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  • From curing kinetics to network structure: A novel approach to the modeling of the network buildup of epoxy-anhydride thermosets

     Fernández Francos, Xavier; Ramis Juan, Xavier; Serra Albet, Àngels
    Journal of polymer science. Part A, polymer chemistry
    Date of publication: 2014-01-01
    Journal article

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    The curing kinetics and network buildup during curing of epoxy-anhydride formulations using tertiary amines as initiators are reviewed in this work. A mechanism-based kinetic and structural model has been defined, showing better prediction capabilities than previous living polymerization and simple regeneration models. The curing kinetics have been analyzed using differential scanning calorimetry (DSC), and the gelation during curing has been determined by combined thermomechanical analysis and DSC. The effect of initiator content and epoxy equivalent weight are taken into account. The network buildup has been modeled using a stochastic network buildup model based on the random combination of primary chains generated by the kinetic model.

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    Influence of end groups in hyperbranched polyesters used as modifiers in the characteristics of epoxy thermosets cured by adipic dihydrazide  Open access

     Tomuta, Adrian Marius; Ramis Juan, Xavier; de la Flor López, Sílvia; Serra Albet, Àngels
    Express polymer letters
    Date of publication: 2013-07
    Journal article

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    Mixtures of diglycidylether of bisphenol A (DGEBA) resin and different ratios of aliphatic-aromatic hyperbranched polyester (HBP) were cured by a latent curing agent, adipic dihydrazide (AH). The HBPs prepared have hydroxyl groups or 10-undecenoyl or allyl groups as chain ends. The curing mixtures were investigated by differential scanning calorimetry (DSC) to study the curing process and to evaluate the kinetic parameters of the different formulations. These studies suggest that HBPs decrease the curing rate of epoxy/AH in the case of vinyl terminated HPB, whereas OH terminated HBP accelerates the first stages and delays the lasts. The thermosets obtained showed an improvement in microhardness and impact strength without any reduction of the Tg and thermal parameters. Microparticle phase separation was observed with the undecenoyl HBP derivatives or when a 10% of allyl HBP derivative was in the formulation.

    Mixtures of diglycidylether of bisphenol A (DGEBA) resin and different ratios of aliphatic-aromatic hyperbranched polyester (HBP) were cured by a latent curing agent, adipic dihydrazide (AH). The HBPs prepared have hydroxyl groups or 10-undecenoyl or allyl groups as chain ends. The curing mixtures were investigated by differential scanning calorimetry (DSC) to study the curing process and to evaluate the kinetic parameters of the different formulations. These studies suggest that HBPs decrease the curing rate of epoxy/AH in the case of vinyl terminated HPB, whereas OH terminated HBP accelerates the first stages and delays the lasts. The thermosets obtained showed an improvement in microhardness and impact strength without any reduction of the Tg and thermal parameters. Microparticle phase separation was observed with the undecenoyl HBP derivatives or when a 10% of allyl HBP derivative was in the formulation.

  • Electrical application of polystyrene (PS) reinforced with old tire rubber (GTR): dielectric, thermal, and mechanical properties

     Mujal Rosas, Ramon Maria; Ramis Juan, Xavier
    Science and engineering of composite materials
    Date of publication: 2013-08
    Journal article

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    Mass production of tires and their subsequent storage after use are serious environmental problems that are being tried to be solved in various ways. One of these is the mixture of these old used tires [ground rubber tire (GTR)] with various thermoplastic and thermostable polymers. The present work aimed to obtain materials suitable for the electric industry from the mixture of polystyrene (PS) with old used tires (GTR), starting from the requirement of minimum recycling costs, i.e., by using vulcanized GTR without any prior treatment but acting on the particle sizes with a simple and inexpensive screening. In order to do so, dielectric, mechanical, thermal, and microstructure analyses were performed for a large number of compounds, which were obtained using three GTR particle sizes (p<200 mu m, 200 mu m500 mu m) and seven concentrations of GTR in the compound (0%, 5%, 10%, 20%, 40%, 50%, and 70%). All these data have allowed an accurate characterization of the properties of the new compounds, and according to these results, possible electrical applications have been explored.

  • New chemically reworkable epoxy coatings obtained by the addition of polyesters with star topologies to diglycidyl ether of bisphenol A resins

     Tomuta, Adrian Marius; Ramis Juan, Xavier; Fernández Francos, Xavier; Ferrando, Francesc; Serra Albet, Àngels
    Progress in organic coatings
    Date of publication: 2013-11
    Journal article

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    A new multiarm star with hyperbranched aromatic-aliphatic polyester core and poly(e-caprolactone) arms (HBPCL) was synthesized and characterized. Mixtures of diglycidyl ether of bisphenol A (DGEBA) resin and different proportions of this star type modifier were cured using a thermal cationic curing agent, Yb(OTf)3. The HBPCL prepared has hydroxyl groups as chain ends, which are capable of chemically incorporating to the epoxy matrix by means of the monomer activated mechanism. This, together with the chemical structure of the modifier, allowed the preparation of new homogeneous thermosets for coating applications. The curing mixtures were investigated by differential scanning calorimetry (DSC) to study the curing process and evaluate the kinetic parameters of the formulations. These studies demonstrated that HBPCL decreased the curing rate and affected the gelation process. The thermosets obtained showed an improvement in impact strength with a discrete reduction of the T g. The modified coatings showed an increased reworkability in alkaline solution with the maintenance of thermal stability. © 2012 Elsevier B.V. All rights reserved.

  • Corrigendum: Network structure and thermomechanical properties of hybrid DGEBA networks cured with 1-methylimidazole and hyperbranched poly(ethyleneimine)s

     Fernández Francos, Xavier; Santiago, David; Ferrando, Francesc; Ramis Juan, Xavier; Salla Tarrago, Jose M.; Serra Albet, Àngels; Sangermano, Marco
    Journal of polymer science. Part B, polymer physics
    Date of publication: 2013-01-25
    Journal article

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  • New epoxy thermosets modified with multiarm star poly(lactide) with poly(ethyleneimine) as core of different molecular weight

     Acebo, Cristina; Fernández Francos, Xavier; Ferrando, Francesc; Serra Albet, Àngels; Ramis Juan, Xavier
    European polymer journal
    Date of publication: 2013-08
    Journal article

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    Multiarm stars containing a hyperbranched poly(ethyleneimine) core of different molecular weight and poly(lactide) arms were synthesized by cationic ring-opening polymerization of lactide from a hyperbranched poly(ethyleneimine) core. After characterization by rheometry, calorimetry, thermogravimetry and nuclear magnetic resonance, these polymers were used as chemically modifiers in the anionic curing of diglycidylether of bisphenol A epoxy resin. The curing process was studied by dynamic scanning calorimetry, demonstrating the influence of the mobility of the reactive species and the hydroxyl content on the curing kinetics. The resulting materials were characterized by thermal and mechanical tests. The addition of the multiarm stars led to homogeneous materials with a slight improvement on the impact strength in comparison with the neat material, without compromising the glass transition temperature. The reworkable nature of the materials was demonstrated by monitoring the changes in their glass transition under thermal rework conditions.

