The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
M C S Ribeiro - One of the best experts on this subject based on the ideXlab platform.
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Mechanical Behaviour Analysis of Polymer Mortars Reinforced with Jute and Piassava Natural Fibres under Alkaline Environments
Materials Science Forum, 2020Co-Authors: M C S Ribeiro, Jordanna C. Vogt, António Torres Marques, António J.m. FerreiraAbstract:The aim of this work is to assess the feasibility of using Polymer mortars reinforced with untreated natural fibres instead of artificial ones, for applications requiring highly alkali resistant materials, such as tanks and drainage systems for wastewater treatment plants. For this purpose, several formulations of Polyester Polymer mortars reinforced with different contents of jute and piassava natural fibres were investigated. Flexural and compressive behaviour, before and after exposure to a strong alkaline solution was analysed and quantified. Test results highlighted the high potential of these materials as basis construction material for precast applications requiring specific resistance under alkaline environments.
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Mechanical behaviour analysis of Polyester Polymer mortars reinforced with tire rubber fibres
Ciência & Tecnologia dos Materiais, 2020Co-Authors: S. P. B. Sousa, M C S Ribeiro, E. M. Cruz, Gonzalo Martinez Barrera, António J.m. FerreiraAbstract:Abstract Tires effective reutilization has become an important research topic in recent years due to the stockpiles increase that creates environmental problems. Recent European regulations forbid the tires burning and landfilling, setting several recycling objectives. Within this context, the reutilization of tire rubber recyclates into cement and Polymer concrete materials, as reinforcement or aggregate replacement, has received lately a great attention. The present work aim is to analyse the modifications induced by tire rubber addition in the mechanical properties of Polyester based Polymer mortars (PM). The effect of different tire rubber fibre amounts (0.1, 0.4 and 0.5 wt.%) were analysed in this investigation. Plain Polymer mortar was also prepared for comparison. Mechanical behaviour of both reinforced and plain Polymer mortars formulations was assessed by flexural and compressive tests. Flexural and compressive strength improvements were particularly significant for PM trial formulation reinforced with the higher amount of tire rubber fibres. The observed trend on mechanical properties seems to indicate that higher increases could be achieved with higher amounts of tire rubber fibres. Thus, further experiments will be required in order to determine the critical amounts of rubber fibre reinforcement that define the turning points on material trend behaviour of PM.
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mix design process of Polyester Polymer mortars modified with recycled gfrp waste materials
Composite Structures, 2013Co-Authors: M C S Ribeiro, Antonio Fiuza, Ana Castro, F J G Silva, M L Dinis, Joao Paulo Meixedo, Mario Rui AlvimAbstract:Abstract In this study, the effect of incorporation of recycled glass fibre reinforced plastics (GFRP) waste materials, obtained by means of shredding and milling processes, on mechanical behaviour of Polyester Polymer mortars (PM) was assessed. For this purpose, different contents of GFRP recyclates, between 4% up to 12% in weight, were incorporated into Polyester PM materials as sand aggregates and filler replacements. The effect of the addition of a silane coupling agent to resin binder was also evaluated. Applied waste material was proceeding from the shredding of the leftovers resultant from the cutting and assembly processes of GFRP pultrusion profiles. Currently, these leftovers as well as non-conform products and scrap resulting from pultrusion manufacturing process are landfilled, with additional costs to producers and suppliers. Hence, besides the evident environmental benefits, a viable and feasible solution for these wastes would also conduct to significant economic advantages. Design of experiments and data treatment were accomplish by means of full factorial design approach and analysis of variance ANOVA. Experimental results were promising toward the recyclability of GFRP waste materials as partial replacement of aggregates and reinforcement for PM materials, with significant improvements on mechanical properties of resultant mortars with regards to waste-free formulations.
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thermal expansion of epoxy and Polyester Polymer mortars plain mortars and fibre reinforced mortars
Polymer Testing, 2003Co-Authors: M C S Ribeiro, J M L Reis, A J M Ferreira, A T MarquesAbstract:Abstract The study was conducted in order to determine the coefficient of thermal expansion of two specific binder formulations of epoxy and unsaturated Polyester Polymer mortars. The variation of this parameter with temperature was also analysed. Polymer concrete and mortars have been observed to have lower coefficients of thermal expansion at lower temperatures than at higher temperatures. Plots of strains vs. temperature are often bilinear, indicating a sharp change in the coefficient of thermal expansion (International Congress on Polymers in Concrete, July 1995). To determine how this discontinuity varies for these two materials, specimens of both formulations were tested for several temperature ranges between −20 and 60 °C. In addition, to determine the influence of fibre reinforcements on thermal expansion of Polymer mortars, epoxy Polymer mortars reinforced with both carbon and glass chopped fibres were also tested for thermal expansion. It was concluded that, for both formulations, the variation of thermal expansion with temperature follows a parabolic law rather than a bilinear law. The reinforcement of chopped glass fibres (1%) has no significant effect on thermal expansion of epoxy Polymer mortar, while the inclusion of carbon fibres (2%) on the same mortar formulation has a reducing effect on thermal expansion of this composite material for temperatures above room temperature.
