This study aims to produce and characterize wood-based composites (WPC) by
in situ
polymerization with poly(vinyl acetate) into juvenile and mature woods from a pine specie. Vacuum-pressure method ...was used to impregnate the wood with a vinyl acetate monomer and benzoyl peroxide (1.5 wt%) was used as initiator. The studied WPC were characterized for treatment parameters (weight percentage gain and specific gravity), as well as chemical (by infrared spectroscopy), thermal (by thermogravimetric analysis) and mechanical (by flexure and hardness tests) features. The
in situ
polymerization yielded improved mechanical properties and increased thermal stabilities, which were attributed to the impregnated poly(vinyl acetate) (especially on the wood surface) as suggested by treatment parameters and infrared spectra. The presented wood treatment may be a key strategy to improve pinewood properties, especially from juvenile wood, which may overcome the properties of the pristine mature wood.
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
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 work deals with the durability of a
wood impregnated with alumina (Al
O
) particles. The samples were impregnated at three different Al
O
weight fractions (c.a. 0.1%, 0.3% and 0.5%) and were ...then exposed to two wood-rot fungi, namely white-rot fungus (
) and brown-rot fungus (
). Thermal and chemical characteristics were evaluated by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric (TG) analyses. The wood which incorporated 0.3 wt% of Al
O
presented a weight loss 91.5% smaller than the untreated wood after being exposed to the white-rot fungus. On the other hand, the highest effectiveness against the brown-rot fungus was reached by the wood treated with 5 wt% of Al
O
, which presented a mass loss 91.6% smaller than that of the untreated pine wood. The Al
O
-treated woods presented higher antifungal resistances than the untreated ones in a way that: the higher the Al
O
content, the higher the thermal stability. In general, the impregnation of the Al
O
particles seems to be a promising treatment for wood protection against both studied wood-rot fungi. Additionally, both FT-IR and TG results were valuable tools to ascertain chemical changes ascribed to fungal decay.
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 study aimed to analyze chemical changes by Fourier Transform Infrared Spectroscopy of Eucalyptus dunnii and Pinus elliottii treated woods subjected to an accelerated decay test with the white ...rot fungus Ganoderma applanatum. The wood test specimens (2,5x2,5x0,9 cm) were impregnated with preservative solutions of chromated copper borate and synthetic pyrethroids and carbamates with 6% concentration by a vaccum-pressure process. After a decay test of 16 weeks, the chemical changes of the treated and untreated wood samples were evaluated by Fourier Transform Infrared Spectroscopy. It was observed that the rot fungus attack caused a variation in the intensity and a displacement of spectrum peaks, indicating a change to the woods’ chemical composition after fungal exposure. The lignin / carbohydrate ratio indicated that the fungus had no preference for a specific cell wall component, pointing to a simultaneous deterioration of cellulose, hemicellulose and lignin in the treated and untreated woods. Finally, the Fourier Transform Infrared Spectroscopy technique, together with the lignin / carbohydrate ratio analysis, proved efficient in the study of the variation of the wood chemical modifications deteriorated by rot fungi.
The aim of the present study is to subject Pinus elliottii wood specimens to TiO2-based modification in order to make them resistant to water and UV radiation. The microwave-assisted solvothermal ...method, which is little reported in the literature, was here in use for this purpose. The adopted methodology led to a 1 % mass gain; although it was a low value, it was enough to fully coat the surface of the wood with nanoparticles to the extent of changing its characteristics and turning it into a functional material. The nanoparticle distribution on the surface of the wood changed your natural topography by increasing the surface area and, consequently, increasing the contact angle of the modified wood (approximately 130°). The leaching test showed that the wood remained coated after it was immersed in water, as well as that it did not lose its water-repelling ability. This result demonstrates the stable interaction between the two materials, due to hydroxyl radicals found in them. The coating also protected the wood against UV radiation for 500 hours of intense exposure, besides preserving its initial color. The properties achieved through this simple and fast modification process provide an alternative to help to improve the performance of the herein investigated wood species, mainly for applications in environments subjected to high solar incidence and humidity.
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.
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.
Este trabalho objetivou avaliar as modificações resultantes do ataque de cupins quanto à higroscopicidade da madeira de Eucalyptus dunnii, E. saligna e Corymbia maculata. Foram utilizados corpos de ...prova com dimensões de 20 x 20 x 150 mm³ (tangencial x radial x longitudinal), sendo avaliado o teor de umidade de equilíbrio (TUE), as contrações lineares dos planos tangencial e radial (βT e βR), a anisotropia da contração (CAβ), a absorção de água (AA) e a taxa de absorção de água (TAA) de amostras de madeira sadias e deterioradas por térmitas Nasutitermes sp. Verificou-se que o ataque dos térmitas causou aumento no TUE e redução no βT, entretanto, βR e CAβ apresentaram variação entre as diferentes espécies. AA e TAA apresentaram alta intensidade de absorção de água nas primeiras horas de imersão, sendo maiores nas amostras do grupo controle em relação às deterioradas. Possivelmente, as variações nos parâmetros relativos à higroscopicidade da madeira das espécies estudadas estão relacionadas ao aumento da porosidade e deterioração, principalmente da celulose e hemiceluloses, afetando diretamente a capacidade da madeira em absorver e perder umidade, comprometendo a sua qualidade.
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