  • Enhancement of the impact strength of cationically cured cycloaliphatic diepoxide by adding hyperbranched poly(glycidol) partially modified with 10-undecenoyl chains

     Flores, Marjori; Morell, Mireia; Fernández Francos, Xavier; Ferrando, Francesc; Ramis Juan, Xavier; Serra Albet, Àngels
    European polymer journal
    Date of publication: 2013-06
    Journal article

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    A hyperbranched poly(glycidol) has been synthesized and modified by acylation with 10-undecenoyl chloride to obtain hyperbranched polymers (HBPs) with different degree of modification. These HBPs have been used as reactive modifiers in a proportion of 3%, 5%, and 10% with respect to a biscicloaliphatic diepoxide cured using ytterbium triflate as thermal cationic initiator. The materials obtained have been characterized and their mechanical properties evaluated. Phase separated materials have been obtained, with a 2-fold increase in impact resistance without sacrificing thermomechanical properties, thermal stability or processability. This good combination of properties can be explained by the achievement of a regular microphase separation with a good interfacial interaction between the microparticles and the epoxy matrix. The compatibility between the HBP and the matrix can be tuned by changing the degree of modification, which leads to a variable amount of available hydroxyl groups of the HBP that can react with the epoxy groups. This chemical bonding occurs through the activated monomer mechanism (AM) which is typical of the cationic homopolymerization of epoxides.

    A hyperbranched poly(glycidol) has been synthesized and modified by acylation with 10-undecenoyl chloride to obtain hyperbranched polymers (HBPs) with different degree of modification. These HBPs have been used as reactive modifiers in a proportion of 3%, 5%, and 10% with respect to a biscicloaliphatic diepoxide cured using ytterbium triflate as thermal cationic initiator. The materials obtained have been characterized and their mechanical properties evaluated. Phase separated materials have been obtained, with a 2-fold increase in impact resistance without sacrificing thermomechanical properties, thermal stability or processability. This good combination of properties can be explained by the achievement of a regular microphase separation with a good interfacial interaction between the microparticles and the epoxy matrix. The compatibility between the HBP and the matrix can be tuned by changing the degree of modification, which leads to a variable amount of available hydroxyl groups of the HBP that can react with the epoxy groups. This chemical bonding occurs through the activated monomer mechanism (AM) which is typical of the cationic homopolymerization of epoxides

  • Enhanced chemical reworkability of DGEBA thermosets cured with rare earth triflates using aromatic hyperbranched polyesters (HBP) and multiarm star HBP-b-poly(e-caprolactone) as modifiers

     Tomuta, Adrian Marius; Fernández Francos, Xavier; Ferrando, Francesc; Ramis Juan, Xavier; Serra Albet, Àngels
    Polymers for advanced technologies
    Date of publication: 2013-11
    Journal article

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    A hyperbranched aromatic polyester (HBPOH) has been synthesized, and poly(e-caprolactone) arms have been grown on some of its end hydroxyl groups (HBPCL). These modifiers have been used in cationic diglycidyl ether of bisphenol A formulations cured with ytterbium triflate as cationic initiator. The effect of HBPOH and HBPCL on the curing kinetics has been studied using differential scanning calorimetry (DSC). The obtained materials have been characterized by dynamomechanical analysis, DSC, thermogravimetric analysis and mechanical tests. The modifiers are incorporated into the thermosetting network because of the participation of the end hydroxyl groups in the cationic curing of epoxides by the activated monomer mechanism. Homogeneous thermosets have been obtained with a remarkable increase in impact strength without sacrificing elastic modulus or hardness. A compromise between the rigid structure of the aromatic hyperbranched core and the flexibilizing effect of the poly(e-caprolactone) arms is believed to be responsible for the overall thermal and mechanical properties of the materials. The use of these polymeric modifiers increases the thermal stability of the resulting materials because of the low degradability of the aromatic ester groups in the hyperbranched core and the incorporation of the modifier into the network structure. However, the presence of such ester groups makes them reworkable by hydrolysis or alcoholysis in an alkaline medium, thus opening a way for recovery of valuable substrates.

  • La evaluación continua como estrategia de aprendizaje en asignaturas de grado

     Cadenato Matia, Ana Maria; Salla Tarrago, Jose M.; Ramis Juan, Xavier; Morancho Llena, Jose Maria; Montserrat Jorda, Jose; Martin Godoy, Jose Luis
    Congreso Nacional de Ingeniería Termodinámica
    Presentation's date: 2013-06
    Presentation of work at congresses

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  • Multiarm star with poly(ethyleneimine) core and poly(epsilon-caprolactone) arms as modifiers of diglycidylether of bisphenol A thermosets cured by 1-methylimidazole

     Acebo, Cristina; Fernández Francos, Xavier; Ferrando, Francesc; Serra Albet, Àngels; Salla Tarrago, Jose M.; Ramis Juan, Xavier
    Reactive and functional polymers
    Date of publication: 2013-03
    Journal article

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    Well-defined multiarm star copolymers, with hyperbranched poly(ethyleneimine) (PEI) as the core and poly(e-caprolactone) (PCL) arms with different degree of polymerization were synthesized by cationic ring-opening polymerization of e-caprolactone from a hyperbranched poly(ethyleneimine) core and used to modify diglycidylether of bisphenol A formulations cured with 1-methylimidazole as anionic initiator. The curing process was studied by dynamic scanning calorimetry (DSC) and FTIR. By rheometry the complex viscosity of the multiarm stars synthesized and the influence of their addition to the reactive mixture was analyzed in detail. The resulting materials were characterized by thermal and mechanical tests. The addition of the multiarm star to the formulation led to homogeneous materials with a slightly toughened fracture in comparison to neat DGEBA thermosets without compromising thermal characteristics.

