Search results for "Hybrid composite"
showing 10 items of 24 documents
Wet electrospinning-aided self-assembly of multifunctional GO-CNT@PCL core-shell nanocomposites with spider leg bioinspired hierarchical architectures
2022
We report a fast route enabling the multiscale design of nanohybrid structures comprising a 3D fibrous network of polycaprolactone (PCL) wrapped by graphene oxide (GO) sheets onto which carbon nanotube (CNT) brushes are anchored. The method relies on electrospinning PCL solutions onto a suspension of GO and CNTs in ethanol. Self-assembly is due to electrostatic wrapping of GO sheets around PCL fibers and 7C-7C stacking between GO and CNTs. Hierarchical architecture and nanopatterned surface allow gathering the starting properties of PCL, GO and CNTs into lightweight (99% porosity) yet robust (1575% stiffness improvement), amphiphilic monoliths that can remove methylene blue and/or methyl or…
Assessment of performance degradation of hybrid flax-glass fiber reinforced epoxy composites during a salt spray fog/dry aging cycle
2022
The main goal of this paper is the evaluation of the performances reversibility of hybrid composites when they are dried after being aged in salt-fog environment. To this aim, epoxy composites reinforced with flax and glass fabrics respectively in the internal and external laminae were at first exposed to salt-fog (i.e., identified as wet phase) and then stored in controlled conditions (i.e., identified as dry phase). The flexural properties evolution of these composites as well as their water uptake and contact angle were monitored at varying time of both phases. The flexural strength and modulus of hybrid composites is 23.4% (17.9%) and 15.5% (12.9%) lower than unaged ones after 30 (15) d…
Benchmarking of strength models for unidirectional composites under longitudinal tension
2018
© 2018 Elsevier Ltd Several modelling approaches are available in the literature to predict longitudinal tensile failure of fibre-reinforced polymers. However, a systematic, blind and unbiased comparison between the predictions from the different models and against experimental data has never been performed. This paper presents a benchmarking exercise performed for three different models from the literature: (i) an analytical hierarchical scaling law for composite fibre bundles, (ii) direct numerical simulations of composite fibre bundles, and (iii) a multiscale finite-element simulation method. The results show that there are significant discrepancies between the predictions of the differe…
Interaction of Gold with Co-Condensed and Grafted HMS-SH Silica: A 29Si {1H} CP-MAS NMR Spectroscopy, XRD, XPS and Au LIII EXAFS Study
2010
Hexagonal mesoporous silica (HMS) is functionalised with mercaptopropyl groups by adopting two different procedures ; co-condensation and grafting. In both cases tetraethylorthosilicate (TEOS) and 3-mercaptopropyltriethoxysilane (3-MPTES) are used as the silicon and sulfur precursors, respectively. The obtained materials are analysed by several techniques such as N 2 sorption, TG-DTA, XRD, SAXS and-solid state 29 Si { 1 H} CP-MAS NMR spectroscopy. By taking advantage of the chemical interaction between gold and the -SH groups, the effect of the thiol addition procedure on the supporting capability of the functionalised silica is evaluated by depositing gold through the incipient wet impregn…
Flax–Glass Fiber Reinforced Hybrid Composites Exposed to a Salt-Fog/Dry Cycle: A Simplified Approach to Predict Their Performance Recovery
2023
Despite natural fibers gaining significant attention in recent decades, their limited performance and poor durability under humid environments cannot allow them to fully replace their synthetic counterparts as reinforcement for structural composites. In such a context, this paper aims to investigate how exposure to a humid/dry cycle affects the mechanical response of epoxy laminates reinforced with flax and glass fibers. In particular, the main goal is to assess the performance evolution of a glass–flax hybridized stacking sequence in comparison with the full glass and flax fiber reinforced composites. To this end, the investigated composites were first exposed to salt-fog for 15 or 30 days…
Durability of flax-basalt hybrid composites for marine applications
2015
The aim of the present work is to evaluate the influence of external layers of mat basalt on the durability behaviour and performances of flax/epoxy laminates. To this scope, long-term aging tests were performed to evaluate the durability of the two different laminates in critical environmental conditions. In particular, Flax composites were constituted by ten layers of bidirectional flax fabric whereas hybrid laminates (i.e. Flax-Basalt) were produced by replacing four external layers of bidirectional flax with four layers of basalt mat. Both laminates had a total average thickness equal to 3 mm. The samples were exposed to critical environmental conditions following the ASTM B 117 standar…
First lamina hybridization of high performance CFRP with Kevlar fibers: Effect on impact behavior and nondestructive evaluation
2022
The impact behavior of a carbon-Kevlar hybrid composite, widely used in sport car manufacturing, was evaluated. To highlight the hybridization effect, comparative analyses were performed with the basic CFRP laminate having the same lay-up. Tensile, bending and low velocity impact tests, followed by nondestructive inspections, highlighted that Kevlar first lamina hybridization leads to an increment in specific impact strength, up to 55%. To assess the most reliable technique to detect the impact damage, nondestructive evaluation was performed by pulsed thermography, phased array ultrasonic technique, computed tomography and digital radiography. Phased array ultrasonic technique can be consid…
A simplified predictive approach to assess the mechanical behavior of pinned hybrid composites aged in salt-fog environment
2020
Abstract Aim of this paper is to assess the predictive capabilities of a simplified theoretical approach on the failure load of aged pinned hybrid composites. In particular, the mechanical performances of glass-flax hybrid epoxy laminates exposed to salt spray fog environment, were used as input data in order to address the analytical model. Preliminarily, the relationship among mechanical performances, failure mechanisms, joint geometry and ageing time, was evaluated by double-lap joint tests on pinned samples at varying joint geometry and ageing time. The bearing and shear out limit stress of samples aged for 60 days under the salt-fog environment underwent a reduction of about 20% compar…
Fracture strength of endodontically treated lateral incisors restored with new zirconia reinforced rice husk nanohybrid composite
2020
Background This study aimed to compare the fracture strength, fracture pattern and type of fracture of endodontically treated maxillary lateral incisors restored with new zirconia reinforced rice husk nanohybrid composite. Material and Methods Eighty mature permanent maxillary lateral incisors from patients age range of 30-60 years with single canal were selected and randomly divided into: Group 1 – RCT + nanofilled composite (Filtek), Group 2 – RCT + microhybrid composite (Zmack), Group 3 – RCT + new nanohybrid composite (Zr-Hybrid) and Group 4 - Intact teeth (control). Standardized mesio-palatal-distal cavity was prepared, and endodontic treatment was carried out using crown-down techniqu…
Exceptional affinity of nanostructured organic-inorganic hybrid materials towards dioxygen: confinement effect of copper complexes
2007
We report the exceptional reactivity towards dioxygen of a nanostructured organic-inorganic hybrid material due to the confinement of copper cyclam within a silica matrix. The key step is the metalation reaction of the ligand, which can occur before or after xerogel formation through the sol-gel process. The incorporation of a Cu(II) center into the material after xerogel formation leads to a bridged Cu(I)/Cu(II) mixed-valence dinuclear species. This complex exhibits a very high affinity towards dioxygen, attributable to auto-organization of the active species in the solid. The remarkable properties of these copper complexes in the silica matrix demonstrate a high cooperative effect for O(2…