Advances in Natural Sciences: Nanoscience and Nanotechnology, 2021
Green chemistry is the preferred approach for the synthesis of metal and metal oxide nanoparticle... more Green chemistry is the preferred approach for the synthesis of metal and metal oxide nanoparticles due to its environmental friendliness, feasibility, and safety to human health when compared with other chemical or physical methods. Caesalpinia spinosa is a promising resource to be applied in the green synthesis of metallic nanoparticles due to the high amount of polyphenols. The aim of the present research was to obtain an antifungal coating functionalised with nanoparticles synthesised from C. spinosa tannin and aqueous solutions of metallic (silver and copper) salts to control biodeterioration of acrylic paints and bricks. Green synthesised NPs were characterised by UV-vis spectroscopy, transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). The silver nanoparticles with average size of 12 nm and obtained from a 500 ppm aqueous solution of C. spinosa tannin inhibit...
A wide variety of inhibitive pigments is now being offered as possible alternatives to chromate a... more A wide variety of inhibitive pigments is now being offered as possible alternatives to chromate and lead compounds for painted metals protection. Unfortunately, the most wide spread of these substitute pigments, zinc phosphate, has, at present, raised some environmental concern because phosphate causes the eutrophication of water courses and zinc itself is toxic. The aim of this research was to study the anticorrosive performance of a mixture consisting of zinc phosphate, modified zeolite and clay (bentonite) in order to diminish phosphate content in paints. The zeolite and the clay were exchanged with La(III) ions, as inorganic green inhibitor. In the first step, the anticorrosion protection by La(III) ions in solution was assessed by electrochemical tests. In the second step, an epoxy-polyamide paint formulated with the pigment mixture applied on galvanized panels was studied by salt spray test and electrochemical noise measurements (ENM). The results showed that it was possible to replace part of the zinc phosphate content in the paint with the exchanged zeolite and the clay.
Silanes are an alternative to replace pretreatments based on Cr(VI) for electrogalvanized steel (... more Silanes are an alternative to replace pretreatments based on Cr(VI) for electrogalvanized steel (ES). As the interaction between the silane and the metal is important to ensure pretreatment efficiency, surface preparation is a critical step. In this sense, the presence of OH groups on the metal surface is essential. In this paper, the surface preparation of ES and a single/double layer application on the corrosion protection afforded by 3-aminopropyltriethoxy silane was studied. The metal surface was cleaned by polishing, electrochemically (employing anodic or cathodic current) or by chemical oxidation. The electrochemical behavior of the cleaned surfaces was analyzed by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Afterwards, the hydrolyzed silane was applied in a single or double layer. Coatings were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy, EIS and by exposure to the humidity chamber. Coatings applied on ES cle...
Biodeterioration in building façades represents an important economic loss related to maintaining... more Biodeterioration in building façades represents an important economic loss related to maintaining a functional protective coating system. Research papers with long-time studies on paint performance exposed to field conditions are scarce. Fungi, cyanobacteria, and algae are frequently present in biofilms formed in outdoor locations. Among these, defacement caused by fungi is known for the broad damage spectrum produced. Therefore, it is important to extend the service life of the protective coatings systems. To reach this goal, studies that consider the action of both biotic and abiotic factors acting simultaneously for prolonged periods are necessary. The present research work presents the assessment carried out on acrylic outdoor paint with a nano-additive exposed to long-term field conditions. Paint with 1% by weight of ZnO particles with nano-sized crystallites (nano-additive) was exposed to natural weathering. Samples with north and south orientation were evaluated by long-term field studies during a period of four years. The incorporation of the nano-additive proved to extend service life. In the paints facing north, the ZnO particles were more efficient for the biodeterioration control.
El biodeterioro constituye un conjunto de procesos físicos y químicos que generan alteraciones en... more El biodeterioro constituye un conjunto de procesos físicos y químicos que generan alteraciones en diversos materiales. La prevención del crecimiento de mohos, así como el desarrollo de medidas de tratamiento apropiadas para los objetos contaminados, son un desafío permanente [1,2]. En este sentido, las pinturas y recubrimientos en general juegan un papel importante como sistemas de conservación y protección de los distintos objetos. El objetivo de este trabajo de investigación fue, en una primera instancia, evaluar la actividad antifúngica in vitro del aceite esencial de Satureja montana (Sm) para luego incorporarlo en una formulación de pintura látex como agente biocida y evaluar su desempeño. Mediante ensayos de contacto in vitro con distintos hongos, se determinó que el aceite esencial al 0.5% v/v, inhibió completamente el crecimiento de todos los hongos. Posteriormente, se formuló una pintura al agua a la que se incorporó como aditivo biocida Sm al 2% p/p y se realizó el ensayo ...
