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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Caracterização química multitécnicas de tintas artísticas brasileiras, um estudo de caso / Multi-technique chemical characterization of Brazilian artistic paints, a case study

Redigolo, Marcelo Miyada 30 November 2018 (has links)
O presente trabalho apresenta a caracterização química de tintas artísticas brasileiras. Diferente de outras matrizes, os materiais de arte fabricados no Brasil não apresentam informações na literatura que auxiliem em sua conservação e restauração. Amostras de tintas acrílicas e a óleo, nacionais e importadas, foram analisadas pelas técnicas espectroscópicas Raman e infravermelho por transformada de Fourier (FTIR), pirólise acoplada a cromatografia a gás e espectrometria de massas (Py-GC/MS) e microscopia eletrônica de varredura acoplada a espectrometria de fluorescência de raios X (SEM-EDS). Resultados de análise indicam que tintas acrílicas brasileiras são compostas por poliestireno (PS), diferentemente das importadas, compostas por polimetilmetacrilato (PMMA). Enquanto as tintas a óleo apresentam composição semelhante (óleo de linhaça), brasileiras e importadas. Duas pinturas do acervo da Pinacoteca do Estado de São Paulo foram selecionadas para um estudo de caso. As obras apresentam a formação de exsudatos em sua superfície, o que demanda a caracterização química como etapa anterior ao desenvolvimento de uma metodologia de restauração. A obra \"Mandala da saudade\", de Sara Goldman-Belz, é composta por tinta spray (alkyd) e a obra \"Três pessoas\", de Marina Saleme, por tinta a óleo. Os resultados de análise apresentam um primeiro passo no estabelecimento de um banco de dados de materiais artísticos fabricados no Brasil para fins de restauração e perícia criminal de obras de arte. / The current work presents the chemical characterization of Brazilian artistic paints. Differently from other matrices, art materials produced in Brazil lack for information in literature that help in their conservation and restoration. Acrylic and oil paint samples, Brazilian and imported, were analyzed by Raman and Fourier transform infrared (FTIR) spectroscopies, pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) and scanning electron microscopy coupled with x-ray fluorescence spectrometry (SEM-EDS). Results indicate that Brazilian acrylic paints are composed of polystyrene (PS), differently from imported ones, composed of polymethyl methacrylate (PMMA). Whereas, oil paints present similar composition (linseed oil), Brazilian and imported. Two paintings from the collection of Pinacoteca do Estado de São Paulo were selected for a case study. Both works of art present formation of exudates on their surface, which demands chemical characterization as a previous step to the development of a restoration methodology. The painting \"Mandala da saudade\", by Sara Goldman-Belz, is composed of spray paint (alkyd) and the painting \"Três pessoas\", by Marina Saleme, is composed of oil paint. Results presented in this thesis are the first step towards the establishment of a database for artistic materials produced in Brazil for purposes of art restoration and forensic science.
92

Comparação dos impactos ambientais de formulações de tintas com a aplicação da avaliação do ciclo de vida. / Comparison of paints formulations environmental impacts with life cicle assessment application.

