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  • 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
    Vol. 33, p. 21-29
    DOI: 10.1016/j.polymertesting.2013.10.013
    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).

    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).

  • Sheets of branched poly(lactic acid) obtained by one-step reactive extrusion-calendering process: physical aging and fracture behavior

     Cailloux, Jonathan; Santana Pérez, Orlando Onofre; Franco Urquiza, Edgar Adrian; Bou Serra, Jorge; Carrasco Alonso, Félix Ángel; Maspoch Ruldua, Maria Lluïsa
    Journal of materials science
    Vol. 49, num. 11, p. 4093-4107
    DOI: 10.1007/s10853-014-8101-y
    Date of publication: 2014-06-01
    Journal article

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    The architectural modifications of a linear poly(D,L-Lactide) acid (PD,L-LA) commercial grade were induced by a one-step reactive extrusion-calendering process using a styrene-glycidyl acrylate copolymer as reactive agent. The melt degradation was counteracted by chain extension and branching reactions, leading to a stabilization of the melt properties and an increase in the molecular weight. For such modified samples [poly(lactic acid) (PLA)-reactive extrusion (REX)], the rate of physical aging at 30 A degrees C was investigated during 1 week in order to simulate industrial storage conditions. Fracture behavior of "de-aged" and "controlled aged" (1 week) samples was investigated using the essential work of fracture (EWF) methodology and the critical tip opening displacement at the crack propagation onset, respectively. These analyses were complemented by digital image correlation analysis and inspection of the fractured surfaces by scanning electronic microscopy. As a result of the architectural modifications, the entanglement network density was increased. Those accounted for a slight decrease in the physical aging rate. Under uniaxial loading, aged reactive extrusion (REX) samples exhibited multiple crazing, leading to a slight increase in strain at break. Nevertheless, as a result of a similar dynamic environment of the entangled polymer coils, de-aged REX samples disclosed similar mechanical properties as compared to their neat counterparts. Regarding de-aged samples, the EWF analysis revealed no changes in the work required for the onset of crack propagation. However, the energy consumed up to the onset of crack propagation of aged PLA-REX samples decreased due to an apparently decreased network extensibility, promoting a premature craze-crack transition.

    The architectural modifications of a linear poly(D,L-Lactide) acid (PD,L-LA) commercial grade were induced by a one-step reactive extrusion-calendering process using a styrene-glycidyl acrylate copolymer as reactive agent. The melt degradation was counteracted by chain extension and branching reactions, leading to a stabilization of the melt properties and an increase in the molecular weight. For such modified samples [poly(lactic acid) (PLA)-reactive extrusion (REX)], the rate of physical aging at 30 A degrees C was investigated during 1 week in order to simulate industrial storage conditions. Fracture behavior of

  • Enhanced general analytical equation for the kinetics of the thermal degradation of poly(lactic acid)/montmorillonite nanocomposites driven by random scission

     Carrasco, Félix; Perez Maqueda, L.A.; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    Polymer degradation and stability
    Vol. 101, num. 1, p. 52-59
    DOI: 10.1016/j.polymdegradstab.2014.01.014
    Date of publication: 2014-03
    Journal article

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    An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of nanocomposites, composed of poly(lactic acid) (PLA) and organo-modified montmorillonite (OMMT) nanoparticles. This improvement has consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(a) = c (1 - a)nam that led to a better adjustment of experimental data and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential and isoconversional methods. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function f(a) = L (L - 1)x(1 - x)L-1, corresponding to a random scission mechanism, has been tested. Once optimized the kinetic model, the thermal degradation kinetics of nanocomposites (0.5 and 2.5% of OMMT) was compared to that of the polymer matrix. Moreover, the thermal stability of nanocomposites was tested and compared to that of the polymer matrix.

    An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of nanocomposites, composed of poly(lactic acid) (PLA) and organo-modified montmorillonite (OMMT) nanoparticles. This improvement has consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(a) = c (1 - a)nam that led to a better adjustment of experimental data and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential and isoconversional methods. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function f(a) = L (L - 1)x(1 - x)L-1, corresponding to a random scission mechanism, has been tested. Once optimized the kinetic model, the thermal degradation kinetics of nanocomposites (0.5 and 2.5% of OMMT) was compared to that of the polymer matrix. Moreover, the thermal stability of nanocomposites was tested and compared to that of the polymer matrix.

  • Improvement of the thermal stability of branched poly(lactic acid) obtained by reactive extrusion

     Carrasco Alonso, Félix Ángel; Cailloux, Jonathan; Sanchez Jimenez, P.E.; Maspoch Ruldua, Maria Lluïsa
    Polymer degradation and stability
    Vol. 104, p. 40-49
    DOI: 10.1016/j.polymdegradstab.2014.03.026
    Date of publication: 2014-06-01
    Journal article

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    One-step reactive extrusion-calendering process (REX-calendering) has been used in order to obtain sheets of 1 mm from poly(lactic acid) modified with a styrene-acrylic multifunctional oligomeric agent. In a preliminary internal mixer study, torque versus time has been monitored in order to ascertain chain extender ratios and reaction time. Once all the parameters were optimized, reactive extrusion experiments have been performed. An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of PLA sheets manufactured by reactive extrusion. This improvement has consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(alpha) = c (1 - alpha)(n) alpha(m) that led to a better adjustment of experimental data and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential methods and n-order reaction kinetics. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function f(alpha) = 2 (alpha(1/2) - alpha), corresponding to a random scission mechanism for L = 2 (as well as other functions for L values up to 8), has been tested. Once optimized the kinetic model, the thermal degradation kinetics of sheets obtained by REX-calendering process was compared to that of conventional sheets and polymer matrix. (C) 2014 Elsevier Ltd. All rights reserved.

