Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains viii, 182 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 107-114).

Thesis (Ph. D.)--University of Washington, 1994. / Vita. Includes bibliographical references (leaves [123]-131).

A wood surface, which is exposed to a high temperature condition, can experience inactivation. Surface inactivation results in reduced ability of an adhesive to properly wet, flow, penetrate, and cure. Thus, an inactivated wood surface does not bond well with adhesives. The changes in surface chemistry, wettability, and adhesion of inactivated wood surfaces, including heartwood of yellow-poplar (Liriodendron tulipifera) and southern pine (Pinus taeda), were studied. Wood samples were dried from the green moisture content condition in a convection oven at five different temperature levels ranging from 50 to 200 °C. The comparative characterization of the surface was done by X-ray photoelectron spectroscopy (XPS), sessile drop wettability, and fracture testing of adhesive bonds. The oxygen to carbon ratio (O/C) decreased and the C1/C2 ratio increased with drying temperature. The C1 component is related to carbon-carbon or carbon-hydrogen bonds, and the C2 component represents single carbon-oxygen bond. A low O/C ratio and a high C1/C2 ratio reflected a high concentration of non-polar wood components (extractives/VOCs) on the wood surface, which modified the wood surface from hydrophilic to more hydrophobic. Wettability was directly related to the O/C ratio and inversely related to the C1/C2 ratio. Contact angle decreased with time and increased with the temperature of exposure. Southern pine had a lower wettability than yellow-poplar, which was due to a greater concentration of non-polar hydrocarbon-type extractives and heat-generated volatiles on the surface. Solvent extraction prior to drying did not improved wettability, whereas, extraction after drying improved wettability. A contribution of extractives migration and VOCs generation played a significant role in the heat-induced inactivation process of southern pine. The maximum strain energy release rate (Gmax) showed that surface inactivation was insignificant for yellow-poplar when exposed to drying temperatures < 187°C. The southern pine was most susceptible to inactivation at drying temperatures > 156°C, particularly when bonded with phenol-formaldehyde (PF) adhesive. Chemical treatments improved the wettability of inactivated wood surfaces, but an improvement in adhesion was not evident for specimens bonded with polyvinyl-acetate (PVA) adhesive. NaOH surface treatment was most effective for improving adhesion of the PF adhesive bond. / Ph. D.

Resumo: O processo de lixamento da madeira é uma prática comum para preparar sua superfície para o revestimento. A qualidade superficial da madeira é diretamente relacionada ao revestimento, aderência, custos de pós processamento e aparência estética do produto. Vários parâmetros influenciam no acabamento superficial da madeira como: espécie de madeira, processo de usinagem e granulometria da lixa. Nesta tese foram coletados dados de rugosidade superficial de amostras das espécies Eucalyptus grandis e Eucalyptus citriodora usinadas em torno tubular em três velocidades de avanço (10, 14 e 18m/min.) e lixadas em lixadeira de cinta vertical dupla por quatro jogos de lixas abrasivas de alumínio zirconado. Estes jogos foram compostos com lixas de granulometrias 80, 100 e 120 (80-100, 80-120, 100-120 e U80-120), sendo a primeira lixa para desbaste e a segunda para acabamento. Concluiu-se que para os três conjuntos de lixas novas empregadas, o conjunto de lixas de granulometrias 80 e 120, para desbaste e acabamento, respectivamente, foi aquele que apresentou o melhor desempenho quanto ao acabamento superficial para as duas espécies. O emprego de lixas usadas não demonstrou perda significativa de rendimento se comparadas às demais combinações de lixas novas. O conjunto de lixas 80-120 apresenta, numa razão proporcional, uma variação de 4% no valor de "Ra" para cada 4 m/min aumentado na velocidade de avanço do torneamento das amostras. Pode-se