http://hdl.handle.net/2117/3619 Mon, 20 May 2013 09:21:35 GMT 2013-05-20T09:21:35Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19348 Title: Novel polycarbonate-graphene nanocomposite foams prepared by CO2 dissolution Authors: Gedler, Gabriel; Sousa Pais Antunes, Marcelo de; Redondo Realinho, Vera Cristina de; Velasco Perero, José Ignacio Abstract: Polycarbonate foams reinforced with 0,5 wt% of graphene were obtained by firstly melt-mixing the polycarbonate and graphene in an internal mixer, compression-moulding the melt-compounded grinded material and lastly dissolving CO2 inside a high pressure vessel. The CO2 desorption behaviour in the unfilled polycarbonate and nanocomposite was studied in terms of the CO2 saturation concentration and desorption diffusion coefficient, with the graphene-filled nanocomposite displaying a higher CO2 loss rate when compared to the neat polycarbonate. The cellular structure of the foams was found to be highly dependent on the saturation/foaming temperature, with smaller cell sizes being obtained with decreasing the temperature. Another parameter that had an important influence was the residual pressure, with higher residual pressure values resulting in foams with more uniform and regular cells. Fri, 17 May 2013 14:42:23 GMT http://hdl.handle.net/2117/19348 2013-05-17T14:42:23Z Gedler, Gabriel; Sousa Pais Antunes, Marcelo de; Redondo Realinho, Vera Cristina de; Velasco Perero, José Ignacio no Polycarbonate foams reinforced with 0,5 wt% of graphene were obtained by firstly melt-mixing the polycarbonate and graphene in an internal mixer, compression-moulding the melt-compounded grinded material and lastly dissolving CO2 inside a high pressure vessel. The CO2 desorption behaviour in the unfilled polycarbonate and nanocomposite was studied in terms of the CO2 saturation concentration and desorption diffusion coefficient, with the graphene-filled nanocomposite displaying a higher CO2 loss rate when compared to the neat polycarbonate. The cellular structure of the foams was found to be highly dependent on the saturation/foaming temperature, with smaller cell sizes being obtained with decreasing the temperature. Another parameter that had an important influence was the residual pressure, with higher residual pressure values resulting in foams with more uniform and regular cells. http://hdl.handle.net/2117/19337 Title: Influence of foaming process on the structure-properties relationship of foamed LDPE/silica nanocomposites Authors: Saiz Arroyo, Cristina; Rodríguez Pérez, Miguel Ángel; Velasco Perero, José Ignacio; Saja, José Antonio de Abstract: In this paper LDPE/silica nanocomposites are foamed by two different processes. First one is the pressure quench method which is based on the use of a physical blowing agent and second one is the improved compression moulding technique. As the latter process uses a chemical blowing agent, both types of foamed nanocomposites will provide very useful information about the relationship between foaming process-microstructure and macroscopic properties. Results have revealed how silica nanoparticles are able to act as nucleating sites during foaming step in both processes; however, the optimum amount of particles strongly depends on the foaming route. Thermal and mechanical properties of solid and foamed nanocomposites have been analyzed by means of thermogravimetric analysis and compression tests. Results have revealed that nanosilica particles act as effective nucleating agents, not only reducing cell size and increasing cell density but also achieving more homogeneous cellular structures. Thermal and mechanical properties are improved due to the presence of silica nanoparticles. It has been found that the improvement degree reached for samples produced using chemical blowing agents is greater than that achieved for samples produced using physical blowing agents. Fri, 17 May 2013 13:27:52 GMT http://hdl.handle.net/2117/19337 2013-05-17T13:27:52Z Saiz Arroyo, Cristina; Rodríguez Pérez, Miguel Ángel; Velasco Perero, José Ignacio; Saja, José Antonio de no A. Foam, A. Particle-reinforcement, B. Microstructures, B. Mechanical properties In this paper LDPE/silica nanocomposites are foamed by two different processes. First one is the pressure quench method which is based on the use of a physical blowing agent and second one is the improved compression moulding technique. As the latter process uses a chemical blowing agent, both types of foamed nanocomposites will provide very useful information about the relationship between foaming process-microstructure and macroscopic properties. Results have