José Ignacio Velasco | Universitat Politecnica de Catalunya (original) (raw)
Papers by José Ignacio Velasco
Polymers
A series of pressure-sensitive adhesives (PSAs) was prepared using a constant monomeric compositi... more A series of pressure-sensitive adhesives (PSAs) was prepared using a constant monomeric composition and different preparation processes to investigate the best combination to obtain the best balance between peel resistance, tack, and shear resistance. The monomeric composition was a 1:1 combination of two different water-based acrylic polymers—one with a high shear resistance (A) and the other with a high peel resistance and tack (B). Two different strategies were applied to prepare the adhesives: physical blending of polymers A and B and in situ emulsion polymerization of A + B, either in one or two steps; in this last case, by polymerizing A or B first. To characterize the polymer, the average particle size and viscosity were analyzed. The glass transition temperature (Tg) was determined by differential scanning calorimetry (DSC). The tetrahydrofuran (THF) insoluble polymer fraction was used to calculate the gel content, and the soluble part was used to determine the average sol m...
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Polymers, 2021
A series of pressure-sensitive adhesives (PSAs) was prepared using a constant monomeric compositi... more A series of pressure-sensitive adhesives (PSAs) was prepared using a constant monomeric composition and different preparation processes to investigate the best combination to obtain the best balance between peel resistance, tack, and shear resistance. The monomeric composition was a 1:1 combination of two different water-based acrylic polymers—one with a high shear resistance (A) and the other with a high peel resistance and tack (B). Two different strategies were applied to prepare the adhesives: physical blending of polymers A and B and in situ emulsion polymerization of A + B, either in one or two steps; in this last case, by polymerizing A or B first. To characterize the polymer, the average particle size and viscosity were analyzed. The glass transition temperature (Tg) was determined by differential scanning calorimetry (DSC). The tetrahydrofuran (THF) insoluble polymer fraction was used to calculate the gel content, and the soluble part was used to determine the average sol m...
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Low-energy instrumented falling dart impact techniques have been applied to characterise the rigi... more Low-energy instrumented falling dart impact techniques have been applied to characterise the rigidity of several series of polyolefinic flexible foams, at relatively high strain rates. Rebound tests were specially designed in order to determine the elastic modulus of the foams by application of a theoretical model that describes the indentation phenomena of a hemispherical element on a sample. A potential relationship between values of the determined elastic modulus and foam density was found and, as expected, the foams based in HDPE showed the higher values of the elastic modulus of all the studied foams, whereas the samples containing EVA resulted in the lower values. Moreover, the elastic modulus determined using hemispherical dart headstocks (indenters) with different diameter resulted in a constant value, as the indentation model applied establishes. The results presented in this paper show the utility of this test to characterise mechanically flexible foams, because it is sens...
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Polymers
Polysulfone nanocomposite foams containing variable amounts of graphene nanoplatelets (0–10 wt%) ... more Polysulfone nanocomposite foams containing variable amounts of graphene nanoplatelets (0–10 wt%) were prepared by water vapor-induced phase separation (WVIPS) and supercritical CO2 (scCO2) dissolution. WVIPS foams with two ranges of relative densities were considered, namely, between 0.23 and 0.41 and between 0.34 and 0.46. Foams prepared by scCO2 dissolution (0.0–2.0 wt% GnP) were obtained with a relative density range between 0.35 and 0.45. Although the addition of GnP affected the cellular structure of all foams, they had a bigger influence in WVIPS foams. The storage modulus increased for all foams with increasing relative density and GnP’s concentration, except for WVIPS PSU-GnP foams, as they developed open/interconnected cellular structures during foaming. Comparatively, foams prepared by scCO2 dissolution showed higher specific storage moduli than similar WVIPS foams (same relative density and GnP content), explained by the microcellular structure of scCO2 foams. As a result...
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Polymers
The present study evaluated the effect of the incorporation of copaiba oil, in direct and in micr... more The present study evaluated the effect of the incorporation of copaiba oil, in direct and in microencapsulated form, into films based on Xanthosoma mafaffa Schott starch. Initially, the characterization of copaiba oil by gas chromatograph coupled with mass spectrometry (GC-MS) and its antimicrobial activity against gram-positive and gram-negative bacteria was performed. The films were produced by the casting technique and characterized in relation to physical, chemical, structural, and antimicrobial activity. Sesquiterpenes, mainly β-caryophyllene, were the predominant compounds in copaiba oil, showing antimicrobial activity against B. subtilis and S. aureus. The films showed forming capacity, however, was observed a decrease in solubility and revealed an increase in hydrophobic characteristics. However, the oil reduced the tensile strength and elongation, while the microcapsules did not influence the mechanical properties in comparison to the control film. From microstructure analy...