    One-step reactive extrusion-calendering process (REX-calendering) has been used in order to obtain sheets of 1 mm from poly(lactic acid) modified with a styrene-acrylic multifunctional oligomeric agent. In a preliminary internal mixer study, torque versus time has been monitored in order to ascertain chain extender ratios and reaction time. Once all the parameters were optimized, reactive extrusion experiments have been performed. An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of PLA sheets manufactured by reactive extrusion. This improvement has consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(alpha) = c (1 - alpha)(n) alpha(m) that led to a better adjustment of experimental data and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential methods and n-order reaction kinetics. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function f(alpha) = 2 (alpha(1/2) - alpha), corresponding to a random scission mechanism for L = 2 (as well as other functions for L values up to 8), has been tested. Once optimized the kinetic model, the thermal degradation kinetics of sheets obtained by REX-calendering process was compared to that of conventional sheets and polymer matrix. (C) 2014 Elsevier Ltd. All rights reserved.

  • Propiedades mecánicas de residuos de PVC provenientes de cables eléctricos

     Franco Urquiza, Edgar Adrian; Maspoch Ruldua, Maria Lluïsa
    Ingenierías
    Vol. 17, num. 62, p. 29-38
    Date of publication: 2014-01
    Journal article

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    En este trabajo se evaluaron las propiedades mecánicas de desechos de cloruro de polivinilo (PVC) proveniente de cables eléctricos. El residuo contenía 60% de PVC , 30% de polietileno, 7% de goma y 3% de fracción metálica. La fracción metálica de separó de forma manual. La recuperación de PVC se realizó mediante el método de flotación. Se prepararon 6 mezclas de PVC con residuo (R). El PVC y las mezclas se ensayaron a tracción, obteniendo una reducción de la resistencia y la ductilidad al incrementar el contenido de residuo. Esta reducción en las propiedades mecánicas se adjudicó a la heterogeniedad de los componentes de la mezcla.

    En este trabajo se evaluaron las propiedades mecánicas de desechos de cloruro de polivinilo (PVC) proveniente de cables eléctricos. El residuo contenía 60% de PVC , 30% de polietileno, 7% de goma y 3% de fracción metálica. La fracción metálica de separó de forma manual. La recuperación de PVC se realizó mediante el método de flotación. Se prepararon 6 mezclas de PVC con residuo (R). El PVC y las mezclas se ensayaron a tracción, obteniendo una reducción de la resistencia y la ductilidad al incrementar el contenido de residuo. Esta reducción en las propiedades mecánicas se adjudicó a la heterogeniedad de los componentes de la mezcla.

  • Caracterización del comportamiento a fractura de un polipropileno copolímero espumado

     Gómez Monterde, Javier; Franco Urquiza, Edgar Adrian; Sanchez Soto, Miguel Angel; Arencón Osuna, David; Santana Pérez, Orlando Onofre; Docampo, RAmon; Maspoch Ruldua, Maria Lluïsa
    Encuentro del Grupo Español de Fractura
    p. 397-402
    Presentation's date: 2014-04-04
    Presentation of work at congresses

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    En el presente trabajo se ha aplicado el concepto de Trabajo Esencial de Fractura (EWF) a un copolímero etilenopropileno en bloque (EPBC) espumado, cuyas características morfológicas y mecánicas eran conocidas. Las probetas presentaron una propagación de grieta cuasi-estable, con diferentes porcentajes de propagación inestable, lo que pudo relacionarse con el espesor de piel no espumada. Debido a este comportamiento, se llevó a cabo la separación de los parámetros de fractura en iniciación de grieta y propagación, así como el cálculo de la apertura del frente de grieta en el momento de inicio de propagación. Como trabajos futuros se propone la aplicación de modelos de crecimiento y coalescencia de microvacíos, considerando como microvacíos las propias celdillas de la estructura espumada.

    En el presente trabajo se ha aplicado el concepto de Trabajo Esencial de Fractura (EWF) a un copolímero etilenopropileno en bloque (EPBC) espumado, cuyas características morfológicas y mecánicas eran conocidas. Las probetas presentaron una propagación de grieta cuasi-estable, con diferentes porcentajes de propagación inestable, lo que pudo relacionarse con el espesor de piel no espumada. Debido a este comportamiento, se llevó a cabo la separación de los parámetros de fractura en iniciación de grieta y propagación, así como el cálculo de la apertura del frente de grieta en el momento de inicio de propagación. Como trabajos futuros se propone la aplicación de modelos de crecimiento y coalescencia de microvacíos, considerando como microvacíos las propias celdillas de la estructura espumada.