    Well-defined multiarm star copolymers, with hyperbranched poly(ethyleneimine) (PEI) as the core and poly(e-caprolactone) (PCL) arms with different degree of polymerization were synthesized by cationic ring-opening polymerization of e-caprolactone from a hyperbranched poly(ethyleneimine) core and used to modify diglycidylether of bisphenol A formulations cured with 1-methylimidazole as anionic initiator. The curing process was studied by dynamic scanning calorimetry (DSC) and FTIR. By rheometry the complex viscosity of the multiarm stars synthesized and the influence of their addition to the reactive mixture was analyzed in detail. The resulting materials were characterized by thermal and mechanical tests. The addition of the multiarm star to the formulation led to homogeneous materials with a slightly toughened fracture in comparison to neat DGEBA thermosets without compromising thermal characteristics.

  • Modification of epoxy¿anhydride thermosets with a hyperbranched poly(ester amide). II. Thermal, dynamic mechanical, and dielectric properties and thermal reworkability

     Fernández Francos, Xavier; Rybak, Andrzej; Sekula, Emil; Ramis Juan, Xavier; Ferrando, Francesc; Okrasa, Lidia; Serra Albet, Àngels
    Journal of applied polymer science
    Date of publication: 2013-06
    Journal article

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    An epoxy¿anhydride formulation used for the coating electrical devices was modified with a commercially available hyperbranched poly(ester amide), Hybrane S2200, to improve the thermal degradability of the resulting thermoset and, thus, facilitate the recovery of substrate materials after the service life of the component. The thermomechanical, mechanical, and dielectric properties and thermal degradability were studied and interpreted in terms of the composition and network structure of the cured thermosets. Although the crosslinking density was significantly reduced with the incorporation of S2200, the glass transition temperature of the fully cured material (Tg8) of the modified thermoset was hardly affected because of the enhancement of H-bonding interactions in the presence of S2200. Despite the different network structures, the combined dielectric and dynamic mechanical analysis revealed that the relaxation dynamics of both networks were very similar. In terms of application, improvements in the dielectric and mechanical properties were observed. The incorporation of S2200 accelerated the thermal decomposition of the material and, thus, facilitated the recovery of the valuable parts from the substrate at the end of the service life of the apparatus.

  • Aplicaciones eléctricas del poliestireno (PS) reforzado con neumáticos fuera de uso (GTR)

     Mujal Rosas, Ramon Maria; Marin Genesca, Marcos; Ramis Juan, Xavier
    Dyna
    Date of publication: 2013-11
    Journal article

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    La masiva producción de neumáticos, así como su posterior almacenamiento después de su utilización constituye un grave problema medioambiental al que se pretende dar salida con diversas soluciones. Una de ellas pasa por mezclar estos neumáticos reutilizados (Ground Tire Rubber GTR) con diversos polímeros termoplásticos y termoestables, siendo esta opción la analizada en el presente trabajo, la cual tiene como objetivo obtener materiales aislantes adecuados para la industria eléctrica a partir de la mezcla del poliestireno (PS) con neumáticos fuera de uso. Como exigencia principal se ha partido de unos costos mínimos de reciclado, es decir, mediante el uso del GTR sin desvulcanizar y sin ningún pretratamiento previo con ácidos, pero en cambio actuando sobre la concentración y tamaños de partículas del GTR, la cual se ha realizada mediante una forma sencilla y económica como es el tamizado. Con este fin se han realizado análisis dieléctricos, mecánicos, térmicos y de la microestructura con un gran número de compuestos, que se han obtenido utilizando los tres tamaños de partículas del GTR (p<200µm, 200500µm), y las siete concentraciones con las que se han formado los compuestos (0%, 5%, 10%, 20%, 40%, 50% y 70% en GTR). Todos estos datos han permitido una caracterización precisa de las propiedades de los nuevos compuestos y, de acuerdo con estos resultados y las Normativas vigentes, se han obtenido las posibles aplicaciones eléctricas de los compuestos.

  • A new two-stage curing system: Thiol-ene/epoxy homopolymerization using an allyl terminated hyperbranched polyester as reactive modifier

     Flores Guillen, Marjorie; Tomuta, Adrian Marius; Fernández Francos, Xavier; Sangermano, Marco; Serra Albet, Àngels; Ramis Juan, Xavier
    Polymer
    Date of publication: 2013-10-04
    Journal article

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    An allyl terminated hyperbranched polyester (HBP) was added to an epoxy formulation containing a trithiol compound to perform a thiol-ene click reaction. By this procedure a flexible thioether network was formed. The photoirradiation of the reactive mixture, which contained a cationic photoinitiator, converted the thioether network in a multifunctional thermal macroinitiator, capable to initiate the cure of the cycloaliphatic epoxy resin(CE) in a second thermal stage. Depending on the proportion of HBP, thermal or photocuring of the epoxy resin took place in different extent, leading to networks with different structures. The photocuring procedure was followed by FTIR and the thermal second stage by DSC. The materials obtained were characterized by DMTA, TGA and SEM. The addition of HBP-Allyl and the trithiol to the formulation allowed increasing the Tg on comparison with the neat epoxy thermoset. The system proposed constitutes a new two-stage dual photo-thermal curing procedure for cycloaliphatic epoxy resins with a thermal latent character.

  • Simultaneous monitoring of curing shrinkage and degree of cure of thermosets by attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy

     Fernández Francos, Xavier; Kazarian, Sergei G.; Ramis Juan, Xavier; Serra Albet, Àngels
    Applied spectroscopy
    Date of publication: 2013-12
    Journal article

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    We present a novel methodology to simultaneously monitor of the degree of cure and curing shrinkage of thermosetting formulations. This methodology is based on the observation of changes in the infrared absorption of reactive functional groups and the groups used as a standard reference for normalization. While the optical path length is exact and controlled in transmission infrared spectroscopy, in attenuated total reflection Fourier transform infrared (ATR FT-IR), the exact determination of volume changes requires the measurement of the refractive indices of the studied system throughout the curing process or at least an indirect parallel measurement of this property. The methodology presented here allows one to achieve quantitative measurements of the degree of cure and shrinkage for thermosets using in situ ATR FT-IR spectroscopy.

  • Thermal curing and photocuring of a DGEBA modified with multiarm star poly(glycidol)-b-poly(e-caprolactone) polymers of different arm lengths

     Morancho Llena, Jose Maria; Cadenato Matia, Ana Maria; Ramis Juan, Xavier; Morell, Mireia; Fernández Francos, Xavier; Salla Tarrago, Jose M.; Serra Albet, Àngels
    Journal of thermal analysis and calorimetry
    Date of publication: 2013-10
    Journal article

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    The influence of two multiarm star polymers, hyperbranched poly(glycidol)-b-poly(e-caprolactone) of different arm lengths, on the thermal curing and the photocuring of a diglycidyl ether of bisphenol A epoxy resin (DGEBA) is studied. Star polymer with short arms PCL-10 decelerates more the thermal curing than the polymer with long arms PCL-30 because the latter is less solubilized in the epoxy matrix and its effect on the polymerization of the resin and the thermal-mechanical properties is less important. The kinetic triplet corresponding to the thermal curing of the different formulations has been determined. In the analysis of the photocuring process, we have also found that short-arm star PCL-10 is better solubilized in the epoxy matrix and its effect on the photocuring kinetics is more significant than that of the long-arm star. The effect of both polymers on the thermal-mechanical properties of the cured thermosets is less important due to the lower solubility at the relatively low photocuring temperatures.

