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Vimal Katiyar - One of the best experts on this subject based on the ideXlab platform.
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Reactive Extrusion of polylactic acid cellulose nanocrystal films for food packaging applications influence of filler type on thermomechanical rheological and barrier properties
Industrial & Engineering Chemistry Research, 2017Co-Authors: Prodyut Dhar, Amit Kumar, Surendra Singh Gaur, Narendren Soundararajan, Arvind Gupta, Siddharth Mohan Bhasney, Medha Milli, Vimal KatiyarAbstract:In this study, we successfully demonstrate single-step industrially scalable Reactive Extrusion of polylactic acid (PLA)/cellulose nanocrystal (CNC)-based cast films which leads to reduced necking, improved processability, melt strength, and rheological behavior. PLA chains grafted onto CNCs, formed cross-linked gel-like structures of high molecular weight (Mw ≈ 150–245 kDa), with varying grafting efficiency (14%–67%) or gel-fraction yield (16%–69%), depending on the type of compatibilizers used. The Reactively processed films show reduction in both oxygen properties (20%–65%) and water vapor barrier properties (27%–50%), along with improved thermomechanical properties. These films finds potential applications for the storage of oil- and dairy-based products, which show shelf lives of ∼5 months and ∼2 weeks, respectively, and are within the standard migration limits, as per the set legislations. Therefore, the present study provides a novel, easily processable Extrusion-based approach for manufacturing su...
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thermally recyclable polylactic acid cellulose nanocrystal films through Reactive Extrusion process
Polymer, 2016Co-Authors: Prodyut Dhar, Debashis Tarafder, Amit Kumar, Vimal KatiyarAbstract:Abstract This paper reports a single step Reactive Extrusion process for fabrication of thermally stable, polylactic acid grafted cellulose nanocrystal(PLA- g -CNC) nanocomposite films using dicumyl peroxide as crosslinking agent. PLA- g -CNC nanocomposites were recycled without significant breakage in the molecular structure of PLA. The grafted PLA chains shields the sulfate and hydroxyl groups of CNCs, thereby enhancing the compatibilization with PLA matrix and preventing thermal degradation during Extrusion. NMR and FTIR spectroscopy studies showed that amorphous PLA chains grafted on CNC surface through C–C bonds formation. Presence of such chemical crosslinks led to efficient transfer of modulus of CNCs to PLA matrix, thereby improving the tensile strength and young's modulus by∼40% and∼490%,respectively. Recycling of PLA- g -CNC doesn't alter the molecular weight, thermal, crystallization and mechanical properties of the nanocomposites significantly. Therefore, the current study provides a novel approach for fabricating CNC-reinforced-PLA nanocomposites which can be easily recycled and reused for multiple cycles.
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.
Prodyut Dhar - One of the best experts on this subject based on the ideXlab platform.
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Reactive Extrusion of polylactic acid cellulose nanocrystal films for food packaging applications influence of filler type on thermomechanical rheological and barrier properties
Industrial & Engineering Chemistry Research, 2017Co-Authors: Prodyut Dhar, Amit Kumar, Surendra Singh Gaur, Narendren Soundararajan, Arvind Gupta, Siddharth Mohan Bhasney, Medha Milli, Vimal KatiyarAbstract:In this study, we successfully demonstrate single-step industrially scalable Reactive Extrusion of polylactic acid (PLA)/cellulose nanocrystal (CNC)-based cast films which leads to reduced necking, improved processability, melt strength, and rheological behavior. PLA chains grafted onto CNCs, formed cross-linked gel-like structures of high molecular weight (Mw ≈ 150–245 kDa), with varying grafting efficiency (14%–67%) or gel-fraction yield (16%–69%), depending on the type of compatibilizers used. The Reactively processed films show reduction in both oxygen properties (20%–65%) and water vapor barrier properties (27%–50%), along with improved thermomechanical properties. These films finds potential applications for the storage of oil- and dairy-based products, which show shelf lives of ∼5 months and ∼2 weeks, respectively, and are within the standard migration limits, as per the set legislations. Therefore, the present study provides a novel, easily processable Extrusion-based approach for manufacturing su...
