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  • Effects of vacuum infusion processing parameters on the impact behavior of carbon fiber reinforced cyclic butylene terephthalate composites

     Aguirregomezkorta, A; Sanchez Soto, Miguel Angel; Aretxaga, G; Sarrionandia, M; Aurrekoetxea Narbarte, Jon
    Journal of composite materials
    Date of publication: 2014-02
    Journal article

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    Carbon fiber reinforced cyclic butylene terephthalate composites have been processed by vacuum infusion under two different non-isothermal processing routes starting from a one-component cyclic butylene terephthalate resin system. One of them was processed under a short cycle with fast cooling, and another one was processed under a long cycle with slow cooling. Both the micro-structure and low-energy impact properties of the composites have been investigated. On one hand, the fast cooling generates randomly dispersed voids and porosities in the resin-rich regions during the crystallization-induced shrinkage. On the other hand, the slow cooling generates a highly crystalline and brittle matrix without porosity. However, many micro-cracks appear in the resin-rich regions due to the combination of the brittleness and longitudinal shrinkage of the matrix. The critical delamination energy of the slow cooled composite is slightly higher than that of the fast cooled one, whereas this latter absorbs over 25% more energy before being penetrated, as well as performing in a less brittle way. The lower interlaminar shear strength of the fast cooled composite is suggested to be the origin of its higher energy absorbing capability and less brittle behavior.

  • Effects of melt blended poss nanofillers on pom and ABS thermal stability

     Vila Ramirez, Narcis
    Defense's date: 2014-02-28
    Universitat Politècnica de Catalunya
    Theses

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    Aquesta tèsis doctoral ha investigat la incorporació de nanocàrregues del tipus Polyhedral Oligomeric Silsesquioxanes (POSS) en materials de base termoplàstica mitjançant el mètode de barreja en estat fos (melt-blending).Particularment, l¿estudi es centra en els efectes de diferents tipologíes de POSS en el comportament de la resistència tèrmica del poli(òxid de metilè) (POM) com a material semicristalí, i l¿acrilonitril-butadiè-estirè (ABS) com a material amorf. Val a dir que la selecció d¿aquests dos polímers tècnics ha estat en part motivada per la seva susceptibilitat inherent a la termodegradació.Diferents nanocompostos basats amb aquests materials s¿han elaborat amb la finalitat d¿estudiar la seva morfología, miscibilitat, estructura, propietats tèrmiques i aparença, així com els beneficis i contrapartides que resulten d¿ells.La preparació dels nanocompostos ha sigut mitjançant el mètode de barreja en estat fos (melt-blending), util.litzant quatre nano-càrregues diferentes per el POM, siguent glicidil, glicidil-Isobutil, aminopropil-isobutil y poli(etilenè-glicol), i tres nano-càrregues per el ABS, siguent amino-propil isobutil, glicidil i trisilanol.La compatibilitat teòrica de les nano-càrregues s¿ha calculat mitjançant el mètode de solubitat de ¿Hoy¿, i s¿ha corroborat amb microscopia electrònica d¿escombrat (SEM) i calorimetría diferencial d¿escombrat (DSC). Posteriorment s¿ha sotmès cada material base i les seves diferents variants de nanocompostos a diferents condicions de termo-oxidació en termes de temperatura i temps d¿exposició.El comportament a la degradació de cada mostra s¿ha quantificat mitjançant els mètodes d¿espectroscopía d¿infraroigs per transformada de Fourier (FTIR), anàlisis de termogravimetría (TGA) incloent cinemàtica de degradació, i finalment mitjançant espectrofotometría (Cielab) per a definir el progrés de l¿aparença de la mostra en termes d¿engroguiment.Els resultats han mostrat, per una banda, que la inclusió dels diferents POSS util.litzats en la matriu de POM ha millorat substancialment l¿estabilitat tèrmica del mateix, i aquesta millora és proporcional a la compatibilitat entre les solubitats del POM i del POSS. El millor comportament s¿ha produït amb l¿adició de la nano-càrrega d¿aminopropilisobutil, amb una temperatura de màxima degradació (TMAX) millorada en 22ºC en relació a la obtinguida amb la matriu de POM. Aquesta millora també es reflexa amb una reducció molt notable en la formació de grups carbonil i en l¿engroguiment sofert en la superfície de la mostra, siguent un 2% i 8% respectivament comparats amb els resultats obtinguts amb la mostra equivalent del material POM original.En contrast, els nanocompostos basats en ABS-g-Ma no han ofert millores en termes d¿estabilitat tèrmica, a pesar d¿una adequada solubitat teòrica entre la matriu i les diferents nano-càrregues util.litzades, així com la bona miscibilitat obtinguda en l¿elaboració de les mostres i posteriorment evidenciada en l¿anàlisi morfològic SEM. Concretament l¿adició de GPOSS i de TPOSS no han aportat beneficis en les propietats del nanocompostos final, i la nano-càrrega APOSS ha afectat negativament a la matriu amb una lleuguera caiguda de la resistència tèrmica.

