1,721,007 research outputs found
Fatigue and Izod impact performance of carbon plain weave textile reinforced epoxy modified with cellulose microfibrils and rubber nanoparticles
No full textThis work details an experimental investigation on understanding the effects of hybrid epoxy resins, filled with micro-fibrillated cellulose (MFC) and carboxylated nitrile-butadiene rubber nanoparticles (XNBR), on the tensile–tensile fatigue performance of carbon plain weave textile reinforced composites. Twelve combinations of MFC and XNBR weight contents in the epoxy resin (from 0% to 0.5% MFC and from 0% to 3% XNBR) were considered for preliminary quasi-static tests and five of them were selected to study the fatigue behaviour considering different loading levels. Moreover, the effect of the twelve fillers contents was observed on the Izod impact strength. The investigation finds that the best fatigue performance, for the considered weight contents of fillers, is of the composite enhanced with the maximum content of MFC. The SEM observations of the fracture surfaces indicate the extensive ‘‘plastic” deformation of the matrix and the improved fibre and matrix adhesion
Cement mortar reinforced with reclaimed carbon fibres, CFRP waste or prepreg carbon waste
No full textThis experimental investigation deals with the effects of reclaimed carbon fibres (RCF), carbon fibre reinforced polymer (CFRP) waste, and prepreg carbon waste (PW) of different contents on the mechanical properties of Portland cement mortar. The mechanical properties of reinforced cement mortars were measured by bending, compression and fracture toughness tests. Moreover, the shrinkage behaviour was observed by restrained drying shrinkage test. The influences of dispersing agent and additives for cement, including mineral and chemical admixtures, were evaluated for a total of 18 different combinations
Carbon plain weave textile reinforced epoxy modified with cellulose nano fibers: effect of CNF length
No full textThe present investigation gives a contribution on understanding the effects of hybrid epoxy resins, enhanced with cellulose nano fibers (CNF), on the mechanical performance of carbon fibers plain weave textile composites. The experimental investigation considered two lengths of CNF for the same weight content (0.3%) in the epoxy resin. The effects on the mechanical performance, compared to the composite with pure resin counterpart, were assessed with: quasi-static tensile and bending loading. Moreover, bending and tensile cyclic loading, for some stress levels, were supposed to detect advantages of the hybrid resin in extending the fatigue life of the textile composite. The results show slight variations of the quasi-static properties and a considerable extension of the fatigue life mainly when the longer CNF are considered
Thermoplastic vs. thermoset epoxy carbon textile composites
No full textThe main advantage of thermoplastic resins compared to thermoset counterpart are: increased toughness, better recyclability, and mainly the ability to deliver fast manufacturing processes. However, available thermoplastic resins (TP) have higher melt viscosity than thermoset ones. Due to high viscosity, the infusion process with conventional thermoplastic resins could lead to inappropriate impregnation of the fiber bundles. Recently, a thermoplastic epoxy resin (TP-EP) was developed with both advantages of thermoset and thermoplastic resins. The TP-EP couples the workability of thermoset, formability and recyclability of thermoplastic. The purpose of the present research is to comparatively assess the mechanical features of thermoplastic and thermoset epoxy carbon textile composites. As main outcome, the composite with highly polymerized thermoplastic epoxy has better mechanical performance than the conventional thermoset epoxy textile composite
The effect of microfibrils cellulose modified epoxy on the quasi-static and fatigue behaviour of open hole carbon textile composites
No full textThe extensive experimental investigation aimed to assess the effects of hybrid epoxy resin with micro-fibrillated cellulose on tensile quasi-static and fatigue behaviour of open hole carbon plain weave composites. The hybridization of the matrix allowed an improved damage tolerance of the composite leading to increase of the quasi-static tensile strength and extension of the fatigue life. The enhanced mechanical performance of the notched composites was connected to the bridging effect of cellulose microfibrils preventing or delaying the cracks propagation in the matrix and along the fibres interface. The better distribution of the stress state was assessed by digital image correlation strain maps around the hole and the imparted fatigue damage was analysed by scanning electron microscope and X-ray micro-computed tomography visualizations
