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Control strategies for reactive extrusion of polypropylene by peroxide degradation - A brief review and an experimental study / S. Wolf in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 472-498 Titre : Control strategies for reactive extrusion of polypropylene by peroxide degradation - A brief review and an experimental study Type de document : texte imprimé Auteurs : S. Wolf, Auteur ; Jürgen Miethlinger, Auteur Année de publication : 2021 Article en page(s) : p. 472-498 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Capteurs (technologie) Contrôle technique Essais (technologie) Extrudeuse bi-vis Extrusion réactive Formulation (Génie chimique) Peroxydes Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : Industry 4.0 and digitalization are widely argued for the future success of numerous industrial solutions. Big data management might lead to the assumption that every issue can be solved numerically without any physical background. To some extent, this strategy will help within the plastics industry in general and in the extrusion technology in particular. However, a deep process knowledge together with process-relevant sensors, as well as the right process arrangements within the processing chain combined with smart data mining methods will be still the key success of industry 4.0. This presentation illustrates, based on a brief review on existing control strategies (Part 1), including sensory and predictive control models for reactive extrusion applied at a real-life on-site best practice project (Part 2), possibilities in combination of process tasks with digitalization approaches for PP-Polymer production. Specifically, rheological research conducted with a novel, patented multi-point rheometer (part 3), will provide a deeper insight into dynamic processes such as reactive extrusion. With those results and derivations thereof, improvements in predictive process control in addition to artificial control systems are made and might even lead to further interesting opportunities. Note de contenu : - BRIEF REVIEW ON CONTROL STRATEGIES FOR REACTIVE EXTRUSION (Part 1) : Control strategies : extrusion control - Soft sensors - Reactive extrusion in general - Reactive extrusion process control of peroxide modified pp - PRACTICAL IMPLEMENTATION OF REACTIVE EXTRUSION CONTROL (PART 2) : Background and problem definition - Theses/proposal for solution - Proof of concept on twin-screw extruder - Smart process engineering and control - Results/validation of the implementation on world-scale production site/adjustable melt quality based on in-line-viscosity measurements - VALIDATION/PROOF OF HYSTERESIS BEHAVIOR WITH SMART SENSORS (PART 3) : Setup and principal test procedure for lab-scale trials - Extensional rheometer/smart process quality device - Results/effect of peroxide during ramp-up and ramp-down (220 °c) - Results/effect of peroxide during ramp-up and ramp-down (temperature variation) - Discussion - Table 1 : Literature review based on Garge et al. (2010) of “modelling of reactive extrusion" and “process control of reactive extrusion - Table 2 : Characteristics of polymer grades (unstabilized powder samples from reactor) for peroxide trials and relevant Russian standards (RussianGOST, 2019) - Table 3 : Standard process parameters for the trials - Table 4 : Formulations for evaluating the ramp-up and ramp-down behavior of PP polymer melts; given quantities are weight percent (wt%) of polymer, masterbatch or premix, whereas the active concentration of peroxide is 10% DOI : https://doi.org/10.1515/ipp-2020-4088 En ligne : https://drive.google.com/file/d/1wDJx2TwgcvJxRJJfcOLY5DGzuum0nuva/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36516 [article]

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Morphology and tensile properties as a function of welding current in thermoplastic induction welds / W. P. Ma in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 499-507 Titre : Morphology and tensile properties as a function of welding current in thermoplastic induction welds Type de document : texte imprimé Auteurs : W. P. Ma, Auteur ; H. C. Bu, Auteur ; F. Y. Wang, Auteur ; H. Y. Yang, Auteur ; Y. Xu, Auteur ; X. H. Zhan, Auteur Année de publication : 2021 Article en page(s) : p. 499-507 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Morphologie (matériaux) Polyéther éther cétone Polymères -- Propriétés mécaniques Polymères -- Propriétés thermiques Soudage par induction Traction (mécanique) Index. décimale : 668.4 Plastiques, vinyles Résumé : Compared to other conventional joining methods, induction welding offers the superiority of avoiding mechanical degradation and satisfying the need for weight reduction in the aircraft industry. In this paper, a metal mesh was adapted as an induction component in the induction welding of polyetheretherketone (PEEK) with various currents. The effect of welding current on the microstructure and mechanical properties of the induction welding joint was further investigated. The results indicate that induction welding joints with the narrow thickness of the fusion zone and high tensile strength can be attained in the welding current range of 7.05 A to 11.05 A. However, when the current exceeds 13.91 A, the excessive heat input leads to the unsteady flow of PEEK or even thermal oxidative degradation and thermal decomposition, which increases the thickness of the fusion zone and reduces the tensile strength of the joint. In addition, the principal fracture mode presents cohesive failure, thereby promoting the tensile strength of the joint. Note de contenu : - EXPERIMENTAL METHODS : Materials and apparatuses - Design of experiment - Specimen preparation - RESULTS AND DISCUSSION : Weld morphology - Tensile properties - Table 1 : Thermal performance of PEEK - Table 2 : Test parameters of PEEK induction welding - Table 3 : The tensile force of Nos. 1 to 4 (N) DOI : https://doi.org/10.1515/ipp-2020-4016 En ligne : https://drive.google.com/file/d/1Dc5KCAgR5yqQaaXWUJ7kQ_tJ1lbfgVI6/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36517 [article]

