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  • Diffusion of CO2 in polymer nanocomposites containing different types of carbon nanoparticles and nanoclays for solid-state microcellular foaming applications

     de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Gedler, Gabriel; Arencón Osuna, David; Velasco Perero, Jose Ignacio
    Journal of nano research
    Date of publication: 2014-01
    Journal article

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    This work considers the study of the diffusion of carbon dioxide in polypropylene and amorphous polymers containing carbon nanoparticles, particularly carbon nanofibres and graphene, as well as nanoclays, to be used in microcellular foaming. The diffusion of CO2 out and into the nanocomposites was studied during high pressure CO2 dissolution, as the amount of CO2 dissolved into the nanocomposite and CO2 desorption rate are crucial in order to have a proper control of foaming. Comparatively, platelet-like nanoparticles slowed down the desorption of CO2 out of the nanocomposites by means of a physical barrier effect, enabling a higher concentration of CO2 to remain in the polymer and be used in foaming. As a consequence of the higher amount of CO2 retained in the polymer and the cell nucleation effect promoted by the nanoparticles, polymer nanocomposite foams presented finer microcellular structures, in the case of PMMA even submicrocellular, and higher specific moduli and electrical conductivities when compared to their pure counterparts.

  • Thermal stability and fire behaviour of flame retardant high density rigid foams based on hydromagnesite-filled polypropylene composites

     de Redondo Realinho, Vera Cristina; Haurie Ibarra, Laia; de Sousa Pais Antunes, Marcelo; Velasco Perero, Jose Ignacio
    Composites Part B: Engineering
    Date of publication: 2014-03
    Journal article

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    The present work deals with the development of new rigid polypropylene composite foams filled with high amounts of flame-retardant systems based on synthetic hydromagnesite, a basic magnesium carbonate obtained from an industrial by-product. A partially-interconnected cellular structure with a cell size around 100 micrometers was obtained for the hydromagnesite-filled PP foams. A 40% reduction of this cell size was observed when a small amount of a combination of montmorillonite and graphene layered nanoparticles was added to the hydromagnesite. The combination of hydromagnesite with an intumescent additive (ammonium polyphosphate) and layered nanoparticles led to improved thermal stability. In particular, the intumescent additive delayed the beginning of the thermal decomposition temperature and the layered nanoparticles split the second step of thermal decomposition in a third peak observed at higher temperatures. Improved flame retardancy, measured by means of cone calorimetry, was observed in the samples containing the intumescent additive. A novel normalized parameter, called foam efficiency ratio (FER), which takes into account the expansion ratio of the foam and the relation of its fire properties with that of the base solid, was also analyzed.

  • Application of layered nanoparticles in the micromechanical reinforcement and flame retardancy of polymer foams

     de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Velasco Perero, Jose Ignacio
    Date of publication: 2013
    Book chapter

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    One of the key objectives of nanotechnology is to develop our knowledge to manipulate matters at nanoscale level to create novel, smart, cost effective and eco-friendly macrostructures to improve quality of human life. Recent advancement in development of nano-materials and structures motivate engineers to design nano-modified smart, effective, high performance and sustainable macro-units. This volume contains recent research progresses on development and application on construction based nanomaterials, market potential, problems regarding conventional building system and nanostructures characterized by higher potency, greater robustness and resilience, increased speed of construction, and lessened environmental impact. It contains vivid discussion on methods, mechanical properties, electrical and resistive properties, thermal conductive and damping properties of nanomaterials like titanium dioxide and carbon nanotubes, ultra high pressure ¿sensitive cement based composites and their potential applications. Authors lucidly and ornately discussed about self cleaning rods, fabrics, electricity generating coatings, heating/ cooling installation systems, micro-electromechanical systems (MEMS) in automobiles, development of nano based structures for disaster protection, waste and pollutant treatment, aviation and land transportation systems, and their applications. Nanotechnology not only finds its use in building highways, dams, bridges and flyovers, but also in making eco-friendly and smart nano-surfaces in ceramics and glasses which currently holds a very potential market globally. This volume will not only expand the knowledge and enhance the analytical ability of the students and researchers, but also help the industrial scientists, engineers, constructors and developers, to address many unsolved problems regarding production and characterisation of construction materials and their prospective applications.

