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  • Photocuring of cycloaliphatic epoxy formulations using polyesters with multiarm star topology as additives

     Flores Guillen, Marjorie; Fernández Francos, Xavier; Ramis Juan, Xavier; Sangermano, Marco; Ferrando Piera, Francesc; Serra Albet, Àngels
    Journal of applied polymer science
    Vol. 131, num. 6, p. 1-9
    DOI: 10.1002/app.40005
    Date of publication: 2014-03-15
    Journal article

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    Multiam star polyesters were synthesized by growing poly(e- caprolactone) (PCL) arms from hyperbranched polyesters cores of different molecular weight and used as polymeric modifiers in UV-curable cationic formulations based on a biscycloaliphatic epoxy resin. The effect of the multiarm stars on the curing kinetics has been investigated by real-time FTIR. The thermal-mechanical properties of the photocured thermosets have been studied with calorimetry and dynamomechanical and thermogravimetric analysis. Impact strength tests have been performed to assess their effect on the toughness of the cured materials. An accelerative effect of these modifiers has been observed as a consequence of the participation of the hydroxyl groups of the modifiers in the cationic curing of the epoxy resin. A modest increase in toughness accompanied by a decrease in the glass transition are observed, as a consequence of the incorporation of the modifiers into the network structure, leading to homogeneous, in situ reinforced materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40005. Copyright © 2014 Wiley Periodicals, Inc.

  • Effect of hydroxyl ended and end-capped multiarm star polymers on the curing process and mechanical characteristics of epoxy/anhydride thermosets

     Acebo Gorostiza, Cristina; Picardi, Annamaria; Fernández Francos, Xavier; de la Flor López, Sílvia; Ramis Juan, Xavier; Serra Albet, Àngels
    Progress in organic coatings
    Vol. 77, num. 8, p. 1288-1298
    DOI: 10.1016/j.porgcoat.2014.04.014
    Date of publication: 2014-08-01
    Journal article

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    Multiarm star polymers have been synthesized by cationic ring-opening polymerization of epsilon-caprolactone from a hyperbranched poly(ethyleneimine) core and end-capped with acetic anhydride. These star polymers have been used as modifiers in diglycidylether of bisphenol A/methyl tetrahydrophthalic anhydride/benzyl dimethylamine formulations. The curing process is studied by dynamic scanning calorimetry and rheometry and the resulting thermosets are characterized by dynamic mechanical thermal analysis and thermogravimetry.; Internal stresses generated during curing are measured and interpreted in terms of the thermal mechanical properties of the cured materials. The influence of the modifier in the toughness improvement of the cured thermosets is determined by standardized impact tests and the microstructure of the material observed by scanning electron microscopy. (C) 2014 Elsevier B.V. All rights reserved.

  • New epoxy-anhydride thermosets modified with multiarm stars with hyperbranched polyester cores and poly(epsilon-caprolactone) arms

     Tomuta, Adrian Marius; Fernández Francos, Xavier; Ferrando Piera, Francesc; Serra Albet, Àngels; Ramis Juan, Xavier
    Polymer-Plastics technology and engineering
    Vol. 53, num. 7, p. 645-654
    DOI: 10.1080/03602559.2013.869599
    Date of publication: 2014-05-11
    Journal article

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    Multiarm star polymers with hyperbranched aromatic or aromatic-aliphatic cores and poly(epsilon-caprolactone) arms have been used as toughness modifiers in epoxy-anhydride formulations catalyzed by benzyldimethylamine. The curing process has been studied by dynamic scanning calorimetry, demonstrating little influence of the mobility of the reactive species and the hydroxyl content on the kinetics of this process. The obtained materials were characterized by thermal and mechanical tests and the microstructure by electron microscopy. Homogeneous thermosets have been obtained with a remarkable increase in impact strength without compromising glass transition temperature, thermal stability or hardness.