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Numerical simulation of fluid flow and mixing dynamics inside planetary roller extruders / J. Winck in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 508-518 Titre : Numerical simulation of fluid flow and mixing dynamics inside planetary roller extruders Type de document : texte imprimé Auteurs : J. Winck, Auteur ; S. Frerich, Auteur Année de publication : 2021 Article en page(s) : p. 508-518 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Eléments finis, Méthode des Extrudeuse à rouleau planétaire Fluides, Mécanique des Mélange Rhéologie Simulation par ordinateur Technique de superposition de maillage Index. décimale : 668.4 Plastiques, vinyles Résumé : In this contribution, the fluid flow and mixing dynamics inside planetary roller extruders are simulated using the finite element method (FEM) and the mesh superposition technique (MST). Three-dimensional configurations with planetary spindles of varying number and geometry of planetary spindles were created to analyse the influence of the spindle configuration and the rotational speed on the process behavior. Therefore, pressure gradients, flow velocities and directions, shear rates, the mixing index and residence time distributions were evaluated. The distributive and dispersive mixing efficiencies varied depending on the planetary spindle configuration, and these configurations thus suit different processing tasks. In comparison to the standard planetary spindles, the TT3 spindles, with their incomplete toothing, and the knob spindles, with their double transversal helical toothing, showed intense axial and radial mixing. In general, the mixing performance of the planetary roller extruder is explained by a high rate of extensional flow and frequent changes in flow type. The reported numerical approach allows, for the first time, a comprehensive observation of the process behavior of planetary roller extruders. Note de contenu : - Simulation methods - Material data - Geometry and spindle rotations - Meshing - Evaluation of mixing dynamics - Table 1 : Cross model parameters of a PLA melt at 180°C (Othman et al., 2014) - Table 2 : Positioning of planetary spindles inside the barrel cylinder for configurations of three, four, five and six planetary spindles - Table 3 : Rotational speed ratios implemented in the simulation - Table 4 : Mesh characteristics of the extruder components - Table 5 : Meshes for the mesh independency study - Table 6 : Investigated discretizations of extruder motions based on the number of time steps for a rotational speed of 20 min– - Table 7 : Selected discretization of extruder motions - Table 8 : Influence of different planetary roller extruder configurations on processing parameters DOI : https://doi.org/10.1515/ipp-2020-4084 En ligne : https://drive.google.com/file/d/1l2rfPrd9cVZ_bgdtKhjhBxhLBGs5zuV2/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36518 [article]

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Synergistic flame-retardant effect of aluminum diethyl phosphinate in PP/IFR system and the flame-retardant mechanism / J.-L. Li in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 519-528 Titre : Synergistic flame-retardant effect of aluminum diethyl phosphinate in PP/IFR system and the flame-retardant mechanism Type de document : texte imprimé Auteurs : J.-L. Li, Auteur ; C.-T. Gao, Auteur ; X. Sun, Auteur ; S.-G. Peng, Auteur ; Y.-W. Wang, Auteur ; S.-H. Qin, Auteur Année de publication : 2021 Article en page(s) : p. 519-528 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caractérisation Carbonisation Chimie analytique Combustion Diéthylphosphinate d'aluminium Formulation (Génie chimique) Intumescence (chimie) Polymères ignifuges Polypropylène Pyrolyse La pyrolyse est la décomposition ou thermolyse d'un composé organique par la chaleur pour obtenir d'autres produits (gaz et matière) qu'il ne contenait pas. L'opération est réalisée en l'absence d'oxygène ou en atmosphère pauvre en oxygène pour éviter l'oxydation et la combustion (L’opération ne produit donc pas de flamme). Il s'agit du premier stade de transformation thermique après la déshydratation. Elle permet généralement d'obtenir un solide carboné, une huile et un gaz. Elle débute à un niveau de température relativement bas (à partir de 200 °C) et se poursuit jusqu'à 1 000 °C environ. Selon la température, la proportion des trois composés résultants est différente. Index. décimale : 668.4 Plastiques, vinyles Résumé : Synergistic flame-retardant effect of aluminum diethyl phosphinate (AlPi) in intumescent flame retardant polypropylene (PP/IFR) system and the