Gláucia Santos Buchmann 23 January 2018 (has links)
Com a crescente demanda do mercado de tintas por produtos mais sustentáveis, toda a cadeia produtiva tem se movimentado para oferecer soluções neste âmbito. Para contemplar o pilar ambiental da sustentabilidade, a redução de Compostos Orgânicos Voláteis (VOC), de alquilfenol etoxilados (APEO) e a substituição de matérias-primas de origem fóssil por vegetal nas formulações de tintas são algumas das práticas em expansão neste setor. No presente estudo, os perfis de impactos ambientais de duas tintas imobiliárias base água foram comparados aplicando-se a metodologia de Avaliação do Ciclo de Vida (ACV) (ABNT NBR ISO 14040 e 14044). Primeiramente, foram desenvolvidas duas fórmulas genéricas não comerciais de tinta standard (ABNT NBR 15079): \"Tinta A\" com matérias-primas de uso convencional e \"Tinta B\" com algumas matérias-primas alternativas, que hipoteticamente contribuiriam com um melhor desempenho ambiental do produto final. Em seguida, ambas fórmulas foram reproduzidas em laboratório, as amostras das tintas foram submetidas a testes de desempenho técnico e com os dados obtidos determinou-se os fluxos de referência para cumprir a unidade funcional definida por cobrir 36 m2 de parede de alvenaria interior por um período mínimo de 4 anos (ABN NBR 15575-1). A ACV tem quatro fases: objetivo e definição do escopo, análise de inventário, avaliação do impacto ambiental e interpretação. Com os objetivos e escopo do estudo definidos, foi realizada uma abrangente coleta de dados, majoritariamente secundários, para possibilitar a Análise de Inventário (ICV). Posteriormente, o ciclo de vida das tintas foi modelado e analisado no software SimaPro 8.2 e na fase de Avaliação de Impactos do Ciclo de Vida (AICV) foi selecionado o método ReCiPe Midpoint (H) v.1.12. Para as sete categorias de impacto analisadas, a \"Tinta B\" apresentou perfil de impactos ambientais reduzido em relação a \"Tinta A\": Mudanças Climáticas (-18,6%), Formação de Oxidantes Fotoquímicos (-19%), Toxicidade Humana (-17,7%), Ecotoxicidade (-30,5%), Depleção de Recursos Fósseis (18,8%), Depleção de Recursos Minerais (-21,4%) e Depleção de Recursos Hídricos (-18,7%). Os resultados do estudo, reforçam a importância da ACV como uma ferramenta eficaz para mensurar o desempenho ambiental de tintas. No entanto, a falta de disponibilidade de dados primários dos processos de toda a cadeia produtiva de tintas dificulta a execução de estudos e compromete a precisão dos resultados. Destaca-se ainda, que a perspectiva do ciclo de vida de produtos e processos foi incluída como requisito da nova versão da norma ISO 14001, que é do interesse de toda a cadeia de valor, portanto, vale considerar a aplicação da ACV na indústria de tintas. / The demand for sustainable products in the paint market has been steadily growing and is pushing the whole production chain to offer solutions following this scenario. The reduction of Volatile Organic Compounds (VOC), alkylphenol ethoxylates (APEO) and the substitution of raw materials of fossil origin by vegetable in the formulations of paints are some of the practices increasing among this sector to meet the environmental sustainability pillar. In the present study, the environmental impact profiles of two water-based architectural paints were compared applying the Life Cycle Assessment (LCA) methodology (ABNT NBR ISO 14040 and 14044). Firstly, two generic non-commercial formulas of standard paint (ABNT NBR 15079) were developed: \"Paint-A\" with conventional raw materials and \"Paint- B\" containing some alternative raw materials, which would hypothetically contribute to a better environmental performance of the final product. Then both formulas were reproduced in the laboratory and the samples of the paints were submitted to technical performance tests. With the data obtained, the reference flows were determined to fulfill the functional unit defined by covering 36 m2 of interior masonry wall by a minimum period of 4 years (ABN NBR 15575-1). The LCA has four phases: goal and scope definition, inventory analysis, environmental impact assessment and interpretation. After goal and scope definition, a comprehensive data collection was carried to enable the Inventory Analysis (LCI). Afterwards, the life cycle of the paints was modeled and analyzed in the SimaPro 8.2 software and in the Life Cycle Impact Assessment (LCIA) phase the ReCiPe Midpoint (H) v.1.12 method was selected. Within seven impact categories analyzed, \"Paint-B\" presented a reduced environmental impact profile compared to \"Paint-A\": Climate Change (-18.6%), Photochemical Oxidants Formation (-19%), Human Toxicity (-18.5%), Ecotoxicity (-30.5%), Fossil Resources Depletion (18.8%), Mineral Resources Depletion (-21.4%) and Water Resources Depletion (-18.7%). The results of the study strengthen the importance of LCA as an effective tool for measuring the environmental performance of paints. However, the lack of availability of primary process data throughout the paint production chain makes it difficult to carry out studies and compromises the accuracy of the results. It is also relevant to highlight that the product and process lifecycle perspective was included as a requirement of the new version of the ISO 14001 standard, which is a matter of concern to the entire value chain, so it is worth considering the application of LCA in the paints industry.
93