  • Polymer/clay aerogel composites with flame retardant agents: mechanical, thermal and fire behavior

     Wang, Liang; Sanchez Soto, Miguel Angel; Maspoch Ruldua, Maria Lluïsa
    Materials and design
    Vol. 52, p. 609-614
    DOI: 10.1016/j.matdes.2013.05.096
    Date of publication: 2013-12
    Journal article

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    Aerogel is a class of material characterized by its high void content and extreme lightness. Different polymer/clay aerogels have been prepared by a simply freeze-thaw process from a suspension with poly(vinyl alcohol) (PVOH) and clay (Na+-MMT). Low density polymer/clay aerogels modified with flame retardant agents were prepared using a similar approach. The addition of flame retardant agents slightly increased the apparent density of the final composites whereas the compression properties were reduced due to the decrease in the polymer/clay interfacial bonding. An exception was the sample containing Al(OH)3 that exhibited higher modulus and stress at maximum deformation. Regarding thermal properties, the presence of ammonium polyphosphate (APP) or silica gel (SG) significantly slowed the rate of aerogel decomposition at the temperature range from 250°C to 500°C while the onset of polymer decomposition was not affected. Fire behavior was analyzed through cone calorimeter suggesting that either the presence of Al(OH)3 or APP reduced the heat release rate of PVOH/clay systems.

  • Enhanced general analytical equation for the kinetics of the thermal degradation of poly(lactic acid) driven by random scission

     Carrasco, Félix; Perez Maqueda, L.A.; Sanchez Jimenez, P.E.; Perejón, A.; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    Polymer testing
    Vol. 32, num. 5, p. 937-945
    DOI: 10.1016/j.polymertesting.2013.04.013
    Date of publication: 2013-08
    Journal article

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    An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of poly(lactic acid) (PLA) at various linear heating rates and at constant rate conditions. This improvement consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(a) = c(1-a)nam, which led to better adjustment of experimental data, and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential and isoconversional methods. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function (a) = 2(a1/2-a), corresponding to a random scission mechanism, has been tested.

    An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of poly(lactic acid) (PLA) at various linear heating rates and at constant rate conditions. This improvement consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(α) = c(1−α)nαm, which led to better adjustment of experimental data, and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential and isoconversional methods. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function (α) = 2(α1/2−α), corresponding to a random scission mechanism, has been tested.

  • Analysis and thermo-mechanical characterization of mixed plastic wastes

     Sanchez Soto, Miguel Angel; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    Polymer-Plastics technology and engineering
    Vol. 52, num. 1, p. 16-23
    DOI: 10.1080/03602559.2012.717240
    Date of publication: 2013
    Journal article

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  • Effect of the unidirectional drawing on the thermal and mechanical properties of PLA films with different L -isomer content

     Velázquez Infante, Julio César; Gámez Pérez, José; Franco Urquiza, Edgar Adrian; Santana Pérez, Orlando Onofre; Carrasco, F; Maspoch Ruldua, Maria Lluïsa
    Journal of applied polymer science
    Vol. 127, num. 4, p. 2661-2669
    DOI: 10.1002/app.37546
    Date of publication: 2013-02-15
    Journal article

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    This work simulates the thermoforming process of two different L-isomer content PLA grades (95.6 and 98%), studying the influence on the induced morphology and the variation in the thermal and tensile properties. The thermoforming process was simulated with uniaxial tensile tests performed at different temperatures and strain rates, reporting the tensile behavior before, during, and after the test. The resulting structural changes were analyzed by wide-angle X-ray scattering and Fourier transformed infrared spectroscopy. Thermal characterization was carried out with differential scanning calorimetry and dynamomechanical thermal analysis. The results showed that, regardless the L-isomer content, drawing at 70°C produced a stable mesomorphic phase that showed greater tensile properties than the original films. This mesomorphic phase, indeed, could be reordered into a crystalline structure under mild annealing conditions (5 min/75°C), if compared with those needed for similar amorphous PLA specimens (60 min/120°C), thus providing a processing opportunity for obtaining thermally stable PLA products at temperatures above 100°C.

  • Determinación de los materiales usados en un protector de parking

     Sanchez Soto, Miguel Angel; Maspoch Ruldua, Maria Lluïsa
    Date: 2013-04-29
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  • Two-step supercritical carbon dioxide dissolution foaming of Bisphenol A polycarbonate: effects of the heating stage parameters on foam characteristics

     Gedler, Gabriel; de Sousa Pais Antunes, Marcelo; Sanchez Soto, Miguel Angel; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    International Conference on Diffusion in Solids and Liquids
    p. 222-
    Presentation's date: 2013-06-25
    Presentation of work at congresses

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    Caracterización mecánica, térmica y a fuego de aerogeles arcilla/polímero modificados con partículas  Open access

     Sanchez Soto, Miguel Angel; Wang, Liang; Martinez Benasat, Antonio; Velasco Perero, Jose Ignacio; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    Congreso Nacional de Materiales Compuestos
    p. 181-186
    Presentation's date: 2013-07-03
    Presentation of work at congresses

