Optimisation du cycle de cuisson d'une pièce moulée en élastomère

Les propriétés des pièces en caoutchouc moulées dépendent fortement du niveau de vulcanisation qui règne au sein du matériau. Le champ de vulcanisation est issu de la cinétique chimique engendrée par l histoire thermique imposée au matériau lors du moulage. L évolution du champ de température au sein de la matière moulée est dictée essentiellement par la régulation thermique des outillages. En ce jour, la profession a besoin d une maîtrise des phénomènes thermiques et de la prédiction des champs de vulcanisation. L objectif de ce travail est donc la création d un outil de prédiction fiable de l état de vulcanisation et l optimisation des conditions thermiques du moulage en vue d obtenir un état souhaité des pièces épaisses. Nous avons développé un outil de prédiction du champ de vulcanisation qui couple les échanges thermiques et l évolution chimique du caoutchouc. Pour valider la pertinence de la prédiction numérique, nous avons conçu et réalisé un outillage thermiquement contrôlé comportant un dispositif de mesure de température original au sein des pièces moulées. Les résultats des mesures permettent de vérifier la maîtrise des échanges thermiques obtenue par le dispositif de moulage que nous avons réalisé. Les mesures permettent également, de valider la modélisation numérique. L outil de simulation ainsi validé est utilisé pour optimiser le cycle de vulcanisation des pièces moulées. Nous avons développer deux méthodes d optimisation: la méthode inverse dédiée à l estimation des niveaux de températures du cycle optimal et la méthode de Levenberg-Marquardt pour optimiser le couple de temps et température nécessaire pour obtenir un champ de vulcanisation désiréMoulded rubber part properties depend strongly on the vulcanization level within the material. The vulcanization field comes from chemical kinetics caused by the thermal history imposed on the material during moulding process. The temperature field evolution within the moulded material depends primarily on the mould boundary conditions. On this day, the profession needs a good mastery of thermal phenomena during moulding process in addition to the vulcanization fields prediction. The objective of this work is the creation of a reliable tool for predicting the state of cure and optimizing thermal moulding conditions in order to obtain a qualified thick rubber parts. We have developed a tool for predicting the vulcanization field which couples the heat transfer model to the rubber chemical history within the mould. In order to validate the digital model, we have developed temperature-controlled moulding device including an original measuring device recording temperatures directly within the moulded part. The control of heat transfers achieved with the moulding equipment is verified with experimental measurements. The measures also validate the numerical modelling. The simulation tool is used to optimize the curing cycle. We have developed two optimization methods to estimate the boundary condition cycle needed to obtain a desired vulcanization field within the part thicknessNANTES-BU Sciences (441092104) / SudocNANTES-Ecole Centrale (441092306) / SudocSudocFranceF

Wide Band-Gap 3,4-Difluorothiophene-Based Polymer with 7% Solar Cell Efficiency: An Alternative to P3HT

Wide Band-Gap 3,4-Difluorothiophene-Based Polymer with 7% Solar Cell Efficiency: An Alternative to P3H

Highly Stretchable and Air-Stable PEDOT:PSS/Ionic Liquid Composites for Efficient Organic Thermoelectrics

Thermoelectric (TE) generators that are capable of providing sustainable energy conversion under dynamic mechanical stresses have been explored for realizing autonomous wearable electronics. However, finding extremely deformable, efficient, and air-stable TE materials is still a major challenge. Here, we report highly stretchable and efficient organic TE materials from aqueous composites of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and ionic liquids (ILs). In this composite, ILs simultaneously enhance the Seebeck coefficient and electrical conductivity of PEDOT:PSS (up to 35 μV K -1 and 538 S cm -1 , respectively) by controlling its oxidation level and nanostructure. Moreover, the resulting fibrous structure with IL-assisted soft domains leads to outstanding mechanical deformability and durability, enabling that the PEDOT:PSS/IL films simply coated on elastomeric substrates maintain the TE functionality under tensile strain (ϵ) up to 70% and repetitive stretching cycles with 30% ϵ without severe degradation in TE performance. Furthermore, we also demonstrate the long-term TE stability of PEDOT:PSS/IL composites maintaining >80% of the initial performance after 10 days under ambient conditions. Our finding proves the potential of this novel composite as a stretchable and air-stable organic TE material