  • Novel epoxy-silica hybrid coatings by using ethoxysilyl-modified hyperbranched poly(ethyleneimine) with improved scratch resistance

     Acebo Gorostiza, Cristina; Fernández Francos, Xavier; Messori, Massimo; Ramis Juan, Xavier; Serra Albet, Àngels
    Polymer
    Vol. 55, num. 20, p. 5028-5035
    DOI: 10.1016/j.polymer.2014.08.021
    Date of publication: 2014-09-26
    Journal article

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    A new hyperbranched poly(ethyleneimine) with ethoxysilyl groups at the chain ends has been synthesized and characterized and then used in epoxy formulations to generate new organic/inorganic hybrid materials. Formulations of different proportions of diglycidylether of bisphenol A and the prepared ethoxysilylated hyperbranched poly(ethyleneimine) were maintained in a thermostatized controlled humidity chamber to form the inorganic silica network by a sol-gel process and then the epoxy resin was cured at higher temperature using 1-methylimidazole as anionic initiator. Transparent hybrid materials were prepared and characterized by thermal tests and their fine morphology was observed by transmission electron microscopy. The formation of the silicon structure was confirmed by 29Si NMR studies. Thermal stability was evaluated by thermogravimetry. Improvement of the mechanical coating performance was confirmed by scratch measurement.

  • A versatile thiol-ene/sol-gel two-stage curing process based on a hyperbranched polyester with different degrees of 10-undecenoyl modification

     Flores Guillen, Marjorie; Foix, David; Serra Albet, Àngels; Ramis Juan, Xavier; Sangermano, Marco
    Macromolecular materials and engineering
    Vol. 299, num. 4, p. 495-503
    DOI: 10.1002/mame.201300264
    Date of publication: 2014-04-01
    Journal article

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    Hybrid thiol-ene system based on a hyperbranched polyester with different degrees of 10-undecenoyl modification are prepared via a dual UV-thermal process. The pristine thiol-ene formulation shows a high reactivity towards UV curing and the addition of the inorganic precursor to the photocurable formulation does not affect the UV-curing process. The crosslinked systems show an increase of T-g by increasing the vinyl functionality content in the HBP and a T-g increase is also evidenced in the hybrid system as a function of inorganic precursor content. Morphological investigations show that the inorganic domains generated in situ are homogeneously distributed throughout the polymeric matrix. By varying the 10-undecenoyl modification in the terminal groups of the HBP, the size of the inorganic domains is tunable and it is possible to decrease the dimension of the silica domains by using the HBP with a higher modification degree.

  • Cure kinetics modeling and thermomechanical properties of cycloaliphatic epoxy-anhydride thermosets modified with hyperstar polymers

     Belmonte, Alberto; Daebritz, Frank; Ramis Juan, Xavier; Serra Albet, Àngels; Void, Brigitte; Fernández Francos, Xavier
    Journal of polymer science. Part B, polymer physics
    Vol. 52, num. 18, p. 1227-1242
    DOI: 10.1002/polb.23555
    Date of publication: 2014-09-15
    Journal article

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    Hyperstar polymers (HSPs) with hyperbranched aromatic polyester core and arms consisting of block copolymers of poly(methyl methacrylate) and poly(hydroxyethyl methacrylate) have been used as polymeric modifiers in cycloaliphatic epoxy-anhydride formulations catalyzed with tertiary amines, with the purpose of enhancing the impact strength of the resulting materials without compromising other thermal and mechanical properties.> In this work, the effect of these polymeric modifiers on the curing kinetics, processing, thermal-mechanical properties and thermal stability has been studied using thermal analysis techniques such as DSC, TMA, DMA, and TGA. The morphology of the cured materials has been analyzed with SEM. The curing kinetics has been analyzed by isoconversional procedures and phenomenological kinetic models taking into account the vitrification during curing, and the degradation kinetics has been analyzed by means of isoconversional procedures, summarizing the results in a time-temperature-transformation (TTT) diagram. The results show that HSPs participate in the crosslinking process due to the presence of reactive groups, without compromising significantly their thermal-mechanical properties. The modified materials show a potential toughness enhancement produced by the formation of a nano-grained morphology. The TTT diagram is shown to be a useful tool for the optimization of the curing schedule in terms of curing completion and safe processing window, as well as for defining storage stability conditions. (C) 2014 Wiley Periodicals, Inc.

