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Morphology, Thermal Behavior and Dynamic Rheological Properties of Wood Polypropylene Composites

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Materials Sciences and Applications 2013年第11期4卷 730-738页

作者： Diène Ndiaye vincent verney Haroutioun Askanian Sophie Commereuc Adams Tidjani Département de Physique Université Cheikh Anta Diop Dakar Sénégal Institut de Chimie de Clermont-Ferrand Université Blaise Pascal Clermont-Ferrand France CNRS UMR 6296 ICCF Université Blaise Pascal Aubière France Institut de Chimie de Clermont-Ferrand Université Blaise Pascal Clermont-Ferrand France Ecole Nationale Supérieure de Chimie de Clermont-Ferrand Université Blaise Pascal Clermont-Ferrand France Section Physique Appliquée Université Gaston Berger Saint-Louis Sénégal Institut de Chimie de Clermont-Ferrand Université Blaise Pascal Clermont-Ferrand France Ecole Nationale Supérieure de Chimie de Clermont-Ferrand Université Blaise Pascal Clermont-Ferrand France

Wood polymer composites (WPCs) were made with pine and polypropylene matrix (PP). The composites were produced by melt blending in a Brabender at 180°C. Characterization of the samples, with the aid of scanning electron microscopy supplemented by microscope photography, showed an improved dispersion of wood in the polymeric material in presence of polypropylene grafted with maleic anhydride (MAPP) or nanoclay. The use of the MAPP instead of clay seems to have enhanced the level of crystallinity in the composites for the same levels of wood loading and also accelerates the crystallization. Melt rheological measurements of neat PP and PP-wood composites were carried out at 180°C with an ARES Rheometer scientific mechanical spectrometer in oscillatory frequency. All the composites materials exhibit viscoelastic values greater than those for neat PP. The samples containing MAPP as comptabilizer show the higher Newtonian viscosity, however, the addition of a small concentration of nanoparticles like nanoclays does not improve the resulting melt viscoelastic behavior of the composite.

关键词： Morphology Thermal Behavior Dynamic Rheological Properties Wood Polypropylene Composites

Effects of Light Radiation Absoption on the Resistance of Sweet Potato Starch-Based Bioplastics

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Journal of Materials Science and Chemical Engineering 2022年第2期10卷 44-52页

作者： Aristide Herlyn Wilfrid Nakavoua Emmanuelle Surya Ouenadio Pascale Ursula Nkoua-Ouassamo vincent verney Laboratory of Natural Substances Chemistry (IRSEN) Brazzaville Congo Laboratory for The Valorisation of Agri-Resources Ecole Normale Superieure Politechnique (ENSP) Marien Ngouabi University Brazzaville Congo UMR 6296 Team Design of Polymers and Macromolecules Scientist Set Cézeaux Institute of Chemistry of Clermont-Ferrand (ICCF) Clermont-Ferrand French

The strength of starch-based bioplastics is a challenge, we tried to overcome this limitation by using electromagnetic radiation in the visible range. Synthetically obtained retrograde bioplastics were subjected to radiation from an Edison-type incandescent lamp. A cross-linked network is obtained within the bioplastic matrix considerably attenuating the usual hygroscopicity of starch and increasing the ability to resist rupture. After this positive behavior, the bioplastics were colored in order to optimize the action of light radiation. The results show a stronger and more compact bioplastic. The green-colored bioplastics show the best performance in the optimization of the resistance.

关键词： Bioplastics Starch Sweet Potato Radiation and Light Stress

The effect of Poly-ethylene-co-glycidyl methacrylate efficiency and clay platelets on thermal and rheological properties of wood polyethylene composites.