Films of gmercap to propyltri methoxysilane are prepared by hydrolysis, condensation and curing a... more Films of gmercap to propyltri methoxysilane are prepared by hydrolysis, condensation and curing at 80 oC. The optical indices, n, k and the thickness d are calculated using the ellipsometry technique.Aprogramme is developed to fit a wide set of ellipsometriciÂÂ andiÂÂ data in the visible optical region 400 nm < e < 600 nm. An increase in the optical absorption k is detected for the lower concentration ofMPTMS attributed to light absorption from the pores.
Natalia Bellotti, Pablo Bellotti, Cecilia Deyá 1 CIDEPINT-Centro de Investigación y Desarrollo en... more Natalia Bellotti, Pablo Bellotti, Cecilia Deyá 1 CIDEPINT-Centro de Investigación y Desarrollo en Tecnología de Pinturas (CICPBA-CONICET), La Plata, Argentina. 2 Investigadora CONICET y Docente de la Facultad de Ciencias Naturales y Museo – UNLP, La Plata, Argentina. 3 Investigadora CONICET y Docente de la Facultad de Ingeniería – UNLP, La Plata, Argentina. a [email protected], b [email protected]
espanolEn este trabajo fue evaluado la capacidad anticorrosiva de extractos de la yerba mate (Ile... more espanolEn este trabajo fue evaluado la capacidad anticorrosiva de extractos de la yerba mate (Ilex paraguariensis) sobre el acero SAE 1010, a fin de ser incorporado en una pintura anticorrosivo. El extracto acuoso se obtuvo a partir de la mezcla de hojas y palos de yerba mate de dos marcas comerciales. Los ensayos preliminares se realizaron mediante tecnicas electroquimicas, microscopia electronica de barrido y analisis de energia dispersiva de rayos X, demostrando que la incorporacion de los extractos contribuye a la disminucion de la velocidad de corrosion del acero generando peliculas protectoras sobre su superficie. En base a estos resultados se formulo una pintura de base acuosa que fue evaluada mediante ensayos de envejecimiento acelerado (camaras de niebla salina y de humedad) y tecnicas electroquimicas (potencial de corrosion y resistencia ionica). Se concluye que los extractos reducen la velocidad de corrosion y que es posible incorporarlos a una pintura anticorrosiva con r...
La colonización fúngica de pinturas es un problema que, en las últimas décadas, atrajo la atenció... more La colonización fúngica de pinturas es un problema que, en las últimas décadas, atrajo la atención, debido a los problemas estéticos que causa, a la degradación de la pintura y a los problemas de salud que puede provocar. Una forma de evitarla es mediante el empleo de pinturas higiénicas, capaces de inhibir el crecimiento de microorganismos, y que permiten, además, la fácil limpieza de la superficie pintada. El objetivo de este trabajo fue evaluar la efectividad de dos biocidas en pinturas. Los biocidas estudiados fueron: salicilato de cinc y benzoato de cinc. Se utilizaron Chaetomium globosum y Alternaria alternate, aislados a partir de sustratos pintados contaminados con hongos, como especies indicadoras de la efectividad de las pinturas. Los resultados mostraron que los compuestos ensayados actúan como inhibidores del desarrollo de Chaetomium globosum y Alternaria alternate tanto puros como formando parte de pinturas acrílicas. La pintura con benzoato de cinc ejerció mayor inhibición que la pintura con salicilato de cinc sobre Alternaria alternate. En el caso de Chaetomium globosum el salicilato de cinc evidenció un mayor efecto inhibidor. Así mismo, los ensayos físicos demostraron que los inhibidores no difundieronde la pintura ni modificaron sus propiedades físicas o reológicas. Tópico 2: Conservación y restauración de Pinturas, Cueros, Textiles, Papel y Metales. Técnicas de Limpieza y restauración.
