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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.

  • Small punch test on the analysis of fracture behaviour of PLA-nanocomposite films

     Rodríguez González, Cristina; Arencón Osuna, David; Belzunce Varela, F. Javier; Maspoch Ruldua, Maria Lluïsa
    Polymer testing
    Date of publication: 2014-02
    Journal article

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    The analysis of the fracture behaviour of polymeric films involves the determination of the specific essential work of fracture, which requires preparation, testing and evaluation of a large number of notched specimens. All these tasks demand significant time and costs; therefore, the use of alternative testing procedures that offer savings of both materials and time are becoming increasingly attractive options. Recently, the Small Punch Test (SPT) has experienced significant development as an alternative to conventional testing procedures in the field of steels and some metallic alloys. This work considers the applicability of SPT to the fracture characterisation of polylactide acid reinforced with organic-modified montmorillonite clay, using several weight percentages of nanoclay. The applicability of the experimental methodology is evaluated through comparison of the results obtained by SPT and conventional testing (tensile and essential work of fracture).

  • On the effect of the different notching techniques on the fracture toughness of PETG

     Martinez Benasat, Antonio; León, Noel; Arencón Osuna, David; Rodríguez Pérez, Jesús; Salazar López, Alicia
    Polymer testing
    Date of publication: 2013-10
    Journal article

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    The fracture toughness of poly (ethylene terephthalate) modified glycol (PETG) has been evaluated using notch sharpening techniques which could be grouped into contact and non-contact procedures. Razor blade tapping, razor blade sliding, razor pressing and broaching are part of the first group, while the femtolaser technique belongs to the second one. Not all the contact procedures generated valid sharp cracks for fracture parameter assessment; indeed none of the samples sharpened via razor sliding generated acceptable sharp cracks. The results revealed that the non-contact femtolaser technique produced the sharpest cracks in this polymer, with crack tip radii of only 0.5 µm, leading to the lowest fracture toughness values. On the contrary, the traditional notch sharpening technique based on razor tapping, recommended in ISO, ESIS and ASTM protocols and standards, generated larger crack tip radii than those introduced via femtolaser and, consequently, resulted in higher fracture toughness values. Both broaching and pressing methods created specimens with smaller crack tip radii compared to those obtained by razor tapping, and hence resulting in intermediate fracture toughness values

    The fracture toughness of poly (ethylene terephthalate) modified glycol (PETG) has been evaluated using notch sharpening techniques which could be grouped into contact and non-contact procedures. Razor blade tapping, razor blade sliding, razor pressing and broaching are part of the first group, while the femtolaser technique belongs to the second one. Not all the contact procedures generated valid sharp cracks for fracture parameter assessment; indeed none of the samples sharpened via razor sliding generated acceptable sharp cracks. The results revealed that the non-contact femtolaser technique produced the sharpest cracks in this polymer, with crack tip radii of only 0.5 μm, leading to the lowest fracture toughness values. On the contrary, the traditional notch sharpening technique based on razor tapping, recommended in ISO, ESIS and ASTM protocols and standards, generated larger crack tip radii than those introduced via femtolaser and, consequently, resulted in higher fracture toughness values. Both broaching and pressing methods created specimens with smaller crack tip radii compared to those obtained by razor tapping, and hence resulting in intermediate fracture toughness values.

  • 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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  • Determinación de las curvas tensión-deformación verdaderas en polímeros

     Maspoch Ruldua, Maria Lluïsa; Loaeza, David; Martinez Benasat, Antonio; Arencón Osuna, David; de Sousa Pais Antunes, Marcelo; Velasco Perero, Jose Ignacio
    Encuentro del Grupo Español de Fractura
    Presentation's date: 2013-03-14
    Presentation of work at congresses

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  • Influencia de la agudización de la entalla sobre los parámetros de la fractura de polímeros

     Martinez Benasat, Antonio; León, Noel; Arencón Osuna, David; Rodríguez Pérez, Jesús; Salazar López, Alicia
    Encuentro del Grupo Español de Fractura
    Presentation's date: 2013-03-14
    Presentation of work at congresses

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  • Influence of the injection moulding parameters on the microstructure and thermal properties of microcellular polyethylene terephthalate glycol foams

     Gómez Gómez, Jaime Francisco; Arencón Osuna, David; Sanchez Soto, Miguel Angel; Martinez Benasat, Antonio
    Journal of cellular plastics
    Date of publication: 2013
    Journal article

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    Microcellular injection moulding is capable of producing lightweight polymeric products. The present study analyses the influence of several representative injection moulding parameters on the foam’s morphology, apparent density and thermo-mechanical properties of PETG, poly(ethylene terephthalate-co-1,4-cyclohexylene-dimethylene terephthalate) specimens. A strong variation of the cell morphology along the melt flow direction has been found, as well as a dependence on the shot volume. The most homogeneous microcellular structure is achieved when low shot volume, intermediate injection speed and low mould temperature are employed. The skin–core structure of the injected parts, determined the thermo-mechanical features of the specimen, which are ruled by the skin layer.