revealed how silica nanoparticles are able to act as nucleating sites during foaming step in both processes; however, the optimum amount of particles strongly depends on the foaming route. Thermal and mechanical properties of solid and foamed nanocomposites have been analyzed by means of thermogravimetric analysis and compression tests. Results have revealed that nanosilica particles act as effective nucleating agents, not only reducing cell size and increasing cell density but also achieving more homogeneous cellular structures. Thermal and mechanical properties are improved due to the presence of silica nanoparticles. It has been found that the improvement degree reached for samples produced using chemical blowing agents is greater than that achieved for samples produced using physical blowing agents. http://hdl.handle.net/2117/19151 Title: Multifunctional nanocomposite foams based on polypropylene with carbon nanofillers Authors: Sousa Pais Antunes, Marcelo de; Gedler, Gabriel; Velasco Perero, José Ignacio Abstract: This work considers the preparation and characterization of polypropylene foams with variable concentrations of graphene and carbon nanofibres, focussing on the influence of the foaming process and the nanofillers on the microstructural and dynamic-mechanical- thermal properties of the foams. Great differences were found in terms of foam morphology depending on the type of foaming process, with foams prepared by physical foaming showing a vertically deformed cell structure, while chemical foams presented an isotropic-like cellular structure. The addition of graphene resulted in foams with higher cell densities and more uniform cellular structures when compared to the ones with nanofibres. All these considerations are of extreme importance, as some of the most promising applications of these polymer foams require a good electromagnetic interference shielding efficiency, which greatly depends on the developed foam morphology. Thu, 09 May 2013 14:05:52 GMT http://hdl.handle.net/2117/19151 2013-05-09T14:05:52Z Sousa Pais Antunes, Marcelo de; Gedler, Gabriel; Velasco Perero, José Ignacio no Graphene nanoplatelets, carbon nanofibres, multifunctional foams, polypropylene, supercritical CO2 dissolution This work considers the preparation and characterization of polypropylene foams with variable concentrations of graphene and carbon nanofibres, focussing on the influence of the foaming process and the nanofillers on the microstructural and dynamic-mechanical- thermal properties of the foams. Great differences were found in terms of foam morphology depending on the type of foaming process, with foams prepared by physical foaming showing a vertically deformed cell structure, while chemical foams presented an isotropic-like cellular structure. The addition of graphene resulted in foams with higher cell densities and more uniform cellular structures when compared to the ones with nanofibres. All these considerations are of extreme importance, as some of the most promising applications of these polymer foams require a good electromagnetic interference shielding efficiency, which greatly depends on the developed foam morphology. http://hdl.handle.net/2117/19040 Title: Structure-property evaluation of trisilanolphenyl POSS®/polysulfone composites as a guide to POSS melt blending Authors: Milliman, Henry; Sánchez Soto, Miguel; Arostegui, Asier; Schiraldi, David A. Abstract: A series of polysulfone/phenyl trisilanol POSS nanocomposites were produced by melt blending by twin screw batch mixing. These materials were then injec- tion molded, and their thermal, mechanical, and morpho- logical properties were tested. The tensile properties of polysulfone were moderately compromised by the addition of phenyl TPOSS, because of the formation of large ( 1 l m) voided POSS aggregates. These domains however did cause the improvement of the impact resistance of the composites as described by the mechanism of crack pinning and bow- ing. Flexural properties remained essentially unchanged, which is attributed to the formation of an aggregate free- skin layer, which formed in the injection molded parts. Thermal behavior of the composites also remained largely unchanged due to the lack of POSS-polymer interactions on the molecular/chain segment scale. Initially, it was hypothesized that a high degree of POSS-polymer interac- tions would be present in these composited based on exami- nation of their chemical structures. This however, was not the case as phase separation was clearly present. This work highlights the need for a better understanding of the predic- tion of POSS-polymer