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chemical resistance of epoxy and Polyester Polymer concrete to acids and salts
Journal of Polymer Engineering, 2002Co-Authors: M C S Ribeiro, C M L Tavares, A J M FerreiraAbstract:The aim of this work is to analyse the chemical resistance of epoxy and Polyester concretes when exposed to acids and salts. The chemical resistance is evaluated through the variation of bending strength and variation of mass, after exposure in acid and salted solutions, for various periods of time. Aqueous solutions of sulphuric acid and sodium chloride were chosen as test solutions. The increasing use of Polymer concrete structures near seawater and residual waters is the main motivation for this research work.
Larry R Dalton - One of the best experts on this subject based on the ideXlab platform.
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large photoinduced birefringence in an optically nonlinear Polyester Polymer
Applied Physics Letters, 1991Co-Authors: William H Steier, Luping Yu, Mai Chen, Larry R DaltonAbstract:A nonlinear optical Polyester with disperse red side groups exhibited a stable photoinduced birefringence, from 0.14 at 850 nm to 0.21 at 633 nm, after exposure to linearly polarized short‐wavelength visible or ultraviolet light. Thin‐film wave plates, birefringent diffraction gratings and waveguides were written in this Polymer using photoexposure. Thin‐ film wave plates of <1 μm thickness showed ≳π/4 phase delay and good temporal stability. A 9:1 diffraction efficiency ratio of the two polarization eigenmodes was measured from thin birefringent gratings. This ratio is in good agreement with the theoretical prediction obtained using a simple three‐level model.
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Large photoinduced birefringence in an optically nonlinear Polyester Polymer
Applied Physics Letters, 1991Co-Authors: William H Steier, Luping Yu, Mai Chen, Larry R DaltonAbstract:A nonlinear optical Polyester with disperse red side groups exhibited a stable photoinduced birefringence, from 0.14 at 850 nm to 0.21 at 633 nm, after exposure to linearly polarized short‐wavelength visible or ultraviolet light. Thin‐film wave plates, birefringent diffraction gratings and waveguides were written in this Polymer using photoexposure. Thin‐ film wave plates of
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large stable photoinduced refractive index change in a nonlinear optical Polyester Polymer with disperse red side groups
Applied Physics Letters, 1991Co-Authors: William H Steier, Luping Yu, Mai Chen, Larry R DaltonAbstract:The photoinduced refractive index change of Polyester with disperse red side groups was studied at several different wavelengths. This material exhibits a large photoinduced index change (0.3 at 633 nm) and in addition when poled has a sizable second‐order nonlinear optical effect. This index change was monitored over 1000 h and long‐term stability was demonstrated. Based on these results, a method using only photomasks to define channel waveguides and other patterns in such Polymers was suggested and experimentally demonstrated. This photoinduced index change may have wide applications in integrated optical systems when these or other similar Polymers are involved.
A Ball - One of the best experts on this subject based on the ideXlab platform.
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an assessment of the properties and degradation behaviour of glass fibre reinforced Polyester Polymer concrete
Composites Science and Technology, 2000Co-Authors: R Griffiths, A BallAbstract:A study has been conducted to investigate the mechanical properties of glass-fibre-reinforced Polyester Polymer concrete. While this material is becoming popular in South Africa for use in the manufacture of manhole and drainage components, little is known about its long term durability. In this study, the modulus of rupture and the fracture toughness of Polyester Polymer concrete were determined by using three-point flexural testing methods. The strengthening effects of glass-fibre reinforcement, woven roving and silane coupling agent additions were then established. In addition, the effect of exposure to various aggressive environments was investigated. It was found that fibre reinforcement of Polymer concrete significantly improves the strength and toughness of the material. Marked deterioration in strength occurs during exposure to UV radiation, acids, alkalis, water and saline solution.
William H Steier - One of the best experts on this subject based on the ideXlab platform.