  • Effect of humidity in charge formation and transport in LDPE

     Aragoneses Aguado, Andres; Tamayo, Ildaberto; Lebrato González, Alexander; Cañadas Lorenzo, Juan Carlos; Diego Vives, Jose Antonio; Arencón Osuna, David; Belana Punseti, Juan
    Journal of electrostatics
    Date of publication: 2013-04-02
    Journal article

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    Charge distribution and transport have been investigated in LDPE films with different humidity content under electric fields up to 130 MV/m. Pulsed electroacoustic measurements showed that, as water content increases, positive charge packets formation in the anode is enhanced and they propagate toward the cathode with higher transit speeds. Fits of surface potential decay measurements showed that charges in dry samples are injected directly into the volume, but the presence of moisture generates new trap centers in the surface of the material. This new trap level causes a charge accumulation on the surface, that gradually passes into the bulk. The observed behavior in development and propagation of charge packets are explained according to these results. Thermally stimulated depolarization current measurements showed a non-distributed relaxation associated to the new trap levels on the surface of the wet samples.

  • Influence of the injection-molding parameters on the cellular structure and thermo-mechanical properties of ethylene-propylene block copolymer foams

     Gómez Gómez, Jaime Francisco; Arencón Osuna, David; Sanchez Soto, Miguel Angel; Martinez Benasat, Antonio
    Advances in polymer technology
    Date of publication: 2013-03
    Journal article

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    Microcellular injection-molding technology is capable of producing lightweight polymeric products. The foam morphology is determined by the injection-molding parameters, and it has been observed that depending on the parameter variations, the cell structure may exhibit substantial morphological differences through the entire section along the melt flow direction of the injected part. The effects of varying injection-molding parameters on foam morphology and thermal mechanical properties of a multiphase ethylene-propylene block copolymer (EPBC) were tested on 5-mm plaque specimens using a constant temperature profile. It has been found that injection speed does not have a significant effect on the thermal-mechanical properties of the foam, whereas shot volume and mold temperature do have a significant influence. Low shot volume produces uniform density cellular structures and larger cores, whereas lower mold temperatures help maintain small cell sizes. Furthermore, the effect of the copolymer’s crystalline phase on foam morphology has been observed. This study identifies the achievable foam morphologies and the thermal-mechanical performance of cellular molded EPBC parts.

  • Caracterización y estudio comparativo de materiales celulares poliméricos obtenidos mediante moldeo por inyección con espumación física o química  Open access

     Gomez Gomez, Jaime Francisco
    Defense's date: 2013-07-15
    Universitat Politècnica de Catalunya
    Theses

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    En el presente trabajo se analizan las estructuras celulares de espumas poliméricas inyectadas a través de los métodos de espumación física o química. Como polímero base para el estudio preliminar de moldeo por inyección de espumación química se ha seleccionado el estireno acrilonitrilo (SAN. Para la segunda etapa se seleccionaron el polietielen tereftalatoglicol, PETG y el etileno-propileno copolímero en bloque EPBC para estudiar las estructuras celulares obtenidas por moldeo por inyección tanto por medio de espumación física, Mucell ®, como a través de espumación química. Los parámetros de proceso de inyección elegidos como variables de estudio han sido la temperatura de inyección, temperatura de molde, velocidad de inyección y el porcentaje de gas. En función del tipo de estudio se han seleccionado distintas geometrías (halterio tipo 1A y/o placa de 100 mm por 100 mm por 5 mm de espesor). La caracterización de la morfología celular se llevó a cabo mediante SEM y microscopía óptica. En algunos casos se llevó a cabo una caracterización térmica mediante DSC y DMTA. La caracterización mecánica se realizó a través de ensayos de tracción y flexión y la caracterización a fractura mediante ensayos con geometría Charpy. Finalmente se efectuó el estudio de la presión en el interior de la cavidad en inyección por espumación física. Como conclusiones generales se observa que a través de espumación física se obtienen estructuras celulares más finas con tamaño de celda menores a 50 μm pero con mayor anisotropía celular a lo largo de la pieza en comparación con las obtenidas por espumación química. Las estructuras obtenidas por espumación química presentan mayor homogeneidad, con celdas en torno a los 50 μm y densidades celulares similares a las obtenidas por espumación física. Todas las muestras presentan una estructura piel/núcleo cuyo ratio se ve afectado por las condiciones de proceso y afecta a los valores de las propiedades mecánicas y a fractura evaluadas.