El objetivo del trabajo fue evaluar el empleo de microesferas de sílice mesoporosa MCM-41 como so... more El objetivo del trabajo fue evaluar el empleo de microesferas de sílice mesoporosa MCM-41 como soporte del carvacrol para el desarrollo de pinturas antifúngicas de base agua. Las MCM-41 se sintetizaron mediante la técnica de Liu et al., fundada en el uso de ligandos de silicatos como precursores inorgánicos hidrolíticos y tensioactivos como especies porógenas. La carga del carvacrol en MCM-41 se realizó por impregnación y posterior adsorción de vapor en un vial herméticamente cerrado incubado a 40 º C durante 24 horas. Se formularon y prepararon pinturas base acuosa en las que se incorporó como aditivo, 2% p/p, microesferas impregnadas con carvacrol (Pintura A), una pintura con microesferas sin impregnar (Pintura B), una pintura con carvacrol 2% p/p en forma libre (Pintura C) y otra pintura control sin microesferas y sin carvacrol (Pintura D). Se pintaron paneles de yeso y se realizaron ensayos de bioresistencia de la película seca frente al hongo Aspergillus sp. Al finalizar el ensayo se realizó una inspección visual y observaciones mediante microscopia electrónica de barrido (MEB). Los resultados mostraron que los paneles con la Pintura C y D se encontraban cubiertos con crecimiento fúngico. El porcentaje de cobertura fue alrededor de un 30 a 70% para la pintura C y un porcentaje mayor a 70% para la pintura D. Las pinturas A y B no presentaron crecimiento a simple vista. Las observaciones en MEB mostraron diferencias entre estas dos últimas, exponiendo crecimiento en el caso de la Pintura B. Estos resultados indican que la incorporación de las microesferas de por sí tienen un efecto biocida, debido muy probablemente al tensioactivo utilizado para su síntesis. A su vez, las micrografías MEB revelan que la impregnación del carvacrol en la sílice mejora aún más el efecto biocida de las microesferas. Este estudio demuestra que las microesferas de sílica mesoporosa MCM-41 podrían ser una alternativa como soporte para la carga del carvacrol en pinturas con actividad antifúngica.
Concerns about ozone layer, contamination, fossils resources and health, has banned or restricted... more Concerns about ozone layer, contamination, fossils resources and health, has banned or restricted the use of traditionally organic solvents in paints. As a consequence, new resins that employed water as main solvent are being studied. Among these resins, alkyds are the most studied one as they can also be synthesised from natural vegetable sources, making them more acceptable. The aim of this paper was to study the anticorrosive behaviour of alkyd / polysaccharide paints containing zinc phosphate or zinc aluminum phosphate as main pigment and their performance against fungal growth. Two different PVC (pigment volume concentration) were studied. Painted panels were studied by exposition to salt spray and humidity chambers, where rusting and blistering degrees were evaluated, and by electrochemical tests (corrosion potential measurements, ionic resistances determination, linear polarization curves and polarization resistances determination). Results showed that these type of paints can be used to protect steel and that the type of pigment and the PVC are important to the protection. Besides, good selection of both also prevents fungi growth in a high humid environment.
El presente trabajo tuvo como objetivo la formulación y elaboración de pinturas alquídicas con nu... more El presente trabajo tuvo como objetivo la formulación y elaboración de pinturas alquídicas con nuevos pigmentos anticorrosivos a base de mordenita intercambiada, amigables con el medio ambiente. La caracterización electroquímica del acero pintado se llevó a cabo por: medidas de conductividad, ensayos de polarización lineal y medidas del potencial de corrosión. La película de pintura ensayada en cada caso fue removida y la superficie fue analizada mediante microscopía electrónica de barrido y análisis de energía dispersiva por rayos X. Los resultados muestran que los nuevos pigmentos incorporados a la pintura proporcionan propiedades anticorrosivas aceptables teniendo en cuenta su bajo impacto ambiental y la utilización de un recurso natural de bajo costo.