  • 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
    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.

  • Efecto de las variables del proceso de inyección sobre la adhesión polímero-tela usando la técnica de decoración en molde

     Dávila, Everling; Candal, María Virginia; Sanchez Soto, Miguel Angel
    Congreso Venezolano de Polímeros
    Presentation's date: 2013-07-16
    Presentation of work at congresses

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    El objetivo de esta investigación es estudiar el efecto de las variables del proceso de inyección sobre la adhesión entre un material polimérico y una tela utilizando la técnica de decoración en el molde (IMD). Se usaron fibras textiles y PEBD formándose una unión del tipo adhesivo. Se evaluó el efecto de las condiciones de proceso (Ps, vi, Ti) en la adhesión, aplicando una matriz de diseño de experimentos (DOE) y se evaluó mecánicamente mediante la técnica de Pelado. Se obtuvo que la variable de mayor influencia en la adhesión es la temperatura de inyección, observándose que al incrementar la misma, la resistencia de la unión adhesiva disminuye.

  • Efecto de las variables de proceso de inyección sobre la morfología de la espuma microcelular de PET-glicolizado

     Sica, Kristy; Sanchez Soto, Miguel Angel; Candal, María Virginia
    Congreso Venezolano de Polímeros
    Presentation's date: 2013-07-15
    Presentation of work at congresses

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    La presente publicación comprende el estudio del efecto de las variables de proceso de inyección sobre la morfología obtenida al espumar Polientilentereftalato glicolizado (PETG) con un agente espumante químico endotérmico. La morfología fue estudiada mediante Microscopía Electrónica de Barrido (SEM). Se pudo observar que a medida que la relación gas/polímero se incrementa, la densidad celular de la espuma de PETG aumenta. A medida que la velocidad de inyección se incrementa, la densidad celular aumenta hasta llegar a un comportamiento asintótico. Por último, se encontró que el factor que genera un mayor efecto es la temperatura del molde, la cual al ser incrementada, genera un aumento de la densidad celular y disminución del diámetro celular.

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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
    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.

  • Properties of POSS blends with pCBT, PMMA, PC and POM thermoplastics

     Abt, Tobias Martin; Sanchez Soto, Miguel Angel; Illescas Fernandez, Silvia; Arostegui, Asier
    International journal of materials and structural integrity
    Date of publication: 2013
    Journal article

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    The influence of the functionalisation of fully or partially condensed POSS cages on the properties of engineering thermoplastic-based nanocomposites is studied. POSS with different organic substituents were selected in accordance with the structure and chemical composition of the host polymer and melt mixed with the corresponding matrix. In general, good dispersion at the nanoscale level was achieved upon the addition of some functionalised POSS, leading to a remarkable increase on the thermal decomposition temperature under nitrogen atmosphere. However, for the polymers having high decomposition temperatures, there were no significant changes on the thermal properties of the nanocomposites. On the other hand, the dispersion of the POSS, whatever its functionalisation was, led to the presence of micron-sized aggregates. The relationships among these effects and the morphological characteristics of the systems were analysed.

  • 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
    Date of publication: 2013
    Journal article

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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.