    In the present work the cell morphologies and mechanical properties of chemically and physically injection molded polymer foams were analyzed. For a preliminary stage using chemical foaming agents, styrene acrylonitrile (SAN) was selected. For the second stage poly (ethylene terephthalate-co-1,4-cyclohexylene-dimethylene terephthalate) (PETG) and an ethylene propylene block copolymer (EPBC) were used to study the cellular structures produced using a chemical foaming agent and the physical foaming Mucell® process. The injection molding parameters selected as study variables were: injection temperature, mold temperature, injection speed and the gas concentration. Depending on the type of study, two different geometries were selected (ISO tensile specimen and/or 100 mm x 100 mm x 5 mm squared plate). Foam morphology characterization was performed using SEM and optical microscopy. In some cases, DSC and DMTA analyses were used for thermal characterization. Mechanical characterization was performed using tensile and flexural tests while fracture behavior was characterized under Charpy impact mode. Finally a mold cavity pressure study was conducted during the physical foaming process. As general conclusions, it has been observed that even though physical foaming with Mucell® is capable of producing finer cell structures, with cell sizes smaller than 50 μm, such structures exhibit a higher degree of anisotropy along the melt flow in the mold cavity than those obtained using chemical foaming agents. Cell structures obtained through chemical foaming present a higher degree of uniformity, with cell sizes in the range of 50 μm and cell densities similar to those obtained through physical foaming. All samples exhibit a skin/core structure whose ratio is influenced by processing conditions, affecting its mechanical properties and fracture behavior.

  • Comportamiento a fractura de láminas de espuma de polipropileno producidas mediante dos métodos diferentes de espumación

     Arencón Osuna, David; de Sousa Pais Antunes, Marcelo; Martinez Benasat, Antonio; 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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  • Nucleation efficiency of talc in the foaming behavior and cellular structure of polyolefin-based foams: new perspectives for optimized lightweight materials

     Meli, Gilles; Abler, Caroline; Jouffret, Frédéric; de Sousa Pais Antunes, Marcelo; Gedler, Gabriel; Arencón Osuna, David; 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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    The research consisted in evaluating the nucleation efficiency of different types of talc (with different particle size distributions, morphologies and even surface modifications) in the foaming behaviour and cellular structure os polypropylene-based materials, with the objective of developing lightweight materials with improved stiffness and lower densities. Nucleation efficiency was first evaluated in talc filled PP foamed with a physical blowing agent inside a high pressure vessel. Depending on different talc characteristics, such a particle size distribution, surface area and morphology, cell density as much as doubled. Optimized foamed PP-talc composites prepared by injection-moulding using the MuCell process displayed further weight reductions for similar stiffness values.

  • High strain rate behaviour of polypropylene microfoams

     Gómez del Río, Teresa; Garrido, Miguel Ángel; Rodríguez Pérez, Jesús; Arencón Osuna, David; Martinez Benasat, Antonio
    International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading
    Presentation's date: 2012-09-05
    Presentation of work at congresses

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  • Influence of the injection moulding parameters on the cellular structure and thermo mechanical properties of ethylene-propylene block copolymer and PETG foams

     Arencón Osuna, David; Sanchez Soto, Miguel Angel; Martinez Benasat, Antonio; Gómez Gómez, Jaime Francisco; Rodríguez Pérez, Jesús; Salazar López, Alicia
    International Conference on Foam Materials & Technology
    Presentation's date: 2012-09-13
    Presentation of work at congresses

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    Microcellular injection moulding technology is capable of producing lightweight polymeric products. Microcellular foams are characterised by cell densities in the order of 109-1015 cells per cm3 and cell sizes between 10-100 μm in diameter. The foam morphology is determined by the injection moulding parameters, and it has been observed that depending on the parameters variations, cell structure may exhibit substantial morphological differences through the entire section, along the melt flow direction of the injected part. Using a constant temperature profile and blowing agent dosage rate, variations of 3 key injection moulding parameters (mould temperature, injection speed and shot volume) were studied to analyse the effect on foam morphology and thermal mechanical properties of single ethylene-propylene block copolymer (EPBC) and poly(ethylene glycol-co-cyclohexane- 1,4- dimethanol therephthalate) (PETG) specimens.

