Toughening of a carbon-fibre composite using electrospun poly(Hydroxyether of Bisphenol A) nanofibrous membranes through inverse phase separation and inter-domain etherification

The interlaminar toughening of a carbon fibre reinforced composite by interleaving a thin layer (~20 microns) of poly(hydroxyether of bisphenol A) (phenoxy) nanofibres was explored in this work. Nanofibres, free of defect and averaging several hundred nanometres, were produced by electrospinning directly onto a pre-impregnated carbon fibre material (Toray G83C) at various concentrations between 0.5 wt % and 2 wt %. During curing at 150 °C, phenoxy diffuses through the epoxy resin to form a semi interpenetrating network with an inverse phase type of morphology where the epoxy became the co-continuous phase with a nodular morphology. This type of morphology improved the fracture toughness in mode I (opening failure) and mode II (in-plane shear failure) by up to 150% and 30%, respectively. Interlaminar shear stress test results showed that the interleaving did not negatively affect the effective in-plane strength of the composites. Furthermore, there was some evidence from DMTA and FT-IR analysis to suggest that inter-domain etherification between the residual epoxide groups with the pendant hydroxyl groups of the phenoxy occurred, also leading to an increase in glass transition temperature (~7.5 °C)

Self-healing dendrimers based on ionic or hydrogen-bonding supramolecular interactions

This PhD project dealt with the development and characterisation of a number of metallo and hydrogen-bonded supramolecular dendrimers for applications in the area of self-healing material

Assessing the temporal stability of surface functional groups introduced by plasma treatments on the outer shells of carbon nanotubes

Plasma treatments are emerging as superior efficiency treatment for high surface to volume ratio materials to tune functional group densities and alter crystallinity due to their ability to interact with matter at the nanoscale. The purpose of this study is to assess for the first time the long term stability of surface functional groups introduced across the surface of carbon nanotube materials for a series of oxidative, reductive and neutral plasma treatment conditions. Both plasma duration dose matrix based exposures and time decay experiments, whereby the surface energy of the materials was evaluated periodically over a one-month period, were carried out. Although only few morphological changes across the graphitic planes of the carbon nanotubes were found under the uniform plasma treatment conditions, the time dependence of pertinent work functions, supported by Raman analysis, suggested that the density of polar groups decreased non-linearly over time prior to reaching saturation from 7 days post treatment. This work provides critical considerations on the understanding of the stability of functional groups introduced across high specific surface area nano-materials used for the design of nano-composites, adsorptive or separation systems, or sensing materials and where interfacial interactions are key to the final materials performance

Surface treatment of PAN based carbon fibers with sulfonated octaphenyl POSS

The electrolytes usually used during electrolytic oxidation process in carbon fibre manufacturing are not environmentally friendly, as creates toxic gases and odors around the production site. In an effort to replace conventional electrolytes, sulfonated octaphenyl POSS (SOP-POSS) based on aqueous solution was used to treat the carbon fiber. IR and 1H NMR analysis confirmed the successful deposition of sulfonation of octaphenyl POSS. Inverse Gas Chromatography (IGC) surface energy changes suggested the removal of defect sites and flaws and better homogeneity in surface chemical activity after treatment. A significant increase in surface oxygen contents for both oxidised and unoxidised fibers was measured in the XPS data for SOP-POSS treated carbon fiber whilst the IGC results showed that similar level of surface polarity can be attained for SOP-POSS treated fibers compared to commercially available sized fibers. The thermodynamic work of adhesion, predicted from IGC surface energy data, showed stronger interaction after sufonation treatment, between the SOP-POSS and carbon fiber

Morphology-properties relationship of gas plasma treated hydrophobic meso-porous membranes and their improved performance for desalination by membrane distillation

The impact on performance of the surface energy and roughness of membrane materials used for direct contact membrane distillation are critical but yet poorly investigated parameters. The capacity to alter the wettability of highly hydrophobic materials such as poly(tetra-fluoro-ethylene) (PTFE) by gas plasma treatments is reported in this paper. An equally important contribution from this investigation arises from illustrating how vaporized material from the treated sample participates after a short while in the composition of the plasma and fundamentally changes the result of surface chemistry processes. The water contact angle across the hydrophobic membranes is generally controlled by varying the plasma gas conditions, such as the plasma power, chamber pressure and irradiation duration. Changes to surface porosity and roughness of the bulk material as well as the surface chemistry, through specific and partial de-fluorination of the surface were detected and systematically studied by Fourier transform infra-red analysis and scanning electron microscopy. It was found that the rupture of fibrils, formed during membrane processing by thermal-stretching, led to the formation of a denser surface composed of nodules similar to these naturally acting as bridging points across the membrane material between fibrils. This structural change has a profound and impart a permanent effect on the permeation across the modified membranes, which was found to be enhanced by up to 10% for long plasma exposures while the selectivity of the membranes was found to remain unaffected by the treatment at a level higher than 99.99%. This is the first time that an investigation demonstrates how the permeation characteristics of these membranes is directly related to data from spectral, morphological and surface charge analyses, which provide new insights on the impact of plasma treatments on both, the surface charge and roughness, of PTFE porous materials