interaction. Mon, 29 Apr 2013 16:56:24 GMT http://hdl.handle.net/2117/19040 2013-04-29T16:56:24Z Milliman, Henry; Sánchez Soto, Miguel; Arostegui, Asier; Schiraldi, David A. no interactions, nanocomposite, polysulfone, POSS, properties, structure A series of polysulfone/phenyl trisilanol POSS nanocomposites were produced by melt blending by twin screw batch mixing. These materials were then injec- tion molded, and their thermal, mechanical, and morpho- logical properties were tested. The tensile properties of polysulfone were moderately compromised by the addition of phenyl TPOSS, because of the formation of large ( 1 l m) voided POSS aggregates. These domains however did cause the improvement of the impact resistance of the composites as described by the mechanism of crack pinning and bow- ing. Flexural properties remained essentially unchanged, which is attributed to the formation of an aggregate free- skin layer, which formed in the injection molded parts. Thermal behavior of the composites also remained largely unchanged due to the lack of POSS-polymer interactions on the molecular/chain segment scale. Initially, it was hypothesized that a high degree of POSS-polymer interac- tions would be present in these composited based on exami- nation of their chemical structures. This however, was not the case as phase separation was clearly present. This work highlights the need for a better understanding of the predic- tion of POSS-polymer interaction. http://hdl.handle.net/2117/18881 Title: Effect of humidity in charge formation and transport in LDPE Authors: Aragoneses Aguado, Andrés; Tamayo, Ildaberto; Lebrato, Alexander; Cañadas Lorenzo, Juan Carlos; Diego Vives, José Antonio; Arencón Osuna, David; Belana Punseti, Juan Thu, 18 Apr 2013 16:39:21 GMT http://hdl.handle.net/2117/18881 2013-04-18T16:39:21Z Aragoneses Aguado, Andrés; Tamayo, Ildaberto; Lebrato, Alexander; Cañadas Lorenzo, Juan Carlos; Diego Vives, José Antonio; Arencón Osuna, David; Belana Punseti, Juan no http://hdl.handle.net/2117/18809 Title: Foamed polypropylene for industrial applications Authors: Sousa Pais Antunes, Marcelo de; Velasco Perero, José Ignacio Abstract: There is a great deal of industrial interest in the development of increasingly lighter materials based on polymer foams with improved specific properties for the most varied purposes, from flexible foams for packaging to rigid ones for structural applications. Due to its good combination of properties and reduced cost, foamed polypropylene (PP) could come as a good option. Depending on the base material, foam density and developed cellular structure and microstructure, PP foams may cover a wide range of characteristics and properties wich, combined with the incorporation of functional fillers, could ultimately result in the development of multifunctional lightweight materials. This chapter presents a review of the most recent developments in polypropylene foams, starting out by the commercially available PP grades thought out for foaming applications, the different types of PP-based foams depending on their characteristics and final uses, from low-density flexible foams for cushioning and packaging to medium-high density foams for structural purposes, and the main industrial foaming processes, going from melt-like foaming to solid state chemical and physical foaming. Recent developments in the field of PP foams are also considered, focusing on the combination of cellular structure control via foaming and the incorporation of micro and nanosized functional fillers, with the ultimate objective of developing PP-based foams with a wide range of properties and unique characteristics, from electrically conductive foams through the incorporation of conductive carbon-based nanofillers to foams with direction-dependent transport properties. Mon, 15 Apr 2013 17:58:18 GMT http://hdl.handle.net/2117/18809 2013-04-15T17:58:18Z Sousa Pais Antunes, Marcelo de; Velasco Perero, José Ignacio no There is a great deal of industrial interest in the development of increasingly lighter materials based on polymer foams with improved specific properties for the most varied purposes, from flexible foams for packaging to rigid ones for structural applications. Due to its good combination of properties and reduced cost, foamed polypropylene (PP) could come as a good option. Depending on the base material, foam density and developed cellular structure and microstructure, PP foams may cover a wide range of characteristics and properties wich, combined with the incorporation of functional fillers, could ultimately result in the development of multifunctional