  • 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
    Vol. 27, num. 9, p. 1-25
    DOI: 10.1177/0892705712470263
    Date of publication: 2014-09-01
    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 mu m, 200 < p < 500 mu m and p > 500 mu m) 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 degrees C) and frequencies (1 x 10(-2) Hz to 3 x 10(6) 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.

  • Comparative analysis of stochastic network build-up methods for the curing of epoxy-anhydride thermosets

     Fernández Francos, Xavier; Serra Albet, Àngels; Ramis Juan, Xavier
    European polymer journal
    Vol. 53, p. 22-36
    DOI: 10.1016/j.eurpolymj.2014.01.015
    Date of publication: 2014-04-01
    Journal article

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    The network build-up of epoxy-anhydride thermosets has been studied using two different stochastic network build-up methods based on the random combination of primary chains or simple fragments. Explicit expressions for relevant statistic averages in the pregel and postgel states have been derived for both methods. The application of both methods to a living polymerization kinetic model leads to strong divergences in the vicinity of the critical conversion at gelation due to growing differences between the real primary chain distribution and the most probable distribution in the fragment model. However, the application of both methods to an initiator regeneration kinetic model leads to identical results because of the distribution of primary chains throughout the whole curing process is a most probable one. (C) 2014 Elsevier Ltd. All rights reserved.

  • 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
    Vol. 52, num. 1, p. 61-75
    DOI: 10.1002/pola.26972
    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.

    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.

  • Nuevos termoestables con tenacidad mejorada a base de sistemas epoxi/anhídrido y polímeros estrella anfifílicos

     Lagunas Calpe, Carlos; Fernández Francos, Xavier; Ferrando Piera, Francesc; Flores Guillen, Marjorie; Serra Albet, Àngels; Salla Tarrago, Jose M.; Morancho Llena, Jose Maria; Ramis Juan, Xavier
    Reunión del Grupo Especializado de Polímeros
    p. 164-165
    Presentation's date: 2014-09-08
    Presentation of work at congresses

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  • Nuevo sistema latente para el curado de resinas epoxi con tioles

     Guzmán, Daylin; Serra Albet, Àngels; Fernández Francos, Xavier; Ramis Juan, Xavier
    Reunión del Grupo Especializado de Polímeros
    p. 44-46
    Presentation's date: 2014-09-08
    Presentation of work at congresses

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  • Novel epoxy-silica hybrid coatings by using ethoxysilyl-modified hyperbranched poly(ethyleneimine) with improved scratch resistance

     Acebo Gorostiza, Cristina; Fernández Francos, Xavier; Messori, Massimo; Ramis Juan, Xavier; Serra Albet, Àngels
    ECNP International Conference on Nanostructured Polymers and Nanocomposites
    p. 68
    Presentation's date: 2014-09-15
    Presentation of work at congresses

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  • Nuevos termoestables con base epoxi obtenidos por adición de poli(etilenimina)s modificadas con ácido 10-undecenoico

     Acebo Gorostiza, Cristina; Fernández Francos, Xavier; de la Flor López, Sílvia; Ramis Juan, Xavier; Serra Albet, Àngels
    Reunión del Grupo Especializado de Polímeros
    p. 174-175
    Presentation's date: 2014-09-08
    Presentation of work at congresses

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  • 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 Piera, Francesc; Okrasa, Lidia; Serra Albet, Àngels
    Journal of applied polymer science
    Vol. 128, num. 6, p. 4001-4013
    DOI: 10.1002/app.38453
    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.

    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 (Tg∞) 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

  • 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 Piera, Francesc; Ramis Juan, Xavier; Serra Albet, Àngels
    Polymers for advanced technologies
    Vol. 24, num. 11, p. 962-970
    DOI: 10.1002/pat.3171
    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.

  • 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
    Vol. 20, num. 3, p. 233-244
    DOI: 10.1515/secm-2012-0131
    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.

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

     Mujal Rosas, Ramon Maria; Marin Genesca, Marcos; Ramis Juan, Xavier
    Dyna
    Vol. 88, num. 6, p. 648-658
    DOI: /DX.DOI.ORG/10.6036/5580
    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.