  • Mechanical¿viscoelastic characterization in nanocomposites

     de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Arencón Osuna, David; Velasco Perero, Jose Ignacio
    Date of publication: 2013-06
    Book chapter

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  • Addition of flame retardants in epoxy mortars: thermal and mechanical characterization

     Haurie Ibarra, Laia; Lacasta Palacio, Ana Maria; Ciudad Alvarez, Aleix; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio
    Construction & building materials
    Date of publication: 2013-05
    Journal article

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    In this work we have studied the effect of different flame retardants on the fire behavior and mechanical properties of epoxy mortars. Flame retardants acting under different mechanisms of action have been compared: phosphate flame retardants as well as magnesium hydroxides and carbonates. Besides the commercial flame retardants we have also used a magnesium basic carbonate obtained from an industrial by-product. The use of an alternative based on an industrial by-product combines an economic and sustainable solution. Different formulations of flame retarded epoxy mortars have been prepared and characterized. The obtained results prove the effectiveness of the tested flame retardants on the improvement of the fire properties of the epoxy mortars without a significant decrease on their mechanical properties.

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    Characterization of polycarbonate foam structures prepared by one-step SC-CO2 dissolution process  Open access

     Gedler, Gabriel; de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio
    International Conference on Foam Materials & Technology
    Presentation's date: 2012-09-12
    Presentation of work at congresses

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    In this communication polycarbonate foams were prepared by a supercritical CO2 dissolution one-step batch foaming process. Firstly, CO2 diffusion behavior in polycarbonate was studied by means of desorption experiments. The cellular structure of foams prepared under different foaming conditions was characterized through scanning electron microscopy. Different foaming temperatures as well as CO2 saturation pressures and times were applied. The foams displayed typical closed-cell structures with cell densities ranging from 3x10⁵ to 3x10⁶ cells/m³ and cell average sizes from around 70 to 150μm. Analysis by X-ray diffraction and differential scanning calorimetry seemed to suggest that slight crystallization took place because of the plasticizing effect of CO2 during saturation and foaming. Thermogravimetric analysis showed a higher thermal stability of the foams when compared to the compact polymer. The preliminary results shown in this work suggest the possibility of developing lightweight polycarbonate components with improved specific thermal properties through carefully controlling the foaming parameters.

    Electronic version of an article published as "FOAMS 2012: 10th International Conference on Foam Materials & Technology : Barcelona, Spain, September 12 - September 13, 2012". Society of Plastics Engineers.

  • Halogen-free flame retardant polyolefin foams

     de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Santana Pérez, Orlando Onofre; Velasco Perero, Jose Ignacio
    International Conference on Foam Materials & Technology
    Presentation's date: 2012-09-12
    Presentation of work at congresses

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    Influencia de las nanocargas en las propiedades termomecánicas de espumas poliméricas  Open access

     de Sousa Pais Antunes, Marcelo; Gedler, Gabriel; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio
    Encuentro del Grupo Español de Fractura
    Presentation's date: 2012-03-22
    Presentation of work at congresses

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    Se presenta la influencia de nanopartículas y nanofibras sobre las propiedades termomecánicas de espumas poliméricas. A una formulación base polipropileno especial para espumación se le incorporaron nanocargas (silicatos laminares) y nanofibras de carbono al objeto de aportar a los materiales celulares resultantes características de multifuncionalidad (rigidezm retardancia a la llama y conductividad). En el presente trabajo se analizan los efectos que introducen las partículas incorporadas sobre las características termodinámicas de las espumas, a través de análisis térmico mecánico dinámico (DMTA), en relación con la composición de las espumas, con su densidad relativa y con su estructura celular. Los resultados han demostrado que la influencia de las nanopartículas y nanofibras añadidas al polímero base de la espuma alcanza, no sólo a su cristalidad, temperaturas de transición características o propiedades mecánicas, sino también a la generación de estructuras celulares más finas y homogéneas que las de sus homónimos de referencia sin partículas.

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    Espumas ignífugas de poliolefina libres de halógenos  Open access

     de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Haurie Ibarra, Laia; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    Congreso Nacional de Materiales
    Presentation's date: 2012-06-01
    Presentation of work at congresses

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    En el presente trabajo se han preparado y caracterizado espumas ignífugas de poliolefinas libres de halógenos. Se ha utilizado para ello una formulación comercial, empleada típicamente en la industria de cables, y se le ha añadido pequeños porcentajes másicos (entre 2 y 4%) de dos sistemas retardantes de llama: "sílice-borato de zinc" y manolaminillas de "montmorillonita y grafeno expandible". Durante la caracterización celular de las espumas, preparadas por espumación química utilizando como agente espumante azodicarbonamida, se ha constatado que la presencia de las nanopartículas promovía una estructura celular con tamaño de celda más pequeño. Mediante un análisis termogravimétrico, se ha observado un aumento del residuo inorgánico de la formulación base a temperaturas superiores a 500ºC. Esta observación puede ser debida, en cierta medida, a un efecto sinérgico entre ambos sistemas retardantes de llama, el cual promueve una mayor estabilidad térmica de la formulación base. Durante la caracterización del comportamiento frente al fuego mediante ensayos de cono calorimétrico, se ha constatado que el sistema "síliceborato de zinc" retarda en tiempo hasta ignición de la llama (mayores valores de TTI) y que la presencia de las nanopartículas disminuye el valor del PHRR (máxima tasa de liberación de calor).

