Search results for "H2"
showing 10 items of 600 documents
Physical Fundamentals of Biomaterials Surface Electrical Functionalization
2020
This article is focusing on electrical functionalization of biomaterial&rsquo
Biodegradable Polymers for the Production of Nets for Agricultural Product Packaging
2021
It is well known that the need for more environmentally friendly materials concerns, among other fields, the food packaging industry. This regards also, for instance, nets used for agricultural product (e.g., citrus fruits, potatoes) packaging. These nets are typically manufactured by film blowing technique, with subsequent slicing of the films and cold drawing of the obtained strips, made from traditional, non-biodegradable polymer systems. In this work, two biodegradable polymer systems were characterized from rheological, processability, and mechanical points of view, in order to evaluate their suitability to replace polyethylene-based polymer systems typically used for agricultural prod…
Improvements in aggregate-paste interface by the hydration of steelmaking waste in concretes and mortars
2019
[EN] The objective of the experimental work is to study the mechanical properties in self-compacting concretes (SCC) in which part of the limestone aggregate has been replaced by granulated blast furnace slag (GBFS) in different percentages ranging from 0% to 60%. The results show that at early ages the SCC with the largest content in slag tend to have lower compressive strengths due to the poor compacting of the aggregates, although in the long-term their strength increases due to the reactivity of the slag. In fact, at the age of 365 days, the mortars made with the substitution of 50% of cement by ground GBFS reach compressive strength similar to that of the mortar made with 100% of cemen…
Graphene Oxide Carboxymethylcellulose Nanocomposite for Dressing Materials.
2020
Sore, infected wounds are a major clinical issue, and there is thus an urgent need for novel biomaterials as multifunctional constituents for dressings. A set of biocomposites was prepared by solvent casting using different concentrations of carboxymethylcellulose (CMC) and exfoliated graphene oxide (Exf-GO) as a filler. Exf-GO was first obtained by the strong oxidation and exfoliation of graphite. The structural, morphological and mechanical properties of the composites (CMCx/Exf-GO) were evaluated, and the obtained composites were homogenous, transparent and brownish in color. The results confirmed that Exf-GO may be homogeneously dispersed in CMC. It was found that the composite has an i…
Experimental Characterization of the Properties of Double-Lap Needled and Hybrid Joints of Carbon/Epoxy Composites
2015
The effect of through-thickness reinforcement by thin 1 mm steel needles (z-pins) on the static tensile strength of double-lap joints of a carbon/epoxy composite was investigated. Two types of joints—z-pinned and hybrid (including glued ones)—were considered. The joints were reinforced in the overlap region with 9, 25, or 36 z-pins. Comparing mechanical properties of the double-lap joints with the corresponding characteristics of their unpinned counterparts, the z-pins were found to be highly effective: the strength and stiffness of the pinned joints increased up to 300% and 280%, respectively. These improvements were due to a transition in the failure mechanism from debonding of the joint …
Improvement in the performance of low temperature H2-O2 fuel cell with chitosanephosphotungstic acid composite membranes
2016
Abstract Free-standing chitosan/phosphotungstic acid polyelectrolyte membranes, prepared by ionotropic gelation on alumina porous supports, were employed as proton conductor in low temperature H 2 –O 2 fuel cell. A drying step on glass substrate was introduced in the fabrication procedure to reduce shrinkage and consequent corrugation. Membranes were tested with electrodes prepared according to different procedures and with two different Pt loadings, namely 0.5 and 1 mg cm −2 . Both the investigated kinds of electrodes allowed to get very promising power peaks of 550 mW cm −2 in spite of the different Pt content. The polarization curves and the electrochemical impedance spectra suggest that…
PBI mixed matrix hollow fiber membrane: Influence of ZIF-8 filler over H2/CO2 separation performance at high temperature and pressure
2020
High performance and commercially attractive mixed-matrix membranes were developed for H2/CO2 separation via a scalable hollow fiber spinning process. Thin (~300 nm) and defect-free selective layers were successfully created with a uniform distribution of the nanosized (~60 nm) zeolitic-imidazole framework (ZIF-8) filler within the polymer (polybenzimidazole, PBI) matrix. These membranes were able to operate at high temperature (150 °C) and pressure (up to 30 bar) process conditions required in treatment of pre-combustion and syngas process gas streams. Compared with neat PBI hollow fibers, filler incorporation into the polymer matrix leads to a strong increase in H2 permeance from 65 GPU t…
Geometric Analysis of Type B Aortic Dissections Shows Aortic Remodeling After Intervention Using Multilayer Stents
2020
Recently, multilayer stents for type B aortic dissections (TBAD) have been proposed to decrease false lumen flow, increase and streamline true lumen flow, and retain branch vessel patency. We aimed to provide a protocol with standardized techniques to investigate aortic remodeling of TBAD by multilayer flow modulators (MFM) in static geometric and hemodynamic analyses. Combining existing literature and new insights, a standardized protocol was designed. Using pre- and postoperative CT scans, geometric models were constructed, lumen dimensions were calculated, computational fluid dynamics (CFD) models were composed, and velocity and pressures were calculated. Sixteen TBAD cases treated with …
Phosphomolybdic acid and mixed phosphotungstic/phosphomolybdic acid chitosan membranes as polymer electrolyte for H2/O2 fuel cells
2017
Abstract Flat, free-standing phosphomolybdic acid and mixed phosphotungstic/phosphomolybdic acid chitosan membranes were prepared by in-situ ionotropic gelation process at room temperature on porous alumina support firstly impregnated by heteropolyacid. Scanning electron microscopy revealed the formation of compact and homogenous polymeric membranes, whose thickness resulted to be dependent on reticulation time, and almost independent on the employed heteropolyacid nature and concentration. X-ray diffraction and Fourier transform infrared spectroscopy evidenced the formation of crystalline membranes without appreciable concentration of unprotonated NH 2 groups and heteropolyacid ions with p…
Effect of Hydrogen and Absence of Passive Layer on Corrosive Properties of Aluminum Alloys
2020
This paper reports the results of research on the effect of hydrogen permeation and the absence of passive layers on the variations in the corrosive properties of aluminum alloys. The study demonstrated that such variations contribute to the deterioration of corrosive properties, which in turn contributes to shortening the reliability time associated with the operation of aluminum alloy structures. The analysis involved structural aluminum alloys: EN AW-1050A, EN AW-5754, and EN AW-6060. It was demonstrated that the absorption of hydrogen by the analyzed alloys led to the shift of the electrode potential to the negative side. The built hydrogen corrosion cells demonstrate in each case the f…