  • Study of the fracture behaviour of flexible polypropylene foams using the Essential Work of Fracture (EWF)

     Arencón Osuna, David; de Sousa Pais Antunes, Marcelo; Martinez Benasat, Antonio; Velasco Perero, Jose Ignacio
    Polymer testing
    Date of publication: 2012-04-01
    Journal article

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  • Films of native and modified starch reinforced with fiber: influence of some extrusion variabels using response surface methodology

     Galicia Garcia, Tomás; Martínez Bustos, F; Jiménez Arévalo, Omar; Arencón Osuna, David; Gámez Pérez, José; Martinez Benasat, Antonio
    Journal of applied polymer science
    Date of publication: 2012-10-25
    Journal article

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    Corn starch (native and phosphorylated) and potato films containing glycerol as plasticizer, and bagasse sugar cane as fiber, were produced by extrusion-calendering process, and characterized for the mechanical properties (tensile stress at rupture rr, elongation at break eb, and Young’s modulus E), water disintegration index (WDI), water absorption capacity (WAC), and luminosity. The evaluated processing variables were: feed moisture, fiber content, and type of starch. The response surface methodology was applied to analyze, and the model of significance was justified by a variance analysis (F-test). The inclusion of fiber provides a mechanical reinforcement to the starch matrix favoring the elongation at break (eb) in thickness films (280–350 lm). Samples formulated with potato starch within the values of feed moisture 18.25, 20.5, and 5 wt % of fiber content, showed an increment in values of tensile stress at rupture (3.80–4.4 MPa) and Young’s modulus (78.47–68.04 MPa). Corn starch films with high fiber content (10%) and low feed moisture (18.25%) values showed a decrement in elongation at break (12.93%). WAC and WDI were low with minimum and intermediate levels of feed moisture and fiber content (0–5%). Luminosity values were an indicative that do not exist degradation in film materials due to condition extrusion process used.

  • Low energy impact indentation of a modified polyethylene terephthalate by instrumented falling weight

     Martinez Benasat, Antonio; Arencón Osuna, David; Navas, Javier; Velasco Perero, Jose Ignacio
    Journal of applied polymer science
    Date of publication: 2012-04-27
    Journal article

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  • Flexed-plate low energy impact of an epoxy-carbon laminate

     Martinez Benasat, Antonio; Xiang, Gao; Arencón Osuna, David
    Polymers and polymer composites
    Date of publication: 2012-07-01
    Journal article

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  • Relevance of the femtolaser notch sharpening on the impact fracture of polycarbonate

     Arencón Osuna, David; Martinez Benasat, Antonio; Moreno, Pablo; Garcia Serrano, Ana
    EUROTEC
    Presentation's date: 2011-11-14
    Presentation of work at congresses

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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.

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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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  • Low energy impact indentation of an epoxy-carbon fiber laminate

     Martinez Benasat, Antonio; Xiang, Gao; Arencón Osuna, David; Velasco Perero, Jose Ignacio
    Polymers and polymer composites
    Date of publication: 2011-08-01
    Journal article

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  • Essential work of fracture (EWF): a useful tool for the fracture toughness characterization of particulate polyolefin composites

     Arencón Osuna, David; de Sousa Pais Antunes, Marcelo; Velasco Perero, Jose Ignacio
    Date of publication: 2011-01-03
    Book chapter

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    The characterization of the fracture toughness of polyolefin composites filled with inorganic particles is commonly solved by means of standardized testing procedures based wherther on the Linear Elastic Fracture Mechanics (LEFM) and the Elastic-Plastic Fracture Mechanics approaches. Fracture parameters as Kc, Gc and Jc are obtained and managed as "material" parameters in plain strain conditions. Nevertheless, particulate polyolefin composites are often in form of film or sheet, making difficult to achieve the specimen size criteria for fracture toughness characterization under plain strain conditions. In such cases, the concept os Essential Work of Fracture (EWF) is nowadays being increasingly applied and considered as a reliable way of fracture toughness determination for this kind of composites. The EWF has traditionally been used for fracture characterization of metals and ductile polymers under plain stress conditions, and most recently applied to ductile particulate composites. In the present chapter, the application of the EWF testing method to the particulate polyolefin composites is reviewed analyzed with regard to the variables of the testing method and the composite characteristics, such as the polyolefin nature and its ductility , the reinforcing particle characteristics and concentration, and the interfacial adhesion level, among others.