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    Los aerogeles son una clase de materiales que se caracteriza por su extrema ligereza y alto contenido de aire. En este trabajo se han preparado diferentes aerogeles polímero/arcilla (PVOH/Na+-MMT) mediante un proceso simple de congelación y liofilización. Mediante esta técnica se han preparado aerogeles modificados conteniendo diferentes agentes ignifugantes en forma de partículas. La adición de dichos agentes causó un ligero incremento de la densidad aparente. Las propiedades mecánicas en compresión tanto a baja como a alta velocidad en general se vieron ligeramente reducidas debido a una menor unión entre el polímero y la arcilla. La excepción fue la muestra modificada con Al(OH)3 que incrementó la rigidez de los compuestos y la tensión a máxima deformación. En cuanto a las propiedades térmicas, la presencia de polifosfato de amonio (APP) o de silica gel (SG) redujo notablemente la velocidad de descomposición de los aerogeles en el rango de temperaturas entre 250ºC y 650ºC, sin embargo, la temperatura de inicio de descomposición no se vio sensiblemente alterada. El comportamiento a fuego se analizó mediante calorimetría de cono y los resultados han indicado que tanto la presencia de Al(OH)3 como de APP retardan la combustión del sistema y reducen la tasa de liberación de calor.

    Los aerogeles son una clase de materiales que se caracteriza por su extrema ligereza y alto contenido de aire. En este trabajo se han preparado diferentes aerogeles polímero/arcilla (PVOH/Na+-MMT) mediante un proceso simple de congelación y liofilización. Mediante esta técnica se han preparado aerogeles modificados conteniendo diferentes agentes ignifugantes en forma de partículas. La adición de dichos agentes causó un ligero incremento de la densidad aparente. Las propiedades mecánicas en compresión tanto a baja como a alta velocidad en general se vieron ligeramente reducidas debido a una menor unión entre el polímero y la arcilla. La excepción fue la muestra modificada con Al(OH)3 que incrementó la rigidez de los compuestos y la tensión a máxima deformación. En cuanto a las propiedades térmicas, la presencia de polifosfato de amonio (APP) o de silica gel (SG) redujo notablemente la velocidad de descomposición de los aerogeles en el rango de temperaturas entre 250ºC y 650ºC, sin embargo, la temperatura de inicio de descomposición no se vio sensiblemente alterada. El comportamiento a fuego se analizó mediante calorimetría de cono y los resultados han indicado que tanto la presencia de Al(OH)3 como de APP retardan la combustión del sistema y reducen la tasa de liberación de calor.

  • 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
    p. 495-500
    Presentation's date: 2013-03-14
    Presentation of work at congresses

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  • Effect of the strain rate and drawing temperature on the mechanical behavior of EVOH and EVOH composites

     Franco Urquiza, Edgar Adrian; Gámez Pérez, José; Velázquez Infante, Julio César; Santana Pérez, Orlando Onofre; Martinez Benasat, Antonio; Maspoch Ruldua, Maria Lluïsa
    Advances in polymer technology
    Vol. 32, num. 1, p. E287-E296
    DOI: 10.1002/adv.21274
    Date of publication: 2012-02-27
    Journal article

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    The effect of the strain rate and draw temperature on the mechanical behavior of ethylene vinyl alcohol (EVOH) and EVOH composites was analyzed. When EVOH is stretched at moderate strain rates, evidence of strain-induced crystallization and recrystallization was observed. Higher strain rates produced less structural variation because the homogeneous flow of the chains and the crystalline perfection are restricted due to the rapid drawing. In reference to the drawing temperature, EVOH showed a diffusive yielding, and the mechanical parameters were reduced due to the softening of the crystalline region. For EVOH composites, the filler hinders the molecular mobility, causing an increase in the strength and restricting the plastic flow. However, the higher temperature, higher molecular mobility, and ductility are not so affected by the filler content

    The effect of the strain rate and draw temperature on the mechanical behavior of ethylene vinyl alcohol (EVOH) and EVOH composites was analyzed. When EVOH is stretched at moderate strain rates, evidence of strain-induced crystallization and recrystallization was observed. Higher strain rates produced less structural variation because the homogeneous flow of the chains and the crystalline perfection are restricted due to the rapid drawing. In reference to the drawing temperature, EVOH showed a diffusive yielding, and the mechanical parameters were reduced due to the softening of the crystalline region. For EVOH composites, the filler hinders the molecular mobility, causing an increase in the strength and restricting the plastic flow. However, the higher temperature, higher molecular mobility, and ductility are not so affected by the filler content.

