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This study evaluated the effect of multi‐walled carbon nanotubes (MWCNT) addition on the thermomechanical, and electrical responses of unidirectional flax fibers/Elium acrylic modified carbon nanotubes‐based composite. The manufacturing process of these laminated composites involved infusing the nanofillers onto the fibers, ensuring good dispersion of MWCNT within the matrix. Regardless of the rate of incorporated nanotubes, this study revealed a significant deterioration of the mechanical properties in tension and viscoelastic properties of the Elium acrylic resin‐based nanocomposite. The electrical conductivity significantly increased for all nanocomposites and laminated composites. In contrast to the nanocomposite, the unidirectional flax fibers/MWCNT/Elium acrylic composite exhibited a considerable improvement in mechanical properties. An increase in Young's modulus and stress at break of about 27% and 23% respectively, was achieved for the material loaded with 2 wt% of MWCNT. The presence of MWCNT reduces the saturation weight by 5% for the unidirectional composite filled with an amount of 1.5 wt% in MWCNT. Highlights: Improving the electrical properties of nanocomposites and unidirectional fibers (UD) composites.Improving the mechanical properties of Elium/flax/multi‐walled carbon nanotubes (MWCNT) composites.Influence of MWCNTs on the water absorption of UD composites.Influence of MWCNT on the glass transition temperature of nanocomposites.Inhibiting polymerization of MWCNT with Elium. [ABSTRACT FROM AUTHOR]

Graphene materials exhibit extraordinary properties, but are difficult to produce. The present work describes the possibility of using a plasma process to exfoliate and functionalize graphite flakes. An impulse plasma phase is generated at a liquid surface to produce chemical species and shock waves in order to modify the reactive liquid as well as the graphite flakes. With this process, industrial graphite was treated. 20% thickness diminution was observed, and the formation of a random turbostratic structure. The exfoliation occurs with small amount of functionalization of the surface. Even after treatment, the graphite flakes present a low defect density compared with other treated graphite obtained by more conventional chemical treatments. This process is a new way to exfoliate graphite and to produce functionalized graphenic materials.

The structure of self-reinforced composites (SRCs) based on ultra-high molecular weight polyethylene (UHMWPE) was studied by means of Wide-Angle X-ray Scattering (WAXS), X-ray tomography, Raman spectroscopy, Scanning Electron Microscopy (SEM) and in situ tensile testing in combination with advanced processing tools to determine the correlation between the processing conditions, on one hand, and the molecular structure and mechanical properties, on the other. SRCs were fabricated by hot compaction of UHMWPE fibers at different pressure and temperature combinations without addition of polymer matrix or softener. It was found by WAXS that higher compaction temperatures led to more extensive melting of fibers with the corresponding reduction of the Herman's factor reflecting the degree of molecular orientation, while the increase of hot compaction pressure suppressed the melting of fibers within SRCs at a given temperature. X-ray tomography proved the absence of porosity while polarized light Raman spectroscopy measurements for both longitudinal and perpendicular fiber orientations showed qualitatively the anisotropy of SRC samples. SEM revealed that the matrix was formed by interlayers of molten polymer entrapped between fibers in SRCs. Moreover, in situ tensile tests demonstrated the increase of Young's modulus and tensile strength with increasing temperature.

The regeneration of bone-soft tissue interface, using functional membranes, remains challenging and can be promoted by improving mesenchymal stem cells (MSCs) paracrine function. Herein, a collagen membrane, used as guided bone regeneration membrane, was functionalized by calcium phosphate, chitosan and hyaluronic acid hybrid coating by simultaneous spray of interacting species process. Composed of brushite, octacalcium phosphate and hydroxyapatite, the hybrid coating increased the membrane stiffness by 50%. After 7 days of MSCs culture on the hybrid coated polymeric membrane, biological studies were marked by a lack of osteoblastic commitment. However, MSCs showed an enhanced proliferation along with the secretion of cytokines and growth factors that could block bone resorption and favour endothelial cell recruitment without exacerbating polynuclear neutrophils infiltration. These data shed light on the great potential of inorganic/organic coated collagen membranes as an alternative bioactive factor-like platform to improve MSCs regenerative capacity, in particular to support bone tissue vascularization and to modulate inflammatory infiltrates., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The control over the crystallinity of chitosan and chitosan/ovalbumin films can be achieved via an appropriate balance of the hydrophilic/hydrophobic interactions during the film formation process, which then controls the release kinetics of ovalbumin. Chitosan films were prepared by solvent casting. The presence of the anhydrous allomorph can be viewed as a probe of the hydrophobic conditions at the neutralization step. The semicrystalline structure, the swelling behavior of the films, the protein/chitosan interactions, and the release behavior of the films were impacted by the DA and the film processing parameters. At low DAs, the chitosan films neutralized in the solid state corresponded to the most hydrophobic environment, inducing the crystallization of the anhydrous allomorph with and without protein. The most hydrophilic conditions, leading to the hydrated allomorph, corresponded to non-neutralized films for the highest DAs. For the non-neutralized chitosan acetate (amorphous) films, the swelling increased when the DA decreased, whereas for the neutralized chitosan films, the swelling decreased. The in vitro release of ovalbumin (model protein) from chitosan films was controlled by their swelling behavior. For fast swelling films (DA = 45%), a burst effect was observed. On the contrary, a lag time was evidenced for DA = 2.5% with a limited release of the protein. Furthermore, by blending chitosans (DA = 2.5% and 45%), the release behavior was improved by reducing the burst effect and the lag time. The secondary structure of ovalbumin was partially maintained in the solid state, and the ovalbumin was released under its native form.

The electrodeposition of hydrogels provides a programmable means to assemble soft matter for various technological applications. We report an anodic method to deposit hydrogel films of the aminopolysaccharide chitosan. Evidence suggests the deposition mechanism involves the electrolysis of chloride to generate reactive chlorine species (e.g., HOCl) that partially oxidize chitosan to generate aldehydes that can couple covalently with amines (presumably through Schiff base linkages). Chitosan's anodic deposition is controllable spatially and temporally. Consistent with a covalent cross-linking mechanism, the deposited chitosan undergoes repeated swelling/deswelling in response to pH changes. Consistent with a covalent conjugation mechanism, proteins could be codeposited and retained within the chitosan film even after detergent washing. As a proof-of-concept, we electroaddressed glucose oxidase to a side-wall electrode of a microfabricated fluidic channel and demonstrated this enzyme could perform electrochemical biosensing functions. Thus, anodic chitosan deposition provides a reagentless, single-step method to electroaddress a stimuli-responsive and biofunctionalized hydrogel film.