flame-retardant mechanism were investigated. The flame retardancy of PP/IFR/AlPi (the mass ratio of IFR to AlPi is 2 : 1) was the best, which was proved by the results of the limiting oxygen index (LOI) test, UL-94 test, and cone calorimeter test ( CCT) test. Here, the LOI value of the sample was as high as 34% and passed the V–0 rating in UL–94 test. The peak heat release rate (PHRR) decreased by 92.57%, the total heat release (THR) reduced by 90.52%. Thermogravimetric (TGA) data showed that the introduction of AlPi improved thermal stability and changed the thermal degradation behavior of PP/IFR composites. Interestingly, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS) and laser Raman spectroscopy (LRS) proved that PP/IFR/AlPi had formed more residual carbon, but the flame retardancy was worse than PP/IFR/AlPi. This is because when the mass ratio of IFR to AlPi is 2 : 1, the synergy between IFR and AlPi was significant, gas-phase flame retardant and condensed-phase flame retardant reached a balance and obtained the best flame retardant effect. Note de contenu : - EXPERIMENTAL : Materials - Preparation of PP/IFR/AlPi composites - Characterization - RESULTS AND DISCUSSION : Flame retardancy of PP/IFR/AlPi composites - Combustion behavior of PP/IFR/AlPi composites - Thermal degradation behavior of PP/IFR/AlPi composites - Residual carbon morphology of PP/IFR/AlPi composites - Chemical composition of residual carbon in PP/IFR/AlPi composites - POSSIBLE FLAME-RETARDANT MECHANISM DISCUSSION - Table 1 : Formulations of PP/IFR/AlPi composites - Table 2 : Results of the LOI and UL-94 tests for PP, PP/IFR/AlPi, PP/IFR, PP/AlPi composites - Table 3 : CCT results of PP, PP/IFR/AlPi, PP/IFR, PP/AlPi composites - Table 4 : TGA and DTG data for PP, PP/IFR/AlPi, PP/IFR, PP/AlPi composites - Table 5 : Chemical composition of the residue chars for PP, PP/IFR/AlPi, PP/IFR and PP/AlPi composites DOI : https://doi.org/10.1515/ipp-2020-4082 En ligne : https://drive.google.com/file/d/1OfUxCdiYtuNX7vTx3Q9KvyYy0W2T1KXk/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36519 [article]

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Predicting the non-linear conveying behavior in single-screw extrusion : a comparison of various data-based modeling approaches used with cfd simulations / W. Roland in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 529-544 Titre : Predicting the non-linear conveying behavior in single-screw extrusion : a comparison of various data-based modeling approaches used with cfd simulations Type de document : texte imprimé Auteurs : W. Roland, Auteur ; C. Marschik, Auteur ; M. Kommenda, Auteur ; A. Haghofer, Auteur ; S. Dorl, Auteur ; S. Winkler, Auteur Année de publication : 2021 Article en page(s) : p. 529-544 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Extrudeuse monovis Matières plastiques -- Extrusion:Polymères -- Extrusion Prévision, Théorie de la Rhéologie Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : The traditional approach to modeling the polymer melt flow in single-screw extruders is based on analytical and numerical analyses. Due to increasing computational power, data-driven modeling has grown significantly in popularity in recent years. In this study, we compared and evaluated databased modeling approaches (i. e., gradient-boosted trees, artificial neural networks, and symbolic regression models based on genetic programming) in terms of their ability to predict – within a hybrid modeling framework – the three-dimensional non-linear throughput-pressure relationship of metering channels in single-screw extruders. By applying the theory of similarity to the governing flow equations, we identified the characteristic dimensionless influencing parameters, which we then varied to create a large dataset covering a wide range of possible applications. For each single design point we conducted numerical simulations and obtained the dimensionless flow rate. The large dataset was divided into three independent sets for training, interpolation, and extrapolation, the first being used to generate and the remaining two to evaluate the models. Further, we added two features derived from expert knowledge to the models and analyzed their influence on predictive power. In addition to prediction accuracy and interpolation and extrapolation capabilities, we evaluated model complexity, interpretability, and time required to learn the models. This study provides a rigorous analysis of various data-based modeling approaches applied to simulation data in extrusion. Note de contenu : - MELT-CONVEYING SIMULATIONS : Governing equations - Dimensionless representation - Traditional melt-conveying model - Parametric design study - Numerical simulations DATA-BASED MODELING : Data preparation – Modeling - Modeling results - Table 1 : Range of values for n, t/Db, and h/w of the new (merged) dataset - Table 2 : Range of Pp,z depending on the power-law exponent of the merged dataset. The numbers of equidistant steps are 61 and 31, respectively, for the "original" and the “additional" data spaces - Table 3 : Number of samples per dataset after data splitting - Table 4 : Value ranges of each feature for the three different datasets - Table 5 : Model performance for the regression task of predicting ΠV from the influencing parameters - Table 6 : Model performance for the regression task of predicting ΠV. Comparing the influence of the additional features F1 and F2 on the prediction error - Table 7 : Performance of the traditional Newtonian melt-conveying models for predicting ΠV - Table 8 : Model constants for the best performing symbolic regression model DOI : https://doi.org/10.1515/ipp-2020-4094 En ligne : https://drive.google.com/file/d/12pNqnSQWNmTVTc1gCK_cszVmf9dWA1eR/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36520 [article]

