack transition.
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sheets of branched poly lactic acid obtained by one step Reactive extrusion calendering process melt rheology analysis
Express Polymer Letters, 2013Co-Authors: Jonathan Cailloux, O O Santana, Edgar Francourquiza, Jordi J Bou, F Carrasco, Jose Gamezperez, M L MaspochAbstract:One-step Reactive extrusion-calendering process (REX-Calendering) was used in order to obtain sheets of 1mm from two PD,L-LA extrusion grades modified with a styrene-acrylic multifunctional oligomeric Agent. In a preliminary internal mixer study, torque versus time was monitored in order to determine chain extender ratios and reaction time. Once all parameters were optimized, Reactive extrusion experiments were performed. Independently of the processing method employed, under the same processing conditions, PD,L-LA with the lower D enan- tiomer molar content revealed a higher reactivity towards the Reactive Agent, induced by its higher thermal sensitivity. REX- Calendering process seemed to minimize the degradations reactions during processing, although a competition between degradation and chain extension/branching reactions took place in both processes. Finally, the rheological characterization revealed a higher degree of modification in the melt rheological behaviour for REX-Calendered samples.
Hezron T Mwakabona - One of the best experts on this subject based on the ideXlab platform.
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metallic iron for safe drinking water provision considering a lost knowledge
Water Research, 2017Co-Authors: Hezron T Mwakabona, Arnaud Igor Ndetchoupe, Karoli N Njau, Chicgoua Noubactep, Kerstin D WydraAbstract:Around year 1890, the technology of using metallic iron (Fe0) for safe drinking water provision was already established in Europe. The science and technology to manufacture suitable Fe0 materials were known and further developed in this period. Scientists had then developed skills to (i) explore the suitability of individual Fe0 materials (e.g. iron filling, sponge iron) for selected applications, and (ii) establish treatment processes for households and water treatment plants. The recent (1990) discovery of Fe0 as Reactive Agent for environmental remediation and water treatment has not yet considered this ancient knowledge. In the present work, some key aspects of the ancient knowledge are presented together with some contemporised interpretations, in an attempt to demonstrate the scientific truth contained therein. It appears that the ancient knowledge is an independent validation of the scientific concept that in water treatment (Fe0/H2O system) Fe0 materials are generators of contaminant collectors.
Edward Phillip - One of the best experts on this subject based on the ideXlab platform.
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ethylene oxide s role as a Reactive Agent during sterilization effects of polymer composition and device architecture
Journal of Biomedical Materials Research Part B, 2013Co-Authors: Edward Phillip, Sanjeeva N Murthy, Durgadas Bolikal, Pallassana Narayanan, Joachim Kohn, Linda Lavelle, Stanko Bodnar, Kurt PricerAbstract:Sterilization conditions need to be optimized to effectively neutralize the bioburden while using short exposure times for minimizing the changes in chemical composition, material properties and device architecture. Towards this goal, effects of ethylene oxide (EtO) exposure parameters such as time, temperature, humidity, and EtO concentration on the polymer properties were investigated by monitoring the changes in composition, and the morphology of different types of structures in a family of poly(ethylene glycol) (PEG)-containing tyrosine-derived polycarbonates. EtO was found to esterify the carboxyl groups present in the desaminotyrosyl-tyrosine groups. Sterilization under conditions more severe than those normally used reduced the glass transition temperature (Tg) and the molecular weight of the polymers, and the presence of PEG in the polymer enhanced this effect. Furthermore, electron micrographs showed that EtO sterilization cycle conditions, even those considered “mild,” were found to damage the fragile structures such as those found in electrospun mats and porous scaffolds. Our study shows that the presence of EtO-susceptible groups, fusible architecture, and surface morphology should be taken into account in choosing the appropriate EtO sterilization conditions. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
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ethylene oxide s role as a Reactive Agent during sterilization effects of polymer composition and device architecture
Journal of Biomedical Materials Research Part B, 2013Co-Authors: Edward Phillip, Sanjeeva N Murthy, Durgadas Bolikal, Pallassana Narayanan, Joachim Kohn, Linda Lavelle, Stanko Bodnar, Kurt PricerAbstract:Sterilization conditions need to be optimized to effectively neutralize the bioburden while using short exposure times for minimizing the changes in chemical composition, material properties and device architecture. Towards this goal, effects of ethylene oxide (EtO) exposure parameters such as time, temperature, humidity, and EtO concentration on the polymer properties were investigated by monitoring the changes in composition, and the morphology of different types of structures in a family of poly(ethylene glycol) (PEG)-containing tyrosine-derived polycarbonates. EtO was found to esterify the carboxyl groups present in the desaminotyrosyl-tyrosine groups. Sterilization under conditions more severe than those normally used reduced the glass transition temperature (Tg) and the molecular weight of the polymers, and the presence of PEG in the polymer enhanced this effect. Furthermore, electron micrographs showed that EtO sterilization cycle conditions, even those considered "mild," were found to damage the fragile structures such as those found in electrospun mats and porous scaffolds. Our study shows that the presence of EtO-susceptible groups, fusible architecture, and surface morphology should be taken into account in choosing the appropriate EtO sterilization conditions.