Models for estimating VOC emissions from latex paints

Ramirez, Leonardo Andres 01 June 2010 (has links)
Many models for predicting volatile organic compounds (VOC) emissions from latex paints have been developed. Earlier models were developed for solvent-borne paints, particularly since these paints evaporate rapidly and can be modeled with simple decay models. However, paint has changed in the past fifty years, and a transition has been made towards water-borne paints. These paints were introduced for indoor applications because they lacked the health hazards and odors of their solvent-borne counterparts. These paints also have organic modifiers, therefore it is very important to predict how these modifiers evaporate from the coated material. New mechanistic models that can predict slow emitting VOCs over long periods of time are not available. An improved ability to predict VOC emissions from latex paints could lead to improved understanding, better policy-making and promotion of environmental regulations that benefit both the consumer and producers of architectural coatings. This research improves on existing models used to estimate VOC emissions off-gassed from latex paints. The developed two layer model (2LM) has a layer for paint and substrate material, and accounts for mass transfer at the paint layer, and diffusion transport between paint and material layers. The model provides a semi-mechanistic way to predict paint drying and VOC emissions from coatings on a variety of substrates. The model only requires the estimation of one parameter (the paint layer diffusion coefficient), unlike other models available that require multiple parameter estimations. This model is robust in the sense that it could be used to predict VOC emissions from paint, as well as predicting the variation of the internal VOC distribution on both paint and material layers with time. The model was tested and validated with empirical data collected from previous controlled chamber experiments, and also with data collected from short evaporation experiments. Critical paint components like polymer and pigment composition and its relation to VOC fate and transport after paint application, both initially and over long periods of time, were explored. Modeling results indicated that the diffusion coefficient of 2,2,4-trimethyl-1,3-pentadediol monoisobutyrate (TMPD-MIB) in the paint layer does not depend on the thickness of the wet paint film, but it depends on the pigment volume concentration (PVC) of the paint. Additionally, a constant diffusion coefficient used in the 2LM was successful for modeling emissions of TMPD-MIB from low pigment volume concentration (LPVC) paints, but it failed to capture the physical mechanisms of the drying film for high pigment volume concentration (HPVC) paints. A major finding from this research was that a detailed gas phase analysis of mass transport for TMPD-MIB would have negligible effects on the predicted overall evaporation rate. Therefore, the entire wet and dry emissions processes are likely dominated by diffusion processes. / text
94

Isotopic Evidence for the Provenance of Turquoise, Mineral Paints, and Metals in the Southwestern United States

Thibodeau, Alyson Marie January 2012 (has links)
Lead and strontium isotopes are two powerful tracers that can be used to identify or constrain the provenance of a wide range of archaeological materials, but these two isotopic tracers have been rarely employed to infer the sources of artifacts in the southwestern USA. This dissertation contains four studies that demonstrate how these isotopic systems can address questions about the sources of three types of archaeological materials found in this region: turquoise, lead-based glaze-paints, and metals. The analysis of 116 samples of turquoise from 17 deposits in the southwestern USA reveals that lead and strontium isotopes are robust and sensitive tracers of turquoise at multiple scales. Isotopic variation among turquoise deposits correlates with broad regional differences in the geologic and tectonic setting of the rocks and mineral deposits which host turquoise mineralization. Many turquoise deposits also have unique isotopic signatures that will enable insights into ancient patterns of turquoise acquisition at regional and local levels. To show the utility of these tracers when applied to archaeological turquoise, I use lead and strontium isotopic measurements to establish that the Silver Bell Mountains are the likely source turquoise found at the Redtail site in the Tucson Basin, Arizona, USA. This dissertation also contains new, high-precision isotopic ratios of lead ores (galena and cerrusite) from four mining districts in New Mexico, including the Cerrillos Hills. All districts studied are possible sources of lead used by Pueblo IV communities to produce glaze paints. These new measurements, made by multiple-collector ICP-MS, define the isotopic composition of the ore deposits with greater precision and accuracy than achieved in previous studies, indicating an opportunity to improve interpretations about the provenance of lead in glaze paints. Lead isotopes are also found to be useful tools for identifying lead and copper metal associated with the 1540-1542 Vázquez de Coronado expedition. Lead shot and copper crossbow boltheads from two sites with archaeological evidence for the expedition's presence were determined to share similar or identical lead isotopic ratios. I propose this specific isotopic "fingerprint" can be used to identify other artifacts belonging to the expedition in the Southwest.
95

