Fabricación de materiales celulares mejorados basados en Poliolefinas. Relación procesado-composición-estructura-propiedades

La investigación desarrollada en esta tesis pretende contribuir al desarrollo de una metodología capaz de producir materiales celulares poliméricos con propiedades mejoradas, que sean capaces de dar una respuesta más eficiente en las aplicaciones para las cuales puedan ser utilizados. Así los objetivos principales de la misma, son por un lado, producir materiales con estructuras celulares y propiedades físicas mejoradas modificando bien la matriz polimérica, bien los parámetros involucrados en el proceso de espumado, o bien ambos a la vez. Por otro lado, los materiales así producidos se han caracterizado tanto desde un punto de vista microscópico como macroscópico, lo que ha permitido establecer la relación composición-estructura-propiedades de dichos materialesDepartamento de Física de la Materia Condensada, Cristalografía y Mineralogía2012-11-0

Effect of mold temperature on the impact behavior and morphology of injection molded foams based on polypropylene polyethylene–octene copolymer blends

Producción CientíficaIn this work, an isotactic polypropylene (PP) and a polyethylene–octene copolymer (POE) have been blended and injection-molded, obtaining solids and foamed samples with a relative density of 0.76. Different mold temperature and injection temperature were used. The Izod impact strength was measured. For solids, higher mold temperature increased the impact resistance, whereas in foams, the opposite trend was observed. In order to understand the reasons of this behavior, the morphology of the elastomeric phase, the crystalline morphology and the cellular structure have been studied. The presence of the elastomer near the skin in the case of high mold temperature can explain the improvement produced with a high mold temperature in solids. For foams, aspects as the elastomer coarsening in the core of the sample or the presence of a thicker solid skin are the critical parameters that justify the improved behavior of the materials produced with a lower mold temperature.Ministerio de Economía, Industria y Competitividad (grant DI-15-07952

Foams with enhanced ductility and impact behavior based on polypropylene composites

Producción CientíficaIn this work, formulations based on composites of a linear polypropylene (L-PP), a long-chain branched polypropylene (LCB-PP), a polypropylene–graft–maleic anhydride (PP-MA), a styrene-ethylene-butylene-styrene copolymer (SEBS), glass fibers (GF), and halloysite nanotubes (HNT-QM) have been foamed by using the improved compression molding route (ICM), obtaining relative densities of about 0.62. The combination of the inclusion of elastomer and rigid phases with the use of the LCB-PP led to foams with a better cellular structure, an improved ductility, and considerable values of the elastic modulus. Consequently, the produced foams presented simultaneously an excellent impact performance and a high stiffness with respect to their corresponding solid counterparts.Unión Europea (Evolution project under grant 314744)Ministerio de Ciencia, Innovación y Universidades - Fondo Europeo de Desarrollo Regional (project RTI2018-098749-B-I00)Junta de Castilla y Leon (project VA275P18

Crosslinked ethylene butyl acrylate copolymer foams with different cellular structure interconnectivity and tortuosity: Microstructure and physical properties

Producción CientíficaIn this work, the cellular structure, physical properties, and the structure–property relationship of several novel crosslinked ethylene butyl acrylate (EBA) foams with different cellular structure interconnectivity (low tortuosity and high tortuosity) have been analyzed and compared to that of closed cell EBA foams and to that of an open-cell polyurethane foam. The results have shown that these materials present interesting properties highly dependent on the tortuosity of the cellular structure. In particular, it has been proved that reducing the tortuosity allows enhancing the acoustic absorption, the oil uptake, and the cushioning behavior. On the other hand, increasing tortuosity allows improving the impact behavior. In addition, the new open-cell materials present an enhanced damping factor for low-frequency vibrations.Ministerio de Economía, Industria y Competitividad (grant DI-15-07952)Ministerio de Asuntos Económicos y Transformación Digital-FEDER, UE (project MAT2015-69234-R)Junta de Castilla y León (project VA275P18

Extensional rheology, cellular structure, mechanical behavior relationships in HMS PP/montmorillonite foams with similar densities

Producción CientíficaThe main goal of this work is to analyze the relationships between the extensional rheological behavior of solid nanocomposites based on high melt strength polypropylene (HMS PP) and montmorillonites (MMT) and the cellular structure and mechanical properties of foams produced from these materials. For this purpose two systems have been analyzed. The first one incorporates organomodified MMT and a compatibilizer and the second system contains natural clays and is produced without the compatibilizer. Results indicate that the extensional rheological behavior of both materials is completely different. The strain hardening of the polymer containing organomodified clays decreases as the clay content increases. As a consequence, the open cell content of this material increaseswith the clay content and hence, themechanical properties get worse. However, in the materials produced with natural clays this relationship is not so clear. While no changes are detected in the extensional rheological behavior by adding these particles, the nano-filled materials show an open cell structure, opposite to the closed cell structure of the pure polymer, which is caused by the fact of having particle agglomerates with a size larger than the thickness of the cell walls and a poor compatibility between the clays and the polymer.Financial support from PIRTU contract of E. Laguna-Gutierrez by Junta of Castile and Leon (EDU/289/2011) and cofinanced by the European Social Fund is gratefully acknowledged. Cristina Saiz-Arroyo would like to acknowledge Spanish Ministry of Economy and Competitiveness (MINECO) via Torres Quevedo Program (PTQ-12-05504). Finally, financial assistance from MINECO and FEDER program (MAT 2012 – 34901) MINECO, FEDER, UE (MAT2015-69234-R) and the Junta de Castile and Leon (VA035U13) are gratefully acknowledged