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Influence of crystal structure on thermo-mechanical properties of injection molded B-nucleated iPP / A. Hamza in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 545-556 Titre : Influence of crystal structure on thermo-mechanical properties of injection molded B-nucleated iPP Type de document : texte imprimé Auteurs : A. Hamza, Auteur ; R. K. Arya, Auteur ; A. D. Palsodkar, Auteur ; G. R. Bhadu, Auteur ; S. J. A. Rizvi, Auteur Année de publication : 2021 Article en page(s) : p. 545-556 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Agent de nucléation Caractérisation Matériaux -- Propriétés thermomécaniques Matières plastiques Matières plastiques -- Moulage par injection Mélange Polymères -- Propriétés thermomécaniques Polymères isotactiques Polypropylène greffé anhydride maléique Structure cristalline (solide) Thermodurcissables -- Propriétés thermomécaniques Index. décimale : 668.4 Plastiques, vinyles Résumé : Isotactic polypropylene (iPP) was nucleated in-situ with calcium pimelate during melt compounding. Calcium pimelate is a highly effective β-nucleator for isotactic polypropylene (iPP). The β-nucleated iPP was characterized by wide angle x-ray diffraction (WAXD) and differential scanning calorimetry (DSC) for its crystallinity and crystal structure. In addition, the injection-molded samples were tested for thermo-mechanical properties. It is found that very low quantity (< 0.1 wt. %) of β-nucleator is required to produce sufficiently high β-crystal fraction (Kβ) in isotactic polypropylene. β-nucleated iPP shows increment of 11 to 14 °C in its heat deflection temperature (HDT). It was also observed that slow cooling rate of β-nucleated iPP promotes the formation of β-crystals and that tensile stretching leads to complete transformation of β crystals into a-crystals at room temperature. It was also revealed that the presence of maleic anhydride grafted polypropylene (PP-g-MA), a well-known coupling agent (or compatibilizer), may reduce the (Kβ) value to a marginal extent. It was also observed that the thermo-mechanical properties were not much affected by the presence of PP-g-MA. Therefore, calcium pimelate may be used as β-nucleator in case of neat as well as reinforced polypropylene containing maleic anhydride as coupling agent. Note de contenu : - EXPERIMENTAL : Materials - Melt compounding - Injection molding - Testing of molded specimens - RESULTS AND DISCUSSION : Effect of concentration of β-nucleator on thermo-mechanical properties of iPP - Effect of coupling agent (PP-g-ma) on the efficiency of β-nucleator - Stretching induced (β-α) transformation in β-iPP - Table 1 : Injection molding parameters - Table 2 : Crystallinity of neat and 𝛽-iPP at different concentrations of 𝛃-nucleator (calculated from WAXD data) - Table 3 : Crystallinity of neat- and 𝛃-iPP at different concentrations of 𝛃-nucleator (calculated from DSC first heating data) - Table 4 : Results of DSC second heating scan for neat and 𝛃-nucleated iPP - Table 5 : Crystallinity values of 𝛃-iPP with different concentration (wt.%) of PP-g-MA - Table 6 : DSC-second melting and crystallization parameters for 𝛃-nucleated iPP containing coupling agent (PP-g-MA) - Table 7 : Effect of stretching on crystallinity and crystal structure DOI : https://doi.org/10.1515/ipp-2020-4106 En ligne : https://drive.google.com/file/d/1fBkbI5UTQhKXftRExRvGTPuJb7sNbvIl/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36521 [article]

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An experimental study on the properties of recycled high-density polyethylene / A. G. Toroslu in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 557-563 Titre : An experimental study on the properties of recycled high-density polyethylene Type de document : texte imprimé Auteurs : A. G. Toroslu, Auteur Année de publication : 2021 Article en page(s) : p. 557-563 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alumine Conduction électrique Essais dynamiques Matières plastiques -- Propriétés mécaniques Matières plastiques -- Recyclage Microscopie électronique à balayage Polyéthylène haute densité Thermocinétique Viscosité Index. décimale : 668.4 Plastiques, vinyles Résumé : Recycling of plastic materials has become more environmentally important than recycling of other materials. The most important problem during recycling is the presence of oil, dirt, dust and metal particles that are mixed with plastic materials. These mixtures can change their its mechanical and physical properties and it is quite costly to remove them completely. Removing iron alloy particles from plastic is possible by using the magnetic method. However, removing non-metallic materials requires extra processing. In this study, the use of recycled High-Density Polyethylene (rHDPE) without an expensive cleaning processes has been investigated. Different amounts of aluminium oxide (Al2O3) were added to High Density Polyethylene (HDPE) to simulate the effect of non-metallic material involved. The effect of these contamination rates on the mechanical and physical properties of HDPE was examined in detail. For this purpose, recyclable materials were produced by mixing rHDPE with 1%, to 7% Al2O3. The results show that up to 7% of the mixture has acceptable effects on the properties of HDPE. When the results of the experiments are examined, it is observed that there is a 3.74% change in the elastic modulus of the material. This means, that up to 7% non-metal contaminated rHDPE material can be used without any costly recycling process. Note de contenu : - Preparation of samples - Injection parameters - Scanning electron microscopy (sem) - Tensile testing - Melt flow index (mfi) - Material hardness - Electrical conductivity - Thermal conductivity DOI : https://doi.org/10.1515/ipp-2020-4071 En ligne : https://drive.google.com/file/d/13X_MTOZianLe1z702Im_j6QqOCvhv5xX/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36522 [article]

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Improvement of mechanical and biological properties of PLA/HNT scaffolds fabricated by foam injection molding : skin layer effect and laser texturing / Meltem Eryildiz in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 564-576 Titre : Improvement of mechanical and biological properties of PLA/HNT scaffolds fabricated by foam injection molding : skin layer effect and laser texturing Type de document : texte imprimé Auteurs : Meltem Eryildiz, Auteur ; M Altan, Auteur ; S. Odabas, Auteur Année de publication : 2021 Article en page(s) : p. 564-576 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Biodégradation Caractérisation Halloysite L'halloysite-7Ã… est une espèce minérale du groupe des silicates sous-groupe des phyllosilicates de formule Al2Si2O5(OH)4 avec des traces de : Ti ; Ca ; Na ; K ; Fe ; Cr ; Mg ; Ni ; Cu. Ses principaux constituants, outre l'oxygène, sont l’aluminium (20,90 %), le silicium (21,76 %), et l’hydrogène (1,56 %). Ingénierie tissulaire Mouillabilité Mousses plastiques Mousses plastiques -- Moulage par injection Mousses plastiques -- Propriétés mécaniques Mousses plastiques -- Propriétés thermiques Nanotubes Polylactique, Acide L'acide polylactique (anglais : polylactic acid, abrégé en PLA) est un polymère entièrement biodégradable utilisé dans l'alimentation pour l'emballage des Å“ufs et plus récemment pour remplacer les sacs et cabas en plastiques jusqu'ici distribués dans les commerces. Il est utilisé également en chirurgie où les sutures sont réalisées avec des polymères biodégradables qui sont décomposés par réaction avec l’eau ou sous l’action d’enzymes. Il est également utilisé pour les nouveaux essais de stent biodégradable. Le PLA peut-être obtenu à partir d'amidon de maïs, ce qui en fait la première alternative naturelle au polyéthylène (le terme de bioplastique est utilisé). En effet, l'acide polylactique est un produit résultant de la fermentation des sucres ou de l'amidon sous l'effet de bactéries synthétisant l'acide lactique. Dans un second temps, l'acide lactique est polymérisé par un nouveau procédé de fermentation, pour devenir de l'acide polylactique. Ce procédé conduit à des polymères avec des masses molaires relativement basses. Afin de produire un acide polylactique avec des masses molaires plus élevées, l'acide polylactique produit par condensation de l'acide lactique est dépolymérisé, produisant du lactide, qui est à son tour polymérisé par ouverture de cycle. Le PLA est donc l’un de ces polymères, dans lequel les longues molécules filiformes sont construites par la réaction d’un groupement acide et d’une molécule d’acide lactique sur le groupement hydroxyle d’une autre pour donner une jonction ester. Dans le corps, la réaction se fait en sens inverse et l’acide lactique ainsi libéré est incorporé dans le processus métabolique normal. On obtient un polymère plus résistant en utilisant l'acide glycolique, soit seul, soit combiné à l’acide lactique. Polymères en médecine Texturation par laser Index. décimale : 668.4 Plastiques, vinyles Résumé : Polylactic acid (PLA) is one of the important materials for orthopedic regenerative engineering applications due to its biodegradability and biocompatibility. Nonetheless, PLA may show insufficient mechanical strength for some bone replacement applications. Halloysite nanotube (HNT) is one of the non-toxic, biocompatible reinforcement for improving mechanical and biological properties of PLA for tissue engineering applications. In this study, PLA/HNT scaffolds were prepared by chemical foam injection molding process. Laser surface texturing was applied on the skin layer of the injection molded scaffolds to enhance the cell viability and hydrophilicity of PLA. The effects of HNT concentration on cell morphology, mechanical and thermal properties, cell viability and biodegradation profile of the scaffolds were studied. The results demonstrated that cell viability increased by 43% in PLA/HNT scaffolds compared to neat PLA. Hydrophilicity of the scaffolds that have thick skin layer was enhanced by the laser surface texturing in two different designs and consequently, cell viability increased about 16%. Surface roughness measurements and water contact angle measurements have verified this result. Note de contenu : - EXPERIMENTAL : Materials - Scaffold fabrication - Texture