The impregnation of low-molecular-weight monomers prior to polymerize them inside the wood may be an efficient way to improve some important wood properties. This work aimed to determine some ...technological properties of wood-based composites (WPC) produced by in situ polymerization, using a pine wood (Pinus elliottii Engelm.) impregnated with methyl methacrylate (MMA). For that, samples taken from both juvenile (JV) and mature (MT) pine woods were treated with MMA. Physical, mechanical, chemical, thermal and morphological features were evaluated. MMA-treated woods from both juvenile and mature woods presented superior physical, mechanical (expect brittleness) and thermal properties when compared to pristine ones. The infrared spectra and morphological analysis by scanning electron microscopy (SEM) confirmed the presence of the monomer inside the pine wood. The juvenile wood presented higher treatability than the mature wood, due to its higher content of intra- and inter-cellular spaces.
This study aimed to evaluate the variations in thermal and chemical characteristics of juvenile Eucalyptus grandis wood submitted to a deterioration test by Nasutitermes termites. For this purpose, a ...biodeterioration test with termites was conducted according to ASTM D 3345 (2008), in which, after the end of the period corresponding to the test (40 days), we evaluated the mass loss, chemical composition and thermal stability of the main components of the deteriorated wood samples and those belonging to the control group. We found that deterioration due to exposure of the samples to Nasutitermes sp. termites caused a mass loss of 66,88% for wood with a density at 12% moisture content of 412 kg/m3. The quantitative chemical composition showed a reduction in the contents of cellulose, hemicellulose and lignin. Analysis of the variations of the organic functional groups related to the chemical composition of the wood by Fourier Transform Infrared Spectroscopy and relative intensity of the spectral bands also showed reductions, demonstrating homogeneous deterioration of the main components of the deteriorated woods. The thermal stability showed an increase in deteriorated wood for most of the temperature ranges, mainly for those that corresponded to losses in moisture and volatiles (25 °C - 100 °C), hemicelluloses (240 °C - 300 °C), celluloses, and together with initial lignin degradation (310 °C to 400 °C), possibly due to the removal of cellulose and hemicellulose, as well as the deposition of substances expelled by the termites in the cell wall. From the results, we conclude that the termites do not have specificity regarding the chemical component and that the deterioration caused variations in the chemical composition of the wood, whereas the opposite was observed for thermal stability, which presented an increase in most of the temperatures ranges for the deteriorated woods compared to the control group.
Organic substances have been used for different wood treatments, especially impregnation procedures, aiming at improve certain wood properties. The objective of this study was to evaluate dimensional ...stability and colourimetric features for a mature pine wood (Pinus elliottii) impregnated by vacuum-pressure process with variable concentrations (10 wt%, 25 wt% and 50 wt%) of furfuryl alcohol and using ethyl alcohol as catalyst. The wood samples were characterized for:linear shrinkages, linear swellings, shrinkage anisotropy, swelling anisotropy, as well as colorimetric parameters (following the CIELab method). The impregnation with furfuryl alcohol increased the dimensional stability of the studied pine wood and the treatment with a concentration of 50 wt% stood out based on these results. Regarding the colourpatterns, there were changes in the final colorimetric appearances of the treated wood samples, which acquired darker and reddish colours when compared to the pristine group. The treatment with 50 wt% of furfuryl alcohol also was responsible for the highest colour change and, because of that, may be indicated for solid wood products with high added value.
This article aimed at thermally treating and charactering the Eucalyptus grandis wood under three different temperatures.
For this, pristine eucalypt samples were treated by heating in a laboratory ...oven at 160 °C, 200 °C and 240 °C, always for 2 h. Treatment parameters (based on weight percentage loss and specific gravity), as well as mechanical (by hardness tests), chemical (by infrared spectroscopy), thermal (by thermogravimetry), and colorimetric (by CIELab method) features were evaluated. Compared to the pristine ones, the treated woods have there was a drop in apparent density at 12 % and consecutively greater thermal stability which is probably related to a previous partial degradation of some major amorphous components (namely cellulose, hemicellulose and lignin), as suggested by the treatment parameters and infrared spectra. Besides of that, the higher the temperature treatment, the higher the loss in surface hardness and the higher the colour darkening. KCI Citation Count: 4
Um dos processos que modificam as propriedades tecnológicas do papel é o refino, podendo este proporcionar mudanças intra e intermoleculares, o que acarreta aumento de sua resistência mecânica, ...variando de acordo com o tipo de fibra que se trabalha. Com isso, o objetivo deste estudo é avaliar os efeitos de diferentes graus de refino sobre as propriedades tecnológicas de papéis produzidos com fibras recicladas e virgens de celulose branqueada de Eucalyptus ssp. A produção e caracterização das propriedades tecnológicas foram feitas seguindo técnicas normativas onde verificou-se a influência na gramatura, espessura, densidade volume específico, Grau Schopper Reigler, resistência ao estouro, resistência a tração e elongamento. Ficou evidenciado que com o aumento do grau do refino, houve um aumento nas propriedades físicas e mecânicas, tanto dos papéis produzidos com fibra virgem como reciclada. Com o uso da correlação de Pearson pode-se constatar que determinadas propriedades possuem uma correlação significativa e diretamente proporcional a um nível de 95% de confiança. Pode-se concluir que a técnica do refinamento faz com que ocorra notoriamente uma melhora nas propriedades físicas e mecânicas de papéis produzidos com fibra virgem e reciclada, apesar do papel reciclado demostrar menores propriedades físicas resultou em melhores resultados em suas propriedades mecânicas com o aumento do grau de refino.