afirmar que, em condições ótimas de lixamento, em média, a cada 0,1mm/rot de aumento no avanço por dente no torneamento, tem-se o aumento de 1% em "Ra". / Abstract: The process of sanding the wood is a common practice to prepare the surface for coating. The surface quality of wood is directly related to the coating, adhesion, costs of post-processing and aesthetic appearance of the product. Several parameters influence the surface finish of the wood as wood species, machining process and particle size of sandpaper. In this thesis the analysis was based on data collected in surface roughness of samples of species Eucalyptus grandis and Eucalyptus citriodora machined in tubiform lathe three feed rate (10, 14 and 18m/min.) and sanded in double vertical belt sander by and four sets of abrasive zirconia aluminium. These sets were composed with grain sizes 80,100 and 120 mesh (80-100, 80-120, 100-120 e U80- 120), the first sandpaper for roughing and second for finishing. It was concluded that for the three new sets of sandpaper used, the combination of grit sizes of 80 and 120, for roughing and finishing, respectively, presented the best performance on the surface finishing for both species. The use of worn sandpaper showed no significant loss of income compared to the other combinations of new sandpaper. The set of sandpaper 80-120 provides, in proportion to a variation of 4% in the value of "Ra" for each 4 m/min increased the feed rate speed of the turning of the samples. Thus, can be conclude that, under optimal conditions of sanding, on average, every 0.1 mm/rev increased in feed per tooth, increases of 1% in "Ra". / Orientador: Marcos Valério Ribeiro / Coorientador: Marcos Tadeu Tiburcio Gonçalves / Banca: Manoel Cleber de Sampaio Alves / Banca: Edson Cocchieri Botelho / Banca: Ivaldo de Domenico Valarelli / Banca: Francisco Antonio Rocco Lahr / Doutor

The controlled degradation of wood surfaces with infrared light from a CO2 pulsed laser facilitated adhesion without the use of additional resins. Laser modification creates a surface phenomenon that physically and chemically alters the natural biopolymer organization of lignocellulosic materials in a way that promotes adhesion when hot pressed using typical industrial equipment. Laser optimization was determined through mechanical and microscopic observation. It was determined that a mild level of laser surface modification (scale of 30 W/mm2) resulted in the highest bond-line strength. The large spot size of the laser beam resulted in evenly modified surfaces. Surface analysis revealed that laser modification changed native wood morphology, hydrolyzed and vaporized hemicellulose, and enriched the surface with cellulose II and lignin. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR FTIR) was used to analyze the bulk of the laser material. This experiment revealed a change in the hydroxyl region related to hydrogen bonding conformations between wood polymers, mainly cellulose. X-ray photoelectron spectroscopy (XPS) provided an elemental composition of the top 5 nanometers of the surface, which resulted in increased carbon-carbon/carbon-hydrogen linkages and decreased oxygen containing bonds due to laser ablation. Static acid-base contact angle analysis was conducted using three probe liquids to find the Lewis acid, Lewis base, and dispersion components of the top nanometer of surface chemistry. Contact angle analysis revealed laser modified samples had a surface free energy that remained similar to the control wood sample. In addition, the dispersion component of the surface free energy increased due to laser ablation while acid-base components were reduced. Atomic force microscopy (AFM) visually displays a reduction in surface roughness due to the laser technique. An additional set of experiments like thermal gravimetric analysis, thermal pre and post treatments, and heated ATR FTIR and XPS support findings which require more investigation into this adhesion phenomenon. / Master of Science

Thesis (Ph. D.)--University of Washington, 1991. / Vita. Includes bibliographical references (leaves [102]-109).