Purpose This paper aims to study five vegetables extracts as possible additives to control bacter... more Purpose This paper aims to study five vegetables extracts as possible additives to control bacterial growth on indoor waterborne paints. The extracts were obtained from the weeds Raphanus sativus, Rapistrum rugosum, Sinapis arvensis, Nicotiana longiflora and Dipsacus fullonum, used in traditional medicine as antimicrobial compounds. Design/methodology/approach Weeds extracts were characterized by Fourier transform infrared spectroscopy and UV–Vis spectrophotometry. Their antibacterial activity against Escherichia coli and Staphylococcus aureus was also determined. Afterward, selected extracts were incorporated in waterborne paint formulations. The paints’ antimicrobial activity was assessed against S. aureus, monitoring biofilm formation by environmental scanning electron microscopy. Findings As a general rule, results showed that tested paints were efficient in inhibiting biofilm formation, especially that formulated with Nicotiana longiflora. Practical implications The tested pain...
One of the most inexpensive and effective method to protect steel against corrosion is paints con... more One of the most inexpensive and effective method to protect steel against corrosion is paints containing active pigments. The traditional way to test these coatings performance is by accelerated tests (exposition to salt spray and/or humidity chambers) and electrochemical tests (corrosion potential, ionic resistance and electrochemical impedance spectroscopy). However, these tests give incomplete information if the results are not correlated to outdoor or service tests. The aim of this work was to evaluate water-borne epoxy anticorrosion paints containing different commercial phosphate pigments. The paints were exposed to a semi-industrial atmosphere for 7 years. Electrochemical tests and accelerated assays were also done in order to find a correlation between laboratory and service tests. The results obtained showed no correlation between those from pigment suspensions and those from painted panels, as it seemed that paint performance is highly dependent on the resin. The pigments zinc iron phosphate and zinc aluminium phosphate performed poorly in pigment suspensions. However, the coatings containing them exhibited the highest ionic resistance, the lowest film capacitance and gave the better results in outdoor tests. Results in outdoor exposure tests correlated with those from impedance measurements.
Fungal growth in damp surfaces of water-damaged buildings is an increasing problem around the wor... more Fungal growth in damp surfaces of water-damaged buildings is an increasing problem around the world, which has adverse effects on both people's health and buildings. By bio-deterioration, fungi can growth in indoor environments and generate materials losses in addition to health problems. Therefore, antifungal coatings must be developed to avoid these problems. Silica is used as supporting additive in coatings, such as the waterborne paints and, on the other hand, the addition of Ag nanoparticles into different materials is being widely studied for its effective antimicrobial properties. The aim of this work was to evaluate the bio-resistance to fungal growth on waterborne coatings containing siliceous additives, by accelerated four-week agar plate assay. The additives were synthesized by the sol-gel method and characterized by potentiometric titration and transmission electron microscopy (TEM). In addition, the paints were observed by scanning electron microscopy (SEM) at the end of the test. To carry out the bioresistance assay, Chaetomium globosum and Alternaria alternata fungi were used. After 4 weeks of assay, paints prepared with the silver-additives were the most efficient inhibiting the growth of both fungi. These paints, after their exposure for 6 months, in an internal environment with sunlight incidence, kept the antifungal activity against Chaetomium globosum and showed a higher activity against Alternaria alternata.
There are nanotechnology-based materials that can be used as antimicrobial additives in different... more There are nanotechnology-based materials that can be used as antimicrobial additives in different applications such as water-borne paints. Antimicrobial paints are important tool in order to avoid indoor biological colonization and therefore prevent paint bio-deterioration and health problems in people and pets. These paints would have application in kitchens, bathrooms and hospitals. The present study evaluated the incorporation of silver (of two different sizes), copper and zinc oxide nanoparticles in indoor waterborne paints and the bio-resistance imparted by them. The antifungal activity of nanoparticles is a less studied topic in relation to the antibacterial activity but is no less important from the environmental point of view. Molds that grow in indoor environments contribute significantly with bioaerosol formation and therefore on air contamination and human health deterioration. In this sense, this research evaluated the nanoparticles' antifungal activity using previously isolated fungi, Chaetomium globosum and Alternaria alternata, on solid medium. Then, the bio-resistance of acrylic paints, with nanoparticles incorporated, was evaluated in Petri dishes and observations were made using scanning electron microscopy. The better results were obtained with the paint that contained silver with the smaller size (10 nm).
