Plastique à renfort de verre | EPFL Graph Search

Un plastique à renfort de verre (ou Polyester Renforcé de fibres de Verre ou Polymère Renforcé aux fibres de Verre, symbolisé habituellement par ses initiales PRV ; en anglais, glass-reinforced plastic ou GRP) est un matériau composite constitué d’une matrice polymère (appelée résine) renforcée par des fibres ou parfois par des microsphères de verre. La résine est généralement un polyester thermodurcissable, un époxyde, un vinylester ou thermoplastique (polyamide, par exemple). Ses propriétés de résistance (mécanique, chimique) et sa densité sont très favorables, comparé aux métaux. Les renforts en verre (fibres, tissus, mats) sont très utilisés et très bon marché, comparés à la fibre de carbone. Ces matériaux trouvent un usage dans de nombreux secteurs : automobile, marine, matériaux de construction, aéronautique, aérospatiale, équipements résistants à la corrosion (tels réservoirs, récipients, tuyaux) Glass reinforcements.jpg|Diverses présentations de [[verre]] utilisées comme r

Recycled Glass Fiber Composites from Wind Turbine Waste for 3D Printing Feedstock: Effects of Fiber Content and Interface on Mechanical Performance

Kazem Fayazbakhsh, Rodolphe Henri

This research validates the viability of a recycling and reusing process for end-of-life glass fiber reinforced wind turbine blades. Short glass fibers from scrap turbine blades are reclaimed and mixed with polylactic acid (PLA) through a double extrusion process to produce composite feedstock with recycled glass fibers for fused filament fabrication (FFF) 3D printing. Reinforced filaments with different fiber contents, as high as 25% by weight, are extruded and used to 3D print tensile specimens per ASTM D638-14. For 25 wt% reinforcement, the samples showed up to 74% increase in specific stiffness compared to pure PLA samples, while there was a reduction of 42% and 65% in specific tensile strength and failure strain, respectively. To capture the level of impregnation of the non-pyrolyzed recycled fibers and PLA, samples made from reinforced filaments with virgin and recycled fibers are fabricated and assessed in terms of mechanical properties and interface. For the composite specimens out of reinforced PLA with recycled glass fibers, it was found that the specific modulus and tensile strength are respectively 18% and 19% higher than those of samples reinforced with virgin glass fibers. The cause for this observation is mainly attributed to the fact that the surface of recycled fibers is partially covered with epoxy particles, a phenomenon that allows for favorable interactions between the molecules of PLA and epoxy, thus improving the interface bonding between the fibers and PLA.

2019

Translucent load-bearing GFRP envelopes for daylighting and solar cell integration in building construction

Carlos Pascual Agullo

This project investigates the light transmittance of load-bearing glass fiber-reinforced polymer (GFRP) laminates with a view to two architectural applications: the daylighting of buildings through load-bearing translucent GFRP envelopes and encapsulation of solar cells into the GFRP building skins of sandwich structures. The total and diffuse visible light transmittances of the laminates were experimentally investigated using a spectrophotometer coupled to an integrating sphere. The refractive indices of polymeric resin and glass fibers were also investigated and numerical ray-tracing simulations were performed to demonstrate the experimentally observed wavelength dependency of light diffusion. The total transmittance and translucency of GFRP laminates were analytically modeled as a function of the reinforcement weight, fiber architecture and fiber volume fraction. Goniophotometric experiments – performed to investigate the directional light scattering of laminates reinforced with different fiber architectures – were demonstrated as an effective method to predict the fiber architecture of translucent GFRP laminates. The optical properties of the laminates, i.e. the total and diffuse transmittances and directionality of light diffusion, were correlated with the experimentally investigated mechanical properties, i.e. the directional tensile strength and E-modulus. The experimental work demonstrated that structural skylights could be designed with GFRP laminates exhibiting a translucency of 0.9 and total light transmittance of 0.5 – minimum values recommended for daylighting of buildings through translucent envelopes – and that solar cells could be encapsulated in load-bearing GFRP laminates with a total light transmittance of around 0.83. A case study was performed using the GFRP/polyurethane sandwich roof of the Novartis Campus Main Gate Building to demonstrate the basic feasibility of integrating skylights and solar cells into the external translucent skin of optimized sandwich structures. Finally, the encapsulation of transparent and colored dye solar cells in translucent GFRP laminates has been explored. Prototype solar panels have been fabricated and a significant weight reduction, increase in structural strength and around 10% reduction of electrical efficiency compared to traditional solar panels with glass encapsulants were achieved.

EPFL2014

Engineering of PEM-PEC photocathodes for solar-driven hydrogen production

Marina Caroline Michèle Caretti

Earth has always been in perpetual evolution, but today we must face its rapid change due to human activity. The intensification of industrial activities and transportation to support our modern lifestyles are the main causes of climate change and the adverse effects on the fauna and flora. In spite of this, the planet has shown resilience and should be able, if the conditions allow, to maintain its balance. Our energy system is at the heart of the transformation we must undertake. To lessen our impact on the environment, we must consider the end of fossil fuels, the main source of greenhouse gas emissions. The immense amount of solar energy which reaches the Earth's surface would be more than enough to meet the world's energy needs, provided that we master its capture and overcome its intermittency. The storage of this energy in solar fuel such as hydrogen is a solution to meet the challenge of intermittent light. Hydrogen can be produced by splitting water molecules into hydrogen and oxygen under the effect of an electric current. Various methods such as proton exchange membrane (PEM) electrolysis can be coupled with solar energy conversion systems to produce carbon-free hydrogen. These technologies are still in their infancy; therefore, their evaluation is a key issue for future energy challenges.The research work presented in this thesis deals with the engineering of a proton exchange membrane photoelectrochemical cell (PEM-PEC) to produce hydrogen from moist air and solar energy. A new porous electrode support combining transparency and electrical conduction has been created. The use of this novel transparent, porous, conductive support (TPCS) for photoelectrode was demonstrated by depositing an n-type semiconductor (hematite, a-Fe2O3) to produce oxygen by solar-assisted water splitting. The hematite-TPCS electrode exhibited a photocurrent of 1.6 mA.cm-2 at 1.6 V vs. RHE (reversible hydrogen electrode). For the photocathode portion different p-type semiconductor layers were studied; first on flat conductive glass and later on the TPCS. Tungsten diselenide (WSe2) nanoflakes produced by liquid phase exfoliation were coated by electrophoretic deposition. Furthermore, an in-situ electro-conversion to form copper oxide (Cu2O) was identified, allowing for production of thin and transparent layers. Subsequently, p-type semiconductor layers (WSe2, Cu2O, organic semiconductors) were deposited on the TPCSs and their photoactivity in liquid media was evaluated. The organic semiconductor was selected based on the ease of implementation and the promising results obtained for the photoreduction of europium in liquid phase, ca. -4.5 mA.cm-2 at 0 V vs. RHE. After Pt catalyst coating, the organic semiconductor based TPCS was tested for hydrogen production in liquid media, exhibiting a photocurrent ca. -1 mA.cm-2 at 0 V vs. RHE. After the implementation in a half PEM-PEC cell for hydrogen production in the gas phase, a photocurrent of -120 µA.cm-2 at 0 V vs. RHE was sustained (i.e., 1 µmol.h-1of H2) for 1 hour.