lightweight materials. This chapter presents a review of the most recent developments in polypropylene foams, starting out by the commercially available PP grades thought out for foaming applications, the different types of PP-based foams depending on their characteristics and final uses, from low-density flexible foams for cushioning and packaging to medium-high density foams for structural purposes, and the main industrial foaming processes, going from melt-like foaming to solid state chemical and physical foaming. Recent developments in the field of PP foams are also considered, focusing on the combination of cellular structure control via foaming and the incorporation of micro and nanosized functional fillers, with the ultimate objective of developing PP-based foams with a wide range of properties and unique characteristics, from electrically conductive foams through the incorporation of conductive carbon-based nanofillers to foams with direction-dependent transport properties. http://hdl.handle.net/2117/18776 Title: The effects of combining nanoclay and steel wires multi-scalar reinforcements on the structure and properties of polyurethane foams Authors: Cano, Álvaro; Sousa Pais Antunes, Marcelo de; Redondo Realinho, Vera Cristina de; Haurie Ibarra, Laia; Velasco Perero, José Ignacio Abstract: In this paper we prepared and characterized several polyurethane composite foams by combining variable concentrations of organophilic clay (montmorillonite) and metal reinforcement, with the objective of developing novel multi-scalar multifunctional rigid foams. The addition of montmorillonite clay promoted foaming and the formation of finer and more homogeneous cellular structures, resulting in foams with compressive elastic moduli and collapse stresses lower than that of the unfilled polyurethane foams. However, a comparative analysis versus the foams’ relative density demonstrated that both mechanical properties follow one single trend for the two materials. The combination of montmorillonite and metal reinforcement further reduced the cell size of foams, ultimately resulting in foams with similar mechanical properties for considerably lower relative densities. Although no important differences in thermal conductivity were found for the polyurethane foams with adding montmorillonite, the incorporation of the metal reinforcement led to considerably higher thermal conductivities, its value increasing with increasing relative density. Thu, 11 Apr 2013 15:37:03 GMT http://hdl.handle.net/2117/18776 2013-04-11T15:37:03Z Cano, Álvaro; Sousa Pais Antunes, Marcelo de; Redondo Realinho, Vera Cristina de; Haurie Ibarra, Laia; Velasco Perero, José Ignacio no Multi-scalar composites, Multifunctional foams, Polyurethane In this paper we prepared and characterized several polyurethane composite foams by combining variable concentrations of organophilic clay (montmorillonite) and metal reinforcement, with the objective of developing novel multi-scalar multifunctional rigid foams. The addition of montmorillonite clay promoted foaming and the formation of finer and more homogeneous cellular structures, resulting in foams with compressive elastic moduli and collapse stresses lower than that of the unfilled polyurethane foams. However, a comparative analysis versus the foams’ relative density demonstrated that both mechanical properties follow one single trend for the two materials. The combination of montmorillonite and metal reinforcement further reduced the cell size of foams, ultimately resulting in foams with similar mechanical properties for considerably lower relative densities. Although no important differences in thermal conductivity were found for the polyurethane foams with adding montmorillonite, the incorporation of the metal reinforcement led to considerably higher thermal conductivities, its value increasing with increasing relative density. http://hdl.handle.net/2117/18730 Title: The role of notch sharpening on the J-fracture toughness of thermoplastic polymers Authors: Salazar, Alicia; Rodríguez, Jesús; Martínez Benasat, Antonio Abstract: The effect of the notch sharpening on the fracture toughness obtained under Elastic–Plastic Fracture Mechanics (EPFMs) approach has been analyzed in two different types of thermoplastic polymers, a semicrystalline multi-phase ethylene–propylene block copolymer and an amorphous polycarbonate. The samples for fracture characterization were sharpened using a steel razor blade and the femtosecond laser ablation technique. Both notching techniques gave rise to the very same size of crack tip radii, 1–2 μm. For all the materials