Advances in Natural Sciences: Nanoscience and Nanotechnology, 2021
Green chemistry is the preferred approach for the synthesis of metal and metal oxide nanoparticle... more Green chemistry is the preferred approach for the synthesis of metal and metal oxide nanoparticles due to its environmental friendliness, feasibility, and safety to human health when compared with other chemical or physical methods. Caesalpinia spinosa is a promising resource to be applied in the green synthesis of metallic nanoparticles due to the high amount of polyphenols. The aim of the present research was to obtain an antifungal coating functionalised with nanoparticles synthesised from C. spinosa tannin and aqueous solutions of metallic (silver and copper) salts to control biodeterioration of acrylic paints and bricks. Green synthesised NPs were characterised by UV-vis spectroscopy, transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). The silver nanoparticles with average size of 12 nm and obtained from a 500 ppm aqueous solution of C. spinosa tannin inhibit...
A wide variety of inhibitive pigments is now being offered as possible alternatives to chromate a... more A wide variety of inhibitive pigments is now being offered as possible alternatives to chromate and lead compounds for painted metals protection. Unfortunately, the most wide spread of these substitute pigments, zinc phosphate, has, at present, raised some environmental concern because phosphate causes the eutrophication of water courses and zinc itself is toxic. The aim of this research was to study the anticorrosive performance of a mixture consisting of zinc phosphate, modified zeolite and clay (bentonite) in order to diminish phosphate content in paints. The zeolite and the clay were exchanged with La(III) ions, as inorganic green inhibitor. In the first step, the anticorrosion protection by La(III) ions in solution was assessed by electrochemical tests. In the second step, an epoxy-polyamide paint formulated with the pigment mixture applied on galvanized panels was studied by salt spray test and electrochemical noise measurements (ENM). The results showed that it was possible to replace part of the zinc phosphate content in the paint with the exchanged zeolite and the clay.
Silanes are an alternative to replace pretreatments based on Cr(VI) for electrogalvanized steel (... more Silanes are an alternative to replace pretreatments based on Cr(VI) for electrogalvanized steel (ES). As the interaction between the silane and the metal is important to ensure pretreatment efficiency, surface preparation is a critical step. In this sense, the presence of OH groups on the metal surface is essential. In this paper, the surface preparation of ES and a single/double layer application on the corrosion protection afforded by 3-aminopropyltriethoxy silane was studied. The metal surface was cleaned by polishing, electrochemically (employing anodic or cathodic current) or by chemical oxidation. The electrochemical behavior of the cleaned surfaces was analyzed by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Afterwards, the hydrolyzed silane was applied in a single or double layer. Coatings were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy, EIS and by exposure to the humidity chamber. Coatings applied on ES cle...
Biodeterioration in building façades represents an important economic loss related to maintaining... more Biodeterioration in building façades represents an important economic loss related to maintaining a functional protective coating system. Research papers with long-time studies on paint performance exposed to field conditions are scarce. Fungi, cyanobacteria, and algae are frequently present in biofilms formed in outdoor locations. Among these, defacement caused by fungi is known for the broad damage spectrum produced. Therefore, it is important to extend the service life of the protective coatings systems. To reach this goal, studies that consider the action of both biotic and abiotic factors acting simultaneously for prolonged periods are necessary. The present research work presents the assessment carried out on acrylic outdoor paint with a nano-additive exposed to long-term field conditions. Paint with 1% by weight of ZnO particles with nano-sized crystallites (nano-additive) was exposed to natural weathering. Samples with north and south orientation were evaluated by long-term field studies during a period of four years. The incorporation of the nano-additive proved to extend service life. In the paints facing north, the ZnO particles were more efficient for the biodeterioration control.
El biodeterioro constituye un conjunto de procesos físicos y químicos que generan alteraciones en... more El biodeterioro constituye un conjunto de procesos físicos y químicos que generan alteraciones en diversos materiales. La prevención del crecimiento de mohos, así como el desarrollo de medidas de tratamiento apropiadas para los objetos contaminados, son un desafío permanente [1,2]. En este sentido, las pinturas y recubrimientos en general juegan un papel importante como sistemas de conservación y protección de los distintos objetos. El objetivo de este trabajo de investigación fue, en una primera instancia, evaluar la actividad antifúngica in vitro del aceite esencial de Satureja montana (Sm) para luego incorporarlo en una formulación de pintura látex como agente biocida y evaluar su desempeño. Mediante ensayos de contacto in vitro con distintos hongos, se determinó que el aceite esencial al 0.5% v/v, inhibió completamente el crecimiento de todos los hongos. Posteriormente, se formuló una pintura al agua a la que se incorporó como aditivo biocida Sm al 2% p/p y se realizó el ensayo ...