The objective of this study is to evaluate chemical characteristics, as well as antioxidant and antibacterial activities of organic compounds extracted from three Eucalyptus woods and Corymbia ...maculate wood using ethanol as a solvent. To obtain the ethanolic extracts, 15 g of a powdered wood sample was mixed with 150 mL of ethyl alcohol 99 % PA by constant mechanical stirring, which was further magnetically mixed at 60 ºC for 24 h. The extractives were analyzed by means of percent yield, Fourier-transform infrared spectrum, inhibitory index (measured after antimicrobial tests), antioxidant activity, and condensed tannins content. The Eucalyptus dunnii extract showed the highest percent yield. The infrared spectra of all the extractives presented similar profiles, with remarkable bands ascribed to the presence of lipophilic extracts, sterols, fatty acids, and other hydroxylated substances, such as carbohydrates and phenolic compounds. In all cases, the higher the concentration of the extractive was, the higher the antioxidant activity was. The antioxidant activity of Eucalyptus saligna extract stood out since overcame that of the positive control (ascorbic acid). Regarding the condensed tannins content, that extract from Eucalyptus grandis excelled
This article aimed at thermally treating and charactering the Eucalyptus grandis wood under three different temperatures. For this, pristine eucalypt samples were treated by heating in a laboratory ...oven at 160 °C, 200 °C and 240 °C, always for 2 h. Treatment parameters (based on weight percentage loss and specific gravity), as well as mechanical (by hardness tests), chemical (by infrared spectroscopy), thermal (by thermogravimetry), and colorimetric (by CIELab method) features were evaluated. Compared to the pristine ones, the treated woods have there was a drop in apparent density at 12 % and consecutively greater thermal stability which is probably related to a previous partial degradation of some major amorphous components (namely cellulose, hemicellulose and lignin), as suggested by the treatment parameters and infrared spectra. Besides of that, the higher the temperature treatment, the higher the loss in surface hardness and the higher the colour darkening.
RESUMO As madeiras apresentam propriedades tecnológicas distintas, por ser material orgânico e heterogêneo, sendo necessário uma avaliação para o uso adequado. Sendo assim, o objetivo deste trabalho ...foi a avaliação de propriedades tecnológicas, sendo elas: massa especifica básica, massa especifica aparente a 12%, teor de umidade de equilíbrio, flexão estática (MOE e MOR), compressão paralela as fibras (Fc e Ec), análise colorimétrica, termogravimetria (TGA e DTG) e fourier transform infrared spectroscopy (FT-IR), das espécies de Corymbia maculata, Eucalyptus grandis, Pinus elliottii. Determinaram-se as propriedades tecnológicas conforme descrito nas normas ASTM D 2395-17 (2017) e ASTM D 143-94 (2014). Em relação as propriedades físico-mecânicas, as species apresentaram diferenças significativas baseadas em análises estatisticas, possuindo destaque a espécie de Corymbia maculata. Em relação a análise colorimétrica, foi verificado que a espécie Corymbia maculata possui uma coloração marrom-avermelhado, a espécie de Pinus elliottii amarelo com tonalidade clara, enquanto o Eucalyptus grandis avermelhada com tonalidade clara. Para o FT-IR foi constatado picos semelhantes entre as espécies, porém com intensidades distintas, sendo estes referentes as vibrações moleculares características dos componentes orgânicos da madeira. Por meio da análise termogravimétrica percebe-se que as espécies de Pinus elliottii e Corymbia maculata, apresentaram maior estabilidade térmica, quando comparadas ao Eucalyptus grandis, possuindo um menor percentual de perda de massa e um retardo de temperatura em relação ao pico máximo de degradação (DTG), próximo aos 400°C, sendo essas propriedades analisadas com testes ANOVA com significância de 5%. Sendo assim destaca-se uma heterogeneidade entre as espécies avaliadas nesse estudo, tanto do ponto de vista físico, mecânico, térmico e químico, fazendo-se necessário a caracterização de tais propriedades para o emprego correto destes materiais.