  • Sheets of branched poly(lactic acid) obtained by one step reactive extrusion calendering process: Melt rheology analysis

     Cailloux, Jonathan; Santana Pérez, Orlando Onofre; Franco Urquiza, Edgar Adrian; Bou Serra, Jorge; Carrasco, F; Gámez Pérez, José; Maspoch Ruldua, Maria Lluïsa
    Express polymer letters
    Vol. 7, num. 3, p. 304-318
    DOI: 10.3144/expresspolymlett.2013.27
    Date of publication: 2012-03
    Journal article

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    One-step reactive extrusion-calendering process (REX-Calendering) was used in order to obtain sheets of 1mm from two PD,L-LA extrusion grades modified with a styrene-acrylic multifunctional oligomeric agent. In a preliminary internal mixer study, torque versus time was monitored in order to determine chain extender ratios and reaction time. Once all parameters were optimized, reactive extrusion experiments were performed. Independently of the processing method employed, under the same processing conditions, PD,L-LA with the lower D enantiomer molar content revealed a higher reactivity towards the reactive agent, induced by its higher thermal sensitivity. REXCalendering process seemed to minimize the degradations reactions during processing, although a competition between degradation and chain extension/branching reactions took place in both processes. Finally, the rheological characterization revealed a higher degree of modification in the melt rheological behaviour for REX-Calendered samples. © BME-PT.

  • Caracterización de piezas inyectadas

     Maspoch Ruldua, Maria Lluïsa; Illescas Fernandez, Silvia; de Redondo Realinho, Vera Cristina
    Date: 2012-01-18
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  • Análisis de defectos en grapas de fijación de tubos en alcantarillados

     Sanchez Soto, Miguel Angel; Maspoch Ruldua, Maria Lluïsa
    Date: 2012-06-14
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  • Comparison of plasticized PVC formulations

     Maspoch Ruldua, Maria Lluïsa; Illescas Fernandez, Silvia; Franco Urquiza, Edgar Adrian
    Date: 2012-02-08
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  • Análisis de grapas de fijación para uso en alcantarillados

     Sanchez Soto, Miguel Angel; Maspoch Ruldua, Maria Lluïsa
    Date: 2012-11-30
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  • Relación estructura-propiedades de films de nanocompuestos de pla  Open access

     Velázquez Infante, Julio Cesar
    Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya
    Theses

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    The development of the present Ph.D. thesis implied the preparation of PLA and nanoclay reinforced PLA films as well as the application of different thermo-mechanical treatments. Two commercial grade PLA matrices were used, and a commercial grade of organomodified montmorillonite clay (o-MMT) was chosen. The mixing of the o-MMT and the PLA was performed using a twin-screw extruder. Films were obtained using two different processing methods: single-screw extrusion and twin-screw extrusion followed by a calendaring process. In the films, different PLA matrices were used as well as several o-MMT concentrations. In some cases a nucleating agent was added. A de-aging thermal treatment was applied to the films, allowing its study in two different states: de-aged and aged. The film¿s behavior was studied during and after thermoforming process using: (i) tensile tests at high temperatures and different deformation speeds, and (ii) sample uniaxial orientation of the material and its later characterization. Film characterization included: (i) nanocomposites¿ morphological analysis (ii) image analysis (iii) molecular size determination of the matrix (iv) thermal behavior analysis (v) mechanical properties determination in tensile mode, and (vi) fracture parameters determination using the EWF technique. Morphological analysis revealed that the nanocomposites presented intercalated structures, although exfoliated laminates and agglomerated particles were observed. FIB-SEM showed that the extrusion-calendaring process generated an anisotropic morphology, which became evident in the PLA/o-MMT films¿ mechanical and fracture behavior. The processing reduced the average molecular weight in the matrices of all the prepared films. Nevertheless, this reduction was more significant in the nanocomposite films than in neat PLA films, and increased with the clay content increase. On the other hand, the de-aging treatment promoted a fragile-ductile transition, which allowed the application of the EWF technique, enabling to correlate the parameters obtained with the thermal, mechanical and morphological characterization. Mechanical parameters in tensile mode were affected with 2.5 wt % clay content. Nevertheless, the presence of clay produced changes in the deformation mechanism, evidenced by a stresswhitening phenomenon due to the formation of micro defects as a product of o-MMT decohesion. The PLA fracture toughness increased with the thermal de-aging treatment. The addition of o- MMT increased the toughness of the aged films, due to the development of energy dissipation mechanisms such as de-cohesion and micro-void growth. This fracture toughness increase is ¿masked¿ in the de-aged films due to the elevated fracture toughness of the matrix. Finally, uniaxial tensile tests performed at high temperatures and different crosshead speeds produced a mesomorphic phase in the PLA matrix, identified with WAXS and FT-IR. The characterization of previously oriented samples revealed the influence of the thermoforming process on the mechanical and thermo-mechanical behavior, relating these variations with the induced morphology by stretching. These results allowed establishing the optimal matrixadditive- processing conditions for the fabrication of thermo-mechanical resistant PLA products through thermoforming.