Quasi-static and fatigue performance of carbon fibre reinforced highly polymerized thermoplastic epoxy
No full textThe experimental investigation aimed to understand the effect of the weight-average molecular weight of thermoplastic epoxy matrix on the quasi-static and fatigue properties of carbon fibre textile reinforced composites. The first part is dedicated to the assessment of the effect on the fibre and matrix adhesion by three scale measurements: single fibre and matrix (micro scale); single yarn and matrix (meso scale); laminate (macro scale). The positive effects at macro scale of the highly polymerised matrix are detailed in the second part considering quasi-static and fatigue tensile loadings. The composite with highly polymerised thermoplastic epoxy matrix showed an improvement of the tensile strength, a better capacity to uniformly distribute the stress/strain state and a considerable enhancement of the fatigue life
Improvement of Bending Strength of Carbon Fiber/Thermoplastic Epoxy Composites <br/>—Effects of Molecular Weight of Epoxy on Carbon Fiber/Matrix Interfacial Strength and Connection of Cracks in Matrix
Get PDFThe bending strength of carbon fiber/thermoplastic epoxy composites (CF/TP-EP Compo.) had bi-linear increase with increase of weight-average molecular weight (Mw) of matrix. The transition in the bending strength appeared at around 55k of Mw (“k” means 103). SEM observation of fractured surface of CF/TP-EP Compo. showed that the fracture mode changed from interfacial failure to fiber breakage dominated failure. The smooth surface of carbon fibers appeared at lower Mw than 55k while some resin remained on the fibers indicating good adhesion between carbon fiber and matrix at higher Mw than 55k. The interfacial shear strength between carbon fiber and matrix bi-linearly increased with an increase of Mw similarly to the bending strength of the composite, measured by the micro droplet test. The dynamic loss tanδ of the matrix measured at 2 Hz also showed a bi-linear relationship with respect to Mw having a knee point at Mw = 55k. The connection probability of two cracks introduced on each side of specimens also confirmed that the interfacial strength between carbon fiber and matrix is the key for the mechanical performance of CF/TP-EP Compo. in bending
High pressure strength of carbon fibre reinforced vinylester and epoxy vessels
No full textHigh pressure vessels with winding lamination of [90/±15] were manufactured adopting a vinylester and an epoxy resin reinforced with carbon fibres. An experimental setup was design to test the vessels up to the burst pressure. The tests results demonstrate a higher ultimate pressure of the carbon/vinylester composite vessel with respect to the epoxy reinforced counterpart. The full field strain measurements by the digital image correlation technique show a delayed of the initiation and propagation of the damage in the carbon/vinylester. Moreover, the carbon/vinylester vessel performed more homogeneous strain distribution with less and shorter hoop cracks than the carbon/epoxy one, as observed also with an X-ray micro tomography system, a laser microscope and a scanning electron microscope
Carbon fiber textile composites using highly-polymerized thermoplastic epoxy: effect of molecular weight of epoxy on the mechanical performance of composites
No full textThe purpose of this study is to reveal the effect of resin molecular weight on the mechanical properties of carbon fabric reinforced thermoplastic epoxy composites (CFRTP). An extensive experimental campaign allowed understanding the influence of the thermoplastic resin with weight-average molecular weight (Mw) ranging from 14,000 to 117,000. Different loading conditions were applied, including quasi-static and cyclic three point bending and tensile loadings. Moreover, fiber-matrix adhesion and interlaminar fracture toughness were measured by micro-droplet and End Notched Flexure (ENF) mode II fracture tests. The mechanical responses highlighted the considerable improvements of the composite performances for thermoplastic epoxy with high polymerization (high molecular weight). It is also shown that an excessive polymerization, greater than 60,000 Mw, is not necessary for composite performance
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