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    Isocyanate toughened pCBT: reactive blending and tensile properties  Open access

     Abt, Tobias Martin; Martinez de Ilarduya Saez de Asteasu, Antxon; Bou Serra, Jorge; Sanchez Soto, Miguel Angel
    Express polymer letters
    Date of publication: 2013-02-01
    Journal article

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    Cyclic butylene terephthalate oligomers (CBT) were reacted in a ring-opening polymerization with three types of isocyanates: a bifunctional aromatic type, a bifunctional aliphatic type and a polymeric aromatic isocyanate. All reactions took place in a batch mixer. The use of 0.5 to 1 wt% isocyanate led to a dramatic increase in elongation at break of polymerized cyclic butylene terephthalate (pCBT), from 8 to above 100%. The stiffness and strength of the modified pCBT, however, were found to slightly decrease. Proton nuclear magnetic resonance (NMR) analysis shows that the formation of thermally stable amide groups is the dominant chain extension reaction mechanism. Gel content measurements suggest a linear structure for samples containing bifunctional isocyanates while pCBT modified with polyfunctional isocyanate exhibited some gel formation at higher isocyanate content. Melting and crystallization temperatures as well as degree of crystallinity were found to decrease with increasing isocyanate content. No phase separation was detected by scanning electron microscopy (SEM) analysis. Moreover, a high degree of polymerization is deduced due to the absence of CBT oligomer crystals.

    Electronic version of an article published as "Express polymer letters" vol. 7, nº. 2, February 2013, p. 172-185.

  • 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.

  • Estudio de la adhesión en uniones poliméricas sobreinyectadas rígido-rígido (ABS/SAN)

     Dávila, Everling; Candal, María Virginia; Sanchez Soto, Miguel Angel
    Revista iberoamericana de polímeros
    Date of publication: 2013-11
    Journal article

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    El objetivo de esta investigación fue estudiar el efecto de las variables del proceso de sobre inyección sobre la resistencia de la unión adhesiva rígido¿rígido entre un par de materiales poliméricos. Se emplearon como materiales el estireno ¿acrilonitrilo (SAN) y el acrilonitrilo¿butadieno ¿estireno (ABS). Se evaluó el efecto de las condiciones de proceso (Psostenida, vinyección , Tfundido)del material sobreinyectado en la adhesión mediante ensayos mecánicos de tracción, trabajo esencial de fractura interfacial empleando geometría DENT, además de mecánica de la fractura interfacial elástico ¿lineal. Se obtuvo un incremento de la resistencia de unión adhesiva al aumentar la temperatura de fundido y la rugosidad de la superficie de contacto del sustrato con el material sobreinyectado.

  • 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.

  • 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.

  • Toughening of in situ polymerized cyclic butylene terephthalate by chain extension with a bifunctional epoxy resin

     Abt, Tobias Martin; Sanchez Soto, Miguel Angel; Martinez de Ilarduya Saez de Asteasu, Antxon
    European polymer journal
    Date of publication: 2012-01-01
    Journal article

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  • Low flammability, foam-like materials based on ammonium alginate and sodium montmorillonite clay

     Chen, H.B.; Wang, Yu-Zhong; Sanchez Soto, Miguel Angel; Schiraldi, D. A
    Polymer
    Date of publication: 2012-11-30
    Journal article

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    Low flammability, foam-like materials based on bio-based, renewable ammonium alginate and sodium montmorillonite clay were fabricated through a simple, environmentally-friendly freeze-drying process in which water is used as solvent. These materials exhibit mechanical properties similar to those of rigid PU foams or balsa; the compressive modulus (1–97 MPa) and density (0.047–0.174 g/cm3) increase with increasing solids content, with an associated change from a layered to network microstructure structure. Calcium ions, either added directly or indirectly via CaCO3/gluconolactone (GDL) are an effective crosslinking agent for alginate, with the GDL route providing the greatest enhancement of mechanical properties. The thermal stability of the aerogels is also enhanced by the presence of crosslinking. The alginate/clay aerogels possess inherently low flammability, as measured by cone calorimetry, with heat release values decreasing as the proportion of clay in the composites is increased.

  • Effects of POSS nanoparticles on ABS-g-Ma thermo oxidation resistance

     Vila Ramirez, N.; Sanchez Soto, Miguel Angel
    Polymer composites
    Date of publication: 2012-10
    Journal article

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    Thermo oxidative degradation at and beyond process- ing temperatures has been carried out on ABS copoly- mer grafted with Maleic Anhydride (ABS- g -Ma) and three nanocomposites with the above material melt-blended with different types of POSS, being amino-propyl isobutyl (APOSS), glycidyl (GPOSS), and trisilanol (TPOSS). The incorporation adequacy of the nanofillers into the matrix has been assessed with scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), whereas the quantification of the thermal degradation behavior of each sample was carried out through infrared spectrography (FTIR), thermogravimetric analysis (TGA) including the degra- dation kinetics and color spectrophotometry (Cielab). Although the results show adequate incorporation and miscibility of the nanofillers into the matrix, the GPOSS and the TPOSS nanocomposites provided no relevant improvements in thermal stability when compared with the base ABS- g -Ma, and the APOSS blend exhibits a very slight decay in almost all the quantitative analysis carried out in this work.

