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Production scientifique
Matière Molle
(421) Articles dans des revues
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Pollution des océans par les plastiques et les microplastiques
Auteur(s): Galgani François, Bruzaud Stéphane, Duflos Guillaume, Fabre P., Gastaldi Emmanuelle, Ghiglione Jeff, Grimaud Régis, George M., Huvet Arnaud, Lagarde Fabienne, Paul-Pont Ika, ter Halle Alexandra
(Article) Publié:
Techniques De L'ingenieur, vol. p. (2020)
Ref HAL: hal-03048415_v2
DOI: 10.51257/a-v1-bio9300
Exporter : BibTex | endNote
Résumé: Les comportements humains et l’utilisation intensive du plastique associés à une faible performance des systèmes de gestion ont engendré une accumulation massive de déchets plastiques dans le milieu marin où ils représentent 50 à 80 % de l’ensemble des déchets. Leur distribution, leurs comportements en mer, leur dégradation et leurs impacts découlent directement de leur composition et propriétés d’usage. Le présent article fait un bilan des connaissances et décrit les principaux enjeux scientifiques, environnementaux et socio-économiques, ainsi que les possibles solutions nécessaires à la gestion d’un problème environnemental devenu global.
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Role of Normal Stress in the Creep Dynamics and Failure of a Biopolymer Gel
Auteur(s): Pommella A., Cipelletti L., Ramos L.
(Article) Publié:
Physical Review Letters, vol. 125 p.268006 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-03139495_v1
DOI: 10.1103/PhysRevLett.125.268006
WoS: WOS:000604249900023
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Résumé: We investigate the delayed rupture of biopolymer gels under a constant shear load by simultaneous dynamic light scattering and rheology measurements. We unveil the crucial role of normal stresses built up during gelation: All samples that eventually fracture self-weaken during the gelation process, as revealed by a partial relaxation of the normal stress concomitant to a burst of microscopic plastic rearrangements.Upon applying a shear stress, weakened gels exhibit in the creep regime distinctive signatures in their microscopic dynamics, which anticipate macroscopic fracture by up to thousands of seconds. The dynamics in fracturing gels are faster than those of nonfracturing gels and exhibit large spatiotemporal fluctuations. A spatially localized region with significant plasticity eventually nucleates, expands progressively, and finally invades the whole sample, triggering macroscopic failure.
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Role of Fast Dynamics in Conductivity of Polymerized Ionic Liquids
Auteur(s): Bocharova Vera, Genix A.-C., Kisliuk Alexander, Sala Gabriele, Osti Naresh C., Mamontov Eugene, Sokolov Alexei P.
(Article) Publié:
Journal Of Physical Chemistry B, vol. 124 p.10539-10545 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-03131544_v1
DOI: 10.1021/acs.jpcb.0c07549
WoS: WOS:000592964600024
Exporter : BibTex | endNote
Résumé: Polymerized ionic liquids (PolyILs) are promising candidates for a broad range of technologies. However, the relatively low conductivity of PolyILs at room temperature has strongly limited their applications. In this work, we provide new insights into the roles of various microscopic parameters controlling ion transport in these polymers, which are crucial for their rational design and practical applications. Using broadband dielectric spectroscopy and neutron and light scattering techniques, we found a clear connection between the activation energy for conductivity, fast dynamics, and high-frequency shear modulus in PolyILs at their glass transition temperature (Tg). In particular, our analysis reveals a correlation between conductivity and the amplitude of fast picosecond fluctuations at Tg, suggesting the possible involvement of fast dynamics in lowering the energy barrier for ion conductivity. We also demonstrate that both the activation energy for ion transport and the amplitude of the fast fluctuations depend on the high-frequency shear moduli of PolyILs, thus identifying a practically important parameter for tuning conductivity. The parameters recognized in this work and their connection to the ionic conductivity of PolyILs set the stage for a deeper understanding of the mechanism of ion transport in PolyILs in the glassy state.
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Chemical-Physical Characterization of a Binary Mixture of a Twist Bend Nematic Liquid Crystal with a Smectogen
Auteur(s): Aouini A., Nobili M., Chauveau E., Dieudonne-George P., Dameme Gauthier, Stoenescu Daniel, Dozov I., Blanc C.