Films of gmercap to propyltri methoxysilane are prepared by hydrolysis, condensation and curing a... more Films of gmercap to propyltri methoxysilane are prepared by hydrolysis, condensation and curing at 80 oC. The optical indices, n, k and the thickness d are calculated using the ellipsometry technique.Aprogramme is developed to fit a wide set of ellipsometriciÂÂ andiÂÂ data in the visible optical region 400 nm < e < 600 nm. An increase in the optical absorption k is detected for the lower concentration ofMPTMS attributed to light absorption from the pores.
Natalia Bellotti, Pablo Bellotti, Cecilia Deyá 1 CIDEPINT-Centro de Investigación y Desarrollo en... more Natalia Bellotti, Pablo Bellotti, Cecilia Deyá 1 CIDEPINT-Centro de Investigación y Desarrollo en Tecnología de Pinturas (CICPBA-CONICET), La Plata, Argentina. 2 Investigadora CONICET y Docente de la Facultad de Ciencias Naturales y Museo – UNLP, La Plata, Argentina. 3 Investigadora CONICET y Docente de la Facultad de Ingeniería – UNLP, La Plata, Argentina. a [email protected], b [email protected]
espanolEn este trabajo fue evaluado la capacidad anticorrosiva de extractos de la yerba mate (Ile... more espanolEn este trabajo fue evaluado la capacidad anticorrosiva de extractos de la yerba mate (Ilex paraguariensis) sobre el acero SAE 1010, a fin de ser incorporado en una pintura anticorrosivo. El extracto acuoso se obtuvo a partir de la mezcla de hojas y palos de yerba mate de dos marcas comerciales. Los ensayos preliminares se realizaron mediante tecnicas electroquimicas, microscopia electronica de barrido y analisis de energia dispersiva de rayos X, demostrando que la incorporacion de los extractos contribuye a la disminucion de la velocidad de corrosion del acero generando peliculas protectoras sobre su superficie. En base a estos resultados se formulo una pintura de base acuosa que fue evaluada mediante ensayos de envejecimiento acelerado (camaras de niebla salina y de humedad) y tecnicas electroquimicas (potencial de corrosion y resistencia ionica). Se concluye que los extractos reducen la velocidad de corrosion y que es posible incorporarlos a una pintura anticorrosiva con r...
La colonización fúngica de pinturas es un problema que, en las últimas décadas, atrajo la atenció... more La colonización fúngica de pinturas es un problema que, en las últimas décadas, atrajo la atención, debido a los problemas estéticos que causa, a la degradación de la pintura y a los problemas de salud que puede provocar. Una forma de evitarla es mediante el empleo de pinturas higiénicas, capaces de inhibir el crecimiento de microorganismos, y que permiten, además, la fácil limpieza de la superficie pintada. El objetivo de este trabajo fue evaluar la efectividad de dos biocidas en pinturas. Los biocidas estudiados fueron: salicilato de cinc y benzoato de cinc. Se utilizaron Chaetomium globosum y Alternaria alternate, aislados a partir de sustratos pintados contaminados con hongos, como especies indicadoras de la efectividad de las pinturas. Los resultados mostraron que los compuestos ensayados actúan como inhibidores del desarrollo de Chaetomium globosum y Alternaria alternate tanto puros como formando parte de pinturas acrílicas. La pintura con benzoato de cinc ejerció mayor inhibición que la pintura con salicilato de cinc sobre Alternaria alternate. En el caso de Chaetomium globosum el salicilato de cinc evidenció un mayor efecto inhibidor. Así mismo, los ensayos físicos demostraron que los inhibidores no difundieronde la pintura ni modificaron sus propiedades físicas o reológicas. Tópico 2: Conservación y restauración de Pinturas, Cueros, Textiles, Papel y Metales. Técnicas de Limpieza y restauración.