under study, the fracture toughness values of the specimens sharpened through femtosecond laser ablation were lower than those measured on samples sharpened using a steel razor blade. The largest differences were achieved for the amorphous polycarbonate. The damage produced ahead of the crack tip through plastic deformation in the steel razor blade sharpened samples over against the lack of damage in the femtolaser sharpened specimens explains the disparity in the fracture values. Besides, the stress state ahead of the crack tip is closely related to the plastic deformation zone to specimen thickness ratio. The fracture toughness values determined from the femtolaser sharpened samples were all in plane strain conditions while the values of the fracture toughness obtained from the steel razor blade sharpened specimens were not. Tue, 09 Apr 2013 11:27:36 GMT http://hdl.handle.net/2117/18730 2013-04-09T11:27:36Z Salazar, Alicia; Rodríguez, Jesús; Martínez Benasat, Antonio no The effect of the notch sharpening on the fracture toughness obtained under Elastic–Plastic Fracture Mechanics (EPFMs) approach has been analyzed in two different types of thermoplastic polymers, a semicrystalline multi-phase ethylene–propylene block copolymer and an amorphous polycarbonate. The samples for fracture characterization were sharpened using a steel razor blade and the femtosecond laser ablation technique. Both notching techniques gave rise to the very same size of crack tip radii, 1–2 μm. For all the materials under study, the fracture toughness values of the specimens sharpened through femtosecond laser ablation were lower than those measured on samples sharpened using a steel razor blade. The largest differences were achieved for the amorphous polycarbonate. The damage produced ahead of the crack tip through plastic deformation in the steel razor blade sharpened samples over against the lack of damage in the femtolaser sharpened specimens explains the disparity in the fracture values. Besides, the stress state ahead of the crack tip is closely related to the plastic deformation zone to specimen thickness ratio. The fracture toughness values determined from the femtolaser sharpened samples were all in plane strain conditions while the values of the fracture toughness obtained from the steel razor blade sharpened specimens were not. http://hdl.handle.net/2117/18709 Title: Influence of the injection-molding parameters on the cellular structure and thermo-mechanical properties of ethylene-propylene block copolymer foams Authors: Gómez Gómez, Jaime Francisco; Arencón Osuna, David; Sánchez Soto, Miguel; Martínez Benasat, Antonio Abstract: Microcellular injection-molding technology is capable of producing lightweight polymeric products. The foam morphology is determined by the injection-molding parameters, and it has been observed that depending on the parameter variations, the cell structure may exhibit substantial morphological differences through the entire section along the melt flow direction of the injected part. The effects of varying injection-molding parameters on foam morphology and thermal mechanical properties of a multiphase ethylene-propylene block copolymer (EPBC) were tested on 5-mm plaque specimens using a constant temperature profile. It has been found that injection speed does not have a significant effect on the thermal-mechanical properties of the foam, whereas shot volume and mold temperature do have a significant influence. Low shot volume produces uniform density cellular structures and larger cores, whereas lower mold temperatures help maintain small cell sizes. Furthermore, the effect of the copolymer’s crystalline phase on foam morphology has been observed. This study identifies the achievable foam morphologies and the thermal-mechanical performance of cellular molded EPBC parts. Mon, 08 Apr 2013 16:23:26 GMT http://hdl.handle.net/2117/18709 2013-04-08T16:23:26Z Gómez Gómez, Jaime Francisco; Arencón Osuna, David; Sánchez Soto, Miguel; Martínez Benasat, Antonio no Microcellular injection-molding technology is capable of producing lightweight polymeric products. The foam morphology is determined by the injection-molding parameters, and it has been observed that depending on the parameter variations, the cell structure may exhibit substantial morphological differences through the entire section along the melt flow direction of the injected part. The effects of varying injection-molding parameters on foam morphology and thermal mechanical properties of a multiphase ethylene-propylene block copolymer (EPBC) were tested on 5-mm plaque specimens using a constant