  • Epoxy/anhydride networks modified with polyhedral oligomeric silsesquioxanes

     Montero Rodríguez, María Belen; Serra Albet, Àngels; Ramirez Gómez, María del Carmen; Ramis Juan, Xavier
    Polymer composites
    Date of publication: 2013-01
    Journal article

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  • Electrical application of polyamide reinforced with old tire rubber (ground tire rubber): Dielectric, thermal, mechanical and structural properties

     Mujal Rosas, Ramon Maria; Òrrit Prat, Jordi; Ramis Juan, Xavier; Marin Genesca, Marcos
    Journal of thermoplastic composite materials
    Date of publication: 2013-02-06
    Journal article

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    Mass production of tires and their subsequent storage after use is a serious environmental problem that is tried to be solved in various ways. One of these ways is the mixture of these old used tires (ground tire rubber (GTR)) with various thermoplastic and thermostable polymers. These blends are made by modifying the pretreatment the GTR is subjected to, the degree of devulcanization, the mixing or pressing conditions, etc. Later the mixtures are analyzed structurally and mechanically, looking for possible industrial applications for them. The present work aims to obtain materials suitable for the electric industry from the mixture of polyamide with old used tires (GTR), starting from the requirement of minimum recycling costs, that is using vulcanized GTR without any prior treatment but acting on the particle sizes with a simple and inexpensive screening. A novelty of this study is the large number of compounds analyzed, and the deep analysis these have been submitted to dielectric, mechanical, thermal and microstructure analyses to get a large number of variables in each test. Compounds were categorized as the three GTR particle sizes (p < 200 µm, 200 < p < 500 µm and p > 500 µm) and seven concentrations of GTR (0%, 5%, 10%, 20%, 40%, 50% and 70%), resulting in a total of 21 new compounds. In addition, in order to have the dielectric tests as much exhaustive as possible and to show the behavior of the compound under widely changing conditions, a wide range of temperatures (30¿120°C) and frequencies (1 × 10-2 Hz to 3 × 106 Hz) were taken into consideration. All these data have provided an accurate characterization of the properties of the new compounds, and according to these results, possible electrical applications have been explored, with the requirement that they must comply with official regulations.

  • Bio-Based polyesters from cyclic monomers derived from carbohydrates.

     Lavilla Aguilar, Cristina
    Defense's date: 2013-11-29
    Universitat Politècnica de Catalunya
    Theses

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    Unexpected differences between thermal and photoinitiated cationic curing oa a diglycidyl ether of bisphenol. A modified with a multiarm star poly (styrene)-b-poly (e-caprolactone) polymer  Open access

     Morancho Llena, Jose Maria; Cadenato Matia, Ana Maria; Ramis Juan, Xavier; Morell, Mireia; Fernández Francos, Xavier; Salla Tarrago, Jose M.; Serra Albet, Àngels
    Express polymer letters
    Date of publication: 2013-03-18
    Journal article

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    The effect of adding a multiarm star poly(styrene)-b-poly("-caprolactone) polymer on the cationic thermal and photoinitiated curing of diglycidyl ether of bisphenol A was studied. This star-polymer decelerated the thermal curing of diglycidyl ether of bisphenol A and modified the final structure of the epoxy matrix. The photocuring was influenced significantly by the addition of the multiarm star. When the proportion of this modifier added was 5%, much more time was necessary for complete photocuring (160 min at 40ºC). In the presence of 10% of modifier, the degree of photocuring reached was very low (0.196 at 120°C). A subsequent thermal post-curing was necessary to cure completely the system. During photocuring in presence of poly(styrene)-b-poly("-caprolactone), the formation of dormant species, which are reactivated when the temperature increases, takes places. The kinetics of the thermal curing and the photocuring was analyzed using an isoconversional method due to the complexity of the reactive process. Applying this method, it has been confirmed the dependence of activation energy on the degree of conversion. The fracture morphology analyzed by scanning electron microscopy exhibited a second phase originated during photocuring by the presence of the modifier.

  • Evaluación continua en termodinámica, asignatura del grado de ingeniería química

     Cadenato Matia, Ana Maria; Ramis Juan, Xavier
    Jornada d'Innovació Docent UPC
    Presentation's date: 2012-07-05
    Presentation of work at congresses

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  • New Improved Thermosets Obtained From Diglycidylether of Bisphenol A and a Multiarm Star Copolymer Based on Hyperbranched Poly(glycidol) Core and Poly(methyl methacrylate) Arms

     Morell, Mireia; Ramis Juan, Xavier; Ferrando, Francesc; Serra Albet, Àngels
    Macromolecular chemistry and physics
    Date of publication: 2012-02-13
    Journal article

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  • Synthesis of a new hyperbranched-linear-hyperbranched triblock copolymer and its use as a chemical modifier for the cationic photo and thermal curing of epoxy resins

     Foix, David; Ramis Juan, Xavier; Sangermano, Marco; Serra Albet, Àngels
    Journal of polymer science. Part A, polymer chemistry
    Date of publication: 2012-03-15
    Journal article

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  • Network structure and thermomechanical properties of hybrid DGEBA networks cured with 1-methylimidazole and hyperbranched poly(ethyleneimine)s

     Fernández Francos, Xavier; Santiago, David; Ferrando, Francesc; Ramis Juan, Xavier; Salla Tarrago, Jose M.; Serra Albet, Àngels; Sangermano, Marco
    Journal of polymer science. Part B, polymer physics
    Date of publication: 2012-11-01
    Journal article

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    The use of commercially available hyperbranched poly(ethyleneimine)s (Lupasol TM , BASF) as polymeric modifiers in diglycidyl ether of bisphenol A thermosetting formulations using 1-methylimidazole (MI) as anionic initiator has been studied. Poly(ethyleneimine)s can get incorporated into the network structure by condensation of amine and epoxy groups. The excess, over-stoichiometric epoxy groups can undergo ani- onic homopolymerization initiated by MI. The thermal, dyna- momechanical, and mechanical properties of the resulting materials have been determined using DSC, thermomechanical analysis (TMA), dynamomechanical analysis (DMA), and me- chanical testing. The effect of the different amine modifiers on the MI networks, determined by their structure, is complex. Low initiator content and high molecular weight modifiers cre- ate significant mobility restrictions, which have a strong effect on the glass transition temperature and the apparent crosslink- ing density of the cured materials.

