Le « Business Case » de la RSE peut- il être source de performance économique pour la PME ?

Corporate Social Responsibility (CSR), reserved for a long time to large companies, is now a strategic issue for all sizes organizations, including SMEs. The business case provides a complementary set of arguments that convince managers that the firm's interest converges with that of the society and that they do not depart from the expectations of the shareholders. The purpose of this paper is to provide a general overview of the debates on the Business Case as a strategy for the adoption of the CSR by the SME and to present the academic controversies that try to demonstrate that adopting a CSR policy is a profitable strategy and can be considered a source of economic performance

Chemically specifi C multiscale modeling of clay-polymer nanocomposites reveals intercalation dynamics, tactoid self-assembly and emergent materials properties

A quantitative description is presented of the dynamical process of polymer intercalation into clay tactoids and the ensuing aggregation of polymerentangled tactoids into larger structures, obtaining various characteristics of these nanocomposites, including clay-layer spacings, out-of-plane clay-sheet bending energies, X-ray diffractograms, and materials properties. This model of clay-polymer interactions is based on a three-level approach, which uses quantum mechanical and atomistic descriptions to derive a coarse-grained yet chemically specifi c representation that can resolve processes on hitherto inaccessible length and time scales. The approach is applied to study collections of clay mineral tactoids interacting with two synthetic polymers, poly(ethylene glycol) and poly(vinyl alcohol). The controlled behavior of layered materials in a polymer matrix is centrally important for many engineering and manufacturing applications. This approach opens up a route to computing the properties of complex soft materials based on knowledge of their chemical composition, molecular structure, and processing conditions.This work was funded in part by the EU FP7 MAPPER project (grant number RI-261507) and the Qatar National Research Fund (grant number 09–260–1–048). Supercomputing time was provided by PRACE on JUGENE (project PRA044), the Hartree Centre (Daresbury Laboratory) on BlueJoule and BlueWonder via the CGCLAY project, and on HECToR and ARCHER, the UK national supercomputing facility at the University of Edinburgh, via EPSRC through grants EP/F00521/1, EP/E045111/1, EP/I017763/1 and the UK Consortium on Mesoscopic Engineering Sciences (EP/L00030X/1). The authors are grateful to Professor Julian Evans for stimulating discussions during the course of this project. Data-storage and management services were provided by EUDAT (grant number 283304)

Cellulose nanocrystals from grape pomace and their use for the development of starch-based nanocomposite films

Nanocomposite films prepared from starch (ST) in the presence of cellulose nanocrystals (CNCs) was performed using grape pomace as raw material. CNCs were obtained by acid hydrolysis and added to filmogenic solutions (1, 2, 5, 10 and 15 g/100 g of ST). Cellulose, CNCs and Nanocomposites were characterized. Amorphous non-cellulosic materials were removed from the grape pomace presented values for CrI 64% and 71% and yield 12 and 70% in Cellulose and CNCs, respectively. Nanocomposites showed smaller permeability and the addition of 5 to 15% CNCs formed more opaque films and had improved tensile strength and Youngs modulus. The addition of CNCs from 5 to 15% proved to be effective in improving mechanical properties and decreasing water vapor permeability, important characteristics in food packaging materials. This study provided an effective method to obtain CNCs from the agroindustrial waste and open the way to produce high-value starch based nanocomposites.The authors are grateful for financial support provided by FAPERJ - Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro, Brazil (E-26.202749/2018), the National Council for Scientific and Technological Development – CNPq (311936/2018-0), and the Coordenação de Aperfeiçoamento Pessoal do Ensino Superior (CAPES). The support during transmission electron microscopy analyses provided by the LABNANO/CBPF is also very much appreciated.info:eu-repo/semantics/publishedVersio

Nanocomposites graphène-polymère thermoplastique: Fabrication et étude des propriétés structurales, thermiques, rhéologiques et mécaniques