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    Thermal stabilization ability of polyhedral oligomeric silsesquioxane nanofillers  Open access

     Vila Ramirez, N.; Sanchez Soto, Miguel Angel
    Plastics research online
    Date of publication: 2012-12-17
    Journal article

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    The polyhedral oligomeric silsesquioxane nanofillers examined in this study provided little or no improvement to the thermal properties of melt-blended acrylonitrile butadiene styrene polymer composites.

    Electronic version of an article published as "Plastics research online", 17 December 2012

  • Development of multifunctional biopolymeric materials for teatment of decubitus ulcers  Open access

     Rocasalbas Lozano, Guillermo
    Defense's date: 2012-11-30
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    Chronic wounds including pressure, venous, arterial and diabetic neuropathic ulcers, represent a significant burden to the healthcare system. These different chronic wound types do not share origin or cause, however they have common features as bacterial infection and continuing influx of polymorphonuclear neutrophils that release high concentrations of matrix metalloproteases (MMPs), myeloperoxidase (MPO) and reactive oxidative species causing excessive degradation of the extracellular matrix (ECM) and the growth factors. Because of the multifactorial nature of virtually all chronic wounds, the therapeutic wound healing approach should emphasize the necessity to investigate wound dressings that possess the ability to directly and indirectly modulate the biochemical environment based on the pathology of chronic to encourage the healing process. The overall aim of the present work was to develop biopolymer wound dressings capable to improve the management of chronic wounds. The specific research objective was defined in three main targets: i) to balance the proteolytic activity of MMPs, ii) to balance the MPO activity and the oxidative environment, and iii) antimicrobial protection. The first part of the thesis aimed to provide suitable materials to perform bioactive biopolymer-based wound dressings. The first step was to provide a versatile functionalization of chitosan platform to improve the sequestering ability over metal dependent enzymes (MMPs) in chronic wounds. In order to impart to chitosan the ability to inhibit MMP, chitosan was functionalized with deferent thiol moieties, which can chelate the zinc cation in the active site of the enzyme, modifying MMP activity. In addition the combination of -NH2 and -SH chemistry allowed grafting of other active agents on the chitosan platform. The second step was the identification and evaluation of natural active agents as chronic wound healing promoters. Polyphenols from bark, twigs and leaf extracts from the medicinal plant Hamamelis virginiana (Witch hazel) were studied for this porpoise and it was found to have both a strong antioxidant activity and an inhibitory effect on MPO and collagenase. The second part of the thesis was focused in the performance and evaluation of new materials for wound healing applications. To this aim, chitosan and/or thiolated chitosan were modified with H. virginiana extracts following different approaches. The first approach was focused to develop a new method for covalent functionalization of thiolated chitosan with polyphenols from H. virginiana extracts. The novelty of this approach consists in the use of thiolysis - a common analytical method for proanthocyanidins characterization - to covalently functionalize natural macromolecules such as chitosan with bioactive phenolic moieties. The phenolics-functionalized chitosan showed improved therapeutic properties in vitro. The second approach focused on the use of laccase-assisted cross-linking between phenolic moieties of H. virginiana with chitosan and gelatin as a functionalization method to obtain stable and bioactive hydrogel wound dressings. H. virginiana extract was oxidized by laccase in a one-step process under mild reaction conditions to covalently crosslink chitosan and gelatin. The physical and mechanical properties of these hydrogels were investigated using different analytical techniques and their potential for chronic wound treatment was evaluated in vitro in terms of antibacterial and inhibitory effect on MPO and collagenase. The results indicated that the polyphenols exerted a dual role in the hydrogel: i) "passive" being a structural element, and ii) "active" modifying the chronic wound environment by attenuating the deleterious MMPs, MPO and ROS activities, and reducing the bacterial load.