Electron-Deficient <i>N</i>‑Alkyloyl Derivatives of Thieno[3,4‑<i>c</i>]pyrrole-4,6-dione Yield Efficient Polymer Solar Cells with Open-Circuit Voltages > 1 V

Poly­(benzo­[1,2-b:4,5-b′]­dithiophene–thieno­[3,4-<i>c</i>]­pyrrole-4,6-dione) (PBDTTPD) polymer donors yield some of the highest open-circuit voltages (<i>V</i>_OC, ca. 0.9 V) and fill factors (FF, ca. 70%) in conventional bulk-heterojunction (BHJ) solar cells with PCBM acceptors. Recent work has shown that the incorporation of ring substituents into the side chains of the BDT motifs in PBDTTPD can induce subtle variations in material properties, resulting in an increase of the BHJ device <i>V</i>_OC to ∼1 V. In this contribution, we report on the synthesis of <i>N</i>-alkyloyl-substituted TPD motifs (TPD­(CO)) and show that the electron-deficient motifs can further lower both the polymer LUMO and HOMO levels, yielding device <i>V</i>_OC > 1 V (up to ca. 1.1 V) in BHJ solar cells with PCBM. Despite the high <i>V</i>_OC achieved (i.e., low polymer HOMO), BHJ devices cast from TPD­(CO)-based polymer donors can reach power conversion efficiencies (PCEs) of up to 6.7%, making these promising systems for use in the high-band-gap cell of tandem solar cells

Electron-Deficient <i>N</i>‑Alkyloyl Derivatives of Thieno[3,4‑<i>c</i>]pyrrole-4,6-dione Yield Efficient Polymer Solar Cells with Open-Circuit Voltages > 1 V

Poly­(benzo­[1,2-b:4,5-b′]­dithiophene–thieno­[3,4-<i>c</i>]­pyrrole-4,6-dione) (PBDTTPD) polymer donors yield some of the highest open-circuit voltages (<i>V</i>_OC, ca. 0.9 V) and fill factors (FF, ca. 70%) in conventional bulk-heterojunction (BHJ) solar cells with PCBM acceptors. Recent work has shown that the incorporation of ring substituents into the side chains of the BDT motifs in PBDTTPD can induce subtle variations in material properties, resulting in an increase of the BHJ device <i>V</i>_OC to ∼1 V. In this contribution, we report on the synthesis of <i>N</i>-alkyloyl-substituted TPD motifs (TPD­(CO)) and show that the electron-deficient motifs can further lower both the polymer LUMO and HOMO levels, yielding device <i>V</i>_OC > 1 V (up to ca. 1.1 V) in BHJ solar cells with PCBM. Despite the high <i>V</i>_OC achieved (i.e., low polymer HOMO), BHJ devices cast from TPD­(CO)-based polymer donors can reach power conversion efficiencies (PCEs) of up to 6.7%, making these promising systems for use in the high-band-gap cell of tandem solar cells

Highly Transparent and UV-Resistant Superhydrophobic SiO₂‑Coated ZnO Nanorod Arrays

Highly transparent and UV-resistant superhydrophobic arrays of SiO₂-coated ZnO nanorods are prepared in a sequence of low-temperature (<150 °C) steps on both glass and thin sheets of PET (2 × 2 in.²), and the superhydrophobic nanocomposite is shown to have minimal impact on solar cell device performance under AM1.5G illumination. Flexible plastics can serve as front cell and backing materials in the manufacture of flexible displays and solar cells

Microwave-synthesized tin oxide nanocrystals for low-temperature solution-processed planar junction organo-halide perovskite solar cells

© 2017 The Royal Society of Chemistry. Tin oxide has been demonstrated to possess outstanding optoelectronic properties such as optical transparency and high electron mobility; therefore, it was successfully utilized as an electron transporting layer in various kinds of solar cells. In this study, for the first time, highly dispersible SnO 2 nanoparticles were synthesized by a microwave-assisted non-aqueous sol-gel route in an organic medium. Ethanol dispersion of the as-prepared nanoparticles was used to cast a uniform thin layer of SnO 2 without the aid of an aggregating agent and at low temperatures. Organohalide perovskite solar cells were fabricated using SnO 2 as the electron transporting layer. Morphological and spectroscopic investigations, in addition to the good photoconversion efficiency obtained, evidenced that the nanoparticles synthesized by this route have optimal properties such as small size and crystallinity to form a continuous film. Furthermore, this method allows high reproducibility and scalability of the film deposition process