Articulos
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Examinando Articulos por Autor "Álvarez-Láinez, M."
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Ítem Functionalization of polyacrylonitrile nanofibers with beta-cyclodextrin for the capture of formaldehyde(Elsevier Ltd, 2016-04-05) Noreña-Caro, D.; Álvarez-Láinez, M.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Polyacrylonitrile (PAN) is frequently used in filtering applications due to its sound mechanical properties, chemical resistance and thermal stability. beta-cyclodextrin (beta CD) can entrap molecules and improve the filters' performance. The removal of formaldehyde, a common indoor pollutant, has increasingly attracted widespread attention. In this work, we present two different methods for the production of electrospun PAN nanofibers containing beta CD capable of capturing formaldehyde from the air. The former comprised the addition of beta CD to PAN/dimethyl sulfoxide solutions and the subsequent electrospinning of the mixture. The latter involved the crosslinking of beta CD on electrospun PAN fibers by alkaline hydrolysis and esterification with citric acid. For both methods, we used solutions with different polymer concentration and viscosity. In addition, the rheology of solutions, as well as the morphology, surface area, chemical structure and thermal resistance of electrospun fibers were analyzed. The formaldehyde capture potential of beta CD containing PAN nanofibers was evaluated using high performance liquid chromatography. Conclusively, we found that, while functionalized PAN nanofibers with average fiber diameter from 432 nm to 647 nm might be used for indoor air purification, functionalized fibers obtained by addition of beta CD are more effective for capturing formaldehyde than fibers obtained by crosslinking of beta CD. (C) 2016 Elsevier Ltd. All rights reserved.Ítem Morphology Development of Immiscibe Quaternary Polyolefin and PS Blends(Taylor and Francis Inc., 2016-01-02) Álvarez-Láinez, M.; González-Gómez, L.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Study of polymer blends that fulfill the current engineering demand has been increased in the last years and multicomponent blends are still a challenge, but increasing the number of components will lead to further complications. We correlated the differences between morphology and blending sequence in quaternary blends of polyolefin with polystyrene, following the available theories that related viscosity and morphology. It was found that high viscous matrices enhance deformation and breakup processes, displaying fibrillar morphologies and finer dispersions. The blending sequence improves the mixing first, by putting all the polyolefin into a ternary blend and after that, adding the polystyrene.Ítem Two-Step Processing Method for Blending High-Performance Polymers with Notable Thermal and Rheological Differences: PEI and PBT(Taylor and Francis Inc., 2018-09-22) Vásquez-Rendón, M.; Sánchez-Arrieta, N.; Álvarez-Láinez, M.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Blends between high-performance polymers (HPP) are barely studied, especially those produced by melting processing. In this work, it is proposed a novel methodology to prepare blends between polymers with notable processing temperature differences: poly(ether imide) (PEI) and poly(butylene terephthalate) (PBT). Processing parameters are settled after thermal and rheological evaluation of pure materials, those results suggest these blends need to be produced by steps. It is found a synergistic effect such as lowering PEI processing temperature and reducing PBT hydrolysis at high temperatures. Propose methodology allows to produce blends between HPP in the whole composition range with the same processing conditions. © 2017, © 2017 Taylor & Francis.Ítem Water-based adhesive formulations for rubber to metal bonding developed by statistical design of experiments(Elsevier Ltd, 2017-03-01) Lasprilla-Botero, J.; Álvarez-Láinez, M.; Acosta, D.A.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Waterborne adhesives for rubber to metal bonding have been available since 1990. However, published information about their formulation has been limited, as proprietary restrictions are exercised by companies. As a consequence, the way these adhesives interact with substrates has not been studied extensively. With the aim of investigating the effect the components of a waterborne adhesive have on rubber to metal bonding, fractional factorial and surface response methodologies of design of experiments were employed in this study. Twenty six formulations were prepared with a polychloroprene latex as the adhesive polymer. Viscosity, wettability and non-volatile solids content were measured with each liquid adhesive, while the mechanical strength was evaluated by applying a tensile mechanical stress over cured solid adhesive films. Adhesion properties were evaluated by using a single lap-shear test on metal to metal joints and a pull-out test on rubber to metal joints. The results showed that the components with the largest relative influence on cohesive and adhesives forces were tackifier resin, silicon dioxide and polychloroprene latex type. In order to better understand the contributions of these variables, mathematical models correlating them with the response variables were obtained. This study is valuable in explaining how, through statistical methods, a waterborne adhesive for rubber to metal bonding can be formulated with a reasonably low number of experiments. © 2016 Elsevier Ltd