preparation – Characterization - RESULTS AND DISCUSSION : Thermal properties - Foam morphology - Texture properties of the scaffolds - Surface wettability - Mechanical properties - Cell proliferation studies - Biodegradability - Table 1 : The processing setups for foam injection molding - Table 2 : Thermal properties determined from DSC - Table 3 : Decomposition temperatures of PLA and PLA/HNT nanocomposites - Table 4 : Foamed sample results - Table 5 : Mechanical properties of PLA based composite scaffolds - Table 6 : Mechanical properties of human tissues (Mi et al., 2013) - Table 7 : Biodegradation rate (%) of the scaffolds DOI : https://doi.org/10.1515/ipp-2020-4090 En ligne : https://drive.google.com/file/d/1unWMpP-w6mD9YE-WVKwpTGG2gY0TxM2Q/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36523 [article]

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Relationship between molecular orientation relaxation during physical aging and heat resistance of polystyrene injection moldings / K. Tao in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 577-585 Titre : Relationship between molecular orientation relaxation during physical aging and heat resistance of polystyrene injection moldings Type de document : texte imprimé Auteurs : K. Tao, Auteur ; K. Yamada, Auteur ; S. Higashi, Auteur ; K. Kago, Auteur ; H. Takeshita, Auteur ; K. Tokumitsu, Auteur Année de publication : 2021 Article en page(s) : p. 577-585 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Basses températures Hautes températures Matières plastiques -- Moulage par micro-injection Orientation moléculaire (matériaux) Polystyrène Résistance thermique Viscoélasticité Index. décimale : 668.4 Plastiques, vinyles Résumé : This work examined the relationship between changes in molecular orientation and the heat resistance (heat distortion temperature) of polystyrene injection moldings following heat treatment below the glass transition temperature. Molecular orientation around the core layer of the injection moldings was found to be relaxed by the heat treatment. Also, in the untreated specimen, the molecular orientation around the core layer was relaxed from 60°C during the heating process. Since loss tangent (tanδ) also increased from 60°C during the heating process in the untreated specimen, it was considered that the increase in tanδ occurred with the molecular motion due to the relaxation of molecular orientation from 60°C. After the heat treatment, because of the relaxation of molecular orientation around the core layer by the heat treatment, the relaxation of molecular orientation from 60 °C did not occur during the subsequent heating process, and the tanδ of the polymer between 60 and 90 °C was decreased. Because this decrease in the tanδ over this temperature range improved the heat resistance of the material, the enhanced heat resistance by the heat treatment was attributed to the suppression of the relaxation of molecular orientation from 60°C during the heating process. Furthermore, relaxation of molecular orientation and enthalpy relaxation were related to improvement in the heat resistance. Note de contenu : - EXPERIMENTAL PROCEDURE : Material - Injection molding - Low temperature heat treatment - High temperature heat treatment - Observation of optical distortion - Evaluation of molecular orientation by laser Raman spectroscopy - Raman mapping of cross sections - Measurement of dynamic viscoelasticity - Determination of heat distortion temperature - Comparison of enthalpy relaxation behaviors - RESULTS AND DISCUSSION : Effect of heat treatment on molecular orientation - Effect of heat treatment on dynamic viscoelasticity - Relationship between molecular orientation and dynamic viscoelasticity - Enthalpy relaxation by heat treatment - Relationship between relaxation of molecular orientation and heat resistance DOI : https://doi.org/10.1515/ipp-2020-4093 En ligne : https://drive.google.com/file/d/1DpG0tvJJ0lDM4WQBVe6Gyf5UNpuBMOZ5/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36524 [article]

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Recycling of bagasse as an agricultural waste and its effect as filler on some mechanical and physical properties of SBR composites / E. S. A. Khalaf in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 586-595 Titre : Recycling of bagasse as an agricultural waste and its effect as filler on some mechanical and physical properties of SBR composites Type de document : texte imprimé Auteurs : E. S. A. Khalaf, Auteur Année de publication : 2021 Article en page(s) : p. 586-595 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bagasse La bagasse est le résidu fibreux de la canne à sucre qu'on a passée par le moulin pour en extraire le suc. Elle est composée principalement de la cellulose de la plante. Ce terme désigne également les tiges de la plante qui fournit l'indigo, quand on les retire de la cuve après la fermentation. L'industrie de la canne produit en grandes quantités la bagasse, résidu de l'extraction du jus de pipe pour la production de rhum ou de sucre. On estime que la production mondiale de bagasse est d'environ 250 millions de tonnes par an. Canne à sucre et constituants Caoutchouc styrène-butadiène Composites à fibres végétales -- Propriétés mécaniques Essais dynamiques Formulation (Génie chimique) Noir de carbone Poudres Rhéologie Index. décimale : 668.4 Plastiques, vinyles