  • Thermal conductivity anisotropy in polypropylene foams prepared by supercritical CO2 dissolution

     de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio; Solórzano Quijano, Eusebio; Rodríguez-Pérez, Miguel Ángel; de Saja, José Antonio
    Materials chemistry and physics
    Date of publication: 2012-09
    Journal article

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  • Thermal stability of polycarbonate-graphene nanocomposite foams

     Gedler, Gabriel; de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio
    Polymer degradation and stability
    Date of publication: 2012
    Journal article

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  • Caracterización de piezas inyectadas

     Maspoch Ruldua, Maria Lluïsa; Illescas Fernandez, Silvia; de Redondo Realinho, Vera Cristina
    Date: 2012-01-18
    Report

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  • Determinación de la dureza Shore D de dos muestras de plástico

     de Redondo Realinho, Vera Cristina
    Date: 2012-03-16
    Report

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  • Ensayo de inflamabilidad, según norma UL 94, de una muestra de ABS

     de Redondo Realinho, Vera Cristina
    Date: 2012-03-28
    Report

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  • Determinación de la temperatura de reblandecimiento Vicat (VST)

     de Redondo Realinho, Vera Cristina
    Date: 2012-06-20
    Report

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  • Determinación de la temperatura de reblandecimiento Vicat (VST)

     de Redondo Realinho, Vera Cristina
    Date: 2012-06-05
    Report

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  • Determinación de la temperatura de reblandecimiento Vicat (VST)

     de Redondo Realinho, Vera Cristina
    Date: 2012-07-06
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  • Determinación de la temperatura de flexión bajo carga (HDT)

     de Redondo Realinho, Vera Cristina
    Date: 2012-07-26
    Report

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  • Improvement of the fire behaviour of PCM in building applications

     Haurie Ibarra, Laia; Lacasta Palacio, Ana Maria; Fernandez Llado, Javier; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio
    International Conference on Energy Storage
    Presentation's date: 2012-05-17
    Presentation of work at congresses

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    Phase change materials (PCM) have been proved to be an effective tool to regulate indoor temperature fluctuations and reduce the energetic demand of buildings [1,2]. Paraffins are among the most common PCM used for thermal storage in building applications. A broad range of melting temperatures, with an elevated heat of fusion associated, can be obtained varying the length of the hydrocarbon chain that forms the paraffins. Furthermore, they exhibit numerous benefits such as the nearly absence of supercooling, chemical stability, low vapor pressure during the phase change and no phase segregation [3]. These paraffins can be incorporated in several forms to building materials like gypsum or concrete [4]. Despite all these advantages, one major concern regarding the paraffins as PCM is their possible contribution to flame propagation in case of fire [5]. Several authors have tried to improve this aspect by combining the paraffins with HDPE polymers to obtain a form-stable PCM [6]. Blends of paraffin and polyethylene usually contain some inorganic filler, which can act improving both the thermal conductivity as well as the flame retardancy of the system [3, 7]. Microencapsulated PCM or paraffins adsorbed in a substrate are designed to be incorporated directly into the building material and, therefore blending with HDPE is less interesting. Another possibility to increase the fire performance of the PCM is the addition of flame retardants directly into the matrix-PCM mixture. Paraffins usually present their combustion between 220-320ºC and therefore the flame retardants selected should act in this temperature range. In this work we have studied the effect of different loads of PCM on the fire behaviour of gypsum boards. In order to improve the fire behaviour of the gypsum-PCM system, two different types of flame retardants have been added. We have chosen two endothermic flame retardants: aluminium hydroxide (ATH) and a synthetic basic magnesium carbonate, hydromagnesite (HM), obtained from an industrial by-product. Both FR have an endothermic decomposition starting around 200ºC and can be found among the cheapest alternatives to achieve flame retardancy.