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Advances in Chemical Engineering and Science 2016年第4期6卷 436-455页

作者： Ansou Malang Badji El Hadj Babacar Ly Diene Ndiaye Abdou Karim Diallo Ndickou Kebe vincent verney Applied Physic Department Gaston Berger University Saint-Louis Senegal Institut de Chimie de Clermont-Ferrand Université Blaise Pascal Clermont-Ferrand France CNRS UMR 6296 ICCF Université Blaise Pascal Aubière France

Global ecological concerns have resulted in an interest in renewable natural materials. Composites based on high density polyethylene (HDPE), wood fiber (Veneer) and containing coupling agents like nanoclay (NC) and poly-ethylene-co-glycidyl methacrylate (PEGMA) were made by melt compounding and then injection molding. In this study, the effects of two variable parameters namely nanoclay and coupling agent on the rheological and thermal properties of wood polyethylene composites (WPECs) were investigated. The study investigates the morphology phase, rheology behaviors and thermal properties by scanning electron microscope, capillary rheometer and thermal gravimetric analyzer. The SEM micrographs of the composites showed that the outer surfaces of the wood were coated by a section of amorphous lignin. The state of dispersion in HDPE/pine/clay composites was improved by EGMA because it could interact with pine flour in addition to clay. The interaction of reinforcement with coupling agent and HDPE matrix is strong based on the observation of the fracture surface of composites when EGMA is present. However the addition of 2.5% clay slightly lowered the initial degradation temperature (Td) but did not improve the thermal stability. Obviously, all the composites materials exhibit viscoelastic values greater than those of neat HDPE.

关键词： Wood HDPE Composite Rheological and Thermal Properties Microscopy TGA

Attempt to Polymerize <i>Cucurbita pepo</i>Oil by Temperature Action and Photolysis

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Open Journal of Applied Sciences 2021年第3期11卷 264-272页

作者： Aristide H. W. Nakavoua Louis Okotaka Ebale Bertin Mikolo vincent verney Gilles Figuérédo Laboratory of Chemistry of Natural Substances (IRSEN) Brazzaville Congo Laboratory of Mechanics Energetics and Engineering Unesco Chair in Engineering Sciences Ecole Nationale Supérieure Polytechnique Marien Ngouabi University Brazzaville Congo Marien Ngouabi University National Polytechnic High School (ENSP) Laboratory for the Valorisation of Agri-Resources Brazzaville Congo Institute of Chemistry of Clermont-Ferrand (ICCF) UMR 6296 Team Design of Polymers and Macromolecules Scientist Set Cézeaux24 Avenue des Landais Clermont Ferrand France LEXVA Analytical 460 rue du Montant 63540 Romagnat France or Henri Mondor Street Biopole Clermont-Limagne 63360 Saint Beauzire Clermont Ferrand France

The study of the polymerization of a vegetable oil has a double interest;industrial but especially food. Industrial because polymers based on vegetable oil are in line with sustainable development;food because an oil which polymerizes easily is a danger for human consumption. Three situations of Cucurbita pepo oil polymerization are carried out in the course of time, the factor retained being temperature. A monitoring of the evolution of the enthalpy by temperature variation by the DSC method allows to report the polymerization of this oil. It happens that a polymerization is triggered in the oil matrix but it seems to fade very quickly, this behavior is general because after sweeping a temperature range of 80°C;100°C and 150°C adding different amounts of Irgacure: the Cucurbita pepo oil resists polymerization through its antioxidant compounds. However, a photolysis of this oil carried out over 8 days shows that it effectively polymerizes after 144 hours, which proves the great capacity of antioxidant compounds to protect this oil. The analyses carried out at 25°C aim to simulate the behavior of the oil at room temperature. The results reveal good resistance to both thermochemical and photochemical polymerization, which opens up great prospects for its development in the food industry and in nutrition.

关键词： Cucurbitea pepo DSC Polymerization Antioxidants Irgacure and Photolysis

Impact of Photonic Action on the Hygroscopy of Sweet Potato Starch-Based Bioplastics from Congo

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Open Journal of Applied Sciences 2022年第1期12卷 42-50页