Made available in DSpace on 2014-06-11T19:32:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-11-06Bitstream added on 2014-06-13T19:26:23Z : No. of bitstreams: 1 tiburcio_ufo_dr_guara.pdf: 1741150 bytes, checksum: 8386659f2613e0cdff19e8b27ff268d8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O processo de lixamento da madeira é uma prática comum para preparar sua superfície para o revestimento. A qualidade superficial da madeira é diretamente relacionada ao revestimento, aderência, custos de pós processamento e aparência estética do produto. Vários parâmetros influenciam no acabamento superficial da madeira como: espécie de madeira, processo de usinagem e granulometria da lixa. Nesta tese foram coletados dados de rugosidade superficial de amostras das espécies Eucalyptus grandis e Eucalyptus citriodora usinadas em torno tubular em três velocidades de avanço (10, 14 e 18m/min.) e lixadas em lixadeira de cinta vertical dupla por quatro jogos de lixas abrasivas de alumínio zirconado. Estes jogos foram compostos com lixas de granulometrias 80, 100 e 120 (80-100, 80-120, 100-120 e U80-120), sendo a primeira lixa para desbaste e a segunda para acabamento. Concluiu-se que para os três conjuntos de lixas novas empregadas, o conjunto de lixas de granulometrias 80 e 120, para desbaste e acabamento, respectivamente, foi aquele que apresentou o melhor desempenho quanto ao acabamento superficial para as duas espécies. O emprego de lixas usadas não demonstrou perda significativa de rendimento se comparadas às demais combinações de lixas novas. O conjunto de lixas 80-120 apresenta, numa razão proporcional, uma variação de 4% no valor de “Ra” para cada 4 m/min aumentado na velocidade de avanço do torneamento das amostras. Pode-se afirmar que, em condições ótimas de lixamento, em média, a cada 0,1mm/rot de aumento no avanço por dente no torneamento, tem-se o aumento de 1% em “Ra”. / The process of sanding the wood is a common practice to prepare the surface for coating. The surface quality of wood is directly related to the coating, adhesion, costs of post-processing and aesthetic appearance of the product. Several parameters influence the surface finish of the wood as wood species, machining process and particle size of sandpaper. In this thesis the analysis was based on data collected in surface roughness of samples of species Eucalyptus grandis and Eucalyptus citriodora machined in tubiform lathe three feed rate (10, 14 and 18m/min.) and sanded in double vertical belt sander by and four sets of abrasive zirconia aluminium. These sets were composed with grain sizes 80,100 and 120 mesh (80-100, 80-120, 100-120 e U80- 120), the first sandpaper for roughing and second for finishing. It was concluded that for the three new sets of sandpaper used, the combination of grit sizes of 80 and 120, for roughing and finishing, respectively, presented the best performance on the surface finishing for both species. The use of worn sandpaper showed no significant loss of income compared to the other combinations of new sandpaper. The set of sandpaper 80-120 provides, in proportion to a variation of 4% in the value of Ra for each 4 m/min increased the feed rate speed of the turning of the samples. Thus, can be conclude that, under optimal conditions of sanding, on average, every 0.1 mm/rev increased in feed per tooth, increases of 1% in Ra.

Bark beetles regulate forest succession by removing weakened or stressed trees and exposing understory species to light from canopy gaps. Subterranean termites are predominate decomposers of coarse woody debris in southern pine forests; however, little is known about their role in forest health and succession. Both groups of insects rely heavily on fungal symbioses to fill their respective ecological niches in southern pine forests. During recent inspections of southern pine timber, we observed that trees in the early stages of bark beetle attack often had subterranean termites in blue-stained portions of the trunk. The frequency of subterranean termite presence in blue-stained areas of trees increased proportionally to the stage of bark beetle attack. However, practically no research has undertaken the challenge of describing how woody resources created by bark beetles are identified and utilized by subterranean termites before any signs of stress are visible. Therefore, this study examined possible facilitative interactions between subterranean termites, bark beetles and their blue-stain fungal associates, and other invertebrates, and investigated the effect of blue-stain fungi on surface properties of wood. Both native (Reticulitermes spp.) and Formosan subterranean termites exhibited a higher feeding preference for blue-stained sapwood than for unstained sapwood in laboratory assays. Native subterranean termites also consumed blue-stained sapwood at a higher rate than decayed wood. This study was the first to demonstrate that wood containing a non-decay fungus could elicit a feeding response from subterranean termites greater than that observed for decayed wood. Additionally, the surface properties of bark beetle-attacked southern pine were initially reduced by blue-stain fungal infection; however, the process of kiln-drying reversed this effect, resulting in a surface that was more conducive to wood product manufacturing.