El objetivo del trabajo fue evaluar el empleo de microesferas de sílice mesoporosa MCM-41 como so... more El objetivo del trabajo fue evaluar el empleo de microesferas de sílice mesoporosa MCM-41 como soporte del carvacrol para el desarrollo de pinturas antifúngicas de base agua. Las MCM-41 se sintetizaron mediante la técnica de Liu et al., fundada en el uso de ligandos de silicatos como precursores inorgánicos hidrolíticos y tensioactivos como especies porógenas. La carga del carvacrol en MCM-41 se realizó por impregnación y posterior adsorción de vapor en un vial herméticamente cerrado incubado a 40 º C durante 24 horas. Se formularon y prepararon pinturas base acuosa en las que se incorporó como aditivo, 2% p/p, microesferas impregnadas con carvacrol (Pintura A), una pintura con microesferas sin impregnar (Pintura B), una pintura con carvacrol 2% p/p en forma libre (Pintura C) y otra pintura control sin microesferas y sin carvacrol (Pintura D). Se pintaron paneles de yeso y se realizaron ensayos de bioresistencia de la película seca frente al hongo Aspergillus sp. Al finalizar el ensayo se realizó una inspección visual y observaciones mediante microscopia electrónica de barrido (MEB). Los resultados mostraron que los paneles con la Pintura C y D se encontraban cubiertos con crecimiento fúngico. El porcentaje de cobertura fue alrededor de un 30 a 70% para la pintura C y un porcentaje mayor a 70% para la pintura D. Las pinturas A y B no presentaron crecimiento a simple vista. Las observaciones en MEB mostraron diferencias entre estas dos últimas, exponiendo crecimiento en el caso de la Pintura B. Estos resultados indican que la incorporación de las microesferas de por sí tienen un efecto biocida, debido muy probablemente al tensioactivo utilizado para su síntesis. A su vez, las micrografías MEB revelan que la impregnación del carvacrol en la sílice mejora aún más el efecto biocida de las microesferas. Este estudio demuestra que las microesferas de sílica mesoporosa MCM-41 podrían ser una alternativa como soporte para la carga del carvacrol en pinturas con actividad antifúngica.
Concerns about ozone layer, contamination, fossils resources and health, has banned or restricted... more Concerns about ozone layer, contamination, fossils resources and health, has banned or restricted the use of traditionally organic solvents in paints. As a consequence, new resins that employed water as main solvent are being studied. Among these resins, alkyds are the most studied one as they can also be synthesised from natural vegetable sources, making them more acceptable. The aim of this paper was to study the anticorrosive behaviour of alkyd / polysaccharide paints containing zinc phosphate or zinc aluminum phosphate as main pigment and their performance against fungal growth. Two different PVC (pigment volume concentration) were studied. Painted panels were studied by exposition to salt spray and humidity chambers, where rusting and blistering degrees were evaluated, and by electrochemical tests (corrosion potential measurements, ionic resistances determination, linear polarization curves and polarization resistances determination). Results showed that these type of paints can be used to protect steel and that the type of pigment and the PVC are important to the protection. Besides, good selection of both also prevents fungi growth in a high humid environment.
El presente trabajo tuvo como objetivo la formulación y elaboración de pinturas alquídicas con nu... more El presente trabajo tuvo como objetivo la formulación y elaboración de pinturas alquídicas con nuevos pigmentos anticorrosivos a base de mordenita intercambiada, amigables con el medio ambiente. La caracterización electroquímica del acero pintado se llevó a cabo por: medidas de conductividad, ensayos de polarización lineal y medidas del potencial de corrosión. La película de pintura ensayada en cada caso fue removida y la superficie fue analizada mediante microscopía electrónica de barrido y análisis de energía dispersiva por rayos X. Los resultados muestran que los nuevos pigmentos incorporados a la pintura proporcionan propiedades anticorrosivas aceptables teniendo en cuenta su bajo impacto ambiental y la utilización de un recurso natural de bajo costo.