作者： Aristide H. W. Nakavoua Anicet F. Binaki Emmanuelle S. Ouenadio Raymond G. Elenga vincent verney Laboratory of Natural Substances Chemistry (IRSEN) Brazzaville Congo Equipe Pluridisciplinaire en Alimentation et Nutrition P&#244le d’Excellence Régionale en Alimentation et Nutrition BP 389 Faculté de Sciences et Techniques Brazzaville Congo Laboratory for the Valorisation of Agri-Resources Ecole Normale Superieure Politechnique (ENSP) Marien Ngouabi Univer-sity Brazzaville Congo Laboratory for materials and Energy Faculty of Science and Technology (FAST) Marien Ngouabi University Brazzaville Congo Institute of Chemistry of Clermont-Ferrand (ICCF) UMR 6296 Team Design of Polymers and Macromolecules Scientist Set Cézeaux24 Avenue des Landais Clermont-Ferrand France

The work carried out here opens another perspective in the valorization of sweet potatoes produced in Congo Brazzaville other than those proposed by BOULA and all. We have shown in this work that the hydrophilic property of starch which limits the production of starch-based bioplastics can be inhibited by using the effects of photonic incandescence. Indeed, light significantly impacts the bioplastic matrix causing a decrease of the sites likely to bind water molecules. However, it would be desirable to apply rheology for a better follow-up of this cross-linking phenomenon. The synthesized retrograde bioplastic having undergone a photonic stress shows better physical properties to be used as packaging and thus to answer the environmental protection.

关键词： Aging Bioplastic Ipomea batata Photonic Stress

Study of the Thermal, Rheological, Morphological and Mechanical Properties of Biocomposites Based on Rod-Of Typha/HDPE Made up of Typha Stem and HDPE

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Advances in Materials Physics and Chemistry 2018年第9期8卷 340-357页

作者： Babacar Niang El Hadj Babacar Ly Abdou Karim Diallo Nicola Schiavone Haroutioun Askanian vincent verney Ansou Malang Badji Mahmoud Kalid Diakite Diéne Ndiaye Section Physique Appliquée Unité de Formation et de Recherche de Sciences Appliquées et de Technologies Université Gaston Berger Saint Louis Sénégal Institut de Chimie de Clermont-Ferrand Université Blaise Pascal Clermont-Ferrand France CNRS UMR 6296 ICCF Université Blaise Pascal Aubière France

The thermal, rheological and morphological properties of composite biomaterials made with mixture of high density polyethylene and typha rod powder (RD) were evaluated. The dynamic mechanical behavior of the samples was studied with 25%, 35% and 45% typha stem powder concentrations. The viscoelastic properties are mainly related to the nature of the polymer and the typha stem powder. Storage (G') and loss (G') moduli increased significantly, depending on the amount of powder in the molten mixture. After a viscosity increase was noticed in low frequency, it decreased in high frequencies, which demonstrates the pseudo-plasticity effect. Morphological and thermal characterization results have shown the dispersion state of the powder and its ability to modify the kinetics crystallization of biocomposites.

关键词： Biocomposite Thermal Rheological Morphological Mechanical Properties

Additive neurorestorative effects of exercise and docosahexaenoic acid intake in a mouse model of Parkinson’s disease

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Neural Regeneration Research 2025年第2期20卷 574-586页

作者： Olivier Kerdiles Méryl-Farelle Oye Mintsa Mi-mba Katherine Coulombe Cyntia Tremblay vincentÉmond Martine Saint-Pierre Clémence Rouxel Line Berthiaume Pierre Julien Francesca Cicchetti Frédéric Calon Facultéde pharmacie UniversitéLaval1050 Avenue de la MédecineQuebecQCCanada Axe Neuroscience Centre de recherche du CHU de Québec-UniversitéLaval(Pavillon CHUL)2705 Boulevard LaurierQuebecQCCanada Institute of Nutrition and Functional Foods QuebecQCCanada Optinutribrain International Associated Laboratory(NutriNeuro FranceINAFCanada)QuebecQCCanada Axe Endocrinologie et Néphrologie Centre de recherche du CHU de Québec-UniversitéLavalQuebecQCCanada Département de Médecine Facultéde MédecineUniversitéLavalQuebecQCCanada Département de Psychiatrie et Neurosciences Facultéde MédecineQuebecQCCanada