Use and environmental impact of antifouling paints in the Baltic Sea

Bighiu, Maria Alexandra January 2017 (has links)
Biocide-based antifouling (AF) paints are the most common method for preventing biofouling, i.e. the growth of algae, barnacles and other organisms on boat hulls. AF paints for leisure boats are predominantly based on copper (Cu) as the main biocide, with zinc (Zn) present as a pigment and stabilizer. Both metals are released from the paint matrix into the water column, leading to contamination of marinas which typically have only limited water exchange. Thus, the aim of this PhD thesis was to describe the use of AF paints in different regions in Sweden, as well as the associated environmental consequences with regard to contamination of the environment and toxicity to non-target aquatic snails. Using a recently developed X-ray fluorescence application, high levels of Cu were detected on boats moored in freshwaters, despite a more than 20-year-old ban, as well as high levels of tin (Sn) on 10 % of the boats, indicating the presence of (old) tributyltin paints (TBT), which might pose an environmental risk and a health hazard for people performing the paint scraping (paper 1). In addition, very high levels of Cu and Zn were measured in the biofouling material collected from the boat hulls, and this is problematic because the biofouling is commonly disposed of on the soil in boatyards at the end of each season. No difference was found in the amount of biofouling on boats coated with Cu or biocide-free paints, which implies that Cu might be currently overused in areas of low salinity and low barnacle density (paper 2). This work also introduces the use of a new species for ecotoxicological field experiments, the snail Theodoxus fluviatilis. Chronic field experiments (paper 3) revealed 6-fold increases in snail mortality, negative growth and up to 67-fold decreased reproduction in marinas, compared to areas not impacted by boating (‘reference areas’). Moreover, a higher prevalence of snails with histopathological alterations (e.g. necrosis of gills, gonads, midgut gland and parasite infestation, among others) was observed in the marinas, compared to the reference areas (paper 4). Statistical modelling indicated that the majority of the toxic effects were best predicted by the metals, most likely originating from AF paints. The results presented in this thesis depict some important aspects of AF paint use in brackish water and highlight the necessity of implementing a suitable management practice for the heavily contaminated biofouling waste in order to minimize the risk to soils. In addition, the evidence of toxicity to snails in marinas can be used as a basis to increase the public understanding of the impact of recreational boating and encourage people to choose less toxic alternatives to AF paints. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>
96

Synthesis And Characterization Of Hyperbranched And Air Drying Fatty Acid Based Resins

Bat, Erhan 01 July 2005 (has links) (PDF)
There has been a considerable effort in the last years to decrease the amount of volatile organic compounds (VOCs) present in organic coatings. The risks to human health and environmental hazards associated with VOCs, governmental directives, and economic factors are the main driving forces behind this effort. One way of achieving less or no VOC containing coating systems is to produce low viscosity resins. Hyperbranched resins owing to their globular structure have low viscosities and are promising materials for decreasing the VOCs. In this research hyperbranched resins having properties close to alkyds were synthesized. Dipentaerythritol, which was used as the core was esterified with dimethylol propionic acid. The hyperbranched polyester was then esterified with the castor oil fatty acids (Castor FA). The hydroxyl group of the ricinoleic acid present in the castor FA was modified with different amounts of linseed oil fatty acids (Linseed FA) and benzoic acid. The chemical characterization of the resins was achieved by FTIR spectroscopy and the thermal properties were determined by DSC. Then, the physical and the mechanical tests were carried out. The resins containing the Castor FA only and 32.5 % Linseed FA in addition to the Castor FA had 24 and 68 Persoz hardness, respectively. The viscosity of the resins decreased from 17.3 Pa&amp / #61655 / s to 5.8 Pa&amp / #61655 / s as the amount of the Linseed FA was increased. The resins showed excellent adhesion, gloss, flexibility and formability.
97

Synthesis Of Oil Based Hyperbranched Resins And Their Modification With Melamine Formaldehyde Resins

Karakaya, Ceylan 01 August 2005 (has links) (PDF)
In this research hyperbranched resins containing fatty acid residues like alkyds were synthesized. Dipentaerythritol which has six hydroxyl groups was used as the core molecule, and it was transesterified with (i) castor oil, and (ii) a mixture of castor oil and linseed oil at 240&deg / C in the presence of sodium hydroxide as catalyst. The resulting molecule, in either case, was then esterified with dimethylol propionic acid at 140&deg / C in the presence of p-toluene sulfonic acid as catalyst. Melamine-formaldehyde resin was synthesized to be used with the synthesized hyperbranched resins, and it was successfully modified by all hyperbranched resins at a ratio of 3:1. FTIR spectroscopy was used to characterize the hyperbranched resins and the thermal properties were determined by DSC. DSC showed that the hyperbranched resins decomposed between 315-345&deg / C. The viscosity of the resin that was synthesized by using only castor oil was 3.0 Pa.s and by using 50% linseed oil it was 1.0 Pa.s. When reacted with dimethylol propionic acid, the former&rsquo / s viscosity increased to 7.0 Pa.s, and the second&rsquo / s viscosity increased to 3.7 Pa.s. The hyperbranched resins showed excellent adhesion, gloss, flexibility, and formability. The mixture of hyperbranched resin plus melamine-formaldehyde resin samples had higher hardness values but lower gloss, adhesion and bending resistance values than the hyperbranched resins, and they had good impact and abrasion resistances.
98

Síntese, caracterização e avaliação do potencial antimicrobiano de nanopartículas de prata em tintas e vernizes acrílicos à base d'água