    he use of commercially available hyperbranched poly(ethyleneimine)s (Lupasol TM , BASF) as polymeric modifiers in diglycidyl ether of bisphenol A thermosetting formulations using 1-methylimidazole (MI) as anionic initiator has been studied. Poly(ethyleneimine)s can get incorporated into the network structure by condensation of amine and epoxy groups. The excess, over-stoichiometric epoxy groups can undergo ani- onic homopolymerization initiated by MI. The thermal, dyna- momechanical, and mechanical properties of the resulting materials have been determined using DSC, thermomechanical analysis (TMA), dynamomechanical analysis (DMA), and me- chanical testing. The effect of the different amine modifiers on the MI networks, determined by their structure, is complex. Low initiator content and high molecular weight modifiers cre- ate significant mobility restrictions, which have a strong effect on the glass transition temperature and the apparent crosslink- ing density of the cured materials.

  • New epoxy thermosets obtained from diglycidylether of bisphenol a and modified hyperbranched polyesters with long aliphatic chains cured by diisocyanates

     Flores, Marjori; Fernández Francos, Xavier; Jimenez Pique, Emilio; Foix, David; Serra Albet, Àngels; Ramis Juan, Xavier
    Polymer engineering and science
    Date of publication: 2012
    Journal article

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    Hyperbranched polyesters modified with long aliphatic chains with vinyl or epoxy groups as chain ends were synthesized and added as modifiers to diglycidyl ether of bisphenol A/toluene-2,4-diisocyanate mixtures in the presence of benzyldimethylamine as catalyst. The influence of the addition of these modifiers on the curing was investigated by thermal analysis and infrared spectroscopy. The materials obtained were investigated by electron microscopy and some mechanical characteristics were determined by nanoindentation tests. Epoxy terminated hyperbranched led to homogeneous materials with high crosslinking densities, whereas vinyl terminated hyperbranched produced phase separated morphologies. The materials showing phase separation presented a tough fracture, whereas the homogeneous materials obtained with epoxidated hyperbranched showed increased brittleness on increasing the proportion of modifier. On increasing the proportion of vinyl terminated hyperbranched in the thermosets, Young’s modulus and hardness decreased but the addition of epoxy terminated hyperbranched did not influence these parameters. The addition of vinylic hyperbranched to the formulations produced a decrease in the curing shrinkage, whereas the epoxidic hyperbranched did not.

  • The Effect of the Degree of Branching in Hyperbranched Polyesters Used as Reactive Modifiers in Epoxy Thermosets

     Foix, David; Khalyavina, Anna; Morell, Mireia; Voit, Brigitte; Lederer, Albena; Ramis Juan, Xavier; Serra Albet, Àngels
    Macromolecular materials and engineering
    Date of publication: 2012-01
    Journal article

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  • Ytterbium triflate as a new catalyst on the curing of epoxy-isocyanate based thermosets

     Flores, Marjori; Fernández Francos, Xavier; Morancho Llena, Jose Maria; Serra Albet, Àngels; Ramis Juan, Xavier
    Thermochimica acta
    Date of publication: 2012-09-10
    Journal article

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  • Multiarm star poly(glycidol)-block-poly(styrene) as modifier of anionically cured diglycidylether of bisphenol A thermosetting coatings

     Morell, Mireia; Fernandez Francos, Xavier; Gombau, Jordi; Ferrando, Francesc; Lederer, Albena; Ramis Juan, Xavier; Voit, Brigitte; Serra Albet, Àngels
    Progress in organic coatings
    Date of publication: 2012-01
    Journal article

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  • Curing and characterization of oxazolidone-isocyanurate-ether networks

     Flores, Marjori; Fernández Francos, Xavier; Morancho Llena, Jose Maria; Serra Albet, Àngels; Ramis Juan, Xavier
    Journal of applied polymer science
    Date of publication: 2012-08-15
    Journal article

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  • Improvement of epoxy thermosets using a thiol-ene based polyester hyperbranched polymer as modifier

     Foix, David; Ramis Juan, Xavier; Ferrando, Francesc; Serra Albet, Àngels
    Polymer international
    Date of publication: 2012-05
    Journal article

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  • The use of dihydrazides as latent curing agents in diglycidyl ether of bisphenol A coatings

     Tomuta, Adrian; Ramis Juan, Xavier; Ferrando, Francesc; Serra Albet, Àngels
    Progress in organic coatings
    Date of publication: 2012-05
    Journal article

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    Dihydrazides of different structure were synthesized and tested as curing agents for DGEBA epoxy coatings. By calorimetric studies their latent characteristics were proved and the kinetics of the curing studied. The temperatures of activation are usually dependant on the melting point of the dihydrazide. The acceleration by base and Lewis acids was proved, but the latent character was diminished. FTIR/ATR allowed characterizing the final structures of the thermosets and confirming that the fully cured was achieved. The thermal stability of the materials and their thermomechanical characteristics were evaluated by TGA and DMTA, respectively. Mechanical properties of the thermosets were also determined.

  • Novel epoxy-anhydride thermosets modified with a hyperbranched polyester as toughness enhancer. I. Kinetics study

     Flores, Marjori; Fernández Francos, Xavier; Ramis Juan, Xavier; Serra Albet, Àngels
    Thermochimica acta
    Date of publication: 2012-09-20
    Journal article

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  • Combined use of sepiolite and a hyperbranched polyester in the modification of epoxy/anhydride coatings: A study of the curing process and the final properties

     Foix, David; Rodríguez, María Teresa; Ferrando, Francesc; Ramis Juan, Xavier; Serra Albet, Àngels
    Progress in organic coatings
    Date of publication: 2012-12
    Journal article

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  • Access to the full text
    Aplicaciones eléctricas del acrilonitrilo butadieno estireno (ABS) reforzado con neumáticos fuera de uso (GTR)  Open access

     Mujal Rosas, Ramon Maria; Òrrit Prat, Jordi; Ramis Juan, Xavier; Marin Genesca, Marcos
    Afinidad: revista de química teórica y aplicada
    Date of publication: 2012-01
    Journal article

