Examinando por Materia "Processing condition"
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Ítem Morphological and mechanical characteristics of rigid polyurethane foams(2009-01-01) Restrepo-Zapata, N.C.; Ossa H., E.A.; Mejia, F.C.; Restrepo-Zapata, N.C.; Ossa H., E.A.; Mejia, F.C.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaCellular materials are formed by solid cells in a gaseous core. They exhibit good strength to mass ratio and they are used as insulators and as a core in sandwich composite manufacture. This work describes an extensive study on the structure and physical-mechanical properties of rigid polyurethane (PU) foams. The effect of composition and processing conditions on the mechanical properties were studied. Morphology, specific strength and density were evaluated to determine the optimal levels of processing for a required application. Foam morphology was characterized using stereoscopy and optical microscopy. A basic mechanical property as compression strength was measured in the plateau zone.Ítem Nodule evolution of ductile cast iron during solidification(SPRINGER, 2014-04-01) Murcia, S. C.; Ossa, E. A.; Celentano, D. J.; Murcia, S. C.; Ossa, E. A.; Celentano, D. J.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaDuctile cast irons are ferrous alloys in which precipitation of graphite in the form of spherical nodules is embedded in a metal matrix to obtain ductility on the material. Despite the importance of the shape of the nodules, the models proposed to predict the solidification of ductile irons assume a perfect spherical shape during the growing process up to the final solidification of the material, which is proved not to be the case in all castings depending on the processing conditions. The influence of the process parameters on the geometry of the nodules in ductile irons was experimentally evaluated and a model to predict the evolution of nodules during solidification was proposed. The proposed model for growth predicts changes in the nodule count as well as in the nodularity based on different laws for carbon diffusion according to the solid fraction, helping to understand the trends found experimentally. © The Minerals, Metals & Materials Society and ASM International 2013.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.