Résumé : In the present study, a series of mixes based on different concentrations of carbon black (CB) as a reinforcing filler and sugarcane bagasse as supplementary filler, were investigated to examine their effects on the mechanical properties of styrene butadiene rubber (SBR) composites. To this end, the first group of mixes deals with the effect of different concentrations of CB ranging from 0 to 80 phr at fixed bagasse concentration of 25 phr. The second group of mixes involves the addition of bagasse with concentrations varying from 10 to 50 phr at 10 intervals with fixed CB concentration of 40 phr. The sizes of the employed ground bagasse powder (GBP) in all prepared formulations ranged from 20 to 180 μm. In addition, 2.5 phr of maleic anhydride (MA) was added to enhance the interfacial adhesion between SBR and agricultural waste fillers (i. e. bagasse). Tensile strength, elongation at break, modulus at 100% elongation, resilience, hardness (Shore A), abrasion and degree of swelling of the rubber vulcanizates were studied. The prepared samples were also analyzed by scanning electron microscopy (SEM) to show the distribution of fiber and the occurrence of fiber-matrix adhesion. The optimum concentration of bagasse to be used simultaneously with CB in SBR composites was found to be 30 phr. Overall, it was found from the obtained results that the addition of GBP up to 50 phr is feasible without impairing the mechanical properties of SBR vulcanizates. Note de contenu : - EXPERIMENTAL : Materials - Experimental techniques - Rheology measurements - Measurement of mechanical properties (astm d-412) - Scanning electron microscopy (sem) - RESULTS AND DISCUSSION : Rheological properties - Physico-mechanical properties - SEM of micro-fractured surfaces - Table 1 : Physico-mechanical properties of bagasse fibers - Table 2 : Compounds formulations - Table 3 : Rheometric characteristics of SBR vulcanizates containing different concentrations of bagasse fibre - Table 4 : Comparison between SBR formulations containing different concentrations of bagasse DOI : https://doi.org/10.1515/ipp-2020-4054 En ligne : https://drive.google.com/file/d/1EbtCGdwZmmI-hlB34TtxKtA1D37szusJ/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36525 [article]

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Use of image analysis for non-destructive testing of thermoformed food packages / O. Eksi in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 596-607 Titre : Use of image analysis for non-destructive testing of thermoformed food packages Type de document : texte imprimé Auteurs : O. Eksi, Auteur Année de publication : 2021 Article en page(s) : p. 596-607 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse d'image L'analyse d'image est la reconnaissance des éléments contenus dans l'image. Il ne faut pas confondre analyse (décomposition en éléments) et traitement (action sur les composantes) de l'image. Contrôle non destructif Emballages en matières plastiques Epaisseur -- Mesure Matières plastiques -- Thermoformage Index. décimale : 668.4 Plastiques, vinyles Résumé : The aim of this study is to determine the thickness distribution of a food package using a non-destructive method. Initially, thickness measurements were carried out using an experimental procedure for thermoformed samples that were used for food packaging. Additionally, in this study, image analysis was used for the first time to determine the thickness distribution of the thermoformed products non-destructively. Image analysis software was employed for the estimation of thickness distribution. Measured thickness results were compared to those estimated using image analysis. Based on the results of the current study, image analysis may be an alternative method for non-destructive testing of thermoformed food packages even in a mass production line. Image analysis can be used to determine not only thickness distribution but also the weakest regions in a food package. Note de contenu : - Material and method - Experimental procedure - Image analysis DOI : https://doi.org/10.1515/ipp-2020-4114 En ligne : https://drive.google.com/file/d/17ADeNV8L5BNmbwi8NL0egZDyjqFC7_ol/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36526 [article]

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Process influences in the combined compacting and back-injection process to produce back-injected self-reinforced composites (SRCS) – analysis via multiple regression modelling / F. Jakob in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 608-619 Titre : Process influences in the combined compacting and back-injection process to produce back-injected self-reinforced composites (SRCS) – analysis via multiple regression modelling Type de document : texte imprimé Auteurs : F. Jakob, Auteur ; Joshua Pollmeier, Auteur ; Hans-Peter Heim, Auteur Année de publication : 2021 Article en page(s) : p. 608-619 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Adhésion Cisaillement (mécanique) Compactage Composites thermoplastiques auto-renforcés Essais (technologie) Polypropylène Rétro-injection Index. décimale : 668.4 Plastiques, vinyles Résumé : A new process to produce back-injected self-reinforced composites (SRCs) is presented. In contrast to other investigations on back-injection of SRCs, a process is presented which allows compacting and back injection of SRCs in one step where the SRCs