temperature profile. It has been found that injection speed does not have a significant effect on the thermal-mechanical properties of the foam, whereas shot volume and mold temperature do have a significant influence. Low shot volume produces uniform density cellular structures and larger cores, whereas lower mold temperatures help maintain small cell sizes. Furthermore, the effect of the copolymer’s crystalline phase on foam morphology has been observed. This study identifies the achievable foam morphologies and the thermal-mechanical performance of cellular molded EPBC parts. http://hdl.handle.net/2117/18426 Title: Halogen-free flame retardant polyolefin foams Authors: Redondo Realinho, Vera Cristina de; Sousa Pais Antunes, Marcelo de; Santana Pérez, Orlando Onofre; Velasco Perero, José Ignacio Abstract: The present work deals with the preparation and characterizacion of an improved fire-resistant ethylene-acrylate foamed material containing calcium carbonate and a silicon elastomer. This grade, usually employed on the cable industry sector, was modified two differents synergistic FR systems : silica/zinc borate (S/ZB) and montmorillonite/graphite nanoplatelets(N). The different formulations were prepared by melt-blending and the foams by a compression-molding foaming process using Azodicarbonamide as chemical blowing agent. Thermal stability and fire behaviour, of both solid and foamed materials were characterized by means of thermogravimetric and cone calorimetric techniques, respectively. Tue, 19 Mar 2013 18:22:58 GMT http://hdl.handle.net/2117/18426 2013-03-19T18:22:58Z Redondo Realinho, Vera Cristina de; Sousa Pais Antunes, Marcelo de; Santana Pérez, Orlando Onofre; Velasco Perero, José Ignacio no The present work deals with the preparation and characterizacion of an improved fire-resistant ethylene-acrylate foamed material containing calcium carbonate and a silicon elastomer. This grade, usually employed on the cable industry sector, was modified two differents synergistic FR systems : silica/zinc borate (S/ZB) and montmorillonite/graphite nanoplatelets(N). The different formulations were prepared by melt-blending and the foams by a compression-molding foaming process using Azodicarbonamide as chemical blowing agent. Thermal stability and fire behaviour, of both solid and foamed materials were characterized by means of thermogravimetric and cone calorimetric techniques, respectively. http://hdl.handle.net/2117/17501 Title: Films of native and modified starch reinforced with fiber: influence of some extrusion variabels using response surface methodology Authors: Galicia Garcia, Tomás; Martínez Bustos, F; Jiménez Arévalo, Omar; Arencón Osuna, David; Gamez Pérez, José; Martínez Benasat, Antonio Abstract: Corn starch (native and phosphorylated) and potato films containing glycerol as plasticizer, and bagasse sugar cane as fiber, were produced by extrusion-calendering process, and characterized for the mechanical properties (tensile stress at rupture rr, elongation at break eb, and Young’s modulus E), water disintegration index (WDI), water absorption capacity (WAC), and luminosity. The evaluated processing variables were: feed moisture, fiber content, and type of starch. The response surface methodology was applied to analyze, and the model of significance was justified by a variance analysis (F-test). The inclusion of fiber provides a mechanical reinforcement to the starch matrix favoring the elongation at break (eb) in thickness films (280–350 lm). Samples formulated with potato starch within the values of feed moisture 18.25, 20.5, and 5 wt % of fiber content, showed an increment in values of tensile stress at rupture (3.80–4.4 MPa) and Young’s modulus (78.47–68.04 MPa). Corn starch films with high fiber content (10%) and low feed moisture (18.25%) values showed a decrement in elongation at break (12.93%). WAC and WDI were low with minimum and intermediate levels of feed moisture and fiber content (0–5%). Luminosity values were an indicative that do not exist degradation in film materials due to condition extrusion process used. Wed, 23 Jan 2013 14:37:09 GMT http://hdl.handle.net/2117/17501 2013-01-23T14:37:09Z Galicia Garcia, Tomás; Martínez Bustos, F; Jiménez Arévalo, Omar; Arencón Osuna, David; Gamez Pérez, José; Martínez Benasat, Antonio no Corn starch (native and phosphorylated) and potato films containing glycerol as plasticizer, and bagasse sugar cane as fiber, were produced by extrusion-calendering process, and characterized for the mechanical properties (tensile stress at rupture rr, elongation at break eb, and Young’s modulus E), water