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    La masiva fabricación de neumáticos, así como su posterior almacenamiento una vez utilizados, constituye un grave problema medioambiental al que se intenta dar salida de diversas formas, entre las que se encuentra el mezclar estos neumáticos fuera de uso (old used tires, GTR) con diferentes polímeros termoplásticos y termoestables. Estas mezclas se realizan variando el tratamiento previo al que se somete el GTR, el grado de desvulcanizado, las condiciones de mezcla o prensado, etc. Posteriormente, se analizan estas mezclas estructural y mecánicamente, buscando posibles aplicaciones industriales para ellas. El presente trabajo, pretende conseguir materiales aptos para la industria eléctrica a partir de la mezcal del Acrilonitrito butadieno estireno (ABS) reutilizado con neumáticos fuera de uso (GTR), pero partiendo del requisito de unos mínimos costes de reciclado posibles. es decir, utilizando GTR vulcanizado y sin aplicar ningún pretratamiento previo, y en cambio, actuando sobre el tamaño de sus partículas, el cual se puede conseguir con un simple y económico tamizado. Otra novedad que introduce el presente estudio, es el elevado número de compuestos analizados, aparte del profundo análisis a los que se les ha sometido (dieléctrico, mecánico, térmico y de microestructura), obteniéndose de cada ensayo una gran cantidad de variables. Los compuestos se obtuvieron tomando como variables los tres tamaños de partícula del GTR (p<200~m, 200500~m), y las siete concentraciones de GTR en la mezcla (0%, 5%, 10%, 20%, 40%, 50% Y 70%), lo que representa, un total de 21 nuevos compuestos. Aparte, para que los ensayos dieléctricos fueran lo más exhaustivos posibles y mostraran el comportamiento del compuesto en condiciones muy diversas, se consideró un amplio régimen de temperaturas (30°C hasta 120°C) así como de frecuencias (1.10.2 Hz hasta 3.106 Hz). Todos estos datos, han permitido caracterizar con bastante exactitud las propiedades de los nuevos compuestos, y dependiendo de estos resultados, se han buscado posibles aplicaciones eléctricas, con el requisito de que éstas debían ajustarse a las Normativas Oficiales.

  • Dielectric, thermal, and mechanical properties of acrylonitrile butadiene styrene reinforced with used tires

     Mujal Rosas, Ramon Maria; Òrrit Prat, Jordi; Ramis Juan, Xavier; Marin Genesca, Marcos; Rahhali, Ahmed
    Advances in polymer technology
    Date of publication: 2012-06-19
    Journal article

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    Mass production of tires as well as their storage or elimination is a real environmental problem. Various methods for recycling of tires are currently used, such as mechanical grinding, which separates vulcanized rubber, steel, and fibers from tires. Rubber is, then, used in several industrial applications such as flooring, insulations, and footwear. This paper focuses on a new application for old used tires (ground tire rubber, GTR). Tire dust and acrylonitrile butadiene styrene (ABS) have been mixed, and the maximum accepted concentration of GTR can be attained while keeping dielectric, thermal, and mechanical properties within acceptable limits, and therefore their possible industrial application will be in manufacturing of, for example, dielectrics for capacitors, low-voltage electric fences or electrical cable pipes, and trays. Actually, tire dust with particle sizes <700 μm has been classified into three different groups depending on the particle sizes (p < 200, 200< p < 500, and p > 500 μm). Afterward, ABS has been mixed with different concentrations of GTR, i.e., 5%, 10%, 20%, 50% and 70%, to establish its properties through thermal, mechanical, and dielectric tests. Finally, the fracture surfaces of the composite samples have been evaluated by using scanning electron microscopy.

    Cop. 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E399–E415, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21287

  • Study on dielectric, mechanical and thermal properties of polypropylene (PP) composites with ground tyre rubber (GTR)

     Mujal Rosas, Ramon Maria; Ramis Juan, Xavier; Marin Genesca, Marcos; Rahhali, Ahmed; Òrrit Prat, Jordi
    Polymers and polymer composites
    Date of publication: 2012
    Journal article

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    Mass production of tyres and their subsequent storage after use is a serious environmental problem whose solution has been attempted in various ways. One of these is the mixture of old, used tyres (GTR) with various thermoplastic and thermostable polymers. These blends are made by modifying the pre-treatment to which the GTR is subjected, the degree of devulcanization, the mixing or pressing conditions, etc. Later, the mixtures are analyzed structurally and mechanically, looking for possible industrial applications. The present work aims to obtain materials suitable for the electrical industry from the mixture of polypropylene (PP) with old used tyres (GTR), starting from the requirement of minimum recycling costs, i.e. by using vulcanized GTR without any prior treatment, but acting on the particle sizes with a simple and inexpensive screening. A large number of composites have been analyzed, and these have been submitted to dielectric, mechanical, thermal and microstructural examination. Composites were obtained using the three GTR particle sizes (p<200 µm, 200500 µm), and the seven concentrations of GTR in the composite (0%, 5%, 10%, 20%, 40%, 50% and 70%), meaning a total of 21 new composites. In addition, in order to have the dielectric tests as exhaustive as possible and show the behaviour of the composite under widely changing conditions, a wide range of temperatures (30 °C to 120 °C) and frequencies (1·10-2 Hz and 3·106 Hz) were used. All these data have allowed an accurate characterization of the properties of the new composites, and according to these results, possible electrical applications have been explored, with the requirement that they must comply with Official Regulations.

    Postprint (author’s final draft)

  • Modification of epoxy-anhydride thermosets using a hyperbranched poly(este-amide): I. Kinetic study

     Fernández-Francos, Xavier; Rybak, Andrzej; Sekula, Robert; Ramis Juan, Xavier; Serra Albet, Àngels
    Polymer international
    Date of publication: 2012-05-16
    Journal article

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    An epoxy-anhydride formulation used for the coating of electrical devices was modified with a commercially available hyperbranched poly(ester-amide), HybraneS2200, in order to improve the thermal degradability of the resulting thermoset and thus facilitate the recovery of substrate materials after use of the component. The curing kinetics of the unmodified and modifiedformulationswerestudied in detail with differential scanning calorimetry,Fourier transform infrared spectroscopyand rheology. The results suggest that S2200 gets incorporated into the network structure and the curing kinetics are accelerated by the presence of hydroxyl groups from S2200.