This study aims to evaluate the effect of thermal treatment in vegetable oil in physical, mechanical, chemical and surface property of the wooden whose two species of the genus Eucalyptus. Initially, we selected six trees, three of which belong for Eucalyptus cloeziana F. Muell species and the others to the Eucalyptus grandis Hill ex Maiden, which gave surce to the samples of physical and mechanical tests. Perform were 20 treatments distributed between the two species, three times (2, 4 and 6 hours) and three temperatures (160, 190 and 220°C), more the control treatments. To the termorretificação was used oil bath laboratory and for drying of the samples, we used a forced circulating air kiln. The analyzes physical evaluated were weight change, equilibrium moisture content, density and hygroscopicity of wood. In mechanical tests was evaluated static and dynamic bending and Janka hardness. Quantity were colorimetric changes, both on the surface and in the center of the parts and the chemical analysis was qualitative lye valuated by infrared spectroscopy (ATR-IR). The results showed that the process of thermal treatment changed signifivantly the physical properties and is the most severe treatment (220°C) the greatest changes; such changes have incriased dimensional stability and decreased hygroscopicity of wood. The modulus of rupture and Janka hardness decreased after thermal treatment application, alredy the modulus of elasticity hadn´t change. The colorimetric provided the color homogenization, in addition to providing a tropical tone treated wood, benefiting its application in aesthetic purposes. Through the technique of ATR - IR was possible to identify the main chemical elements changed by process of thermal treatment as hemicellulose, cellulose, lignin and extractives, which were the basis for the explanation of the changes occurring in the wood. In general, the process thermal treatment vegetable oil applied to the Eucalyptus grandis and Eucalyptus cloeziana caused significant modifications, which could provide the use of wood treated in environments unsuitable prior to its use. / O presente estudo teve por objetivo avaliar o efeito da termorretificação em óleo vegetal nas propriedades físicas, mecânicas, químicas e superficiais da madeira de duas espécies do gênero Eucalyptus. Inicialmente foram selecionadas seis árvores, das quais três são referentes a espécie Eucalyptus cloeziana F. Muell e as demais de Eucalyptus grandis Hill ex Maiden, as quais deram origem aos corpos de prova para ensaios físicos e mecânicos. Foram realizados 20 tratamentos, distribuídos entre as duas espécies, três tempos (2, 4 e 6 horas) e três temperaturas (160, 190 e 220ºC), mais os tratamentos controle. Para a realização da termorretificação foi utilizado um banho de óleo laboratorial e, para a cura dos corpos de prova, utilizou-se uma estufa de circulação de ar forçada. As análises físicas avaliadas foram: a variação de massa, o teor de umidade de equilíbrio, a massa específica e higroscopicidade a da madeira. Nos ensaios mecânicos avaliou-se a flexão estática, flexão dinâmica e dureza Janka. Quantificou-se as mudanças colorimétricas, tanto na superfície, quanto no centro das peças e a análise química foi avaliada qualitativamente por espectroscopia no infravermelho (ATR-IR). Os resultados mostraram que o processo de termorretificação alterou significativamente as propriedades físicas, sendo nos tratamentos mais severos (220ºC) as maiores modificações; tais alterações aumentaram a estabilidade dimensional e diminuíram a higroscopicidade da madeira. O módulo de ruptura e a dureza Janka diminuíram após a aplicação dos tratamentos de termorretificação, já no módulo de elasticidade não houve alteração. As alterações colorimétricas proporcionaram a homogeneização da cor, além de conceder um tom marrom a madeira tratada, beneficiando sua aplicação em fins estéticos. Através da técnica de ATR IR foi possível identificar os principais elementos químicos alterados pelo processo de termorretificação, como hemiceluloses, celulose, lignina e extrativos, dos quais serviram de base para a explicação das modificações ocorridas na madeira. De modo geral, o processo de termorretificação em óleo vegetal aplicado à madeira de Eucalyptus cloeziana e Eucalyptus grandis ocasionou modificações relevantes, as quais, podem proporcionar o emprego da madeira tratada em ambientes antes impróprias ao seu uso.