disintegration index (WDI), water absorption capacity (WAC), and luminosity. The evaluated processing variables were: feed moisture, fiber content, and type of starch. The response surface methodology was applied to analyze, and the model of significance was justified by a variance analysis (F-test). The inclusion of fiber provides a mechanical reinforcement to the starch matrix favoring the elongation at break (eb) in thickness films (280–350 lm). Samples formulated with potato starch within the values of feed moisture 18.25, 20.5, and 5 wt % of fiber content, showed an increment in values of tensile stress at rupture (3.80–4.4 MPa) and Young’s modulus (78.47–68.04 MPa). Corn starch films with high fiber content (10%) and low feed moisture (18.25%) values showed a decrement in elongation at break (12.93%). WAC and WDI were low with minimum and intermediate levels of feed moisture and fiber content (0–5%). Luminosity values were an indicative that do not exist degradation in film materials due to condition extrusion process used. http://hdl.handle.net/2117/17425 Title: Characterization of polycarbonate foam structures prepared by one-step SC-CO2 dissolution process Authors: Gedler, Gabriel; Sousa Pais Antunes, Marcelo de; Redondo Realinho, Vera Cristina de; Velasco Perero, José Ignacio Abstract: In this communication polycarbonate foams were prepared by a supercritical CO2 dissolution one-step batch foaming process. Firstly, CO2 diffusion behavior in polycarbonate was studied by means of desorption experiments. The cellular structure of foams prepared under different foaming conditions was characterized through scanning electron microscopy. Different foaming temperatures as well as CO2 saturation pressures and times were applied. The foams displayed typical closed-cell structures with cell densities ranging from 3x10⁵ to 3x10⁶ cells/m³ and cell average sizes from around 70 to 150μm. Analysis by X-ray diffraction and differential scanning calorimetry seemed to suggest that slight crystallization took place because of the plasticizing effect of CO2 during saturation and foaming. Thermogravimetric analysis showed a higher thermal stability of the foams when compared to the compact polymer. The preliminary results shown in this work suggest the possibility of developing lightweight polycarbonate components with improved specific thermal properties through carefully controlling the foaming parameters. Description: Electronic version of an article published as "FOAMS 2012: 10th International Conference on Foam Materials & Technology : Barcelona, Spain, September 12 - September 13, 2012". Society of Plastics Engineers. Fri, 18 Jan 2013 14:33:47 GMT http://hdl.handle.net/2117/17425 2013-01-18T14:33:47Z Gedler, Gabriel; Sousa Pais Antunes, Marcelo de; Redondo Realinho, Vera Cristina de; Velasco Perero, José Ignacio no In this communication polycarbonate foams were prepared by a supercritical CO2 dissolution one-step batch foaming process. Firstly, CO2 diffusion behavior in polycarbonate was studied by means of desorption experiments. The cellular structure of foams prepared under different foaming conditions was characterized through scanning electron microscopy. Different foaming temperatures as well as CO2 saturation pressures and times were applied. The foams displayed typical closed-cell structures with cell densities ranging from 3x10⁵ to 3x10⁶ cells/m³ and cell average sizes from around 70 to 150μm. Analysis by X-ray diffraction and differential scanning calorimetry seemed to suggest that slight crystallization took place because of the plasticizing effect of CO2 during saturation and foaming. Thermogravimetric analysis showed a higher thermal stability of the foams when compared to the compact polymer. The preliminary results shown in this work suggest the possibility of developing lightweight polycarbonate components with improved specific thermal properties through carefully controlling the foaming parameters. http://hdl.handle.net/2117/17247 Title: Influence of the injection moulding parameters on the microstructure and thermal properties of microcellular polyethylene terephthalate glycol foams Authors: Gómez Gómez, Jaime Francisco; Arencón Osuna, David; Sánchez Soto, Miguel; Martínez Benasat, Antonio Abstract: Microcellular injection moulding is capable of producing lightweight polymeric products. The present study analyses the influence of several representative injection moulding parameters on the foam’s morphology, apparent density and thermo-mechanical properties of PETG, poly(ethylene terephthalate-co-1,4-cyclohexylene-dimethylene terephthalate) specimens. A