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large photoinduced birefringence in an optically nonlinear Polyester Polymer
Applied Physics Letters, 1991Co-Authors: William H Steier, Luping Yu, Mai Chen, Larry R DaltonAbstract:A nonlinear optical Polyester with disperse red side groups exhibited a stable photoinduced birefringence, from 0.14 at 850 nm to 0.21 at 633 nm, after exposure to linearly polarized short‐wavelength visible or ultraviolet light. Thin‐film wave plates, birefringent diffraction gratings and waveguides were written in this Polymer using photoexposure. Thin‐ film wave plates of <1 μm thickness showed ≳π/4 phase delay and good temporal stability. A 9:1 diffraction efficiency ratio of the two polarization eigenmodes was measured from thin birefringent gratings. This ratio is in good agreement with the theoretical prediction obtained using a simple three‐level model.
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Large photoinduced birefringence in an optically nonlinear Polyester Polymer
Applied Physics Letters, 1991Co-Authors: William H Steier, Luping Yu, Mai Chen, Larry R DaltonAbstract:A nonlinear optical Polyester with disperse red side groups exhibited a stable photoinduced birefringence, from 0.14 at 850 nm to 0.21 at 633 nm, after exposure to linearly polarized short‐wavelength visible or ultraviolet light. Thin‐film wave plates, birefringent diffraction gratings and waveguides were written in this Polymer using photoexposure. Thin‐ film wave plates of
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large stable photoinduced refractive index change in a nonlinear optical Polyester Polymer with disperse red side groups
Applied Physics Letters, 1991Co-Authors: William H Steier, Luping Yu, Mai Chen, Larry R DaltonAbstract:The photoinduced refractive index change of Polyester with disperse red side groups was studied at several different wavelengths. This material exhibits a large photoinduced index change (0.3 at 633 nm) and in addition when poled has a sizable second‐order nonlinear optical effect. This index change was monitored over 1000 h and long‐term stability was demonstrated. Based on these results, a method using only photomasks to define channel waveguides and other patterns in such Polymers was suggested and experimentally demonstrated. This photoinduced index change may have wide applications in integrated optical systems when these or other similar Polymers are involved.
A J M Ferreira - One of the best experts on this subject based on the ideXlab platform.
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reinforced Polymer concrete physical properties of the matrix and static dynamic bond behaviour
Cement & Concrete Composites, 2005Co-Authors: Tomas J Sanjose, Inigo Vegas, A J M FerreiraAbstract:Abstract The paper aims at analysing the performance of Polyester Polymer Concrete (PPC) reinforced with steel and FRP rebars. The PPC is also compared with conventional cement concrete. On the one hand, the effect of the Polymer matrix microstructure on the mechanical performance (compression and flexural strength, deformability and Young’s modulus) is discussed. On the other hand, static and dynamic bond behaviour under pure pull-out forces between the PPC and different rebars is tackled. It is analysed the behaviour of metallic and non-metallic rebars embedded in a PPC matrix when they are subjected to both monotonic and cyclic loads. Likewise, analogous tests were performed on cement concrete specimens in order to be able to compare the bonding performance in both types of concrete.
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thermal expansion of epoxy and Polyester Polymer mortars plain mortars and fibre reinforced mortars
Polymer Testing, 2003Co-Authors: M C S Ribeiro, J M L Reis, A J M Ferreira, A T MarquesAbstract:Abstract The study was conducted in order to determine the coefficient of thermal expansion of two specific binder formulations of epoxy and unsaturated Polyester Polymer mortars. The variation of this parameter with temperature was also analysed. Polymer concrete and mortars have been observed to have lower coefficients of thermal expansion at lower temperatures than at higher temperatures. Plots of strains vs. temperature are often bilinear, indicating a sharp change in the coefficient of thermal expansion (International Congress on Polymers in Concrete, July 1995). To determine how this discontinuity varies for these two materials, specimens of both formulations were tested for several temperature ranges between −20 and 60 °C. In addition, to determine the influence of fibre reinforcements on thermal expansion of Polymer mortars, epoxy Polymer mortars reinforced with both carbon and glass chopped fibres were also tested for thermal expansion. It was concluded that, for both formulations, the variation of thermal expansion with temperature follows a parabolic law rather than a bilinear law. The reinforcement of chopped glass fibres (1%) has no significant effect on thermal expansion of epoxy Polymer mortar, while the inclusion of carbon fibres (2%) on the same mortar formulation has a reducing effect on thermal expansion of this composite material for temperatures above room temperature.
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chemical resistance of epoxy and Polyester Polymer concrete to acids and salts
Journal of Polymer Engineering, 2002Co-Authors: M C S Ribeiro, C M L Tavares, A J M FerreiraAbstract:The aim of this work is to analyse the chemical resistance of epoxy and Polyester concretes when exposed to acids and salts. The chemical resistance is evaluated through the variation of bending strength and variation of mass, after exposure in acid and salted solutions, for various periods of time. Aqueous solutions of sulphuric acid and sodium chloride were chosen as test solutions. The increasing use of Polymer concrete structures near seawater and residual waters is the main motivation for this research work.