  • Determinacion de la resistencia dinámica a clivaje de adhesivos estructurales

     Sanchez Soto, Miguel Angel; Abt, Tobias Martin
    Date: 2012-11-12
    Report

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  • Linea ECO de lápices cosméticos

     Sanchez Soto, Miguel Angel
    Date: 2012-03-30
    Report

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  • Desarrollo de un acople prototipo para terminal transductor de equipos ecográficos

     Sanchez Soto, Miguel Angel; Gómez Gómez, Jaime Francisco
    Date: 2012-12-12
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  • Determinacion de la resistencia dinámica a clivaje de adhesivos estructurales

     Sanchez Soto, Miguel Angel; Abt, Tobias Martin
    Date: 2012-11-27
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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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  • Análisis de defectos en grapas de fijación de tubos en alcantarillados

     Sanchez Soto, Miguel Angel; Maspoch Ruldua, Maria Lluïsa
    Date: 2012-06-14
    Report

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  • Estudio de mezclas de poliestireno y microesferas de vidrio: Comportamiento a impacto y predicción de inicio de fallo

     Sanchez Soto, Miguel Angel; Martinez Benasat, Antonio; Lladó, D; Briz, A; López-Vera, D
    Encuentro del Grupo Español de Fractura
    Presentation of work at congresses

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  • Indentación por impacto de baja energía

     Jiménez, O; Sanchez Soto, Miguel Angel; Gámez, R; Martinez Benasat, Antonio
    Encuentro del Grupo Español de Fractura
    Presentation of work at congresses

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  • Influence of clay and polymer on the morphology and properties of PVOH/clay aerogels

     Sanchez Soto, Miguel Angel; Rojas, J.; Illescas Fernandez, Silvia; Abt, Tobias Martin; Caceres Moreno, Maria Angelica; Arostegui, Asier
    Congreso Nacional de Materiales Compuestos
    Presentation's date: 2011-07-08
    Presentation of work at congresses

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  • Adhesion between polypropylene and steel by over moulding

     Sanchez Soto, Miguel Angel; Illescas Fernandez, Silvia; Abt, Tobias Martin; Candal, María Virginia; Gómez, Jaime Francisco
    EUROTEC
    Presentation's date: 2011-11-14
    Presentation of work at congresses

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    Fractura postcedencia de polímeros  Open access

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

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  • Fabricación y caracterización e aerogeles de arcilla/polímero

     Montalbán, L.; Sanchez Soto, Miguel Angel; Candal, María Virginia
    Revista latinoamericana de metalurgia y materiales
    Date of publication: 2011
    Journal article

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    El principal objetivo de este estudio fue la fabricación de aerogeles de arcilla/polímero a partir de montmorillonita (MMT–Na+) y un polímero biodegradable (Polivinil alcohol PVOH) los cuales se esperan que puedan sustituir en el mercado a las espumas poliméricas convencionales (Poliestireno (PS) expandido o Poliuretano (PU)) en aplicaciones para aislamiento térmico, resistencia mecánica al impacto (embalajes) y construcción. Se estudió, además, el efecto de agregar agentes retardantes a la llama sobre las formulaciones preparadas. Los aerogeles de MMT-Na+/PVOH poseen propiedades mecánicas (compresión e impacto) y térmicas similares a las del PUR.

  • Impact behaviour of carbon fibre reinforced epoxy and non-isothermal cyclic butylene terephthalate composites manufactured by vacuum infusion

     Agirregomezkorta, A.; Martinez Benasat, Antonio; Sanchez Soto, Miguel Angel; Aretxaga, G.; Sarrionandia, Mariasun; Aurrekoetxea Narbarte, Jon
    Composites Part B: Engineering
    Date of publication: 2011-07
    Journal article

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    Carbon fibre reinforced cyclic butylene terephthalate (CF-pCBT) composites non-isothermally processed by vacuum infusion starting from a one-component system have been successfully manufactured. Both the micro-structure and low-energy impact properties of the CF-pCBT have been investigated and compared with an epoxy system (CF-epoxy). The CF-pCBT composite presents higher solidification shrinkage than the CF-epoxy one, and its void content doubles that of the CF-epoxy. The CF-epoxy composite’s critical delamination threshold energy is slightly higher than that of the CF-pCBT, whereas the CF-pCBT composite absorbs twice as much energy before being penetrated. The lower interlaminar shear strength of the CF-pCBT composite is suggested to be the origin of its higher energy absorbing capability and less brittle behaviour.