The works of this thesis have helped contribute to the understanding and development of the physics and chemistry of materials. In this study, new high-performance thermoplastic polymer nanocomposites with enhanced structural, thermal and mechanical properties have been fabricated by using graphene, graphene oxide and modified carbon nanotubes as reinforcing nanofillers or nucleating agents. In the first time, Graphene nanosheets (GNs) have been obtained throughout the exfoliation of natural graphite by using an efficiency chemical route. Several characterizations techniques have confirmed that the GNs have been successfully formed in large quantity. The obtained graphene derivatives exhibit high structural quality with nanoscale thickness ranging between 0.95 and 1 nm and lateral dimensions of 0.1 to 1 μm. In the second time, we describe the fabrication by extrusion process of graphene-based nanocomposites by using the PP, HDPE and PVDF matrices. The effects of graphene content on the structural, thermal, mechanical and rheological properties were reported, and the obtained results were discussed in terms of morphology and state of dispersion and distribution of the graphene nanomaterial within the polymer matrices. Morphological characterizations of the nanocomposites have shown the graphene is well dispersed within the polymer matrices, with the presence of only few aggregates. Increasing GNs content resulted in a significant increase in both mechanical and thermal properties with only few percent of GNs loading. Rheological behavior of the as-prepared nanocomposites showed a Maxwellian-like behavior for low GNs concentrations and a viscoelastic solid-like behavior for GNs content exceeding the concentration of the percolation threshold (~1 %). The improvements obtained for selected properties of nanocomposites can broaden the scope of thermoplastic polymers Finally, two different fillers were separately used as nucleating agents of the peiezoelectricly active β-polymorph in the PVDF polymer. the first is the exfoliated graphene oxide nanosheets (GOn) that were obtained by exfoliation of bulk graphite oxide in DMF solvent via a sonication treatement and the second is the multi walled carbon nanotubes (CNTs) coated by a polymeric surfactant (Polyvinylpyrrolidone, PVP) that were obtained by sonification of CNTs in a aqueous solution in presence of PVP surfactant (CNTs-PVP). These nanomaterials (GOn and CNTs-PVP) exhibit high compatibility with the PVDF polymer due to the strong and specific interaction between carbonyl group (C=O) in GOn and CNTs-PVP surfaces and fluorine group (CF2) in PVDF. Nanocomposite films of PVDF/GOn and PVDF/CNTs-PVP were prepared via the solution casting method with various filler contents. Several techniques show that the both PVDF nanocomposite films exhibit a purely piezoelectric β-phase at low content of filler (0.1 wt%). Mechanical properties of the studied PVDF nanocomposite films were also largely affected by addition either GOn or CNTs-PVP. The flexible nanocomposite films obtained in this study at very low content of external nucleating agents can be used as active materials in the field of piezoelectric applications.Les travaux de cette thèse ont permis de contribuer à la compréhension et au développement de la physique et de la chimie des matériaux. Dans cette étude, des nouveaux nanocomposites polymères de hautes performances structurales, thermiques et mécaniques ont été fabriqués en utilisant le graphène, l'oxyde de graphène et les nanotubes de carbone modifiés comme nanocharges de renforcement ou des agents de nucléation. L'étude a porté, d'une part, sur des échantillons nanocomposites à matrices polypropylène (PP), polyéthylène haut densité (PEHD) et polyfluorure de vinylidène (PVDF) fabriqués par un procédé d'extrusion et d'autre part, sur des films nanocomposites à matrice PVDF fabriqués par un procédé de mélange en solution suivi par l'approche coulée-évaporation. Les nanofeuillets de graphène (NFG) et ceux d'oxyde de graphène (NFOG) ont été obtenus via l'exfoliation du graphite naturel en utilisant une méthode chimique. Des techniques de caractérisation expérimentales ont confirmé que les NFG et NFOG ont été bien formés en large quantité avec une haute qualité structurale, une épaisseur entre 0,95-1nm et des dimensions latérales entre 0,1 et 1μm. Les nanotubes de carbone (NTC) ont été fonctionnalisés par un surfactant polymérique, la polyvinylpyrrolidone (PVP), via le mécanisme d'adsorption physique, afin d'augmenter leur dispersion dans des solvants organiques et des matrices polymères. Les propriétés structurales (morphologie et propriétés rhéologiques), thermiques (stabilité thermique, comportement de cristallisation et de fusion), mécaniques (traction, flexion) des matrices sélectionnées (PP, HDPE et PVDF) ont été largement améliorées par l'addition de faibles fractions massiques des NFG (< 3%). Les améliorations obtenues au niveau des propriétés sélectionnées des nanocomposites peuvent étre élargir le champ d'application des polymères thermoplastiques. Des approches efficaces ont été développées afin de produire des films nanocomposites à matrice PVDF chargés par les nanofeuillets d'oxyde de graphène (NFOG) et les nanotubes de carbone modifiés (NTC/PVP). Ces films ont été fabriqués dans le cadre de contrôler la structure cristalline du PVDF et ce en terme de phase β (responsable de la piézoélectricité). Ainsi que des améliorations très significatives des propriétés mécaniques et thermiques ont été réalisées par l'addition de faibles fractions massiques de NFOG et NTC (< 2 %)