Purpose This paper aims to study five vegetables extracts as possible additives to control bacter... more Purpose This paper aims to study five vegetables extracts as possible additives to control bacterial growth on indoor waterborne paints. The extracts were obtained from the weeds Raphanus sativus, Rapistrum rugosum, Sinapis arvensis, Nicotiana longiflora and Dipsacus fullonum, used in traditional medicine as antimicrobial compounds. Design/methodology/approach Weeds extracts were characterized by Fourier transform infrared spectroscopy and UV–Vis spectrophotometry. Their antibacterial activity against Escherichia coli and Staphylococcus aureus was also determined. Afterward, selected extracts were incorporated in waterborne paint formulations. The paints’ antimicrobial activity was assessed against S. aureus, monitoring biofilm formation by environmental scanning electron microscopy. Findings As a general rule, results showed that tested paints were efficient in inhibiting biofilm formation, especially that formulated with Nicotiana longiflora. Practical implications The tested pain...
One of the most inexpensive and effective method to protect steel against corrosion is paints con... more One of the most inexpensive and effective method to protect steel against corrosion is paints containing active pigments. The traditional way to test these coatings performance is by accelerated tests (exposition to salt spray and/or humidity chambers) and electrochemical tests (corrosion potential, ionic resistance and electrochemical impedance spectroscopy). However, these tests give incomplete information if the results are not correlated to outdoor or service tests. The aim of this work was to evaluate water-borne epoxy anticorrosion paints containing different commercial phosphate pigments. The paints were exposed to a semi-industrial atmosphere for 7 years. Electrochemical tests and accelerated assays were also done in order to find a correlation between laboratory and service tests. The results obtained showed no correlation between those from pigment suspensions and those from painted panels, as it seemed that paint performance is highly dependent on the resin. The pigments zinc iron phosphate and zinc aluminium phosphate performed poorly in pigment suspensions. However, the coatings containing them exhibited the highest ionic resistance, the lowest film capacitance and gave the better results in outdoor tests. Results in outdoor exposure tests correlated with those from impedance measurements.
Fungal growth in damp surfaces of water-damaged buildings is an increasing problem around the wor... more Fungal growth in damp surfaces of water-damaged buildings is an increasing problem around the world, which has adverse effects on both people's health and buildings. By bio-deterioration, fungi can growth in indoor environments and generate materials losses in addition to health problems. Therefore, antifungal coatings must be developed to avoid these problems. Silica is used as supporting additive in coatings, such as the waterborne paints and, on the other hand, the addition of Ag nanoparticles into different materials is being widely studied for its effective antimicrobial properties. The aim of this work was to evaluate the bio-resistance to fungal growth on waterborne coatings containing siliceous additives, by accelerated four-week agar plate assay. The additives were synthesized by the sol-gel method and characterized by potentiometric titration and transmission electron microscopy (TEM). In addition, the paints were observed by scanning electron microscopy (SEM) at the end of the test. To carry out the bioresistance assay, Chaetomium globosum and Alternaria alternata fungi were used. After 4 weeks of assay, paints prepared with the silver-additives were the most efficient inhibiting the growth of both fungi. These paints, after their exposure for 6 months, in an internal environment with sunlight incidence, kept the antifungal activity against Chaetomium globosum and showed a higher activity against Alternaria alternata.
There are nanotechnology-based materials that can be used as antimicrobial additives in different... more There are nanotechnology-based materials that can be used as antimicrobial additives in different applications such as water-borne paints. Antimicrobial paints are important tool in order to avoid indoor biological colonization and therefore prevent paint bio-deterioration and health problems in people and pets. These paints would have application in kitchens, bathrooms and hospitals. The present study evaluated the incorporation of silver (of two different sizes), copper and zinc oxide nanoparticles in indoor waterborne paints and the bio-resistance imparted by them. The antifungal activity of nanoparticles is a less studied topic in relation to the antibacterial activity but is no less important from the environmental point of view. Molds that grow in indoor environments contribute significantly with bioaerosol formation and therefore on air contamination and human health deterioration. In this sense, this research evaluated the nanoparticles' antifungal activity using previously isolated fungi, Chaetomium globosum and Alternaria alternata, on solid medium. Then, the bio-resistance of acrylic paints, with nanoparticles incorporated, was evaluated in Petri dishes and observations were made using scanning electron microscopy. The better results were obtained with the paint that contained silver with the smaller size (10 nm).
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Papers by Cecilia Deyá