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thermally recyclable polylactic acid cellulose nanocrystal films through Reactive Extrusion process
Polymer, 2016Co-Authors: Prodyut Dhar, Debashis Tarafder, Amit Kumar, Vimal KatiyarAbstract:Abstract This paper reports a single step Reactive Extrusion process for fabrication of thermally stable, polylactic acid grafted cellulose nanocrystal(PLA- g -CNC) nanocomposite films using dicumyl peroxide as crosslinking agent. PLA- g -CNC nanocomposites were recycled without significant breakage in the molecular structure of PLA. The grafted PLA chains shields the sulfate and hydroxyl groups of CNCs, thereby enhancing the compatibilization with PLA matrix and preventing thermal degradation during Extrusion. NMR and FTIR spectroscopy studies showed that amorphous PLA chains grafted on CNC surface through C–C bonds formation. Presence of such chemical crosslinks led to efficient transfer of modulus of CNCs to PLA matrix, thereby improving the tensile strength and young's modulus by∼40% and∼490%,respectively. Recycling of PLA- g -CNC doesn't alter the molecular weight, thermal, crystallization and mechanical properties of the nanocomposites significantly. Therefore, the current study provides a novel approach for fabricating CNC-reinforced-PLA nanocomposites which can be easily recycled and reused for multiple cycles.
Philippe Dubois - One of the best experts on this subject based on the ideXlab platform.
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design of multistimuli responsive shape memory polymer materials by Reactive Extrusion
Chemistry of Materials, 2014Co-Authors: Florence Pilate, Jean-marie Raquez, Rosica Mincheva, Julien De Winter, Pascal Gerbaux, Richard Todd, Philippe DuboisAbstract:Shape-memory polymers (SMPs) are a class of stimuli-responsive materials that have attracted tremendous attention in various applications, especially in the medical field. While most SMPs are thermally actuated, relating to a change of thermal transition (e.g., melting temperature), SMPs that can be actuated upon exposure to light are emerging. Recently, there has been new interest into multiple stimuli-responsive SMPs in order to cover the range of applications for these smart materials. In this work, poly(ester-urethane)s (PURs) made of heating-responsive poly(e-caprolactone) (PCL) segments of various degrees of crystallinity and photoresponsive N,N-bis(2-hydroxyethyl) cinnamide (BHECA) monomer were successfully prepared using Reactive Extrusion technology to design dual-stimuli-responsive SMPs (DSRSMP). In order to tune the SMP properties (temperature or light), the crystallinity of the PCL segment was finely adjusted by the copolymerization of e-caprolactone with para-dioxanone in bulk at 160 °C using...
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tunable and durable toughening of polylactide materials via Reactive Extrusion
Macromolecular Materials and Engineering, 2014Co-Authors: Georgio Kfoury, Jean-marie Raquez, Fatima Hassouna, Valerie Toniazzo, David S Ruch, Philippe DuboisAbstract:To tune the toughness of PLA, a novel pathway to chemically modify PLA via Reactive Extrusion in the presence of “Reactive” PEG derivatives is proposed. PEG methyl ether methacrylate (MAPEG) and PEG methyl ether acrylate (AcrylPEG) are melt-mixed and extruded with PLA in the presence of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (L101) as a free-radical initiator. Molecular characterization reveals that about 20 and 65%, respectively, of the initially introduced MAPEG and AcrylPEG can be grafted onto the PLA backbone. The plasticization effect is demonstrated by a significant decrease of the glass transition temperature and storage modulus together with a significant increase of the elongation at break as compared to neat PLA.
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Design of Multistimuli-Responsive Shape-Memory Polymer Materials by Reactive Extrusion
2014Co-Authors: Florence Pilate, Jean-marie Raquez, Rosica Mincheva, Julien De Winter, Pascal Gerbaux, Richard Todd, Philippe DuboisAbstract:Shape-memory polymers (SMPs) are a class of stimuli-responsive materials that have attracted tremendous attention in various applications, especially in the medical field. While most SMPs are thermally actuated, relating to a change of thermal transition (e.g., melting temperature), SMPs that can be actuated upon exposure to light are emerging. Recently, there has been new interest into multiple stimuli-responsive SMPs in order to cover the range of applications for these smart materials. In this work, poly(ester-urethane)s (PURs) made of heating-responsive poly(ε-caprolactone) (PCL) segments of various degrees of crystallinity and photoresponsive N,N-bis(2-hydroxyethyl) cinnamide (BHECA) monomer were successfully prepared using Reactive Extrusion technology to design dual-stimuli-responsive SMPs (DSRSMP). In order to tune the SMP properties (temperature or light), the crystallinity of the PCL segment was finely adjusted by the copolymerization of ε-caprolactone with para-dioxanone in bulk at 160 °C using tin(II) octoate. The resulting polyester segments were then coupled with BHECA using n-octyl diisocyanate at 130 °C. The SMP properties of resulting PURs were correlated with DSC and DMTA measurements. Further addition of di- and tetracinnamate PCL segments into these SMPs was also studied in order to enhance the photoactuated SMP properties
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maleated thermoplastic starch by Reactive Extrusion
Carbohydrate Polymers, 2008Co-Authors: Jean-marie Raquez, Madhusudhan Srinivasan, Yogaraj Nabar, Boo Young Shin, Ramani Narayan, Philippe DuboisAbstract:Novel maleated thermoplastic starch (MTPS) with both improved processing and reactivity useful in the melt-blending with biodegradable polyester was prepared through in situ Reactive modification of thermoplastic starch (TPS) with maleic anhydride (MA) as esterification agent. Glycerol was used as plasticizer. Physico-chemical parameters of MTPS were determined at different MA contents, while keeping both the content in glycerol (20 wt% by starch), and the processing temperature constant (150 °C). Soxhlet extraction attested for the complete incorporation of glycerol into the starch backbone during the maleation process at low content in MA. In addition, two-dimensional liquid-phase NMR measurements attested for the preferential esterification of starch backbone at C6, together with the occurrence of some hydrolysis and glucosidation reactions. Such reactions promoted by MA moieties reduced the intrinsic viscosity of the MTPS, expecting an improvement in its processability. WAXS diffraction analyses confirmed the complete disruption of the granular structure of native starch in MTPS during the Reactive Extrusion processing.