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Polymers
Polysulfone (PSU) foams containing 0–10 wt% graphene nanoplatelets (GnP) were prepared using two ... more Polysulfone (PSU) foams containing 0–10 wt% graphene nanoplatelets (GnP) were prepared using two foaming methods. Alongside the analysis of the cellular structure, their thermal conductivity was measured and analyzed. The results showed that the presence of GnP can affect the cellular structure of the foams prepared by both water vapor induced phase separation (WVIPS) and supercritical CO2 (scCO2) dissolution; however, the impact is greater in the case of foams prepared by WVIPS. In terms of thermal conductivity, the analysis showed an increasing trend by incrementing the amount of GnP and increasing relative density, with the tortuosity of the cellular structure, dependent on the used foaming method, relative density, and amount of GnP, playing a key role in the final value of thermal conductivity. The combination of all these factors showed the possibility of preparing PSU-GnP foams with enhanced thermal conductivity at lower GnP amount by carefully controlling the cellular struct...
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Polymers
The growing global awareness about environmental preservation has stimulated the search for alter... more The growing global awareness about environmental preservation has stimulated the search for alternatives to replace conventional plastics made from fossil sources. One of the advantages is using polymers from renewable sources, such as starch and gelatin, which, in addition to being biodegradable, may also be edible. The incorporation of cranberry into a polymeric matrix can transfer bioactive composite films, colour and flavour to the film, which are characteristic of this fruit, expanding its application to fruit stripes or colourful coatings for specific foods. In this context, the aim of this work was to evaluate the influence of the incorporation of 0, 5, 15, 25, 35, 45 and 55% (solids mass/biopolymer mass) cranberry powder on the microstructure, thermal properties, ascorbic acid content and sensory analysis of gelatin and arrowroot starch films obtained by casting. Scanning electron microscopy (SEM) images showed that the incorporation of cranberry made the film surface rough ...
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Polymers
This research work evaluated the influence of the type of incorporation and variation in the conc... more This research work evaluated the influence of the type of incorporation and variation in the concentration of blackberry pulp (BL) and microencapsulated blackberry pulp (ML) powders by freeze-drying on the chemical and physical properties of arrowroot starch films. Blackberry powders were added to the film-forming suspension in different concentrations, 0%, 20%, 30% and 40% (mass/mass of dry starch) and through two different techniques, directly (D) and by sprinkling (S). Scanning electron microscopy (SEM) images revealed that the incorporation of blackberry powder has rendered the surface of the film rough and irregular. Films incorporated with BL and ML powders showed an increase in thickness and water solubility and a decrease in tensile strength in comparison with the film containing 0% powder. The incorporation of blackberry BL and ML powders into films transferred colour, anthocyanins and antioxidant capacity to the resulting films. Films added with blackberry powder by sprink...
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Composites Part B: Engineering, 2016
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Materials Today: Proceedings, 2016
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ABSTRACT
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ABSTRACT
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The increasingly demanding industrial requirements for polymers with enhanced specific properties... more The increasingly demanding industrial requirements for polymers with enhanced specific properties and functional characteristics have aroused a great interest in the development of lightweight nanocomposites by combining foaming with the addition of functional nanosized fillers [1]. In midst of these, graphene-based materials have recently generated a great attention as a way to extend the range of applications of polymers [2-3] due to their combination of high mechanical and transport properties, enabling to overcome some of the limitations of common conducting polymers, such as high cost, low thermal stability and poor mechanical performance. Among currently available graphene-based materials scalable to mass production, graphene nanoplatelets have emerged as an interesting multifunctional filler for polymer foams [1,4]. Nevertheless, there is still a considerable lack of information regarding the influence that these nanoparticles have on the microstructure and cellular structure...
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Postharvest Biology and Technology, 2015
ABSTRACT Edible films have been studied as potential substitutes for conventional plastics in foo... more ABSTRACT Edible films have been studied as potential substitutes for conventional plastics in food packaging. Their development provides a new alternative for the application of hydrocolloids, following global trends of environmental preservation. Taking this into account, the aim of this study was to develop and evaluate physicochemical properties (thickness, solubility in water and acid, water vapor permeability, opacity, tensile strength and elongation at break) of composite films based on corn starch (native, modified waxy or waxy) and gelatin, plasticized with glycerol or sorbitol. After this initial screening, the formulation presenting the physicochemical properties more appropriate was applied as an edible composite coating onto Red Crimson grapes to extend the shelf-life. The addition of gelatin significantly increased mechanical strength, solubility in water, permeability to water vapor, and thickness of the biofilms, while also decreasing the opacity. Composite films prepared with sorbitol had significantly lower permeability to water vapor and higher tensile strength than the films plasticized with glycerol. Improved appearance was observed in coated grapes after 21 days storage under refrigerated conditions, which had lower weight loss than the control group. Sensory evaluation showed that all the coatings did not affect acceptability scores.