    El desarrollo de la presente tesis doctoral implicó la preparación de films de PLA y PLA reforzado con arcilla, así como la aplicación de diferentes tratamientos termomecánicos a los mismos. Las matrices utilizadas fueron dos grados comerciales de PLA, mientras que la arcilla elegida fue una montmorillonita comercial organomodificada (o-MMT). El mezclado de la o-MMT con el PLA se realizó mediante extrusión doble husillo. Los films se obtuvieron utilizando dos vías de procesamiento diferente: extrusión monohusillo y extrusión doble husillo, ambas seguidas de un calandrado. En los films se varió la matriz, la concentración de o-MMT y, en algunos casos, se adicionó un agente nucleante. A los films se les aplicó un tratamiento térmico de rejuvenecimiento, lo que permitió su estudio en dos estados diferentes: rejuvenecido y envejecido. El comportamiento de los films durante y después de un proceso de termoconformado se estudió mediante: (i) ensayos de tracción a elevada temperatura y diferentes velocidades de deformación y (ii) orientación uniaxial de muestras de los materiales y su posterior caracterización. La caracterización de los films incluyó: (i) análisis de la morfología de los nanocompuestos (ii) análisis de imágenes (iii) determinación del tamaño molecular de la matriz de PLA, (iv) análisis del comportamiento térmico (v) determinación de las propiedades mecánicas a tracción y (vi) determinación de los parámetros a fractura mediante la aplicación de la técnica de EWF. El análisis morfológico reveló que los nanocompuestos presentaron estructuras intercaladas, aunque también se observaron laminillas exfoliadas y partículas aglomeradas. La observación por microscopia FIB-SEM demostró que durante el proceso de extrusión-calandrado se generó una morfología anisotrópica, lo que se evidenció en el comportamiento mecánico y a fractura de los films de PLA/o-MMT.

  • anales de mecanica de la fractura

     LLOP, MF; Vilaseca, F; Pellach, F; Maspoch Ruldua, Maria Lluïsa; Mutje, P
    Encuentro del Grupo Español de Fractura
    p. 235-238
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  • Anales de mecanica de la fractura

     Gimenez, E; Lagaron, Jm; Gamez Pérez, Jose; Saura, J; Maspoch Ruldua, Maria Lluïsa
    Encuentro del Grupo Español de Fractura
    p. 169-174
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  • The multi-scalar effect of incorporating nanofillers and cellulosic-based reinforcements into polyurethane foams: towards the development of low cost structural lightweight materials

     de Sousa Pais Antunes, Marcelo; Maspoch Ruldua, Maria Lluïsa; Velasco Perero, Jose Ignacio
    International Conference on Foam Materials & Technology
    Presentation's date: 2012-09-13
    Presentation of work at congresses

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  • Access to the full text
    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).

  • 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
    Vol. 50, num. 9, p. 5239-5247
    DOI: 10.1021/ie101375f
    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.

  • 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
    Vol. 30, num. 4, p. 187-200
    Date of publication: 2011
    Journal article

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  • Fracture behavior of quenched poly(lactic acid)

     Gamez Pérez, Jose; Velázquez Infante, Julio César; Franco Urquiza, Edgar Adrian; Pages Figueras, Pedro; Carrasco, F; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    Express polymer letters
    Vol. 5, num. 1, p. 82-91
    DOI: 10.3144/expresspolymlett.2011.9
    Date of publication: 2011-01
    Journal article

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    The effect of a quenching treatment applied on heated cast sheet extruded films of two poly(lactic acid) (PLA) commercial grades, with different optical purities, was studied. The thermal and mechanical properties of the films, as well as their fracture behavior, were assessed by differential scanning calorimetry (DSC), tensile tests, and the essential work of fracture (EWF) approach. The heating-quenching treatment causes a de-aging effect with an increase in the free volume of polymer chains evidenced by a decrease in the glass transition temperature (Tg) and a decrease in the tensile stiffness and yield stress. As a result, there is an abrupt increase in ductility, finding a dramatic change in the fracture behavior, from brittle to ductile. The use of digital image correlation (DIC) of the strain field analysis during fracture testing has allowed relating the decrease on the yield stress promoted by quenching with the crack propagation kinetics. The use of the EWF method to characterize the fracture toughness of PLA has allowed to measure this enhancement on toughness, finding that the specific essential work of fracture (we) and the plastic term (!wp) parameters increased 120% and 1200%, respectively, after the quenching process.

    The effect of a quenching treatment applied on heated cast sheet extruded films of two poly(lactic acid) (PLA) commercial grades, with different optical purities, was studied. The thermal and mechanical properties of the films, as well as their fracture behavior, were assessed by differential scanning calorimetry (DSC), tensile tests, and the essential work of fracture (EWF) approach. The heating-quenching treatment causes a de-aging effect with an increase in the free volume of polymer chains evidenced by a decrease in the glass transition temperature (Tg) and a decrease in the tensile stiffness and yield stress. As a result, there is an abrupt increase in ductility, finding a dramatic change in the fracture behavior, from brittle to ductile. The use of digital image correlation (DIC) of the strain field analysis during fracture testing has allowed relating the decrease on the yield stress promoted by quenching with the crack propagation kinetics. The use of the EWF method to characterize the fracture toughness of PLA has allowed to measure this enhancement on toughness, finding that the specific essential work of fracture (we) and the plastic term (!wp) parameters increased 120% and 1200%, respectively, after the quenching process.