  • Effect of superelastic shape memory alloy wires on the impact behaviour of carbon fiber reinforced in situ polymerized poly(butylene terephthalate) composites

     Aurrekoetxea Narbarte, Jon; Zurbitu, J.; Ortiz de Mendibil, I.; Aguirregomezkorta, A.; Sanchez Soto, Miguel Angel; Sarrionandia, Mariasun
    Materials letters
    Date of publication: 2011-03-15
    Journal article

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  • Sobreinyección de PP-TPV. Estudio experimental de la adhesión en la interfase

     Candal Pazos, Maria Virginia
    Defense's date: 2011-07-18
    Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya
    Theses

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  • Fire behavior testing of aerogels using cone calorimeter

     Sanchez Soto, Miguel Angel
    Date: 2011-02-12
    Report

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  • fire behaviour testing of aerogels using cone calorimeter

     Sanchez Soto, Miguel Angel
    Date: 2011-02-10
    Report

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  • Plastic nanocomposites for better thermal resistance

     Vilà, Sin; Sanchez Soto, Miguel Angel; Illescas Fernandez, Silvia
    Plastics research online
    Date of publication: 2011-12-02
    Journal article

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  • Enhancement of POM thermooxidation resistance through POSS nanoparticles

     Vila Ramirez, N.; Sanchez Soto, Miguel Angel; Illescas Fernandez, Silvia
    Polymer composites
    Date of publication: 2011-10
    Journal article

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  • The morphology and properties of melt-mixed polyoxymethylene/ monosilanolisobutyl-POSS composites

     Illescas Fernandez, Silvia; Sanchez Soto, Miguel Angel; Milliman, Henry; Schiraldi, D. A; Arostegui, Asier
    High performance polymers
    Date of publication: 2011-09
    Journal article

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    In this study, the morphology and thermo-mechanical behavior of composites formed by a polyoxymethylene (POM) matrix and monosilanolisobutyl polyhedral oligomeric silsesquioxane (msib-POSS) filler have been studied. The msib- POSS molecules were added to the POM by direct melt blending at loadings between 0 and 10 wt.%. Hydrogen bonding interactions were detected between POM and msib-POSS Si–OH groups, increasing their mutual compatibility and leading to nanometer-size dispersion of some msib-POSS molecules. These interactions do not prevent POSS aggregation during blending, but lead to micron-scale msib-POSS domains. The thermal decomposition temperature of the composites remained practically constant under inert and oxidative conditions. The low temperature thermal transition (g) and glass transition temperature (Tg) of POM were found to move to higher temperatures only when 2.5 wt.% of msib-POSS was added, indicating that POSS is physically linked to the POM chains, restricting their motion under those conditions. Low content (2.5 wt.%) of msib-POSS results in antiplastization, whereas higher levels of POSS lead to a decrease in the storage modulus of the polymer. The relationships among these effects and the morphological characteristics of the systems will be discussed herein

  • Toughening of in situ polymerized cyclic butylene terephthalate by addition of tetrahydrofuran

     Abt, Tobias Martin; Sanchez Soto, Miguel Angel; Illescas Fernandez, Silvia; Aurrekoetxea Narbarte, Jon; Sarrionandia, Mariasun
    Polymer international
    Date of publication: 2011-04
    Journal article

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    A new method of toughening polymerized cyclic butylene terephthalate (pCBT) with tetrahydrofuran (THF) is proposed. The pCBT was prepared by in situ ring-opening polymerization of a commercial cyclic butylene terephthalate, a cyclic form of poly(butylene terephthalate), in the presence of THF. In comparison to conventionally polymerized pCBT, the resultant material was found to be ductile, showing a strain at break of well above 100% in tensile tests. Other matrix properties, such as tensile modulus, tensile strength and glass transition temperature, were not significantly altered by the addition of THF. It was found that the presence of THF enhanced the polymerization reaction, resulting in an increased molecular weight and a narrowed molecularweightdistribution. Moreover, remaining oligomers after polymerization were extractedby the THF anda toughened oligomer-free pCBT was obtained. The influence of time and temperature on the long-time toughening action of THF was studied. The results showed that samples became brittle after 3months when subjected to a temperature of 80 ◦C, resulting in a reduction of the toughening action. c 2010 Society of Chemical Industry

  • Estudio de la adhesión en uniones de polímeros obtenida mediante sobreinyección para aplicaciones biomédicas