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It is well known the relevance given to the study of heat transfer in polymer foams, as one of th... more It is well known the relevance given to the study of heat transfer in polymer foams, as one of the main applications is as lightweight thermal insulating elements. Alongside some of the possible strategies for improving the thermal insulating characteristics of polymer foams, there is also a tremendous interest in further extending the applications of these materials, mainly focusing on improving their poor mechanical properties. Although there is a great deal of interest in preparing and studying polypropylene foams, largely due to their good balance of properties and reduced cost, there is still lack of information regarding their mechanical and thermal conduction characterizations. With that in mind, this chapter considers the preparation, structure and properties of different polypropylene and polypropylene-based nanocomposite foams, focusing on the importance of the foam’s cellular structure and microstructure characteristics and/or filler’s orientation and dispersion in the me...
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Conference code: 88784, Export Date: 11 July 2013, Source: Scopus, Language of Original Document:... more Conference code: 88784, Export Date: 11 July 2013, Source: Scopus, Language of Original Document: English, Correspondence Address: Cano, Á.; Centre Català Del Plàstic, Departament de Ciència Dels Materials i Enginyeria Metal lúrgica, Universitat Politècnica de Catalunya, C/Colom 114, E-08222 Terrassa (Barcelona), Spain, References: Lee, L.J., Zeng, C., Cao, X., Han, X., Shen, J., Xu, G., (2005) Comp. Sci. Tech., 65, p. 2344;, Sponsors: Kiefel; SABIC Innovative Plastics; A. Schulman EMEA; PolyOne; Ticona Engineering Polymers; Senoplast
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Boletín de la Sociedad Española de Cerámica y Vidrio, 2000
ABSTRACT
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The Journal of Supercritical Fluids, 2015
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The present work deals with the preparation and characterizacion of an improved fire-resistant et... more 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.
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Polymers
A series of pressure-sensitive adhesives (PSAs) was prepared using a constant monomeric compositi... more A series of pressure-sensitive adhesives (PSAs) was prepared using a constant monomeric composition and different preparation processes to investigate the best combination to obtain the best balance between peel resistance, tack, and shear resistance. The monomeric composition was a 1:1 combination of two different water-based acrylic polymers—one with a high shear resistance (A) and the other with a high peel resistance and tack (B). Two different strategies were applied to prepare the adhesives: physical blending of polymers A and B and in situ emulsion polymerization of A + B, either in one or two steps; in this last case, by polymerizing A or B first. To characterize the polymer, the average particle size and viscosity were analyzed. The glass transition temperature (Tg) was determined by differential scanning calorimetry (DSC). The tetrahydrofuran (THF) insoluble polymer fraction was used to calculate the gel content, and the soluble part was used to determine the average sol m...
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Polymers, 2021
A series of pressure-sensitive adhesives (PSAs) was prepared using a constant monomeric compositi... more A series of pressure-sensitive adhesives (PSAs) was prepared using a constant monomeric composition and different preparation processes to investigate the best combination to obtain the best balance between peel resistance, tack, and shear resistance. The monomeric composition was a 1:1 combination of two different water-based acrylic polymers—one with a high shear resistance (A) and the other with a high peel resistance and tack (B). Two different strategies were applied to prepare the adhesives: physical blending of polymers A and B and in situ emulsion polymerization of A + B, either in one or two steps; in this last case, by polymerizing A or B first. To characterize the polymer, the average particle size and viscosity were analyzed. The glass transition temperature (Tg) was determined by differential scanning calorimetry (DSC). The tetrahydrofuran (THF) insoluble polymer fraction was used to calculate the gel content, and the soluble part was used to determine the average sol m...
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Low-energy instrumented falling dart impact techniques have been applied to characterise the rigi... more Low-energy instrumented falling dart impact techniques have been applied to characterise the rigidity of several series of polyolefinic flexible foams, at relatively high strain rates. Rebound tests were specially designed in order to determine the elastic modulus of the foams by application of a theoretical model that describes the indentation phenomena of a hemispherical element on a sample. A potential relationship between values of the determined elastic modulus and foam density was found and, as expected, the foams based in HDPE showed the higher values of the elastic modulus of all the studied foams, whereas the samples containing EVA resulted in the lower values. Moreover, the elastic modulus determined using hemispherical dart headstocks (indenters) with different diameter resulted in a constant value, as the indentation model applied establishes. The results presented in this paper show the utility of this test to characterise mechanically flexible foams, because it is sens...