  • 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
    Vol. 67, num. 12, p. 1427-1436
    DOI: 10.1366/13-07169
    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.

  • 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
    Vol. 54, num. 21, p. 5473-5481
    DOI: 10.1016/j.polymer.2013.07.056
    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.

  • Access to the full text
    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
    Vol. 7, num. 7, p. 565-576
    DOI: 10.3144/expresspolymlett.2013.54
    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.

  • 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
    Vol. 114, p. 409-416
    DOI: 10.1007/s10973-012-2919-9
    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.

    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.

  • 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 Piera, Francesc; Ramis Juan, Xavier; Salla Tarrago, Jose M.; Serra Albet, Àngels; Sangermano, Marco
    Journal of polymer science. Part B, polymer physics
    Vol. 51, num. 9, p. 772-773
    DOI: 10.1002/polb.23254
    Date of publication: 2013-01-25
    Journal article

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  • 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 Piera, Francesc; Serra Albet, Àngels
    Progress in organic coatings
    Vol. 76, num. 11, p. 1616-1624
    DOI: 10.1016/j.porgcoat.2013.07.010
    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.

    A new multiarm star with hyperbranched aromatic–aliphatic polyester core and poly(ɛ-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 Tg. The modified coatings showed an increased reworkability in alkaline solution with the maintenance of thermal stability.

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

     Acebo Gorostiza, Cristina; Fernández Francos, Xavier; Ferrando Piera, Francesc; Serra Albet, Àngels; Ramis Juan, Xavier
    European polymer journal
    Vol. 49, num. 8, p. 2316-2326
    DOI: 10.1016/j.eurpolymj.2013.05.015
    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.

  • Access to the full text
    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
    Vol. 7, num. 7, p. 595-606
    DOI: 10.3144/expresspolymlett.2013.57
    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.

  • 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 Piera, Francesc; Ramis Juan, Xavier; Serra Albet, Àngels
    European polymer journal
    Vol. 49, num. 6, p. 1610-1620
    DOI: 10.1016/j.eurpolymj.2013.02.011
    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

  • New and improved thermosets based on epoxy resins and dendritic polyesters

     Adrian Marius Tomuta
    Universitat Rovira i Virgili
    Theses

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    Epoxy resins constitute a class of thermosets which contains more than one epoxide group per molecule, which are very reactive to many curing agents like aromatic or aliphatic amines, acid anhydrides or isocyanates. They are used as reinforced composites, adhesives, high performance coatings and encapsulating materials. Epoxy thermosets have excellent electrical and mechanical properties, good adhesion to many metals and resistance to moisture and thermal and environment exposure. Curing agents ¿ [+]that show no activity under normal conditions but show activity by external stimulation, like temperature, can be called ¿¿latent curing agents¿. Among the thermal latent curing agents dicyandiamide (DICY) is one of the most employed in epoxy resin technology. The latent nature of this type of curing agents is due to the insolubility in epoxy resins at room temperature. The use of dihydrazides as curing agents has been scarcely reported in scientific literature but there are some dihydrazides commercially available as latent curing agents. In the present study a series of dihydrazides with different structures were prepared by reaction of dicarboxylic diester with hydrazine hydrate in ethanol. These compounds were studied as curing agents in DGEBA/dihydrazide 2:1 (mol/mol) formulations demonstrating their latent character. In the dihydrazides we have prepared, with aliphatic, cycloaliphatic and aromatic moieties a relationship between the melting point of the dihydrazides and the initial curing temperature was observed with the exception of the cycloaliphatic dihydrazide, which was amorphous but initiate the cure at the highest temperature.