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Thermomechanical treatments seek to increase the wood density, throught of the temperature and pressure combination, which results in a material with improved physical and mechanical properties. Thus, the study aimed to evaluate the influence of thermomechanical treatments in Pinus elliottii Engelm and Eucalyptus grandis W. Hill ex Maiden wood. So, were prepared from five trees of each species, wood pieces that have been submitted to six different thermomechanical treatments. For this purpose, we used a laboratory oil bath to perform preheating of wood and a hydraulic press with the temperatures of the dishes ranging from 150 to 190°C. Compression time used was between 30 and 60 min. After, physical (compression rate, weight loss, equilibrium moisture content, density, dimensional stability and hygroscopicity), mechanical (static bending, dynamic bending and Janka hardness), surface (colorimetry and roughness) and infrared spectroscopy (ATR-IR) tests were performed. For statistical analysis, we used qualitative factorial 3 x 2, with three temperature levels and two compression time and Tukey test. Furthermore, it was performed to compare the treatments with the control. The main results for the technological properties showed that the degree of compression and mass loss increased with the temperature increase. The equilibrium moisture content decreased and the density obtained increases. For the dimensional stability was observed that there was a reduction of the effect of the return densified wood, and hygroscopicity was increased in both wood species. The mechanical properties showed increases with the densification, except for the Janka hardness and dynamic flexion in E. grandis wood treated with high temperatures. Infrared spectroscopy showed degradation of the amorphous cellulose and hemicellulose, providing a proportional increase of crystalline cellulose and lignin. The color of the densified wood was changed presenting surface browning, measured by decrease in brightness L* parameter. Roughness was reduced, making the surface softer wood. Before the alterations, it is indicated using thermomechanical treatment with temperature of 150°C and the compression time of 60 min. In this respect, it is recommended the use of densified wood floors and coatings, even for softwoods (conifers). / Os tratamentos termomecânicos visam aumentar a densidade da madeira, por meio da combinação entre temperatura e pressão, o que resulta em um material com as propriedades físico-mecânicas melhoradas. Nesse sentido, o presente estudo teve como objetivo avaliar a influência dos tratamentos termomecânicos na madeira. Para tanto, foram confeccionadas peças de madeira, a partir de cinco árvores de Pinus elliottii Engelm e Eucalyptus grandis W. Hill ex Maiden que foram submetidas a seis tratamentos termomecânicos. Para tal, foi utilizado um banho de óleo laboratorial para realizar o pré-aquecimento da madeira e uma prensa hidráulica com a temperatura dos pratos variando de 150 a 190°C e o tempo de compressão entre 30 e 60 min. Na sequência, foram realizados os ensaios físicos (grau de compressão, perda de massa, teor de umidade de equilíbrio, densidade, estabilidade dimensional e higroscopicidade), mecânicos (flexão estática, flexão dinâmica e dureza Janka), de superfície (colorimetria e rugosidade) e espectroscopia no infravermelho (ATR-IR). Para a análise estatística foi utilizado o arranjo fatorial qualitativo 3 x 2, com três níveis de temperatura (150, 170 e 190°C) e dois de tempo de compressão (30 e 60 min) e comparados pelo teste de Tukey. Além disso, foi realizado a comparação dos tratamentos com o controle pelo teste de Dunnett. Os principais resultados encontrados para as propriedades tecnológicas mostraram que o grau de compressão, a perda de massa e a densidade aumentaram com o acréscimo da temperatura, já o teor de umidade de equilíbrio apresentou decréscimo com a elevação da temperatura. Para a estabilidade dimensional foi observado que houve redução pelo efeito do retorno da madeira densificada e a higroscopicidade foi aumentada na madeira de ambas as espécies. As propriedades mecânicas apresentaram acréscimo com a densificação, com exceção para a dureza Janka e flexão dinâmica da madeira de E. grandis tratada com altas temperaturas. Por meio da espectrometria no infravermelho foi verificado a partir da razão de pico que houve degradação de hemiceluloses e celulose amorfa, proporcionando aumento proporcional de celulose cristalina e lignina. A coloração da madeira densificada foi alterada apresentando escurecimento superficial, quantificado pelo decréscimo do parâmetro de claridade L*. Já a rugosidade foi reduzida, tornando a superfície da madeira mais suave. Diante das alterações ocorridas é indicado utilizar tratamento termomecânico com a temperatura de 150°C e o tempo de compressão de 60 min. Nesse aspecto, é recomendado a utilização da madeira densificada como assoalhos e revestimentos, mesmo para as madeiras macias (coníferas).