Edgar Francourquiza - One of the best experts on this subject based on the ideXlab platform.
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sheets of branched poly lactic acid obtained by one step Reactive extrusion calendering process physical aging and fracture behavior
Journal of Materials Science, 2014Co-Authors: Jonathan Cailloux, O O Santana, Edgar Francourquiza, Jordi J Bou, F Carrasco, Ll M MaspochAbstract:The architectural modifications of a linear poly(D,L-Lactide) acid (PD,L-LA) commercial grade were induced by a one-step Reactive extrusion–calendering process using a styrene-glycidyl acrylate copolymer as Reactive Agent. The melt degradation was counteracted by chain extension and branching reactions, leading to a stabilization of the melt properties and an increase in the molecular weight. For such modified samples [poly(lactic acid) (PLA)-Reactive extrusion (REX)], the rate of physical aging at 30 °C was investigated during 1 week in order to simulate industrial storage conditions. Fracture behavior of “de-aged” and “controlled aged” (1 week) samples was investigated using the essential work of fracture (EWF) methodology and the critical tip opening displacement at the crack propagation onset, respectively. These analyses were complemented by digital image correlation analysis and inspection of the fractured surfaces by scanning electronic microscopy. As a result of the architectural modifications, the entanglement network density was increased. Those accounted for a slight decrease in the physical aging rate. Under uniaxial loading, aged Reactive extrusion (REX) samples exhibited multiple crazing, leading to a slight increase in strain at break. Nevertheless, as a result of a similar dynamic environment of the entangled polymer coils, de-aged REX samples disclosed similar mechanical properties as compared to their neat counterparts. Regarding de-aged samples, the EWF analysis revealed no changes in the work required for the onset of crack propagation. However, the energy consumed up to the onset of crack propagation of aged PLA-REX samples decreased due to an apparently decreased network extensibility, promoting a premature craze–crack transition.
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sheets of branched poly lactic acid obtained by one step Reactive extrusion calendering process melt rheology analysis
Express Polymer Letters, 2013Co-Authors: Jonathan Cailloux, O O Santana, Edgar Francourquiza, Jordi J Bou, F Carrasco, Jose Gamezperez, M L MaspochAbstract:One-step Reactive extrusion-calendering process (REX-Calendering) was used in order to obtain sheets of 1mm from two PD,L-LA extrusion grades modified with a styrene-acrylic multifunctional oligomeric Agent. In a preliminary internal mixer study, torque versus time was monitored in order to determine chain extender ratios and reaction time. Once all parameters were optimized, Reactive extrusion experiments were performed. Independently of the processing method employed, under the same processing conditions, PD,L-LA with the lower D enan- tiomer molar content revealed a higher reactivity towards the Reactive Agent, induced by its higher thermal sensitivity. REX- Calendering process seemed to minimize the degradations reactions during processing, although a competition between degradation and chain extension/branching reactions took place in both processes. Finally, the rheological characterization revealed a higher degree of modification in the melt rheological behaviour for REX-Calendered samples.