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in situ compatibilization of maleated thermoplastic starch polyester melt blends by Reactive Extrusion
Polymer Engineering and Science, 2008Co-Authors: Yogaraj Nabar, Jean-marie Raquez, Ramani Narayan, Philippe DuboisAbstract:This article concerns the utilization of maleated thermoplastic starch (MTPS) in the Reactive Extrusion melt-blending with poly(butylene adipate-co-terephthalate) (PBAT) in blown film applications. First, MTPS was prepared from cornstarch with glycerol (plasticizer) and maleic anhydride (MA; esterification agent). MTPS was then melt-blended with PBAT in a subsequent downstream Extrusion operation. The effects of both polyester and MA contents were studied on the physicochemical parameters of melt-blends. For high polyester fractions (>60 wt%), PBAT-g-MTPS graft copolymers were obtained through transesterification reactions. They were promoted by the MA-derived acidic moieties grafted onto the starch backbone as shown by selective Soxhlet extraction experiments and FTIR analyses. At lower polyester content, no significant reaction occurred more likely due to an inversion in the phase morphology between both components. Tensile properties of PBAT-g-MTPS graft copolymer containing 70 wt% polyester were much higher as the TPS/PBAT melt-blend modified with MA. This can be explained by a finer morphology of the dispersed phase in the continuous PBAT matrix, and an increased interfacial area for the grafting reaction as attested by morphological studies. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.
Jean-marie Raquez - One of the best experts on this subject based on the ideXlab platform.
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design of multistimuli responsive shape memory polymer materials by Reactive Extrusion
Chemistry of Materials, 2014Co-Authors: Florence Pilate, Jean-marie Raquez, Rosica Mincheva, Julien De Winter, Pascal Gerbaux, Richard Todd, Philippe DuboisAbstract:Shape-memory polymers (SMPs) are a class of stimuli-responsive materials that have attracted tremendous attention in various applications, especially in the medical field. While most SMPs are thermally actuated, relating to a change of thermal transition (e.g., melting temperature), SMPs that can be actuated upon exposure to light are emerging. Recently, there has been new interest into multiple stimuli-responsive SMPs in order to cover the range of applications for these smart materials. In this work, poly(ester-urethane)s (PURs) made of heating-responsive poly(e-caprolactone) (PCL) segments of various degrees of crystallinity and photoresponsive N,N-bis(2-hydroxyethyl) cinnamide (BHECA) monomer were successfully prepared using Reactive Extrusion technology to design dual-stimuli-responsive SMPs (DSRSMP). In order to tune the SMP properties (temperature or light), the crystallinity of the PCL segment was finely adjusted by the copolymerization of e-caprolactone with para-dioxanone in bulk at 160 °C using...
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tunable and durable toughening of polylactide materials via Reactive Extrusion
Macromolecular Materials and Engineering, 2014Co-Authors: Georgio Kfoury, Jean-marie Raquez, Fatima Hassouna, Valerie Toniazzo, David S Ruch, Philippe DuboisAbstract:To tune the toughness of PLA, a novel pathway to chemically modify PLA via Reactive Extrusion in the presence of “Reactive” PEG derivatives is proposed. PEG methyl ether methacrylate (MAPEG) and PEG methyl ether acrylate (AcrylPEG) are melt-mixed and extruded with PLA in the presence of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (L101) as a free-radical initiator. Molecular characterization reveals that about 20 and 65%, respectively, of the initially introduced MAPEG and AcrylPEG can be grafted onto the PLA backbone. The plasticization effect is demonstrated by a significant decrease of the glass transition temperature and storage modulus together with a significant increase of the elongation at break as compared to neat PLA.