  • Determinación de la temperatura de reblandecimiento Vicat (VST)

     de Redondo Realinho, Vera Cristina
    Date: 2012-07-20
    Report

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  • Test for flammability of plastic materials: UL 94-HB

     de Redondo Realinho, Vera Cristina
    Date: 2012-05-28
    Report

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  • Determinación de la temperatura de reblandecimiento Vicat (VST)

     de Redondo Realinho, Vera Cristina
    Date: 2012-06-21
    Report

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  • Determinación de la temperatura de reblandecimiento Vicat (VST)

     de Redondo Realinho, Vera Cristina
    Date: 2012-04-23
    Report

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  • Determinación de la temperatura de flexión bajo carga (HDT)

     de Redondo Realinho, Vera Cristina
    Date: 2012-05-11
    Report

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    Novel polycarbonate-graphene nanocomposite foams prepared by CO2 dissolution  Open access

     Gedler, Gabriel; de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio
    IOP Conference Series: Materials Science and Engineering
    Date of publication: 2012
    Journal article

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    Polycarbonate foams reinforced with 0,5 wt% of graphene were obtained by firstly melt-mixing the polycarbonate and graphene in an internal mixer, compression-moulding the melt-compounded grinded material and lastly dissolving CO2 inside a high pressure vessel. The CO2 desorption behaviour in the unfilled polycarbonate and nanocomposite was studied in terms of the CO2 saturation concentration and desorption diffusion coefficient, with the graphene-filled nanocomposite displaying a higher CO2 loss rate when compared to the neat polycarbonate. The cellular structure of the foams was found to be highly dependent on the saturation/foaming temperature, with smaller cell sizes being obtained with decreasing the temperature. Another parameter that had an important influence was the residual pressure, with higher residual pressure values resulting in foams with more uniform and regular cells.

    Originally published as "IOP Conference Series: Materials Science and Engineering", vol. 31, no 1, 2012. DOI:10.1088/1757-899X/31/1/012008. .

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    Caracterización mecánica de espumas rígidas multifuncionales de poliuretano  Open access

     de Sousa Pais Antunes, Marcelo; Cano, Álvaro; de Redondo Realinho, Vera Cristina; Arencón Osuna, David; Velasco Perero, Jose Ignacio
    Congreso Nacional de Materiales Compuestos
    Presentation's date: 2011-07-06
    Presentation of work at congresses

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    En el presente trabajo se prepararon y caracterizaron espumas de poliuretano con refuerzo multi-escalar combinando concentraciones variables de arcilla organofílica (montmorillonita) y de lana de esparto, con el propósito de desarrollar espumas rígidas multifuncionales. La incorporación de montmorillonita contribuyó a favorecer la espumación y la formación de estructuras celulares más finas y homogéneas, resultando en espumas con esfuerzos de colapso a compresión inferiores a los obtenidos para las espumas de poliuretano. Sin embargo, un análisis comparativo frente a la densidad relativa, demuestra que las propiedades mecánicas de ambas series de espumas siguen una única tendencia común. La combinación de lana de esparto y montmorillonita contribuyó a reducir aún más el tamaño celular, promoviendo simultáneamente la apertura parcial de las celdas, lo que resulta es espumas con esfuerzos de colapso inferiores.

  • The effects of combining nanoclay and steel wires multi-scalar reinforcements on the structure and properties of polyurethane foams

     Cano, Álvaro; de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Haurie Ibarra, Laia; Velasco Perero, Jose Ignacio
    SPE EUROTEC Plastics Technical Conference
    Presentation's date: 2011
    Presentation of work at congresses

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    In this paper we prepared and characterized several polyurethane composite foams by combining variable concentrations of organophilic clay (montmorillonite) and metal reinforcement, with the objective of developing novel multi-scalar multifunctional rigid foams. The addition of montmorillonite clay promoted foaming and the formation of finer and more homogeneous cellular structures, resulting in foams with compressive elastic moduli and collapse stresses lower than that of the unfilled polyurethane foams. However, a comparative analysis versus the foams’ relative density demonstrated that both mechanical properties follow one single trend for the two materials. The combination of montmorillonite and metal reinforcement further reduced the cell size of foams, ultimately resulting in foams with similar mechanical properties for considerably lower relative densities. Although no important differences in thermal conductivity were found for the polyurethane foams with adding montmorillonite, the incorporation of the metal reinforcement led to considerably higher thermal conductivities, its value increasing with increasing relative density.