are partly consolidated only via melt pressure inside the cavity. The mechanical properties of SRCs depend to a large extent on the process parameters of temperature and pressure during manufacture. These parameters are not yet known for back-injected areas. Sensors inside of the cavity measure the influences on the temperature and pressure conditions in the cavity. Initial studies on adhesion were carried out and analysed. For this purpose, shear tests of the back-injected component were carried out and a maximum shear strength of 5.81 MPa was determined for the materials used here. The investigations also show a dependence on the Distance from the Gate (DG) and the Mass temperature (TM). First microscopic examinations show good bonding between the SRC and the injection molded part, with no voids or air pockets in the boundary layer. It can also be seen that successful consolidation takes place in the area of the back injection. Note de contenu : - EXPERIMENTAL SETUP : Process sequences - Construction of the tool - Experimental part - Measuring and data assessment - RESULTS AND DISCUSSION : Regression based analysis – supervised machine learning - Shear-off tests - Microscopic examinations - Table 1 : Parameter settings DOI : https://doi.org/10.1515/ipp-2020-4105 En ligne : https://drive.google.com/file/d/1adgWM8gw2ZdjW_XVzM-AFsqCe58UgNsA/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36527 [article]

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Utilizing pyrolytic biomass products for rubber reinforcement : effect of the silica content in biomass feed stocks / L.-Y. Yu in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 620-629 Titre : Utilizing pyrolytic biomass products for rubber reinforcement : effect of the silica content in biomass feed stocks Type de document : texte imprimé Auteurs : L.-Y. Yu, Auteur ; B.-C. Xue, Auteur ; M.-M. Qian, Auteur ; Y.-X. Li, Auteur ; Z.-X. Chen, Auteur ; Y.-C. Zhu, Auteur ; X.-F. Wang, Auteur Année de publication : 2021 Article en page(s) : p. 620-629 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Biochar Le biochar est un amendement du sol issu de la pyrolyse de biomasse. Il est utilisé en agriculture pour augmenter la qualité des sols, et donc leur productivité ; il est également utilisé dans la lutte contre le réchauffement climatique comme solution de séquestration à long terme de carbone atmosphérique dans les sols. Le biochar se différencie du charbon de bois par son utilisation (comme intrant plutôt que comme combustible) et donc par son impact environnemental (il agit comme un puits de carbone plutôt que de libérer du CO2 dans l'atmosphère lors de la combustion). Caoutchouc Caractérisation Charges (matériaux) Composites -- Propriétés mécaniques Formulation (Génie chimique) Polymérisation Silice La silice est la forme naturelle du dioxyde de silicium (SiO2) qui entre dans la composition de nombreux minéraux. La silice existe à l'état libre sous différentes formes cristallines ou amorphes et à l'état combiné dans les silicates, les groupes SiO2 étant alors liés à d'autres atomes (Al : Aluminium, Fe : Fer, Mg : Magnésium, Ca : Calcium, Na : Sodium, K : Potassium...). Les silicates sont les constituants principaux du manteau et de l'écorce terrestre. La silice libre est également très abondante dans la nature, sous forme de quartz, de calcédoine et de terre de diatomée. La silice représente 60,6 % de la masse de la croûte terrestre continentale. Index. décimale : 668.4 Plastiques, vinyles Résumé : Biochar has been exploited as a substitution of carbon black in the rubber industry and various biochars exhibit diverse reinforcing abilities due to the different compositions. This work aims at studying the effect of silica on the modification process and reinforcing performance through the comparison of three biochars with different contents of silica, pyrolytic rice husks (PRH, 34 wt%), pyrolytic bamboos (PB, 7 wt%) and pyrolytic corn cobs (PC, 0.4 wt%). The results reveal that PRH requires higher rotational speed (300 min–1) than PB (200 min–1) and PC (200 min–1) to achieve similar particle sizes during the ball milling process because of the aggregations of higher silica content. Meanwhile, silica-rich pyrolytic biomass exhibits enhanced reinforcement on mechanical properties and thermal stability of rubber, and the elongation at break of vulcanizates continues to improve with increasing silica contents. Combined with the energy consumption and reinforcement, biochar containing a little amount of silica is more suitable to be widely used as bio-filler in rubber industry. This work should serve as a valuable reference to select appropriate biochar for the production of bio-fillers with high reinforcement. Note de contenu : - EXPERIMENTAL : Materials - Preparation of biochar fillers - Preparation of fillers/NR vulcanizates - Characterization - RESULTS AND DISCUSSION : Characterization of fillers - Properties of filler/NR vulcanizate - Table 1 : Formulation of the NR composites - Table 2 : Curing characteristics of PRH, PB and PC - Table 3 : The mechanical properties of NR vulcanizates reinforced with various fillers DOI : https://doi.org/10.1515/ipp-2020-4102 En ligne : https://drive.google.com/file/d/1HrCQg8Nu6pWoW4PSp9IRE2aCzpizi1hO/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36528 [article]

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