  • Influence Of Composition And Microstructure On Properties Of New Trimethylene Carbonate/Glycolide Copolymers With Biomedical Applications

     Díaz Celorio, Elena
    Defense's date: 2012-07-23
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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  • Nuevos termoestables mejorados basados en resinas epoxi y polímeros dendríticos

     Cadenato Matia, Ana Maria; Salla Tarrago, Jose M.; Morancho Llena, Jose Maria; Ramis Juan, Xavier
    Participation in a competitive project

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  • Study of the thermal degradation of bioactive sol¿gel coatings for the optimization of its curing process

     Hernández-Escolano, Miriam; Ramis Juan, Xavier; Jiménez-Morales, A; Juan-Díaz, M; Suay, Julio
    Journal of thermal analysis and calorimetry
    Date of publication: 2012-02
    Journal article

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    A set of materials has been prepared by sol–gel process containing different quantities of hydroxyapatite (0, 2.5 and 5% HAp w/w) using as silica precursors glycidyloxypropyltrimethoxysilane (GPTMS) and triethoxyvinylsilane (VTES). In order to optimize the curing process to obtain sintherized systems (inorganic network) or hybrid systems (organic–inorganic) a TG and FTIR studies have been developed and degradation kinetic triplet parameters were obtained (the activation energy, pre-exponential factor, and function of degree of conversion). The kinetic study was analyzed by means of an integral isoconversional non-isothermal procedure (model free), and the kinetic model was determined by the Coats–Redfern method and through the compensation effect (IKR). All the systems followed the n = 6 kinetic model. The addition of HAp increases the thermal stability of the systems. The isothermal degradation was simulated from non-isothermal data, and the curing process could be defined to obtain the two types of materials. Temperature under 250 °C allows the formation of hybrids networks

  • New aromatic-aliphatic hyperbranched polyesters with vinylic end groups of different length as modifiers of epoxy/anhydride thermosets

     Tomuta, Adrian Marius; Ferrando, Francesc; Serra Albet, Àngels; Ramis Juan, Xavier
    Reactive and functional polymers
    Date of publication: 2012-09
    Journal article

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    The synthesis and characterization of two new aromatic–aliphatic hyperbranched polyesters modified with long and short vinylic chains was reported. These hyperbranched polymers were used as toughening modifiers of epoxy/anhydride thermosets. The curing of mixtures of diglycidyl ether of bisphenol A and hexahydro-4-methylphtalic anhydride with different proportions of both hyperbranched polymers using N,N-benzyldimethylamine as catalyst was investigated by differential scanning calorimetry. The kinetic of curing process was established using an isoconversional integral procedure. The characterization of these materials was done by means of several thermal analysis techniques and their morphology was investigated by electron microscopy. The addition of highly branched structures led to homogeneous morphologies and a more toughening fracture of the thermosets in comparison to the neat epoxy/anhydride material. The modified thermosets presented slightly lower glass transition temperature than the unmodified one and the thermal stability barely changed by the addition of the modifiers.

  • Efficient impact resistance improvement of epoxy/anhydride thermosets by adding hyperbranched polyesters partially modified with undecenoyl chains

     Flores, Marjori; Fernández Francos, Xavier; Ferrando, Francesc; Ramis Juan, Xavier; Serra Albet, Àngels
    Polymer
    Date of publication: 2012-10-26
    Journal article

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    Boltorn H30 hyperbranched polyester has been modified by acylation with 10-undecenoyl chloride to obtain HBPs with different degree of modification. These HBPs have been used as reactive modifiers, in a proportion of 5 and 10%, of DGEBA/MHHPA/BDMA formulations. The materials obtained have been characterized and their mechanical properties evaluated. Depending on the degree of modification of the HBP, homogeneous or phase separated materials were obtained, which influence the properties. When the degree of modification of the HBP was a 76%, a 4-fold increase in impact resistance was achieved without sacrificing thermomechanical characteristics, thermal stability or processability. This has been attributed to the regular microphase separation achieved and to the good interfacial interaction of the microparticles with the epoxy matrix by formation of covalent bonds between the remaining hydroxyl groups at the shell of the HBP and the anhydride as the curing agent.

    Boltorn H30 hyperbranched polyester has been modified by acylation with 10-undecenoyl chloride to obtain HBPs with different degree of modification. These HBPs have been used as reactive modifiers, in a proportion of 5 and 10%, of DGEBA/MHHPA/BDMA formulations. The materials obtained have been characterized and their mechanical properties evaluated. Depending on the degree of modification of the HBP, homogeneous or phase separated materials were obtained, which influence the properties. When the degree of modification of the HBP was a 76%, a 4-fold increase in impact resistance was achieved without sacrificing thermomechanical characteristics, thermal stability or processability. This has been attributed to the regular microphase separation achieved and to the good interfacial interaction of the microparticles with the epoxy matrix by formation of covalent bonds between the remaining hydroxyl groups at the shell of the HBP and the anhydride as the curing agent.

  • Thermal Analysis of Enhanced Poly (vinyl alcohol)-Based Proton-Conducting Membranes Crosslinked with Sulfonation Agents for direct Methanol Fuel Cells

     Morancho Llena, Jose Maria; Salla Tarrago, Jose M.; Cadenato Matia, Ana Maria; Fernández-Francos, Xavier; Colomer Vilanova, Pere; Calventus Sole, Yolanda; Ramis Juan, Xavier; Ruiz Mansilla, Rafael
    Journal of applied polymer science
    Date of publication: 2012-06-25
    Journal article

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  • COMPOSICIÓN Y PROCEDIMIENTO PARA EL ENTRECRUZAMIENTO DE UNA RESINA EPOXI CON UN ISOCIANATO, Y MATERIAL ENTRECRUZADO OBTENIDO

     Serra Albet, Àngels; Flores Guillen, Marjorie; Mantecón, Ana; Ramis Juan, Xavier; Fernandez Francos, Xavier; Salla Tarrago, Jose M.
    Date of request: 2012-01-26
    Invention patent

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  • Desarrollo de un protocolo para un sistema de gestión interna de la calidad de asignaturas de la titularidad de grado

     Cadenato Matia, Ana Maria; Salla Tarrago, Jose M.; Ramis Juan, Xavier; Morancho Llena, Jose Maria; Montserrat Jorda, Jose; Martin Godoy, Jose Luis
    Congreso Nacional de Ingeniería Termodinámica
    Presentation's date: 2011-06-15
    Presentation of work at congresses

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  • Estudio calorimétrico de los cambios en la cristalinidad de membranas conductoras de polivinil alcohol entrecruzadas con ácido sulfosuccínico para pilas de combustible de metanol

     Salla Tarrago, Jose M.; Cadenato Matia, Ana Maria; Morancho Llena, Jose Maria; Fernandez Francos, Xavier; Ramis Juan, Xavier
    Congreso Nacional de Ingeniería Termodinámica
    Presentation's date: 2011-06-15
    Presentation of work at congresses