  • Informe técnico del estudio de rotura de racors

     Arencón Osuna, David
    Date: 2011-10-28
    Report

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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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  • 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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  • Fracture behaviour of flexible polyethylene foams for potential use in damping applications

     Velasco Perero, Jose Ignacio; de Sousa Pais Antunes, Marcelo; Arencón Osuna, David; Martinez Benasat, Antonio
    Applied mechanics and materials
    Date of publication: 2011-09
    Journal article

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    The application of the essential work of fracture (EWF) methodology for the fracture behavior characterization of closed-cell low density polyethylene flexible foams is discussed in the present paper. The thickness of the foamed sheet and the relative orientation of the initial crack were the main parameters studied. The interpretation of the results is carried out on the basis of the material microstructure and the applicability of the testing method.

  • Relevancia de la agudización de la entalla mediante femtoláser sobre la fractura de polímeros

     Martinez Benasat, Antonio; Gamez Pérez, Jose; Arencón Osuna, David; Rodríguez Pérez, Jesús; Salazar López, Alicia
    Simposio Latinoamericano de Polímeros y Congreso Iberoamericano de Polímeros
    Presentation's date: 2010-07-14
    Presentation of work at congresses

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  • 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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  • Experimental study on the strength of adhesion obtained by over-molding between different materials

     Sanchez Soto, Miguel Angel; Arencón Osuna, David; Candal, María Virginia; Illescas Fernandez, Silvia
    Date of publication: 2010-11-01
    Book chapter

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  • Determination of the crack initiation energy of films in plane stress

     Martinez Benasat, Antonio; Segovia, Angelica; Arencón Osuna, David; Illescas Fernandez, Silvia; Rodríguez Pérez, Jesús
    Encuentro del Grupo Español de Fractura
    Presentation's date: 2010-03-18
    Presentation of work at congresses

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  • Fracture behaviour of thermosetting polymers for ophtalmic lenses

     Martinez Benasat, Antonio; Artús, Pau; Dürsteter, Juan Carlos; Arencón Osuna, David
    Engineering failure analysis
    Date of publication: 2010-01-01
    Journal article

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  • Effect of a Dodecylsulfate-Modified Magnesium-Aluminum Layered Double Hydroxide on the Morphology and Fracture of Polystyrene and Poly(styrene-co-acrylonitrile) Composites

     de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Arencón Osuna, David; Fernandez, Ai; Velasco Perero, Jose Ignacio
    Journal of applied polymer science
    Date of publication: 2009-03
    Journal article

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    Fracture toughness of polypropylene-based particulate composites  Open access

     Arencón Osuna, David; Velasco Perero, Jose Ignacio
    Materials
    Date of publication: 2009-11-30
    Journal article

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    The fracture behaviour of polymers is strongly affected by the addition of rigid particles. Several features of the particles have a decisive influence on the values of the fracture toughness: shape and size, chemical nature, surface nature, concentration by volume, and orientation. Among those of thermoplastic matrix, polypropylene (PP) composites are the most industrially employed for many different application fields. Here, a review on the fracture behaviour of PP-based particulate composites is carried out, considering the basic topics and experimental techniques of Fracture Mechanics, the mechanisms of deformation and fracture, and values of fracture toughness for different PP composites prepared with different particle scale size, either micrometric or nanometric.

    Electronic version of an article published as "Materials" vol. 2, no 4, 2009, p. 2046-2094. DOI no 10.3390/ma2042046.

