Washington Luiz Esteves Magalhães | Universidade Federal do Paraná (original) (raw)
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Papers by Washington Luiz Esteves Magalhães
A madeira é composta principalmente por polissacarídeos de celulose (de 40% a 60% da biomassa sec... more A madeira é composta principalmente por polissacarídeos de celulose (de 40% a 60% da biomassa seca) e hemicelulose (de 20% a 40%) e pela lignina (de 10% a 25%), um polímero polifenólico que proporciona a força estrutural para as plantas (HAMELINCK et al., 2005). Tecnologias para produzir biocombustíveis (como etanol, butanol ou vários hidrocarbonetos) e produtos de química verde provenientes de materiais lignocelulósicos são experiências com avanços significativos no esforço para satisfazer as necessidades de energia global e de substâncias químicas. Converter celulose em etanol envolve dois passos principais: quebrar as longas cadeias das moléculas de celulose em açúcares e fermentá-los para etanol. Para a determinação do potencial de formação de açúcares redutores a partir de amostras de madeira, duas etapas são requeridas: a hidrólise e a quantificação da concentração destes açúcares. A importância da otimização na etapa de hidrólise da madeira busca viabilizar que a celulose e h...
Polímeros, 2013
ABSTRACT Compósitos de resina Poliuretana (PU) derivada de óleo de mamona e partículas de bambu (... more ABSTRACT Compósitos de resina Poliuretana (PU) derivada de óleo de mamona e partículas de bambu (Dendrocalamus giganteus) foram preparados com 10, 15 e 20% em peso de PU pelo processo de prensagem. O objetivo do presente estudo foi criar uma solução para aproveitar resíduos da manufatura do bambu, minimizando impactos negativos ao meio ambiente, adicionando-lhe uma resina que não contém compostos orgânicos voláteis (COV). A sua caracterização foi feita através de análises físicas e termogravimetria. A associação de PU com partículas de bambu produziu efeitos esperados como a diminuição no teor de umidade, inchamento e absorção de água com o aumento do percentual de PU. Nos ensaios de dureza Shore D obteve-se um aumento gradual da rigidez superficial com o acréscimo em percentual de resina PU.
Surface and Coatings Technology, 2002
Cold plasmas were produced by electrical glow discharges in a gas medium at reduced pressure and ... more Cold plasmas were produced by electrical glow discharges in a gas medium at reduced pressure and at low frequency. The precursor gases used were ethylene, acetylene, butene-1, and vapor of vinyl acetate. The treatment caused the solid softwood surface to become hydrophobic; ...
Journal of Applied Polymer Science, 2004
Caribbean pine impregnated by the full cell treatment schedule with styrene, furfuryl alcohol (FF... more Caribbean pine impregnated by the full cell treatment schedule with styrene, furfuryl alcohol (FFA), and styrene-FFA monomers was cured for 48 h at 100°C. Styrene did not penetrate inside the wood cell wall; instead, it adhered on the cell wall surfaces and fill cell lumens. The volume contraction during the formation of polystyrene causes the volume contraction of the wood sample. The permanent volumetric swelling is attained only for samples treated with FFA, which is caused by cell wall impregnation. The dimensional stability of the treated wood samples is evaluated with the antiswell efficiency coefficient (ASE). The water repellency is expressed as the water-repellent effectiveness (WRE). Treatment with styrene improves the water repellence, whereas a double treatment increases the dimensional stability. Lixiviation slightly affects the ASE and WRE coefficients. The treatments improve the Shore D hardness in comparison to untreated wood.
Holzforschung, 2000
Mahogany is one of the most valuable woods and was widely used until it was included in Appendix ... more Mahogany is one of the most valuable woods and was widely used until it was included in Appendix II of the Convention on International Trade in Endangered Species as endangered species. Mahogany wood sometimes is traded under different names. Also, some similar woods belonging to the Meliaceae family are traded as ''mahogany'' or as being of a ''mahogany pattern''. To investigate the feasibility of the use of near infrared spectroscopy for wood discrimination, the mahogany (Swietenia macrophylla King.), andiroba or crabwood (Carapa guianensis Aubl.), cedar (Cedrela odorata L.), and curupixá (Micropholis melinoniana Pierre) woods were examined. Four discrimination models based on partial least squares-discriminant analysis were developed based on a calibration set composed of 88 samples and a test set with 44 samples. Each model corresponds to the discrimination of a wood species from the others. Optimization of the model was performed by means of the OPUS ᭨ software followed by statistical analysis software (Matlab ᭨ ). The observed root mean square errors of predictions were 0.14, 0.09, 0.12, and 0.06 for discriminations of mahogany, cedar, andiroba, and curupixá, respectively. The separations of the species obtained based on the difference in the predicted values was at least 0.38. This makes it possible to perform safe discriminations with a very low probability of misclassifying a sample. This method can be considered accurate and fast.