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Design of Multistimuli-Responsive Shape-Memory Polymer Materials by Reactive Extrusion
2014Co-Authors: Florence Pilate, Jean-marie Raquez, Rosica Mincheva, Julien De Winter, Pascal Gerbaux, Richard Todd, Philippe DuboisAbstract:Shape-memory polymers (SMPs) are a class of stimuli-responsive materials that have attracted tremendous attention in various applications, especially in the medical field. While most SMPs are thermally actuated, relating to a change of thermal transition (e.g., melting temperature), SMPs that can be actuated upon exposure to light are emerging. Recently, there has been new interest into multiple stimuli-responsive SMPs in order to cover the range of applications for these smart materials. In this work, poly(ester-urethane)s (PURs) made of heating-responsive poly(ε-caprolactone) (PCL) segments of various degrees of crystallinity and photoresponsive N,N-bis(2-hydroxyethyl) cinnamide (BHECA) monomer were successfully prepared using Reactive Extrusion technology to design dual-stimuli-responsive SMPs (DSRSMP). In order to tune the SMP properties (temperature or light), the crystallinity of the PCL segment was finely adjusted by the copolymerization of ε-caprolactone with para-dioxanone in bulk at 160 °C using tin(II) octoate. The resulting polyester segments were then coupled with BHECA using n-octyl diisocyanate at 130 °C. The SMP properties of resulting PURs were correlated with DSC and DMTA measurements. Further addition of di- and tetracinnamate PCL segments into these SMPs was also studied in order to enhance the photoactuated SMP properties
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maleated thermoplastic starch by Reactive Extrusion
Carbohydrate Polymers, 2008Co-Authors: Jean-marie Raquez, Madhusudhan Srinivasan, Yogaraj Nabar, Boo Young Shin, Ramani Narayan, Philippe DuboisAbstract:Novel maleated thermoplastic starch (MTPS) with both improved processing and reactivity useful in the melt-blending with biodegradable polyester was prepared through in situ Reactive modification of thermoplastic starch (TPS) with maleic anhydride (MA) as esterification agent. Glycerol was used as plasticizer. Physico-chemical parameters of MTPS were determined at different MA contents, while keeping both the content in glycerol (20 wt% by starch), and the processing temperature constant (150 °C). Soxhlet extraction attested for the complete incorporation of glycerol into the starch backbone during the maleation process at low content in MA. In addition, two-dimensional liquid-phase NMR measurements attested for the preferential esterification of starch backbone at C6, together with the occurrence of some hydrolysis and glucosidation reactions. Such reactions promoted by MA moieties reduced the intrinsic viscosity of the MTPS, expecting an improvement in its processability. WAXS diffraction analyses confirmed the complete disruption of the granular structure of native starch in MTPS during the Reactive Extrusion processing.
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in situ compatibilization of maleated thermoplastic starch polyester melt blends by Reactive Extrusion
Polymer Engineering and Science, 2008Co-Authors: Yogaraj Nabar, Jean-marie Raquez, Ramani Narayan, Philippe DuboisAbstract:This article concerns the utilization of maleated thermoplastic starch (MTPS) in the Reactive Extrusion melt-blending with poly(butylene adipate-co-terephthalate) (PBAT) in blown film applications. First, MTPS was prepared from cornstarch with glycerol (plasticizer) and maleic anhydride (MA; esterification agent). MTPS was then melt-blended with PBAT in a subsequent downstream Extrusion operation. The effects of both polyester and MA contents were studied on the physicochemical parameters of melt-blends. For high polyester fractions (>60 wt%), PBAT-g-MTPS graft copolymers were obtained through transesterification reactions. They were promoted by the MA-derived acidic moieties grafted onto the starch backbone as shown by selective Soxhlet extraction experiments and FTIR analyses. At lower polyester content, no significant reaction occurred more likely due to an inversion in the phase morphology between both components. Tensile properties of PBAT-g-MTPS graft copolymer containing 70 wt% polyester were much higher as the TPS/PBAT melt-blend modified with MA. This can be explained by a finer morphology of the dispersed phase in the continuous PBAT matrix, and an increased interfacial area for the grafting reaction as attested by morphological studies. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.
