Articulos
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Examinando Articulos por Autor "Álvarez-Láinez M.L."
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Ítem Effect of the Phenological Stage in the Natural Rubber Latex Properties(Springer New York LLC, 2019-01-01) Zapata-Gallego N.T.; Álvarez-Láinez M.L.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Natural Rubber Latex (NRL) from Hevea brasiliensis is a material studied because of their industrial applications. For its natural origin, it is possible to find rubber particles, proteins, phospholipids and ashes. These non-rubber content are responsible for the latex colloidal stability. H. brasiliensis tree goes through four stages during the year, changing its nutritional requirements and as a result the rubber yield and stability. Most studies have correlated latex characteristics and yield with tree age and clonal origin but none of them with phenological stages. The impact of the phenological stage on the material properties has not been completely identified yet. In this work, the influence of the clonal origin and the phenological stage with the material properties is studied. Thermal behavior, microstructural analysis, morphological study, colloidal stability and rheology are analyzed for FX3864, IAN710 and AIN873 clones during 1 year. NRL is an amorphous material but during the high-yield period, a melting point is observed. Flowering is the stage when phospholipids, protein and isoelectric point are higher. Phenological stages do not affect the rubber, but the main changes are in the non-rubber content. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Ítem PTFE as a toughness modifier of high-performance PEI/PBT blends: Morphology control during melt processing(John Wiley and Sons Ltd, 2021-02-01) Vásquez-Rendón M.; Álvarez-Láinez M.L.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)High-performance PEI/PBT blends are brittle because of phase distribution and blends densification. New morphologies developed by adding PTFE to PEI matrix during melt processing favor the toughness improvement of PEI/PBT blends. Ternary PEI/PBT/PTFE processability is not compromised by PTFE addition, and miscibility study by modulated differential scanning calorimetry and harmonic mean method shows that PTFE does not interfere with PEI and PBT interaction. Dual-phase and spore-like morphologies are formed for both PEI/PBT and PEI/PBT/PTFE blends, and they strongly influenced their mechanical performance. Although tensile strength of ternary blends does not decrease by PTFE addition, elongation at break deteriorates for blends with PEI concentrations <70 wt%. Nevertheless, blends with 80 wt% increase their ductility, and a synergic effect is observed in impact resistance results. PTFE acts as an impact modifier of PEI/PBT blends due to its distribution in the PEI matrix as debonded spheres and nanoparticles well-embedded in PEI matrix. © 2020 John Wiley & Sons LtdÍtem Tailoring the mechanical, thermal, and flammability properties of high-performance PEI/PBT blends exhibiting dual-phase continuity(Elsevier Ltd, 2018-10-10) Vásquez-Rendón M.; Álvarez-Láinez M.L.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Binary PEI/PBT blends are prepared using a two-step melt processing method. Miscibility study by MDSC and DMA reveals partial miscibility, and new evidence on the morphological evolution of PEI/PBT blends is presented. Two groups of blends are recognized: PBT-rich blends and PEI-rich blends, as well as phase inversion at concentrations close to 50 wt% of PEI. Mechanical, thermal, and flame resistance performance is influenced by blends morphology, and an opportunity for tailoring blends properties is recognized. Tensile modulus shows synergic contribution for 50/50 and 80/20 blends and yield strength is strongly affected by interfacial adherence between constituents. In addition, elongation at break is compromised by PBT-rich blends morphology, and by PEI-rich blends densification. The 50/50 blend exhibits the best elongational at break result due to its co-continuous morphology. Thermal stability and flammability tests reveal that PEI improves the thermal resistance and charring of PBT, particularly for 50/50 blend. © 2018 Elsevier Ltd