Bookmarks Related papers MentionsView impact
Polymers
Polysulfone nanocomposite foams containing variable amounts of graphene nanoplatelets (0–10 wt%) ... more Polysulfone nanocomposite foams containing variable amounts of graphene nanoplatelets (0–10 wt%) were prepared by water vapor-induced phase separation (WVIPS) and supercritical CO2 (scCO2) dissolution. WVIPS foams with two ranges of relative densities were considered, namely, between 0.23 and 0.41 and between 0.34 and 0.46. Foams prepared by scCO2 dissolution (0.0–2.0 wt% GnP) were obtained with a relative density range between 0.35 and 0.45. Although the addition of GnP affected the cellular structure of all foams, they had a bigger influence in WVIPS foams. The storage modulus increased for all foams with increasing relative density and GnP’s concentration, except for WVIPS PSU-GnP foams, as they developed open/interconnected cellular structures during foaming. Comparatively, foams prepared by scCO2 dissolution showed higher specific storage moduli than similar WVIPS foams (same relative density and GnP content), explained by the microcellular structure of scCO2 foams. As a result...
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Polymers
The present study evaluated the effect of the incorporation of copaiba oil, in direct and in micr... more The present study evaluated the effect of the incorporation of copaiba oil, in direct and in microencapsulated form, into films based on Xanthosoma mafaffa Schott starch. Initially, the characterization of copaiba oil by gas chromatograph coupled with mass spectrometry (GC-MS) and its antimicrobial activity against gram-positive and gram-negative bacteria was performed. The films were produced by the casting technique and characterized in relation to physical, chemical, structural, and antimicrobial activity. Sesquiterpenes, mainly β-caryophyllene, were the predominant compounds in copaiba oil, showing antimicrobial activity against B. subtilis and S. aureus. The films showed forming capacity, however, was observed a decrease in solubility and revealed an increase in hydrophobic characteristics. However, the oil reduced the tensile strength and elongation, while the microcapsules did not influence the mechanical properties in comparison to the control film. From microstructure analy...
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Polymers
Polysulfone (PSU) foams containing 0–10 wt% graphene nanoplatelets (GnP) were prepared using two ... more Polysulfone (PSU) foams containing 0–10 wt% graphene nanoplatelets (GnP) were prepared using two foaming methods. Alongside the analysis of the cellular structure, their thermal conductivity was measured and analyzed. The results showed that the presence of GnP can affect the cellular structure of the foams prepared by both water vapor induced phase separation (WVIPS) and supercritical CO2 (scCO2) dissolution; however, the impact is greater in the case of foams prepared by WVIPS. In terms of thermal conductivity, the analysis showed an increasing trend by incrementing the amount of GnP and increasing relative density, with the tortuosity of the cellular structure, dependent on the used foaming method, relative density, and amount of GnP, playing a key role in the final value of thermal conductivity. The combination of all these factors showed the possibility of preparing PSU-GnP foams with enhanced thermal conductivity at lower GnP amount by carefully controlling the cellular struct...
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Polymers
The growing global awareness about environmental preservation has stimulated the search for alter... more The growing global awareness about environmental preservation has stimulated the search for alternatives to replace conventional plastics made from fossil sources. One of the advantages is using polymers from renewable sources, such as starch and gelatin, which, in addition to being biodegradable, may also be edible. The incorporation of cranberry into a polymeric matrix can transfer bioactive composite films, colour and flavour to the film, which are characteristic of this fruit, expanding its application to fruit stripes or colourful coatings for specific foods. In this context, the aim of this work was to evaluate the influence of the incorporation of 0, 5, 15, 25, 35, 45 and 55% (solids mass/biopolymer mass) cranberry powder on the microstructure, thermal properties, ascorbic acid content and sensory analysis of gelatin and arrowroot starch films obtained by casting. Scanning electron microscopy (SEM) images showed that the incorporation of cranberry made the film surface rough ...