(Article) Publié:
Crystals, vol. 10 p.1110 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-03113887_v1
DOI: 10.3390/cryst10121110
WoS: WOS:000601985600001
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Résumé: Nematic twist-bend phases (N-TB) are new types of nematic liquid crystalline phases with attractive properties for future electro-optic applications. However, most of these states are monotropic or are stable only in a narrow high temperature range. They are often destabilized under moderate cooling, and only a few single compounds have shown to give room temperature N-TB phases. Mixtures of twist-bend nematic liquid crystals with simple nematogens have shown to strongly lower the nematic to N-TB phase transition temperature. Here, we examined the behaviour of new types of mixtures with the dimeric liquid crystal [4 ',4 '-(heptane-1,7-diyl)bis(([1 ',1 ''-biphenyl]4 ''-carbo-nitrile))] (CB7CB). This now well-known twist-bend nematic liquid crystal presents a nematic twist-bend phase below T approximate to 104 degrees C. Mixtures with other monomeric alkyl or alkoxy -biphenylcarbonitriles liquid crystals that display a smectic A (SmA) phase also strongly reduce this temperature. The most interesting smectogen is 4 '-Octyl-4-biphenylcarbonitrile (8CB), for which a long-term metastable N-TB phase is found at room and lower temperatures. This paper presents the complete phase diagram of the corresponding binary system and a detailed investigation of its thermal, optical, dielectric, and elastic properties.
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Pollution des océans par les plastiques et les microplastiques Pollution of oceans by plastics and microplastics
Auteur(s): Francois Galgani, Stéphane Bruzaud, Guillaume Duflos, Fabre P., Emmanuelle Casdaldi, Jeff Ghiglione, Régis Grimaud, George M., Arnaud Huvet, Fabienne Lagarde, Ika Paul-Pont, Alexandra Halle
(Article) Publié:
Techniques De L'ingenieur, vol. p. (2020)
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Microstructure Characterization of Oceanic Polyethylene Debris
Auteur(s): Rowenczyk Laura, Dazzi Alexandre, Deniset-Besseau Ariane, Beltran Victoria, Goudounèche Dominique, Wong-Wah-Chung Pascal, Boyron Olivier, George M., Fabre P., Roux C., Mingotaud Anne-Françoise, ter Halle Alexandra
(Article) Publié:
Environmental Science And Technology, vol. 54 p.4102-4109 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-02990067_v1
DOI: 10.1021/acs.est.9b07061
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Résumé: Plastic pollution has become a worldwide concern. It was demonstrated that plastic breaks down to nanoscale particles in the environment, forming so-called nanoplastics. It is important to understand their ecological impact, but their structure is not elucidated. In this original work, we characterize the microstructure of oceanic polyethylene debris and compare them to the nonweathered objects. Cross-sections are analysed by several emergent mapping techniques. We highlight deep modifications of the debris within a layer a few hundred microns thick. The most 2 intense modifications are macromolecule oxidation and a considerable decrease in the molecular weight. The adsorption of organic pollutants and trace metals is also confined to this outer layer. Fragmentation of the oxidized layer of the plastic debris is the most likely source of nanoplastics. Consequently nanoplastic chemical nature differ greatly from plastics.
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Texturing edible oil with crystals of phenolic compounds: Platelets versus rods
Auteur(s): Pommella A., Mathonnat M., In M.
(Article) Publié:
Journal Of Food Engineering, vol. 283 p.110039 (2020)
Ref HAL: hal-03049250_v1
DOI: 10.1016/j.jfoodeng.2020.110039
Exporter : BibTex | endNote
Résumé: Cinnamic acid and acetosyringone recrystallize in vegetable oil as platelets and rods respectively. After dissolution at high temperature(100°C) and upon cooling down to room temperature, their crystallites aggregate into a tenuous network which spans the entire volume of the system even at low mass fraction such as 1%. The whole system behaves as a soft solid characterized by an elastic modulus reaching 1MPa for mass fraction below 10% in the linear regime. The elastic modulus of cinnamic acid based oleogels varies with mass fraction as (-0) 2. For acetosyringone based oleogels, the elastic modulus varies non monotonically with concentration. This has been correlated to a morphological crossover from jammed spherulites at low mass fraction to entangled rods at higher mass fraction. Spherulite formation is related to the presence of branching points along the rods that result from secondary nucleation events. A new empirical parameter is defined from rheological data which reflects how far from equilibrium the solidification proceeds in nonisothermal conditions. This parameter accounts for the different concentration regimes of morphology and rheological properties that have been observed experimentally for acetosyringone.
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