Antunes, Fabiana Sedina January 2013 (has links)
Percebe-se um interesse da indústria de fabricação de tintas na utilização de nanopartículas de prata devido às suas propriedades antimicrobianas. Neste trabalho, objetivou-se sintetizar e caracterizar soluções coloidais de nanopartículas de prata para ser um potencial aditivo antimicrobiano em tintas acrílicas à base d’água. No processo experimental, as nanopartículas de prata foram preparadas pela redução de íons de prata por boroidreto de sódio e estabilizada, utilizando citrato trissódico dihidrado. As caraterizações das nanopartículas de prata foram realizadas por espectroscopia de UV-Visível, microscopia eletrônica de transmissão e antibiograma contra bactérias Gram-positivas e Gram-negativas. Os espectros de UV-vis foram muito similares para as NPs Ag 18 ppm e para as NPs Ag 1000 ppm com os espectros de absorção na região de 400nm, que indica a presença de NPs Ag com forma esférica. Pela microscopia eletrônica de transmissão confirmou-se a presença das NPs Ag na forma esférica e observou-se a diferença de tamanho de partículas, sendo que para as NPs Ag a média foi de 7,32 nm e para NPs Ag 1000 ppm foi de 15,2 nm. O antibiograma demonstrou que as NPs Ag 18 ppm e de 1000 ppm apresentam atividade antibacteriana contra a bactéria Gram-negativa Escherichia coli e contra a bactéria Gram-positiva Staphylococcus aureus. No filme de tinta aplicado, avaliou-se a diferença de cor da tinta branca após a adição das NPs Ag, utilizando um espectrofotômetro e a perda de brilho após o ensaio de intemperismo acelerado sob radiação UV-B. Foi verificado que as NPs Ag não têm efeito sobre a perda de brilho do filme de tinta, porém induzem ao amarelamento do mesmo. Os resultados foram positivos para o ensaio de resistência a bactérias conforme a norma JIS Z 2801:2000 somente para as amostras de tinta acrílica à base d’água e verniz acrílico à base d’água com 100 ppm de NPs Ag. Para as amostras de tintas e vernizes com 3,6 ppm e 30 ppm de NPs Ag não houve efeito inibitório. Para o ensaio de resistência a fungos, segundo a norma ABNT NBR 14941, as tintas não apresentaram efeito inibitório satisfatório. / There is a particular interest of the paint manufacturing industry by using silver nanoparticles due its antimicrobial properties. This study has as objective to synthesize and characterize silver nanoparticles colloidal solutions as a potential antimicrobial additive in water-based acrylic paints. In the experimental process, the silver nanoparticles were prepared by reduction the silver ions by sodium borohydride and used trisodium citrate dihydrate as stabilizing agent. The characterizations of the silver nanoparticles were realized by spectroscopy in the infrared region, transmission electronic microscopy and Gram positive and Gram negative antibiograms. The UV-vis results were similar for the NPs Ag 18 ppm and NPs Ag 1000 ppm samples with the absorption spectra in the range of 400nm, which indicates the presence of de NPs Ag in a spherical format. By the transmission electron microscopy it was noted the presence of NPs Ag in a spherical format and differences in the particles sizes for NPs Ag (media of 7.32 nm) and for NPs Ag 1000 ppm (media of 15.2 nm) samples. The antibiogram test demonstrates that the 18 ppm and the 1000 ppm NPs Ag showed antibacterial activity against the Gram negative bacterium Escherichia coli and against the Gram positive bacteria Staphylococcus aureus. In the paint film, it was avaluated the difference of the white color after the incorporation of the NPs Ag using a spectrophotometer and the brightness lost after the UV-B accelerated weathering testing. It was noted that the NPs Ag had no effect in the brightness lost of the paint film; however inducing to the yellowing of the same. The results were positive for the bacterial resistances according to JIS Z 2801:2000 only for the water-based acrylic paints and varnish containing 100 ppm of NPs Ag. For the samples with 3,6 ppm and 30ppm it was not noted an inhibitory effect. Finally, for the fungal resistance according to ABNT NBR 14941 the paints do not showed satisfactory inhibitory effect.
99

Estudo do comportamento de tintas para a aplicacao em instalacoes nucleares

YAMASHITA, TOSHIYUKI 09 October 2014 (has links)
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100

Investigacao do tratamento com moleculas auto-organizaveis para substituicao da cromatizacao da liga AA5052H32 no preparo da superficie previo a pintura

REIS, FERNANDO M. dos 09 October 2014 (has links)
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