ABSTRACT The woods have distinct technological properties, as they are organic and heterogeneous material, requiring an assessment for proper use. Therefore, the objective of this work was the evaluation of technological properties, which are: basic density, apparent density at 12%, equilibrium moisture content, static flexion (MOE and MOR), parallel compression of the fibers (Fc and Ec), colorimetric analysis, thermogravimetry (TGA and DTG) and Fourier transform infrared spectroscopy (FT-IR), of the species of Corymbia maculata, Eucalyptus grandis, Pinus elliottii. The technological properties were determined as described in the ASTM D 2395-17 (2017) and ASTM D 143-94 (2014) standards. Regarding the physical-mechanical properties, the species showed significant differences based on statistical analysis, highlighting the species of Corymbia maculata. Regarding the colorimetric analysis, it was found that the species Corymbia maculata has a reddish-brown color, the Pinus elliottii species loves it with a light shade, while the Eucalyptus grandis reddish with a light shade. For FT-IR, similar peaks were found between species, but with different intensities, these being related to the molecular vibrations characteristic of the organic components of wood. Through thermogravimetric analysis, it can be seen that the species of Pinus elliottii and Corymbia maculata, presented greater thermal stability when compared to Eucalyptus grandis, having a lower percentage of mass loss and a delay in temperature in relation to the maximum peak of degradation ( DTG), close to 400 ° C, and these properties were analyzed with ANOVA tests with 5% significance. Thus, there is a heterogeneity among the species evaluated in this study, both from a physical, mechanical, thermal and chemical point of view, making it necessary to characterize these properties for the correct use of these materials.
RESUMO Este estudo tem como objetivo, avaliações e correlações entre propriedades físicas da madeira, sendo estas, massa especifica básica, teor de umidade, absorção de água, perda de massa em 50°C e ...100°C, contração linear máximo (β), coeficiente de anisotropia de contração (Ca β), inchamento linear máximo (α) e coeficiente de anisotropia de inchamento (Ca α), sendo analisado para as madeiras das seguintes espécies: Corymbia citriodora, Corymbia maculata, Eucalyptus dunnii, Eucalyptus grandis, Eucalyptus saligna e Eucalyptus tereticornis. Para isso, foram confeccionados corpos de prova de 20 mm x 20 mm x 15 mm. Para as análises físicas, os corpos de prova foram submersos em água até a saturação, condicionados sob temperatura de 20°C com umidade relativa (UR) de 65% e secos em estufa (100 ± 3°C). Foram coletados dados de massa e dimensões desses corpos de prova em cada uma dessas etapas, para posterior cálculo das propriedades tecnológicas. Observou-se que as madeiras das sete espécies apresentaram diferença significativa. Analisando-se as propriedades de perda de massa a 100°C e massa específica básica, como também, anisotropia para inchamento (Ca α) e contração (Ca β), apresentam uma correlação significativa, sendo diretamente proporcional. A massa específica básica e absorção de água, perda de massa a 100°C e absorção de água, Coeficiente de Anisotropia de Contração (Ca β) e absorção de água, apresentaram correlações significativas, sendo essas propriedades inversamente proporcionais. As madeiras do gênero Corymbia apresentaram valores médios de propriedades tecnológicas, superiores às do gênero Eucalyptus, destacando a madeira Corymbia citriodora.
ABSTRACT This study aims at assessing and correlating physical properties of wood, such as basic specific mass, moisture content, water absorption, loss of mass at 50 ° C and 100 ° C, maximum linear contraction (β), coefficient of contraction anisotropy (Ca β), maximum linear swelling (α) and coefficient of swelling anisotropy (Caα), being analyzed for wood of the following species: Corymbia citriodora, Corymbia maculata, Eucalyptus dunnii, Eucalyptus grandis, Eucalyptus saligna and Eucalyptus tereticornis. For that, 20 mm x 20 mm x 15 mm specimens were prepared. For the physical analyzes, the specimens were submerged in water until saturated, conditioned at a temperature of 20 ° C with relative humidity (RH) of 65% and oven dried (100 ± 3 ° C). Mass data and dimensions of these specimens were collected in each of these stages, for later calculation of the technological properties. It was observed that the wood of the seven species presented significant difference. Analyzing the mass loss properties at 100 ° C and basic specific mass, as well as anisotropy for swelling (Ca α) and contraction (Caβ), they present a significant correlation, being directly proportional. The basic specific mass and water absorption, loss of mass at 100 ° C and water absorption, Coefficient of Contraction Anisotropy (Caβ) and water absorption, showed significant correlations, being these inversely proportional properties. The wood of the genus Corymbia presented average values of technological properties superior to those of the genus Eucalyptus, highlighting the wood Corymbia citriodora.