strong variation of the cell morphology along the melt flow direction has been found, as well as a dependence on the shot volume. The most homogeneous microcellular structure is achieved when low shot volume, intermediate injection speed and low mould temperature are employed. The skin–core structure of the injected parts, determined the thermo-mechanical features of the specimen, which are ruled by the skin layer. Wed, 09 Jan 2013 18:45:19 GMT http://hdl.handle.net/2117/17247 2013-01-09T18:45:19Z Gómez Gómez, Jaime Francisco; Arencón Osuna, David; Sánchez Soto, Miguel; Martínez Benasat, Antonio no Microcellular injection moulding is capable of producing lightweight polymeric products. The present study analyses the influence of several representative injection moulding parameters on the foam’s morphology, apparent density and thermo-mechanical properties of PETG, poly(ethylene terephthalate-co-1,4-cyclohexylene-dimethylene terephthalate) specimens. A strong variation of the cell morphology along the melt flow direction has been found, as well as a dependence on the shot volume. The most homogeneous microcellular structure is achieved when low shot volume, intermediate injection speed and low mould temperature are employed. The skin–core structure of the injected parts, determined the thermo-mechanical features of the specimen, which are ruled by the skin layer. http://hdl.handle.net/2117/17211 Title: Low flammability, foam-like materials based on ammonium alginate and sodium montmorillonite clay Authors: Chen, Hong-Bing; Wang, Yu-Zhong; Sánchez Soto, Miguel; Schiraldi, David A. Abstract: Low flammability, foam-like materials based on bio-based, renewable ammonium alginate and sodium montmorillonite clay were fabricated through a simple, environmentally-friendly freeze-drying process in which water is used as solvent. These materials exhibit mechanical properties similar to those of rigid PU foams or balsa; the compressive modulus (1–97 MPa) and density (0.047–0.174 g/cm3) increase with increasing solids content, with an associated change from a layered to network microstructure structure. Calcium ions, either added directly or indirectly via CaCO3/gluconolactone (GDL) are an effective crosslinking agent for alginate, with the GDL route providing the greatest enhancement of mechanical properties. The thermal stability of the aerogels is also enhanced by the presence of crosslinking. The alginate/clay aerogels possess inherently low flammability, as measured by cone calorimetry, with heat release values decreasing as the proportion of clay in the composites is increased. Tue, 08 Jan 2013 12:25:20 GMT http://hdl.handle.net/2117/17211 2013-01-08T12:25:20Z Chen, Hong-Bing; Wang, Yu-Zhong; Sánchez Soto, Miguel; Schiraldi, David A. no Low flammability, foam-like materials based on bio-based, renewable ammonium alginate and sodium montmorillonite clay were fabricated through a simple, environmentally-friendly freeze-drying process in which water is used as solvent. These materials exhibit mechanical properties similar to those of rigid PU foams or balsa; the compressive modulus (1–97 MPa) and density (0.047–0.174 g/cm3) increase with increasing solids content, with an associated change from a layered to network microstructure structure. Calcium ions, either added directly or indirectly via CaCO3/gluconolactone (GDL) are an effective crosslinking agent for alginate, with the GDL route providing the greatest enhancement of mechanical properties. The thermal stability of the aerogels is also enhanced by the presence of crosslinking. The alginate/clay aerogels possess inherently low flammability, as measured by cone calorimetry, with heat release values decreasing as the proportion of clay in the composites is increased. http://hdl.handle.net/2117/17208 Title: Thermal stabilization ability of polyhedral oligomeric silsesquioxane nanofillers Authors: Vilà Ramirez, N.; Sánchez Soto, Miguel Abstract: The polyhedral oligomeric silsesquioxane nanofillers examined in this study provided little or no improvement to the thermal properties of melt-blended acrylonitrile butadiene styrene polymer composites. Description: Electronic version of an article published as "Plastics research online", 17 December 2012 <http://www.4spepro.org/pdf/004523/004523.pdf> Tue, 08 Jan 2013 11:51:37 GMT http://hdl.handle.net/2117/17208 2013-01-08T11:51:37Z Vilà Ramirez, N.; Sánchez Soto, Miguel no The polyhedral oligomeric silsesquioxane nanofillers examined in this study provided little or no improvement to the thermal properties of melt-blended acrylonitrile butadiene styrene polymer composites.