  • Estudi de defectes en peces (BECQUET 585) obtingudes mitjançant emmotllament per injecció

     Martinez Benasat, Antonio; Arencón Osuna, David
    Date: 2009-11-06
    Report

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  • Estudi de defectes en peces (TAPA GOLF) obtingudes mitjançant emmotllament per injecció

     Martinez Benasat, Antonio; Arencón Osuna, David
    Date: 2009-12-15
    Report

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    Microstructure anisotropy in polyolefin flexible foams  Open access

     de Sousa Pais Antunes, Marcelo; Arencón Osuna, David; de Redondo Realinho, Vera Cristina; Velasco Perero, Jose Ignacio
    IOP Conference Series: Materials Science and Engineering
    Date of publication: 2009-11
    Journal article

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    The use of polyolefin flexible foams with typical thicknesses between 1 and 3 mm produced by a physical foaming extrusion process is nowadays quite widespread in the packaging sector. Their high flexibility and closed-cell structure allows them to show good energy absorption properties under low loading conditions. Although the compressive response of these materials is well known, the inner microstructure developed during processing induce a high anisotropy that is responsible for their direction-dependent tensile and fracture behaviours. In this work, two different polyolefin-based foams, with densities ranging from 20 to 45 kg/m3, were studied. The induced microstructure anisotropy was characterized by micro- Raman. With this technique, the relative orientations of both crystalline and amorphous phases in the foam’s base polymer could be determined and thus related to their mechanical properties measured in the different directions.

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    Low Energy Dart Test for Mechanical Evaluation of Ophthalmic Materials  Open access

     Martinez Benasat, Antonio; Artús, Pau; Dürsteter, J C; Arencón Osuna, David
    Optometry and vision science
    Date of publication: 2009-08
    Journal article

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    Purpose. Many impact tests fail to rigorously analyze the polymer behavior at impact, because they are performed in an energy range too different from real-life incidents, use specimens with other geometries than those of their final application, or they do not take in account polymer viscoelastic nature. A novel low energy impact method that overcomes current method limitations is presented for ophthalmic polymers and advances our understanding of the behavior of these materials under impact conditions. Method. Plate-shaped specimens of two known materials, CR-39 and Superfin, were tested in an energy range around their failure limit. A non-conservative model was proposed to predict the dynamic response of the specimens that did not fail. Both the deflection and indentation mechanisms were introduced in the model, which was solved using a fourth order Runge-Kutta numerical method. Damper coefficients that were introduced to model the energy dissipation and elastic modulus were obtained after the fitting process. Rupture stress and absorbed energy at failure were obtained from the specimens that failed. Results. Very good agreement between experimental and calculated data was observed. Under non-failure conditions, Superfin and CR-39 showed similar elastic modulus, although slightly larger energy dissipation was observed for CR-39. However, Superfin clearly outperformed CR-39 when measuring rupture stress and absorbed energy at failure with values 54% and 170% larger, respectively. Conclusions. Low energy impact methods are a very powerful tool to study and compare ophthalmic materials. The model satisfactorily predicted the behavior of materials in low energy impact conditions and can be used to obtain critical material characteristics. In this particular case, the method was used to quantify mechanical differences among CR-39 and Superfin. Of these two, the latter is the best performing material.

    Martinez AB, Artus P, Dursteler JC, Arencon D. Low energy dart test for mechanical evaluation of ophthalmic materials. Optom Vis Sci 2009;86:979-87. Reproduced with permission. ©The American Academy of Optometry 2009.

  • Non-isothermal crystallization kinetics and activity of filler in polypropylene/Mg¿Al layered double hydroxide nanocomposites

     Ardanuy Raso, Monica; Velasco Perero, Jose Ignacio; Realinho, V; Arencón Osuna, David; Martinez Benasat, Antonio
    Thermochimica acta
    Date of publication: 2008-12
    Journal article

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  • Comportamiento a la fractura de materiales para lentes oftálmicas

     Martinez Benasat, Antonio; Artús, P; Dürsteter, J C; Arencón Osuna, David
    Encuentro del Grupo Español de Fractura
    Presentation's date: 2008-03-06
    Presentation of work at congresses

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  • Essential work of fracture analysis of glass micro sphere-filled polypropylene and polypropylene/poly (ethylene terephthalateco-isophthalate) blend-matrix composites

     Arencón Osuna, David; Velasco Perero, Jose Ignacio; de Redondo Realinho, Vera Cristina; de Sousa Pais Antunes, Marcelo; Maspoch Ruldua, Maria Lluïsa
    Polymer testing
    Date of publication: 2007-09
    Journal article

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  • Aplicación del trabajo esencial de fractura a polipropileno cargado con microesferas de vidrio

     Arencón Osuna, David; Folgueira, J; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    Encuentro del Grupo Español de Fractura
    Presentation's date: 2007-03-15
    Presentation of work at congresses

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