A madeira é composta principalmente por polissacarídeos de celulose (de 40% a 60% da biomassa sec... more A madeira é composta principalmente por polissacarídeos de celulose (de 40% a 60% da biomassa seca) e hemicelulose (de 20% a 40%) e pela lignina (de 10% a 25%), um polímero polifenólico que proporciona a força estrutural para as plantas (HAMELINCK et al., 2005). Tecnologias para produzir biocombustíveis (como etanol, butanol ou vários hidrocarbonetos) e produtos de química verde provenientes de materiais lignocelulósicos são experiências com avanços significativos no esforço para satisfazer as necessidades de energia global e de substâncias químicas. Converter celulose em etanol envolve dois passos principais: quebrar as longas cadeias das moléculas de celulose em açúcares e fermentá-los para etanol. Para a determinação do potencial de formação de açúcares redutores a partir de amostras de madeira, duas etapas são requeridas: a hidrólise e a quantificação da concentração destes açúcares. A importância da otimização na etapa de hidrólise da madeira busca viabilizar que a celulose e h...
Polímeros, 2013
ABSTRACT Compósitos de resina Poliuretana (PU) derivada de óleo de mamona e partículas de bambu (... more ABSTRACT Compósitos de resina Poliuretana (PU) derivada de óleo de mamona e partículas de bambu (Dendrocalamus giganteus) foram preparados com 10, 15 e 20% em peso de PU pelo processo de prensagem. O objetivo do presente estudo foi criar uma solução para aproveitar resíduos da manufatura do bambu, minimizando impactos negativos ao meio ambiente, adicionando-lhe uma resina que não contém compostos orgânicos voláteis (COV). A sua caracterização foi feita através de análises físicas e termogravimetria. A associação de PU com partículas de bambu produziu efeitos esperados como a diminuição no teor de umidade, inchamento e absorção de água com o aumento do percentual de PU. Nos ensaios de dureza Shore D obteve-se um aumento gradual da rigidez superficial com o acréscimo em percentual de resina PU.
Surface and Coatings Technology, 2002
Cold plasmas were produced by electrical glow discharges in a gas medium at reduced pressure and ... more Cold plasmas were produced by electrical glow discharges in a gas medium at reduced pressure and at low frequency. The precursor gases used were ethylene, acetylene, butene-1, and vapor of vinyl acetate. The treatment caused the solid softwood surface to become hydrophobic; ...
Journal of Applied Polymer Science, 2004
Caribbean pine impregnated by the full cell treatment schedule with styrene, furfuryl alcohol (FF... more Caribbean pine impregnated by the full cell treatment schedule with styrene, furfuryl alcohol (FFA), and styrene-FFA monomers was cured for 48 h at 100°C. Styrene did not penetrate inside the wood cell wall; instead, it adhered on the cell wall surfaces and fill cell lumens. The volume contraction during the formation of polystyrene causes the volume contraction of the wood sample. The permanent volumetric swelling is attained only for samples treated with FFA, which is caused by cell wall impregnation. The dimensional stability of the treated wood samples is evaluated with the antiswell efficiency coefficient (ASE). The water repellency is expressed as the water-repellent effectiveness (WRE). Treatment with styrene improves the water repellence, whereas a double treatment increases the dimensional stability. Lixiviation slightly affects the ASE and WRE coefficients. The treatments improve the Shore D hardness in comparison to untreated wood.
Holzforschung, 2000
Mahogany is one of the most valuable woods and was widely used until it was included in Appendix ... more Mahogany is one of the most valuable woods and was widely used until it was included in Appendix II of the Convention on International Trade in Endangered Species as endangered species. Mahogany wood sometimes is traded under different names. Also, some similar woods belonging to the Meliaceae family are traded as ''mahogany'' or as being of a ''mahogany pattern''. To investigate the feasibility of the use of near infrared spectroscopy for wood discrimination, the mahogany (Swietenia macrophylla King.), andiroba or crabwood (Carapa guianensis Aubl.), cedar (Cedrela odorata L.), and curupixá (Micropholis melinoniana Pierre) woods were examined. Four discrimination models based on partial least squares-discriminant analysis were developed based on a calibration set composed of 88 samples and a test set with 44 samples. Each model corresponds to the discrimination of a wood species from the others. Optimization of the model was performed by means of the OPUS ᭨ software followed by statistical analysis software (Matlab ᭨ ). The observed root mean square errors of predictions were 0.14, 0.09, 0.12, and 0.06 for discriminations of mahogany, cedar, andiroba, and curupixá, respectively. The separations of the species obtained based on the difference in the predicted values was at least 0.38. This makes it possible to perform safe discriminations with a very low probability of misclassifying a sample. This method can be considered accurate and fast.