  • Toughness improvement of epoxy thermosets by adding dendritic structures

     Flores Guillén, Marjorie
    Universitat Rovira i Virgili
    Theses

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    Las resinas epoxi se encuentran entre los materiales termoestables más importantes utilizados en un gran abanico de aplicaciones tales como adhesivos, matrices para materiales compuestos, recubrimientos de superficies y encapsulamiento de componentes electrónicos. La principal razón de su amplio uso es la buena combinación entre resistencia a la tracción y a la corrosión, rigidez y buenas propiedades eléctricas. Sin embargo, debido a su elevado grado de entrecruzamiento, las resinas epoxi ¿ [+]tienen una baja resistencia al impacto, la cual limita su uso en algunas aplicaciones específicas. Para contrarrestar este efecto, a las resinas epoxi se les añaden distintos modificantes entre los que se pueden destacar los polímeros hiperramificados. En esta tesis doctoral se plantea estudiar el efecto de la incorporación de distintos modificantes poliméricos a resinas epoxi convencionales glicidílicas y cicloalifáticas en el proceso de curado y en las características del material final. Estos agentes modificantes tienen estructuras dendríticas y son polímeros hiperramificados y estrellas. Unos son derivados de los poliésteres comerciales Boltorn® y otros con estructuras hiperramificadas de poliéter o poliéster, previamente sintetizadas y en algunos de los casos modificados en los grupos finales con estructuras alifáticas. Respecto a los sistemas de curado utilizados han sido diferentes los agentes seleccionados. En primer lugar se estudiaron los diisocianatos catalizados por aminas, sustituyéndose estos catalizadores por triflato de iterbio. El mecanismo de reacción en ambos casos fue estudiado por FTIR y mediante calorimetría pudiéndose determinar las reacciones que tenían lugar y cuantificar la proporción de grupos funcionales presentes en la red. También se estudiaron 2 otros agentes como son los anhídridos en presencia de amina terciaria, o los triflatos de lantánido, iniciadores catiónicos. Los sistemas anteriormente citados actúan térmicamente. De forma alternativa se han estudiados sistemas fotoiniciados catiónicos. Finalmente, se ha estudiado un nuevo sistema en dos etapas que se basa en una reacción tipo click (tiol-eno), que tiene lugar fotoquímicamente, y que en presencia de fotoiniciadores catiónicos, genera sales de sulfonio que son iniciadores catiónicos.

  • Unexpected differences between thermal and photoinitiated cationic curing of a DGEBA modified with a multiarm star poly(styrene)-b-poly(e-caprolactone) polymer

     Morancho Llena, Jose Maria; Cadenato Matia, Ana Maria; Ramis Juan, Xavier; Morell, Mireia; Fernández Francos, Xavier; Serra Albet, Àngels; Salla Tarrago, Jose M.
    International Symposium Frontiers in Polymer Science
    p. P1.28
    Presentation's date: 2013-05
    Presentation of work at congresses

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  • Enhancement of the impact strength of cationically cured cycloaliphatic diepoxide by adding hyperbranched polyglycidol partially modified with undecenoyl chains

     Flores Guillen, Marjorie; Morell, Mireia; Fernández Francos, Xavier; Ramis Juan, Xavier; Serra Albet, Àngels; Ferrando Piera, Francesc
    International Symposium Frontiers in Polymer Science
    p. P1.24
    Presentation's date: 2013-05
    Presentation of work at congresses

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  • Modification of diglycidylether of bisphenol: A thermosets with multiarm star polymers with poly(ethyleneimine) core and polyester arms cured by 1- methylimidazole

     Acebo Gorostiza, Cristina; Fernández Francos, Xavier; Serra Albet, Àngels; Ramis Juan, Xavier; Ferrando Piera, Francesc
    Congreso de Jóvenes Investigadores en Polímeros
    p. I-03
    Presentation's date: 2013-05-27
    Presentation of work at congresses

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  • New multiarm star based on aromatic hyperbranched polyester core and poly(e-caprolactone) arms as toughness modifiers of epoxy thermosets

     Tomuta, Adrian; Fernández Francos, Xavier; Ferrando Piera, Francesc; Serra Albet, Àngels; Ramis Juan, Xavier
    International Symposium Frontiers in Polymer Science
    p. P1.17
    Presentation's date: 2013-05-05
    Presentation of work at congresses

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

     Acebo Gorostiza, Cristina; Serra Albet, Àngels; Ramis Juan, Xavier; Fernández Francos, Xavier; Ferrando Piera, Francesc
    International Symposium Frontiers in Polymer Science
    p. P1.153
    Presentation's date: 2013-05
    Presentation of work at congresses