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    En este trabajo se analizan los cambios en el grado de cristalización y en los hábitos cristalinos que el ácido sulfosuccínico (SSA) produce en membranas de polivinil alcohol (PVA). Las membranas resultantes del entrecruzamiento del PVA con SSA, un agente que incorpora además grupos sulfónicos que hacen al conjunto un buen conductor protónico, pueden utilizarse como electrolito en pilas de combustible alimentadas directamente con metanol (DMFC). Por medio de ensayos dinámicos de fusión y cristalización por calorimetría DSC se han obtenido el grado de cristalinidad y los parámetros cinéticos de cristalización de las diferentes membranas fabricadas. Para el análisis cinético se ha utilizado el método de Avrami modificado para ensayos no isotérmicos y el método de Ozawa modificado. Los ensayos calorimétricos se han complementado con ensayos mecánicos en un analizador dinámico mecánico con el que se han medido las variaciones del módulo elástico con la temperatura. Los análisis de muestras mediante espectroscopia infrarroja con transformada de Fourier y reflectancia total atenuada (FTIR-ATR) han servido para complementar el análisis de la cristalinidad y determinar el alcance de la posible degradación de las membranas al someterlas a temperaturas elevadas. Entre los resultados que se mostrarán en esta comunicación, cabe destacar la disminución drástica de la cristalinidad al añadir el SSA en proporciones pequeñas y la importancia que tiene el contenido de agua estructural en el desarrollo de la cristalinidad tanto en membranas de PVA solo como en membranas de PVA-SSA y las consecuencias que todo ello tiene en su resistencia térmica y mecánica.

  • Protocolo para un sistema de gestión interna de la calidad de asignaturas en los títulos de grado

     Cadenato Matia, Ana Maria; Salla Tarrago, Jose M.; Ramis Juan, Xavier; Morancho Llena, Jose Maria; Montserrat Jorda, Jose; Martin Godoy, Jose Luis
    Congreso Nacional de Ingeniería Termodinámica
    Presentation's date: 2011-06-15
    Presentation of work at congresses

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  • Effect of a hyperbranched polymer over the thermal curing and the photocuring of an epoxy resin

     Morancho Llena, Jose Maria; Cadenato Matia, Ana Maria; Ramis Juan, Xavier; Fernandez Francos, Xavier; Flores Guillen, Marjorie; Salla Tarrago, Jose M.
    Journal of thermal analysis and calorimetry
    Date of publication: 2011
    Journal article

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    In this study, the authors study by calorimetry the influence of hyperbranched polyester Boltron®H40 on the thermal curing and the photocuring of a diglycidyl ether of bisphenol epoxy resin (DGEBA) using ytterbium (III) trifluoromethanesulfonate and triarylsulfonium hexafluorantimonate as thermal and photo cationic initiators, respectively. In the dynamic thermal curing at different heating rates, the authors have seen a decelerating effect when H40 is added to DGEBA, the system with 10% of H40 being the slowest. An isoconversional method has been used to determine the apparent activation energy of the thermal curing. In the isothermal photocuring at low temperatures, the authors have also appreciated a decelerating effect on adding H40, obtaining a minimum conversion when the H40 proportion is 15%. However, at high temperatures, the photocuring process can be accelerated at the first part of this process. This behavior is a consequence of the temperature dependence of H40 solubility in DGEBA, the viscosity of the system, and the hydroxyl-induced chain-transfer reaction. The values found of the maximum glass transition temperature in the thermal curing and in the photocuring, show that H40 is not completely solubilized in the reacted system.

    In this study, the authors study by calorimetry the influence of hyperbranched polyester Boltron®H40 on the thermal curing and the photocuring of a diglycidyl ether of bisphenol epoxy resin (DGEBA) using ytterbium (III) trifluoromethanesulfonate and triarylsulfonium hexafluorantimonate as thermal and photo cationic initiators, respectively. In the dynamic thermal curing at different heating rates, the authors have seen a decelerating effect when H40 is added to DGEBA, the system with 10% of H40 being the slowest. An isoconversional method has been used to determine the apparent activation energy of the thermal curing. In the isothermal photocuring at low temperatures, the authors have also appreciated a decelerating effect on adding H40, obtaining a minimum conversion when the H40 proportion is 15%. However, at high temperatures, the photocuring process can be accelerated at the first part of this process. This behavior is a consequence of the temperature dependence of H40 solubility in DGEBA, the viscosity of the system, and the hydroxyl-induced chain-transfer reaction. The values found of the maximum glass transition temperature in the thermal curing and in the photocuring, show that H40 is not completely solubilized in the reacted system

  • New thermosets obtained from bisphenol A diglycidyl ether and hydroxyl-ended hyperbranched polymers partially blocked with benzoyl and trimethylsilyl groups

     Foix, David; Fernandez Francos, Xavier; Salla Tarrago, Jose M.; Serra Albet, Àngels; Morancho Llena, Jose Maria; Ramis Juan, Xavier
    Polymer international
    Date of publication: 2011-03
    Journal article

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  • Influence of the end groups of hyperbranched poly(glycidol) on the cationic curing and morphology of diglycidylether of bisfenol A thermosets

     Santiago, David; Morell, Mireia; Fernandez Francos, Xavier; Serra Albet, Àngels; Salla Tarrago, Jose M.; Ramis Juan, Xavier
    Reactive and functional polymers
    Date of publication: 2011-03
    Journal article

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    The cationic curing of DGEBA with hyperbranched polymers (HBPs) based on poly(glycidol) using ytterbium triflate as initiator, has been studied. Poly(glycidol) (PG) has been synthesized and the terminal hydroxyl groups have been partially end-capped with benzoyl end groups to produce benzoylated poly(glycidol) (PGBz). The hydrophylic character caused by the high hydroxyl group content of unmodified PG limits its solubility in DGEBA, while a partial modification with benzoyl groups makes PGBz fully miscible in DGEBA. Therefore, important differences are observed with respect to the curing kinetics, network development, properties and morphology of the cured materials, which may be related to the hydroxyl group content of the HBPs.

  • UV generation of a muiltifunctional hyperbranched thermal crosslinker to cure epoxy resin

     Foix, David; Ramis Juan, Xavier; Serra Albet, Àngels; Sangermano, Marco
    Polymer
    Date of publication: 2011-07-07
    Journal article

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    A new hyperbranched polymer (HBP) was obtained via an iterative synthetic procedure that consists of esterification and thiol-ene click reaction. This polymer was used as a latent multifunctional macroinitiator for the dual curing of a commercially available cycloaliphatic epoxy resin and this process was studied by photo-DSC and FTIR. The presence of thioether groups in the HBP structure leads, by photoirradiation, to the formation of sulfonium salts, which are thermal cationic initiating species. The materials obtained were characterized by DMTA, TGA, gel content and FESEM. By means of the last technique domains of HBP as a second phase within the epoxy matrix were observed.