There is a need to develop interventions to slow or reverse the degeneration of dopamine neurons in Parkinson’s disease after *** that preclinical and clinical studies suggest benefits of dietary n-3 polyunsaturated fatty acids,such as docosahexaenoic acid,and exercise in Parkinson’s disease,we investigated whether both could synergistically interact to induce recovery of the dopaminergic ***,mice received a unilateral stereotactic injection of 6-hydroxydopamine into the striatum to establish an animal model of nigrostriatal *** weeks after lesion,animals were fed a docosahexaenoic acid-enriched or a control diet for the next 8 *** this period,the animals had access to a running wheel,which they could use or *** acid treatment,voluntary exercise,or the combination of both had no effect on(i)distance traveled in the open field test,(ii)the percentage of contraversive rotations in the apomorphine-induction test or(iii)the number of tyrosine-hydroxylase-positive cells in the substantia nigra pars ***,the docosahexaenoic acid diet increased the number of tyrosine-hydroxylase-positive terminals and induced a rise in dopamine concentrations in the lesioned *** to docosahexaenoic acid treatment or exercise alone,the combination of docosahexaenoic acid and exercise(i)improved forelimb balance in the stepping test,(ii)decreased the striatal DOPAC/dopamine ratio and(iii)led to increased dopamine transporter levels in the lesioned *** present results suggest that the combination of exercise and docosahexaenoic acid may act synergistically in the striatum of mice with a unilateral lesion of the dopaminergic system and provide support for clinical trials combining nutrition and physical exercise in the treatment of Parkinson’s disease.

关键词： 6-hydroxydopamine dopamine dopamine transporter exercise neurorestoration Parkinson’s disease polyunsaturated fatty acids omega-3

Tourism Developments Increase Tsunami Disaster Risk in Pangandaran, West Java, Indonesia

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International Journal of Disaster Risk Science 2021年第5期12卷 764-769页

作者： vincent Nijman Department of Social Sciences Oxford Brookes UniversityOxford OX30BP.United Kingdom

On 17 July 2006,the tourist resort of Pangandaran on Java’s south coast was hit by a tsunami,resulting in 413 fatalities and severe damage to *** tsunami resulted in major rebuilds with a focus on mass *** of the impact of a future tsunami focussed on building development and suggest limited change since *** article presents a case study on the development of(largely domestic)tourism in Pangandaran and how this has increased the tsunami disaster *** numbers were stable at about 900,000 visitors a year prior to the tsunami,down to slightly over 250,000 visitors a year in its aftermath,and from 2007 onwards numbers are doubling every three years to about 4 million visitors in *** increase has been most pronounced during *** to 2006,Pangandaran was characterized by wooden structures and one-and two-story buildings of clay-brick masonry;by 2019,14 three to sixstory hotels have been erected along the *** many more visitors,most of whom are unfamiliar with tsunami risks,and shelter facilities for less than a quarter of visitors during peak times,future impacts and the potential cost to life are considerably higher now than in 2006,especially if a tsunami were to hit over a *** tourists upon arrival and throughout their stay should be better informed about the risks of tsunamis,and of the location of tsunami shelters and evacuation routes.

关键词： Disaster resilience Effective warning Indonesia Risk mitigation Tourism Tsunami

Strain and stress analysis on Zn multicrystal film by XRD method

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中国有色金属学会会刊：英文版 2006年第B2期16卷 735-738页

作者： vincent JI LIM UMR CNRS8006ENSAM 151Boulevard de I'Hopital75013 ParisFrance

A new method was denonstrated to determine stress in a single crystal for multicrystal material and this new method could be specially applied for any symmetric crystalline systems. The strain tensor e was determined by the change of the metric tensor G before the initial state and after the deformed state in the crystal reference system. Then stress tensor at grain scale was calculated by the HOOK's law. The stress evaluations were carried out in coarse grains of a thin galvanized coating on a steel substrate during tensile loading. This makes it possible to link the microstructure evolution to the elastic heterogeneity at grain scale or between the grains.

关键词：锌多晶膜单晶应力应变分析 XRD法锌镀层