  • Processing of poly(lactic acid)/organomontmorillonite nanocomposites: Microstructure, thermal stability and kinetics of the thermal decomposition

     Carrasco, F; Gámez Pérez, José; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    Chemical engineering journal
    Vol. 178, p. 451-460
    DOI: 10.1016/j.cej.2011.10.036
    Date of publication: 2011-12-15
    Journal article

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  • Influence of crystallinity on the fracture toughness of poly(lactic acid)/montmorillonite nanocomposites prepared by twin-screw extrusion

     Gamez Pérez, Jose; Nascimento, L.; Bou Serra, Jorge; Franco Urquiza, Edgar Adrian; Santana Pérez, Orlando Onofre; Carrasco Alonso, Félix Ángel; Maspoch Ruldua, Maria Lluïsa
    Journal of applied polymer science
    Vol. 120, num. 2, p. 896-905
    DOI: 10.1002/app.33191
    Date of publication: 2011-04-15
    Journal article

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  • Comparación de formulaciones de PVC plastificado

     Maspoch Ruldua, Maria Lluïsa; Illescas Fernandez, Silvia; Franco Urquiza, Edgar Adrian
    Date: 2011-11-15
    Report

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    Caracteritzar el comportamnet de diferents plastificants en una resina de PVC.

  • Comparación de formulaciones de PVC plastificado: efecto del envejecimiento

     Maspoch Ruldua, Maria Lluïsa; Illescas Fernandez, Silvia; Franco Urquiza, Edgar Adrian
    Date: 2011-11-21
    Report

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  • Modificación del PLA mediante extrusión reactiva para la mejora del procesado, del comportamiento a fractura y de la preparación de nanocompuestos biodegradables

     Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa; Franco Urquiza, Edgar Adrian
    Competitive project

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  • Compuestos de PLA/o-MMT: caracterización morfológica y mecánica

     Velázquez-Infante, Julio; Franco Urquiza, Edgar Adrian; Santana Pérez, Orlando Onofre; Martinez Benasat, Antonio; Maspoch Ruldua, Maria Lluïsa; Gamez Pérez, Jose; Carrasco, F
    Congreso Nacional de Materiales Compuestos
    p. 159-164
    Presentation's date: 2011-07-06
    Presentation of work at congresses

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  • Copolymers from poly(lactic acid) (PLA) and chain extenders or branching agents

     Hitos-Rodriguez, Ángel; Bacardit Dalmases, Anna; Olle Otero, Luis; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa; Bou Serra, Jorge
    European Polymer Congress
    p. 57
    Presentation's date: 2011-06-26
    Presentation of work at congresses

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  • Chain architecture modifications of Poly(Lactic Acid) by reactive extrusion

     Santana Pérez, Orlando Onofre; Callioux, Jonathan; Franco Urquiza, Edgar Adrian; Bou Serra, Jorge; CARRASCO, FELIX; Gámez Pérez, José; Maspoch Ruldua, Maria Lluïsa
    European Polymer Congress
    p. 298-
    Presentation's date: 2011-06-26
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  • Biodegradation in compost of recycled low density polyethylene/polycaprolactone blends

     Bou Serra, Jorge; Marroyo Molina, Luis Miguel; Alla Bedahnane, Abdelilah; Olle Otero, Luis; Bacardit Dalmases, Anna; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    European Polymer Congress
    p. 36
    Presentation's date: 2011-06-26
    Presentation of work at congresses

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  • Simultaneous EWF, JIC and CTOD assessed on ductile polymer films

     Martinez Benasat, Antonio; Gámez Pérez, José; Delgado, A; Maspoch Ruldua, Maria Lluïsa
    International Conference on Fracture of Polymers, Composites and Adhesives
    p. O5.3-
    Presentation's date: 2011-09-13
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    Fractura postcedencia de polímeros  Open access

     Maspoch Ruldua, Maria Lluïsa; Franco Urquiza, Edgar Adrian; Santana Pérez, Orlando Onofre; Gamez Pérez, Jose; Sanchez Soto, Miguel Angel; Velasco Perero, Jose Ignacio; Martinez Benasat, Antonio
    Encuentro del Grupo Español de Fractura
    p. 21-29
    Presentation's date: 2011-04-08
    Presentation of work at congresses

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  • Reactive extrusion of poly(lactic acid) with styrene-acrylic-glycidil methacrylate

     Santana Pérez, Orlando Onofre; Cailloux, Jonathan; Franco Urquiza, Edgar Adrian; Bou Serra, Jorge; Carrasco, Félix; Gámez Pérez, José; Maspoch Ruldua, Maria Lluïsa
    EUROTEC
    p. 146-150
    Presentation's date: 2011-11-14
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  • 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
    p. 1-10
    Presentation's date: 2011-05-10
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  • Essential work of fracture analysis of the tearing of a ductile polymer film

     Martinez Benasat, Antonio; Segovia, Angelica; Gamez Pérez, Jose; Maspoch Ruldua, Maria Lluïsa
    Engineering fracture mechanics
    Vol. 77, num. 14, p. 2654-2661
    DOI: 10.1016/j.engfracmech.2010.07.017
    Date of publication: 2010-09
    Journal article

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    The fracture behaviour of a 0.5 mm thick ethylene-propylene block copolymer, previously evaluated using the essential work of fracture method, has been analyzed again in more detail, using different plots, allowing the determination of the crack initiation displacement and stress. In such plots is evidenced that the especific essential work of fracture, we, corresponds to the energy just up to crack initiation value that can be related with Јo. Also, it has been found a novel relationship between the plastic term ßwp and the crack initiation stress, σi.