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  • New hybrid materials containing in situ generated silica particles based on thiol-ene crosslinking using hyperbranched polymers as macromonomers

     Flores Guillen, Marjorie; Serra Albet, Àngels; Ramis Juan, Xavier; Sangermano, Marco; Foix, David
    International Symposium Frontiers in Polymer Science
    p. P.1.31
    Presentation's date: 2013-05
    Presentation of work at congresses

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  • 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
    Vol. 34, num. 1, p. 96-108
    DOI: 10.1002/pc.22381
    Date of publication: 2013-01
    Journal article

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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 Gorostiza, Cristina; Fernández Francos, Xavier; Ferrando Piera, Francesc; Serra Albet, Àngels; Salla Tarrago, Jose M.; Ramis Juan, Xavier
    Reactive and functional polymers
    Vol. 73, num. 3, p. 431-441
    DOI: 10.1016/j.reactfunctpolym.2012.11.007
    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.

  • Modificació de reïnes epoxi amb polímers de tipus estrella basats en nucli de polietilenimina i braços de poliéster, curats amb anhídrid

     Acebo Gorostiza, Cristina; Picardi, Annamaria; Serra Albet, Àngels; Ramis Juan, Xavier; Fernández Francos, Xavier; de la Flor López, Sílvia
    Trobada de Joves Investigadors dels Països Catalans
    p. 43
    Presentation's date: 2013-11-28
    Presentation of work at congresses

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

     Acebo Gorostiza, Cristina; Fernández Francos, Xavier; Ferrando Piera, Francesc; Serra Albet, Àngels; Salla Tarrago, Jose M.; Ramis Juan, Xavier
    Baltic Polymer Symposium
    p. 103
    Presentation's date: 2013-09-19
    Presentation of work at congresses

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  • 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
    p. 1339-1346
    Presentation's date: 2013-06
    Presentation of work at congresses

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  • 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
    Vol. 124, num. SI, p. E57-E65
    DOI: 10.1002/app.35500
    Date of publication: 2012-06-25
    Journal article

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  • 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
    Vol. 61, num. 12, p. 1710-1725
    DOI: 10.1002/pi.4259
    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.

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

     Tomuta, Adrian Marius; Ferrando Piera, Francesc; Serra Albet, Àngels; Ramis Juan, Xavier
    Reactive and functional polymers
    Vol. 72, num. 9, p. 556-563
    DOI: 10.1016/j.reactfunctpolym.2012.05.008
    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.

  • 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
    Vol. 52, num. 12, p. 2597-2610
    DOI: 10.1002/pen.23225
    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.

  • 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 Piera, Francesc; Lederer, Albena; Ramis Juan, Xavier; Voit, Brigitte; Serra Albet, Àngels
    Progress in organic coatings
    Vol. 733, num. 1, p. 62-69
    DOI: 10.1016/j.porgcoat.2011.09.001
    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
    Vol. 125, num. 4, p. 2779-2789
    DOI: 10.1002/app.35504
    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 Piera, Francesc; Serra Albet, Àngels
    Polymer international
    Vol. 61, num. 5, p. 727-734
    DOI: 10.1002/pi.3230
    Date of publication: 2012-05
    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
    Vol. 50, num. 6, p. 1133-1142
    DOI: 10.1002/pola.25872
    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 Piera, Francesc; Ramis Juan, Xavier; Salla Tarrago, Jose M.; Serra Albet, Àngels; Sangermano, Marco
    Journal of polymer science. Part B, polymer physics
    Vol. 50, num. 21, p. 1489-1503
    DOI: 10.1002/polb.23145
    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.

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

     Flores, Marjori; Fernández Francos, Xavier; Ferrando Piera, Francesc; Ramis Juan, Xavier; Serra Albet, Àngels
    Polymer
    Vol. 53, num. 23, p. 5232-5241
    DOI: 10.1016/j.polymer.2012.09.031
    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.

  • 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
    Vol. 297, num. 1, p. 85-94
    DOI: 10.1002/mame.201100078
    Date of publication: 2012-01
    Journal article

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