  • Composite and biocomposite foams based on polypropylene with reinforcements and functional fillers prepared by supercritical CO2 dissolution

     de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Ardanuy Raso, Monica; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    International Conference Blowing Agents and Foaming Processes
    Presentation's date: 2011-05-10
    Presentation of work at congresses

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  • Fire behaviour of flame-retardant rigid polypropylene foams

     de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Velasco Perero, Jose Ignacio
    EUROTEC
    Presentation's date: 2011-11-15
    Presentation of work at congresses

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    Determinación de KIC en compuestos de fibra corta a 1 m/s  Open access

     Martinez Benasat, Antonio; Arencón Osuna, David; Franco Urquiza, Edgar Adrian; de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina
    Congreso Nacional de Materiales Compuestos
    Presentation's date: 2011-07-07
    Presentation of work at congresses

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  • Characterization of rigid polypropylene-based microcellular foams produced by batch foaming processes

     Velasco Perero, Jose Ignacio; de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Ardanuy Raso, Monica
    Polymer engineering and science
    Date of publication: 2011
    Journal article

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    The properties of polypropylene (PP) foams can be extended by controlling the cellular structure and adding functional fillers. PP-based microcellular foams having an interesting combination of mechanical and transport properties were prepared by two different batch foaming processes. The batch processes employed were a semisolid state CO2 dissolution physical foaming process and a chemical one based on the dissolution of the gases generated by the thermal decomposition of a chemical blowing agent in the molten state. The role of the cellular structure and nanofillers (5 wt% of organoclay and 10–20 wt% of cellulosic fibers) on the foam properties and CO2 diffusion rate was discussed. Foams with expansion ratios around 3 but different cell structures were prepared and studied concerning their structural characteristics. For unfilled foams prepared by CO2 dissolution, the microcellular structure resulted in the highest values of the specific storage modulus. A fraction of organically-treated montmorillonite dispersed into the PP matrix resulted in superior mechanical properties due to the combined effect of a finer cell structure and inherent higher stiffness of the silicate layers. Despite displaying an opencell structure, foams reinforced with high contents of cellulosic fibers showed increased specific storage moduli with respect to the unfilled foams

  • Polypropylene foams: production, structure and properties

     de Sousa Pais Antunes, Marcelo; Velasco Perero, Jose Ignacio; de Redondo Realinho, Vera Cristina
    Date of publication: 2011-11-01
    Book chapter

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  • Caracterización de probetas de PEHD inyectadas

     Arencón Osuna, David; Franco Urquiza, Edgar Adrian; de Redondo Realinho, Vera Cristina
    Date: 2011-11-30
    Report

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  • Determinación del grado de reticulación de 7 muestras de tubo por DSC

     Velasco Perero, Jose Ignacio; de Redondo Realinho, Vera Cristina
    Date: 2011-10-28
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  • Medidas de espesores de films de PE / adhesivo

     de Redondo Realinho, Vera Cristina
    Date: 2011-05-24
    Report

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  • Medidas de espesores de films de PE

     de Redondo Realinho, Vera Cristina
    Date: 2011-02-04
    Report

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  • Caracterización mecánica a tracción y determinación de la densidad y grado de contracción de probetas de PEHD inyectadas

     Arencón Osuna, David; Franco Urquiza, Edgar Adrian; de Redondo Realinho, Vera Cristina
    Date: 2011-11-04
    Report

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  • Mechanical Properties and Morphology of Multifunctional Polypropylene Foams

     de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Ardanuy Raso, Monica; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    Cellular polymers
    Date of publication: 2011
    Journal article

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  • Microcellular Foaming of Layered Double Hydroxide-Polymer Nanocomposites

     Martinez Benasat, Antonio; de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    Industrial & engineering chemistry research
    Date of publication: 2011
    Journal article

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    Microcellular foams of polystyrene (PS), poly(styrene-co-acrylonitrile) (SAN), and poly(methyl methacrylate) (PMMA) having organically modified layered double hydroxides (LDH) were prepared using a high-pressure CO2 dissolution foaming process and characterized both structurally and thermo-mechanically. The saturation concentration of CO2 was found to increase with the incorporation of LDH nanoparticles into the PMMA, while the opposite effect was observed in the PS and SAN nanocomposites with respect to the pure polymers. The CO2 desorption diffusion coefficient substantially decreased in the nanocomposites comparatively to the respective pure polymers. The incorporation of hydrotalcite (HT) into the polymers and subsequent foaming resulted in foams with finer and more isotropic cellular structures, related to a cell nucleation effect promoted by the particles. No significant differences were found among the several foamed nanocomposites. Both PS and SAN nanocomposite foams displayed higher glass transition temperatures than the respective unfilled ones, related to a higher amount of residual CO2 in the last, favoring plasticization. The contrary effect was observed inPMMA, attributed to a combined plasticizing effect promoted by the higher affinity of PMMA for CO2 and greater interaction with the organically modified HT platelets. Although no significant differences were found among the several nanocomposite foams and respective unfilled counterparts, the incorporation of HT limited the reduction observed in the specific storage moduli with foaming, related to a finer cellular structure induced by the HT particles.