  • Processing of poly (lactic acid) (PLA) and PLA / montmotillonite nanocomposites in a pilot plant: a study of structural changes and thermal stability

     Pages Figueras, Pedro; Carrasco Alonso, Félix Ángel; Gamez Pérez, Jose; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    Afinidad: revista de química teórica y aplicada
    Vol. 67, num. 546, p. 107-113
    Date of publication: 2010-03
    Journal article

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    Se aplican procesos de transformación y tratamiento de termoplásticos (inyección, extrusión-inyección y recocido) al àcido poliláctico (PLA) y a determinados nanocompuestos PLA/montmorillonita, con objeto de estudiar las variaciones de la estructura físico-química del PLA durante su procesado en planta piloto. El grado de cristalinidad de los materiales se estudió mediante calorimetría de barrido diferencial (DSC), difracción de rayos X (XRD) y espectroscopía FTIR, constatándoses que el procesado mecánico provoca la pràctica desaparición de la estructura cristalina del PLA, que se recupera mediante el recocido. Además, la técnica FTIR ha permitido el estudio de interacciones químicas entre los componentes de los nanocompuestos. Por otro lado, se ha estudiado la estabilidad térmica de muestras de PLA y de sus nanocompuestos, a partir de temperaturas de descomposición características, que se obtienen de los termogramas TGA.

  • Effects of composition and transesterification catalysts on the physico-chemical and dynamic properties of PC/PET blends rich in PC

     Al-Jabareen, Ahmad; Illescas Fernandez, Silvia; Maspoch Ruldua, Maria Lluïsa; Santana Pérez, Orlando Onofre
    Journal of materials science
    Vol. 45, num. 24, p. 6623-6633
    DOI: 10.1007/s10853-010-4753-4
    Date of publication: 2010-12
    Journal article

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  • Effect of the recycling and annealing on the mechanical and fracture properties of poly(lactic acid)

     Nascimento, L.; Gamez Pérez, Jose; Santana Pérez, Orlando Onofre; Velasco Perero, Jose Ignacio; Maspoch Ruldua, Maria Lluïsa; Franco Urquiza, Edgar Adrian
    Journal of polymers and the environment
    Vol. 18, num. 4, p. 654-660
    DOI: 10.1007/s10924-010-0229-5
    Date of publication: 2010-12
    Journal article

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    The aim of this work is to evaluate the use of Poly(lactic acid)(PLA) industrial waste as a source of raw material for certain applications, as well to understand the effects of the annealing on the fracture behaviour of PLA. PLA waste has been simulate by an initial step of extrusion in a single screw extruder and pelletizing. Specimens of virgin and reprocessed PLA were obtained by injection molding. An anneling treatment capable of increasing the percentage of cristallinity (determined by differential scanning calorimetry) was also analyzed in reprocessed and non reprocessed specimens. The fracture behaviour was studied at slow and high testing speed, applying the linear elastic fracture mechanics (LEFM) on single edge notched bend (SENB) specimens. This study revealed that the fracture toughness of the reprocessed PLA was basically the same that the virgin PLA and also that the increase in the crystalline fraction produced an improvement on the fracture toughness, at slow loagind rate.

  • The effect of organo-modifier on the structure and properties of poly[ethylene¿(vinyl alcohol)]/organo-modified montmorillonite composites

     Franco Urquiza, Edgar Adrian; Gamez Pérez, Jose; Sanchez Soto, Miguel Angel; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    Polymer international
    Vol. 59, num. 6, p. 778-786
    DOI: 10.1002/pi.2788
    Date of publication: 2010-02-02
    Journal article

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  • Fracture behaviour of de-aged poly(lactic acid) assessed by essential work of fracture and J-Integral methods

     Santana Pérez, Orlando Onofre; Rodríguez, C.; Belzunce Varela, F. Javier; Gamez Pérez, Jose; Carrasco Alonso, Félix Ángel; Maspoch Ruldua, Maria Lluïsa
    Polymer testing
    Vol. 29, num. 8, p. 984-990
    DOI: 10.1016/j.polymertesting.2010.09.004
    Date of publication: 2010-12
    Journal article

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    The applicability of the essential work of fracture (EWF) in SENB geometry as an alternative to the J-integral methodology has been assessed. An amorphous poly(lactic acid) (PLA) with ductile behaviour promoted by a de-ageing heat treatment has been used. The results demonstrate that the EWF technique can be used as a simple alternative methodology to determine the J0.2 value in plane strain conditions, using the ESIS-2000 protocol and ASTME813-87 standard. As a validation of the range of ligament length to be used in the EWF analysis, the SENB solution of the Slip Line Field theory could be employed.

  • Kinetics of the thermal decomposition of processed poly(lactic acid)

     Carrasco Alonso, Félix Ángel; Pages Figueras, Pedro; Gamez Pérez, Jose; Santana Pérez, Orlando Onofre; Maspoch Ruldua, Maria Lluïsa
    Polymer degradation and stability
    Vol. 95, num. 12, p. 2508-2514
    DOI: 10.1016/j.polymdegradstab.2010.07.039
    Date of publication: 2010-12
    Journal article

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