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Polymers
This research work evaluated the influence of the type of incorporation and variation in the conc... more This research work evaluated the influence of the type of incorporation and variation in the concentration of blackberry pulp (BL) and microencapsulated blackberry pulp (ML) powders by freeze-drying on the chemical and physical properties of arrowroot starch films. Blackberry powders were added to the film-forming suspension in different concentrations, 0%, 20%, 30% and 40% (mass/mass of dry starch) and through two different techniques, directly (D) and by sprinkling (S). Scanning electron microscopy (SEM) images revealed that the incorporation of blackberry powder has rendered the surface of the film rough and irregular. Films incorporated with BL and ML powders showed an increase in thickness and water solubility and a decrease in tensile strength in comparison with the film containing 0% powder. The incorporation of blackberry BL and ML powders into films transferred colour, anthocyanins and antioxidant capacity to the resulting films. Films added with blackberry powder by sprink...
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Composites Part B: Engineering, 2016
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Materials Today: Proceedings, 2016
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Bookmarks Related papers MentionsView impact
ABSTRACT
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ABSTRACT
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The increasingly demanding industrial requirements for polymers with enhanced specific properties... more The increasingly demanding industrial requirements for polymers with enhanced specific properties and functional characteristics have aroused a great interest in the development of lightweight nanocomposites by combining foaming with the addition of functional nanosized fillers [1]. In midst of these, graphene-based materials have recently generated a great attention as a way to extend the range of applications of polymers [2-3] due to their combination of high mechanical and transport properties, enabling to overcome some of the limitations of common conducting polymers, such as high cost, low thermal stability and poor mechanical performance. Among currently available graphene-based materials scalable to mass production, graphene nanoplatelets have emerged as an interesting multifunctional filler for polymer foams [1,4]. Nevertheless, there is still a considerable lack of information regarding the influence that these nanoparticles have on the microstructure and cellular structure...
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Postharvest Biology and Technology, 2015
ABSTRACT Edible films have been studied as potential substitutes for conventional plastics in foo... more ABSTRACT Edible films have been studied as potential substitutes for conventional plastics in food packaging. Their development provides a new alternative for the application of hydrocolloids, following global trends of environmental preservation. Taking this into account, the aim of this study was to develop and evaluate physicochemical properties (thickness, solubility in water and acid, water vapor permeability, opacity, tensile strength and elongation at break) of composite films based on corn starch (native, modified waxy or waxy) and gelatin, plasticized with glycerol or sorbitol. After this initial screening, the formulation presenting the physicochemical properties more appropriate was applied as an edible composite coating onto Red Crimson grapes to extend the shelf-life. The addition of gelatin significantly increased mechanical strength, solubility in water, permeability to water vapor, and thickness of the biofilms, while also decreasing the opacity. Composite films prepared with sorbitol had significantly lower permeability to water vapor and higher tensile strength than the films plasticized with glycerol. Improved appearance was observed in coated grapes after 21 days storage under refrigerated conditions, which had lower weight loss than the control group. Sensory evaluation showed that all the coatings did not affect acceptability scores.
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It is well known the relevance given to the study of heat transfer in polymer foams, as one of th... more It is well known the relevance given to the study of heat transfer in polymer foams, as one of the main applications is as lightweight thermal insulating elements. Alongside some of the possible strategies for improving the thermal insulating characteristics of polymer foams, there is also a tremendous interest in further extending the applications of these materials, mainly focusing on improving their poor mechanical properties. Although there is a great deal of interest in preparing and studying polypropylene foams, largely due to their good balance of properties and reduced cost, there is still lack of information regarding their mechanical and thermal conduction characterizations. With that in mind, this chapter considers the preparation, structure and properties of different polypropylene and polypropylene-based nanocomposite foams, focusing on the importance of the foam’s cellular structure and microstructure characteristics and/or filler’s orientation and dispersion in the me...
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Conference code: 88784, Export Date: 11 July 2013, Source: Scopus, Language of Original Document:... more Conference code: 88784, Export Date: 11 July 2013, Source: Scopus, Language of Original Document: English, Correspondence Address: Cano, Á.; Centre Català Del Plàstic, Departament de Ciència Dels Materials i Enginyeria Metal lúrgica, Universitat Politècnica de Catalunya, C/Colom 114, E-08222 Terrassa (Barcelona), Spain, References: Lee, L.J., Zeng, C., Cao, X., Han, X., Shen, J., Xu, G., (2005) Comp. Sci. Tech., 65, p. 2344;, Sponsors: Kiefel; SABIC Innovative Plastics; A. Schulman EMEA; PolyOne; Ticona Engineering Polymers; Senoplast
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Boletín de la Sociedad Española de Cerámica y Vidrio, 2000
ABSTRACT
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The Journal of Supercritical Fluids, 2015
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The present work deals with the preparation and characterizacion of an improved fire-resistant et... more 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.
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