RESUMO O Pinus elliottii Engelm. possui uma vasta possibilidade de aplicações, porém, apresenta características indesejáveis às quais podem ser atenuadas com a adoção dos tratamentos de ...termorretificação e a furfurilação. Assim, este trabalho analisou a influência que os tratamentos de furfurilição e termorretificação exerceram em propriedades tecnológicas da madeira de Pinus elliottii. Para tanto, confeccionaram-se corpos de prova com dimensões de 15 x 15 x 250 mm (tangencial, radial e longitudinal), distribuídos igualmente em 5 tratamentos: controle, furfurilação com carga de 25% de álcool furfurílico (T F25%) e termorretificação em diferentes temperaturas (T 180°C, T 200°C e T 220°C). Avaliaram-se a variação da massa (ΔM) segundo adaptação da norma ASTM D 2017 (2005), à massa específica aparente ao teor de umidade de 12% (ρ12%), os módulos de elasticidade (MOE) e ruptura (MOR) obtidos pelo ensaio de flexão estática conforme a norma ASTM D 143 (2014), e a variação colorimétrica da madeira em conformidade com as recomendações do sistema CIE-L*a*b*. Verificou-se que o tratamento com furfurol provocou: aumentos significativos na massa, ρ12%, MOR, e causou o escurecimento da madeira, não afetando significativamente o MOE, em 5% de probabilidade de erro. Os tratamentos de termorretificação afetaram significativamente a perda de massa, contudo a maior diferença foi observada no tratamento T 220°C, o qual acarretou redução significativa no MOR em relação ao grupo controle, destacando-se que tal tratamento deixou a madeira com coloração semelhante aquela adquirida pela madeira tratada com furfurol. Conclui-se que ambos os tratamentos causaram o escurecimento da madeira de Pinus elliottii agregando assim valor estético, sendo que o tratamento à base de furfurol, com carga de 25%, ocasionou melhora nas propriedades tecnológicas da madeira. Apesar dos tratamentos de termorretificação terem aumentado o MOE, geraram perda de massa significativa, principalmente nos tratamentos mais agressivos, comprometendo assim possíveis usos da madeira com finalidade estrutural.
ABSTRACT The Pinus elliottii Engelm. has a wide range of applications, but it has undesirable characteristics that can be attenuated with the adoption of thermal rectification and furfurylation treatments. Thus, this work analyzed the influence of two treatments of modification, furfurilatyon and thermal rectification, in technological properties of Pinus elliottii Engelm. wood. For this, samples with dimensions of 15 x 15 x 250 mm (tangential, radial and longitudinal) were prepared, distributed equally among 5 treatments: control, furfurylation with 25% loading of furfuryl alcohol (T F25 %) and thermortification at different temperatures (T 180 ° C, T 200 ° C and T 220 ° C). It were evaluated the mass loss (PM) according to ASTM D 2017 (2005), specific gravity at 12% moisture content (ρ12%), elastic modulus (MOE) and rupture (MOR) by performing the static bending test in accordance with ASTM D 143 (2014), and wood color variation in accordance with the CIE-L*a*b* system recommendations. It was verified that the treatment with furfurol caused: significant increases in the mass, ρ12%, MOR, and caused the wood darkening, not significantly affecting the MOE, in 5% probability of error. The thermal rectification treatments significantly affected the mass loss, however the highest difference was observed in the T 220 ° C treatment, which caused a significant reduction on MOR in relation to the control group, highlighting that such treatment left the wood with coloration similar to that obtained by wood treated with furfurol. It's concluded that both treatments caused darkening of Pinus elliottii wood, thus adding aesthetic value, being that the furfurol treatment with a 25% load caused an improvement on technological properties of wood. In spite of the thermal rectification treatments increased the MOE, they generated significant mass loss, mainly in the more aggressive treatments, thus compromising possible uses of the wood with structural purpose.
PDF