  • Influence of nanoclay concentration on the CO2 diffusion and physical properties of PMMA montmorillonite microcellular foams

     de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Martinez Benasat, Antonio; Velasco Perero, Jose Ignacio
    Industrial & engineering chemistry research
    Date of publication: 2011-11-08
    Journal article

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  • Diseño y caracterización de mezclas EVA/plastómero para su empleo en compuestos de aislamiento acústico

     Niubó Eslava, Maria; Fernández, Ana Inés; Haurie Ibarra, Laia; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio
    Congreso Nacional de Materiales
    Presentation's date: 2010-06-24
    Presentation of work at congresses

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    En el desarrollo de materiales aislantes acústicos para sectores como la automoción, se utilizan habitualmente compuestos poliméricos con un contenido en cargas inorgánicas superior al 70% en peso. Este hecho obliga a utilizar matrices que mantengan en el compuesto la ductilidad necesaria para su termoconformado. En este trabajo se ha aplicado el diseño estadístico de mezclas al estudio del comportamiento térmico y mecánico de mezclas preparadas con dos grados de EVA de diferente contenido en acetato de vinilo y un plastómero de etileno y buteno. En particular, se ha estudiado la evolución de las entalpías y temperaturas de fusión y cristalización, así como la estabilidad térmica y el comportamiento mecánico de las mezclas en función de su composición.

  • Preparación y caracterización de espumas microcelulares nanoreforzadas

     de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Santana Pérez, Orlando Onofre; Sanchez Soto, Miguel Angel; Velasco Perero, Jose Ignacio
    Congreso Nacional de Materiales
    Presentation's date: 2010-06-24
    Presentation of work at congresses

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  • Preparación y caracterización de espumas multifuncionales de polipropileno

     de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Martinez Benasat, Antonio; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    Congreso Nacional de Materiales
    Presentation's date: 2010-06-24
    Presentation of work at congresses

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    La combinación de la espumación junto con refuerzos funcionales permite ampliar el rango de propiedades de los sólidos, añadiendo a una elevada rigidez específica la regulación de otras características como las propiedades de transporte. Aunque las espumas poliolefínicas se encuentren extendidas, las ventajas de emplear PP en lugar de PE sólo empiezan a ser importantes para densidades > 100 kg/m3. Por ello, en este trabajo se presenta el estudio de la influencia de la espumación e incorporación de varios refuerzos en las propiedades de espumas de PP de densidad media-alta. Se muestra que la presencia de nanopartículas de montmorillonita induce estructuras celulares más isotrópicas, mejorando su comportamiento mecánico, pero sin alterar la conductividad térmica [1-2]. La incorporación de elevados porcentajes de carga mineral resulta en espumas rígidas con marcadas anisotropías celulares y térmicas, e interesantes propiedades de resistencia al fuego. También pueden obtenerse espumas conductoras eléctricas por incorporación de nanofibras de carbono con posibilidades en aplicaciones como el pintado electrostático

  • Thermal Conductivity of Carbon Nanofibre-Polypropylene Composite Foams

     de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Solórzano Quijano, Eusebio; Rodríguez-Pérez, Miguel Ángel; de Saja, José Antonio; Velasco Perero, Jose Ignacio
    Defect and diffusion forum
    Date of publication: 2010
    Journal article

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    Carbon nanofibre-reinforced polypropylene nanocomposites containing from 5 to 20 wt.% of carbon nanofibres and a chemical blowing agent were melt-compounded and later foamed using compression-moulding. Alongside their foaming behaviour analysis and cellular characterization, foams showing an increasingly finer isometric cellular structure with increasing the amount of nanofibres, their thermal conductivity was determined using the Transient Plane Source Method (TPS). Contrarily to the electrical conductivity, which has previously been shown to rise with increasing the amount of carbon nanofibres [1], the addition of the nanofibres did not significantly alter the thermal conductivity of the PP foams, their value being mainly affected by the relative density, only slight differences being assessed for the higher expansion ratio PP-CNF foams

  • Characterization of Highly Oriented Organoclay/Poly(methyl methacrylate) Moulded Nanocomposites

     de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio; de Sousa Pais Antunes, Marcelo; Sanchez Soto, Miguel Angel; Maspoch Ruldua, Maria Lluïsa
    Journal of nanoscience and nanotechnology
    Date of publication: 2010-02
    Journal article