Taller Integrado I "Orgía Mecánica". Innovación Educativa

Un espacio pedagógico de convergencia para el aprendizaje y la práctica dialógica de la Aequitectura. Memoria de la experiencia realizada en la Escuela Técnica Superior de Arquitectura de Madrid en Noviembre de 200

Effect of the elastomer viscosity on the morphology and impact behavior of injection molded foams based on blends of polypropylene and polyolefin elastomers

Producción CientíficaThe impact resistance of injection-molded polypropylene (PP) parts is severely reduced when they are foamed. It is necessary to implement strategies, such as elastomer toughening, to increase the impact behavior of foamed parts. However, the knowledge on the effect of elastomer addition on the morphology, cellular structure, and impact of injection-molded cellular parts is very limited. In this work, foamed parts based on blends of PP and polyolefin elastomers have been produced and characterized. A high and a low viscosity octene-ethylene copolymer (EOC) and a high viscosity butene-ethylene copolymer (EBC) were employed. The blends have been thermally and rheological characterized. Solids materials and foams (relative density 0.76) were injection-molded. The solid phase and cellular structure morphologies were studied using scanning electron microscopy. The results showed that elastomer toughening has been successful to obtain an improvement of the impact behavior in solid and cellular polymers. In this case, EOC materials provide an appropriate interfacial adhesion and optimized cellular structure which results in high impact resistance. The optimum elastomer to improve the properties is the EOC with a higher viscosity which provides impact resistance with n values below 3 due to the toughening of polymer matrix, thick skin thickness, and low cell size.Junta de Castilla y León (grant VA275P18)Ministerio de Ciencia, Innovación y Universidades (project RTI2018-098749-B-I00

Dietary inflammatory index and all-cause mortality in large cohorts: The SUN and PREDIMED studies

[Background]: Inflammation is known to be related to the leading causes of death including cardiovascular disease, several types of cancer, obesity, type 2 diabetes, depression-suicide and other chronic diseases. In the context of whole dietary patterns, the Dietary Inflammatory Index (DII®) was developed to appraise the inflammatory potential of the diet. [Objective]: We prospectively assessed the association between DII scores and all-cause mortality in two large Spanish cohorts and valuated the consistency of findings across these two cohorts and results published based on other cohorts.[Design]: We assessed 18,566 participants in the “Seguimiento Universidad de Navarra” (SUN) cohort followed-up during 188,891 person-years and 6790 participants in the “PREvencion con DIeta MEDiterránea” (PREDIMED) randomized trial representing 30,233 person-years of follow-up. DII scores were calculated in both cohorts from validated FFQs. Higher DII scores corresponded to more proinflammatory diets. A total of 230 and 302 deaths occurred in SUN and PREDIMED, respectively. In a random-effect meta-analysis we included 12 prospective studies (SUN, PREDIMED and 10 additional studies) that assessed the association between DII scores and all-cause mortality.[Results]: After adjusting for a wide array of potential confounders, the comparison between extreme quartiles of the DII showed a positive and significant association with all-cause mortality in both the SUN (hazard ratio [HR] = 1.85; 95% CI: 1.15, 2.98; P-trend = 0.004) and the PREDIMED cohort (HR = 1.42; 95% CI: 1.00, 2.02; P-trend = 0.009). In the meta-analysis of 12 cohorts, the DII was significantly associated with an increase of 23% in all-cause mortality (95% CI: 16%–32%, for the highest vs lowest category of DII).[Conclusion]: Our results provide strong and consistent support for the hypothesis that a pro-inflammatory diet is associated with increased all-cause mortality. The SUN cohort and PREDIMED trial were registered at clinicaltrials.gov as NCT02669602 and at isrctn.com as ISRCTN35739639, respectively.Supported by the official funding agency for biomedical research of the Spanish Government, Instituto de Salud Carlos III (ISCIII), through grants provided to research networks specifically developed for the trial (RTIC G03/140, to R.E.; RTIC RD 06/0045, to Miguel A. Martínez-González) and through Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBERobn), and by grants from Centro Nacional de Investigaciones Cardiovasculares (CNIC 06/2007), Fondo de Investigación Sanitaria–Fondo Europeo de Desarrollo Regional (Proyecto de Investigación (PI) 04-2239, PI 05/2584, CP06/00100, PI07/0240, PI07/1138, PI07/0954, PI 07/0473, PI10/01407, PI10/02658, PI11/01647, P11/02505, PI13/00462, PI13/00615, PI13/01090, PI14/01668, PI14/01798, PI14/01764), Ministerio de Ciencia e Innovación (Recursos y teconologia agroalimentarias(AGL)-2009-13906-C02 and AGL2010-22319-C03 and AGL2013-49083-C3-1- R), Fundación Mapfre 2010, the Consejería de Salud de la Junta de Andalucía (PI0105/2007), the Public Health Division of the Department of Health of the Autonomous Government of Catalonia, Generalitat Valenciana (Generalitat Valenciana Ayuda Complementaria (GVACOMP) 06109, GVACOMP2010-181, GVACOMP2011-151), Conselleria de Sanitat y, PI14/01764 AP; Atención Primaria (CS) 2010-AP-111, and CS2011-AP-042), and Regional Government of Navarra (P27/2011).). Drs. Shivappa and Hébert were supported by grant number R44DK103377 from the United States National Institute of Diabetes and Digestive and Kidney Diseases