     Dávila, Everling A.; Candal Pazos, Maria Virginia; Sanchez Soto, Miguel Angel
    Argentinean Congress on Computacional Mechanics - South American Congress on Computacional Mechanics
    Presentation's date: 2010-10-18
    Presentation of work at congresses

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    El objetivo de esta investigación radica en el estudio de la adhesión entre materiales poliméricos rígidos mediante la técnica de la sobreinyección. Específicamente, se estudió el efecto de las variables del proceso de sobreinyección de los pares estudiados que podrían afectar la adhesión entre ellos, formando una estructura del tipo rígido-rígido (hard-hard). Se propone este tipo de unión para la fabricación de piezas en el sector de la medicina. Se emplearon como polímeros de estudio: acrilonitrilo-butadieno-estireno (ABS) y poli-metil-metacrilato (PMMA). Mediante este sistema de pares de materiales se evaluó el efecto de las condiciones de proceso (Presión sostenida (Ps), Velocidad de inyección (vi) y Temperatura de inyección (Tf)) en la resistencia adhesiva. El sistema fue evaluado mediante ensayos mecánicos de tracción, obteniendo una mayor resistencia adhesiva al incrementar las condiciones de inyección.

  • 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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  • Fracture behaviour of an EPBC film. Study of the relationships between J0 and EWF

     Martinez Benasat, Antonio; Delgado, A; Segovia, A; Sanchez Soto, Miguel Angel; Salazar López, Alicia
    Encuentro del Grupo Español de Fractura
    Presentation's date: 2010-10-18
    Presentation of work at congresses

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    The fracture behavior for a film of ethylene-propylene block copolymer has been studied applying the essential work of fracture method. Double-Edge Notch Tensile (DDENT) specimens were sharpened by two different techniques. The first technique has been using the conventional method of the razor blade; the second one, using a femtolaser ablation beam. The notch tip radiuses were quite similar. In the case of the razor blade method, some plastic deformation at the crack tip was found. The essential work of fracture (we) value for femtolaser sharpened specimens was significantly shorter than for the razor blade sharpening specimens. In this order, the slopes corresponding to the plastic work dissipation factor (wp) were quite similar. Results aim to say that the initiation point and the corresponding energy for which we is achieved may be considered as the energy of initiation (J0) for the crack growing propagation. The propagation behavior seems to be the same for both notch sharpening methods. The J0 value at initiation and we were quite similar; the wp terms are analyzed from J-R plots.

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    Nanocomposites of in-situ polymerized cyclic butylene terephthalate and polyhedral oligomeric silsesquioaxanes  Open access

     Abt, Tobias Martin; Illescas Fernandez, Silvia; de Sousa Pais Antunes, Marcelo; Caceres Moreno, Maria Angelica; Sanchez Soto, Miguel Angel
    Congreso Nacional de Jóvenes Investigadores en Polímeros
    Presentation's date: 2010-05-03
    Presentation of work at congresses

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    Nanocomposites were prepared by in-situ polymerization of CBT®, a cyclic form of poly(butylene terephthalate) (PBT) and polyhedral oligomeric silsesquioxane (POSS®) with 2.5, 5 and 10 wt% POSS content. Three different types of POSS were used; two with reactive functional groups, Trisilanolphenyl POSS (TPOSS) and Glycidyl POSS (G-POSS) and one POSS type having non-reactive functionality, Isooctyl POSS (I-POSS). SEM analysis showed that I-POSS was finely dispersed at a nanoscale level within the CBT, whereas T-POSS and GPOSS formed agglomerates microscaled rather than nanoscaled. T-POSS hinders the polymerization reaction of the CBT, resulting in a poor consolidation of the composite. However, Glycidyl POSS was found to crosslink the CBT during polymerization, making it possible to alter the final material properties. All nanocomposites with 10 wt% POSS content showed a hindered cold crystallization and subsequently showed no melting peak of the formed polymer in a DSC scan.

    Postprint (author’s final draft)

  • 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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  • The Role of Polyhedral Oligomeric Silsesquioxane on the Thermo-Mechanical Properties of Polyoxymethylene Copolymer Based Nanocomposites

     Illescas Fernandez, Silvia; Schiraldi, D. A; Sanchez Soto, Miguel Angel; Velasco Perero, Jose Ignacio; Arostegui, Asier
    Journal of nanoscience and nanotechnology
    Date of publication: 2010-02
    Journal article

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  • 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
    Date of publication: 2010-02-02
    Journal article

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