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  • Heat Transfer of Mineral-Filled Polypropylene Foams

     de Sousa Pais Antunes, Marcelo; de Redondo Realinho, Vera Cristina; Martinez Benasat, Antonio; Solórzano Quijano, Eusebio; Rodríguez-Pérez, Miguel Ángel; Velasco Perero, Jose Ignacio
    Defect and diffusion forum
    Date of publication: 2010
    Journal article

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    The thermal conductivity of unfilled polypropylene foams produced using different foaming processes has previously been demonstrated to be mainly affected by the foam’s bulk density [1]. The influence of adding inorganic particles is now studied, with the thermal conductivity of the mineral-filled PP foams being determined using the Transient Plane Source Method (TPS). To this end, two different fillers were used. The incorporation of high amounts (50 and 70 wt.%) of magnesium hydroxide resulted in considerably higher thermally conductive foamed materials, with interesting thermal anisotropies being observed for the higher expansion ratio foams. On the contrary, adding montmorillonite (MMT) nanoparticles did not considerably alter the thermal conductivity of the foams, their value being mainly affected by the relative density.

  • Characterization of carbon nanofibre-reinforced polypropylene foams

     de Sousa Pais Antunes, Marcelo; Velasco Perero, Jose Ignacio; de Redondo Realinho, Vera Cristina; Arencón Osuna, David
    Journal of nanoscience and nanotechnology
    Date of publication: 2010
    Journal article

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  • Preparación y caracterización de espumas multifuncionales a base de nanocompuestos de poliolefinas  Open access  awarded activity

     de Sousa Pais Antunes, Marcelo
    Defense's date: 2010-07-23
    Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya
    Theses

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    En esta tesis doctoral se presenta la preparación y caracterización de espumas rígidas multifuncionales obtenidas a partir de compuestos y nanocompuestos en base polietileno (PE) y polipropileno (PP), indagando en la relación existente entre la espumación, la estructura y microestructura de las espumas y sus respectivas propiedades.En primer lugar se realizó un análisis de la influencia de la espumación en la estructura de las espumas y respectivas propiedades. Se consideraron dos procesos de espumación: espumación química por compresión y espumación física por disolución de gas. En un ámbito más específico, se establecieron las condiciones y metodología para la preparación de espumas microcelulares de PP por un proceso de disolución de gas a elevada presión y espumación por control de la caída de presión. Se obtuvo una relación prácticamente lineal para estas espumas entre el módulo de almacenamiento y el producto del módulo del sólido por la densidad relativa de la espuma, demostrando la eficacia del proceso de espumación.Se analizó la influencia de la densidad relativa y de la estructura celular y microestructura en las propiedades mecánicas y de transporte de las espumas. En ambos casos se consideraron modelos de predicción de las propiedades de las espumas, tratando de analizar la eficacia de la espumación en la mejora de las propiedades específicas. En lo que concierne a la conductividad térmica, se demostró que ésta resulta prácticamente independiente de la estructura celular de la espuma, siendo estimada como el producto de la conductividad del sólido por la densidad relativa.En una segunda etapa se incorporaron distintos tipos de refuerzos funcionales a la matriz polimérica, en particular nanopartículas laminares de montmorillonita (MMT), nanofibras de carbono (CNF) y elevados porcentajes de hidróxido de magnesio (Mg(OH)2), y se procedió a su espumación, con el objetivo de extender el rango de propiedades y por ende de aplicaciones de las espumas. Se observó que la incorporación de refuerzos nanométricos al PP y PE resulta en un incremento de las propiedades mecánicas específicas de las espumas, fruto de un efecto combinado de nucleación de celdas por parte de los mismos y refuerzo de las paredes celulares. Consecuencia directa de su estructura celular más fina e isotrópica, las espumas de estos nanocompuestos presentan un comportamiento mecánico más isotrópico que el observado en las espumas sin refuerzos.La incorporación de ambos refuerzos nanométricos no afectó considerablemente a la conductividad de los sólidos y de las espumas. En el caso particular de las nanofibras de carbono, y aunque los sólidos presenten un valor constante de la conductividad independientemente de la concentración de CNF, se observa un incremento lineal de la conductividad en las espumas al incrementar el porcentaje de CNF, demostrando que la espumación contribuye a mejorar el mecanismo de transferencia térmica.La espumación de compuestos muy cargados de PP con Mg(OH)2 posibilitó la obtención de espumas con una estructura celular tanto isotrópica y de reducido tamaño de celda, como espumas con celdas orientadas en la dirección del crecimiento, dependiendo de la composición y la densidad relativa. La anisotropía celular induce una orientación preferencial de las partículas de Mg(OH)2, que a su vez afecta a la microestructura del polímero y a la conductividad térmica de las espumas, ésta última incrementándose en la dirección de crecimiento de la espuma.Con las nanofibras de carbono se lograron importantes mejoras en la conductividad eléctrica, siendo que las espumas presentan valores inferiores de la concentración crítica de nanofibras para conducción comparativamente a los sólidos.Asimismo, se demostró que la estructura celular y microestructura del PP en las espumas con CNF afecta enormemente al comportamiento de conducción eléctrica. Así, una estructura celular altamente orientada en la dirección de crecimiento, conlleva a superiores valores de la conductividad eléctrica en esa dirección debido a una reorientación parcial de las nanofibras.La incorporación de elevados porcentajes de Mg(OH)2 y posterior espumación resultó en espumas con propiedades mejoradas de resistencia al fuego, indicativas de una mayor auto-extinguibilidad en las espumas.Por último, se ha tratado de aplicar una nueva técnica de expandometría óptica y respectiva metodología de análisis de imagen para el seguimiento del proceso de espumación química en compuestos poliolefínicos.