Surface treatment of pan based carbon fibers with sulfonated octaphenyl poss

The electrolytes are heavily used during the electrolytic oxidation process in carbon fibre manufacturing, creates toxic gases and odors around the production site. In an effort to replace these electrolytes, sulfonated octaphenyl POSS (SOP-POSS) based on aqueous solution was used to treat the carbon fiber. IR and 1H NMR analysis confirmed the successful deposition of sulfonation of octaphenyl POSS. Inverse Gas Chromatography (IGC) surface energy changes suggested the removal of defect sites and flaws and better homogeneity in surface chemical activity after treatment. A significant increase in surface oxygen contents for both oxidised and unoxidised fibers was measured in the XPS data for SOP-POSS treated carbon fiber whilst the IGC results showed that similar level of surface polarity can be attained for SOP-POSS treated fibers compared to commercially available sized fibers. The thermodynamic work of adhesion, predicted from IGC surface energy data, showed stronger interaction after sufonation treatment, between the SOP-POSS and carbon fiber

Characteristics and care of chronic hepatitis C treated with direct-acting antivirals in migrants

BACKGROUND AND AIMS: Hepatitis C is poorly documented in migrants. The published studies mainly concern the screening in this population and are limited to some countries in Europe and North America. This study aimed to evaluate the characteristics and care of chronic hepatitis C in this population compared to the nonmigrant population, in the era of direct-acting antivirals (DAAs). METHOD: We performed a retrospective analysis based on data presented at the multidisciplinary team meetings of our tertiary care center between 2015 and 2019. RESULTS: We included 277 migrant- and 1390 nonmigrant patients mono-infected with hepatitis C virus (HCV) and treated with DAAs. The majority of the migrants were from Eastern European countries. In multivariable analysis, BMI classes associated with more obesity (OR = 1.84; 95% CI, 1.37-2.49; P < 0.001) and therapeutic patient education (OR = 3.91; 95% CI, 2.38-6.49; P < 0.001) were positively associated with migrant status, whereas age (OR = 0.92; 95% CI, 0.90-0.94; P < 0.001), female gender (OR = 0.46; 95% CI, 0.28-0.74; P = 0.002), modes of contamination with less drug use, transfusion history or nosocomial risk, as well more unknown mode (OR = 0.70; 95% CI, 0.50-0.96; P = 0.031), alcohol consumption (OR = 0.48; 95% CI, 0.29-0.73; P = 0.001), types of structures with less care in a general hospital or health network of general practitioners and more care in a university hospital or primary addictology center (OR = 0.78; 95% CI, 0.60-0.99; P = 0.046) and opioid substitution therapy (OR = 0.25; 95% CI, 0.08-0.68; P = 0.008) were negatively associated with migrant status. The substained virologic response 12 was close to 97% in both groups. CONCLUSION: Despite multiple differences in characteristics and therapeutic care between the two populations, the chances of healing hepatitis C were the same among migrant- compared with nonmigrant patients

Psychiatric disorders and hepatitis C treated with direct-acting antivirals in a French reference center

HCV can cause psychiatric disorders. It is crucial to re-evaluate them with direct-acting antiviral treatment (DDAs), since the interferon-based treatments of the past were capable of causing identical psychiatric adverse effects. A system of multidisciplinary team (MDT) meetings was implemented in France in December 2014 in regional reference centers with the aim of controlling the prescription and administration of these new treatments, along with optimizing how the patients undergoing these treatments are followed up. Our study sought to compare the characteristics and type of medical care received for chronic hepatitis C in patients with (PSY+ group) and without (PSY- group) psychiatric disorders using data from MDT meetings in the Alsace area of France collected from 2015 to 2019.All included patients were mono-infected and treated with DAAs in successive rounds between 2015 and 2019, as per recommendations from the French Hepatology Society. We compared the two groups (PSY+ and PSY-) based on 21 variables regarding the characteristics and medical care of hepatitis C.Psychiatric disorders were observed in 15% of patients. On multivariate analysis, a positive correlation was found between them and drug use (OR: 2.35; 95%CI: 1.40-3.98; p=0.001), excessive alcohol consumption (OR: 1.92; 95%CI: 0.98-3.69; p=0.05), smoking (OR: 1.81; 95%CI: 1.09-2.98; p=0.02), and incidence of drug interactions (OR: 3.94; 95%CI: 2.15-7.17; p <0.001). The only negative correlation found was with pangenotypic DAA administration (OR: 0.55; 95%CI: 0.32-0.92; p=0.02). SVR 12 was 98.05% in the PSY+ group, not significantly different from that of the PSY- group.All in all, the psychiatric disorders observed in patients suffering from chronic hepatitis C are primarily associated with using psycho-active substances, with no impact on SVR 12 rates