    The aim of this research work was to prepare and characterize rigid multifunctional foams obtained from polyethylene (PE) and polypropylene (PP)-based composites and nanocomposites, investigating on the relations between foaming, structure and microstructure of the foams and their final properties.First of all, we analyzed the influence of the foaming process on the foam structure and respective properties. Two foaming processes were considered: compression-moulding chemical foaming and gas dissolution physical foaming. More specifically, we established the conditions and methodology for preparing PP microcellular foams by means of a high-pressure gas dissolution process and later foaming by sudden pressure drop (pressure-quench method). We found an almost linear relation between the storage moduli of these foams and the product of the moduli of the solids and the relative density, demonstrating the effectiveness of this foaming process.Besides, we analyzed the influence of the relative density, cellular structure and microstructure on the mechanical and transport properties of the foams. On both cases, we considered different models for predicting the properties of the foams, with the objective of correlating the efficiency of foaming in improving the specific properties.Concerning thermal conductivity, its value was found to be almost independent of the foam's cellular structure, and could be estimated as the product of the conductivity of the solid and the relative density.In a second stage of the thesis, different types of functional fillers were added to the polymer matrix, particularly montmorillonite nanoparticles (MMT), carbon nanofibres (CNF) and high amounts of magnesium hydroxide (Mg(OH)2), and the materials were later foamed, with the objective of extending their range of properties and thus possible applications. The incorporation of nanometric-sized fillers to PP and PE resulted in an increase of the foams' specific mechanical properties, direct result of a combined effect of cell nucleation and cell wall reinforcement by the fillers. Due to their finer and more isotropic cellular structures, these nanocomposite foams displayed a more isotropic-like mechanical behaviour than their unfilled counterparts.The incorporation of both nano-sized fillers did not considerably alter the thermal conductivity of both solids and foams. In the particular case of carbon nanofibres, and although solids presented a value of conductivity that was found to be independent of the amount of nanofibres, we observed a linear increase in the foams with increasing the concentration of CNF, showing that foaming improves the efficiency of the thermal conduction mechanism.From highly-filled Mg(OH)2-PP composites it was possible to prepare foams with an isotropic cellular structure with small cell sizes, as well as foams with cells highly elongated in the growth direction, depending on the composition and relative density. This cellular anisotropy induced a preferential Mg(OH)2 orientation, that in turn affected the polymer's microstructure and thermal conductivity of the foams, with conductivity increasing in the cell growth direction with increasing cell orientation.Carbon nanofibres enabled to improve the electrical conductivity, with foams displaying lower CNF critical concentrations for electrical conduction than solids. Also, it was demonstrated that the cellular structure and microstructure of PP-CNF foams enormously affects their electrical conduction behaviour. A cellular structure highlyoriented in the direction of foam growth resulted in foams with higher electrical conductivities in said direction, due to a partial reorientation of the nanofibres perpendicular to the foam's surface.The incorporation of Mg(OH)2 to PP and later foaming improved the flame retardancy behaviour, with foams exhibiting a higher extinguishability than the respective solid composites.Last but not least, a novel optical expandometry technique and respective image analysis methodology was developed to follow-up the evolution of the chemical foaming of polyolefinic composites.