This study was designed to examine effects of alcohol-benzene solubles, hemicellulose, modified cellulose, lignin and modified lignin residuals in refined Douglas fir Asplund fibre on the heat-activated polymerization of tempering oil applied to wet-batch process hardboards. Thin (0.05 cm.thickness) experimental boards were prepared with good formation properties and reproducibility for the study. Results of oil-tempering, heat-treatment and humidification treatments were compared with and without modifying the raw stock. Oil-tempering was most effective on boards made from unmodified or alcohol-benzene extracted fibre. An ultimate tensile strength increase of 105% approximates gains had in commercial practice. Heat-treatment alone was ineffective in developing extra strength, possibly because of extended hot-pressing of the boards. Among the wood constituents investigated lignin was involved.in approximately 80% of the extra strength development on oil-tempering. It was found that oil-tempering effects could be severely depressed by mild oxidation of the fibre with acidified sodium chlorite (NaClO₂) solution at 70° C. Accompanying weight loss was below 5%. Alternatively, partial deactivation was obtained by inhibition of the fibre surface or precondensing the lignin in the raw stock with hot-water-soluble hemlock bark tannins. The tannins were introduced into the fibre structure by a new method including hot-soaking and cold-precipitation at 3% slurry consistency. Strength development on oil-tempering was thus reduced by the oxidation treatment to approximately 20% which was unaffected by further chemical treatment. This residual strength increase may be due to some other effect than lignin. Evidence for a chemical mechanism is suggested by observations that only a limited portion of the oil takes part in strength development, pointing toward limited sites available for polycondensation. Possibly, these sites are inactivated.by even mild oxidizing treatments of the fibre. This suggests that lignin quality is more important than quantity of lignin, alcohol-benzene solubles, hemicellulose or cellulose in the oil-tempering mechanism. These findings are contradictory to the literature. To date, lignin has not been considered an important wood constituent in strength development of different wood products by impregnation, and condensation-polymerization systems with unsaturated compounds. Further removal of lignin from the fibre (10 to 25% weight loss) improved formation and bonding of fibres and the subsequent strength properties of boards. This conforms to well described mechanisms accompanying fibre delignification. Additional lignin removal (25 to 35% weight loss with 5% or less residual lignin) lowered fibre viscosity and board strength. Experimental strength and elasticity data across the 0 to 5% and 10 to 15% weight loss range were fitted according to a mathematical model. The site and bonding mechanism between lignin and tempering oil have not been described. Some suggestion is made as to how this might occur. / Forestry, Faculty of / Graduate

Biodeterioration tests were done to investigate the decay resistance property of slurry brominated wet-process high-density hardboard. The advantage of resistance against decay will increase the marginal economics of the brominated board which was developed initially as a fire-resistant materials only. Non-brominated and brominated hardboards were examined, using a soil-jar method, for their resistance to decay by four brcwn-rot and two white-rot fungi. Six types of hardboard were used; fiber only, fiber plus phenolic resin, and fiber plus polyethyleniffline resin, as well as three brominated counterparts for these three control treatments. Although the influence of the adhesive on the rates of decay was small, the polyethylenimine resin, which contained high amount of nitrogen compound, showed some stimulatory effect. Bromination significantly increased the resistance of hardboard to decay by brown-rot fungi, although this resistance could be reduced by leaching the brcminated board in cold water before attack by the fungi. It is probable that the formation of bromhydrins of lignin by bromination of the hardboard prevented the attack of the hardboards by two white-rot fungi. Among the brown-rot fungi, Lenzites trabea Pers. ex Pr, was the most sensitive to growing on brominated board. It was also found that brown-rot fungi were more active in decaying both non-brominated and brominated hardboard which were initially at a moisture content of 8% compared with 20%, Using either wet heat or ethylene oxide, as sterilization treatments of the boards, gave no difference in the subsequent decay rates of non-brominated boards by the brown-rot fungi. With brominated boards, the ethylene oxide treatment appeared to increase their susceptibility to decay by these fungi. The soil-jar method, modified from ASTM D1413-76, proved to be a suitable technique for evaluating the decay resistance of hardboard. / Forestry, Faculty of / Graduate

Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 50-52.

Thesis (M.S.)--University of Wisconsin, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The racking performance of light-frame shear walls subjected to monotonic and cyclic loading is the focus of this thesis. The sheathing materials investigated are oriented strandboard (OSB), hardboard, fiberboard, and gypsum wallboard. The objectives of this study were to (1) obtain and compare performance characteristics of each sheathing material; (2) compare the effects of monotonic loading versus the cyclic loading response; (3) investigate the contribution of gypsum in walls with dissimilar sheathing materials on opposite sides of the wall; and (4) study the effects of using overturning anchors. The monotonic tests, which incorporated the use of hold-downs, were performed according to ASTM E564. Half of the cyclic tests were performed with hold-downs, and half were performed without hold-downs. The cyclic tests were performed according to the recently adopted cyclic testing procedure ASTM E2126. A total of forty-five walls were tested with various configurations. The size of the walls was 1.2 x 2.4m (4 x 8ft). Two tests were performed with each sheathing material subjected to each type of loading: monotonic, cyclic with hold-downs, and cyclic without hold-downs. Two tests were then performed with OSB, hardboard, or fiberboard on one side of the wall and gypsum on the other side of the wall to study the effects of using dissimilar sheathing materials on the shear walls. The OSB and hardboard exhibited similar performance, and were the strongest of the four sheathing materials. Fiberboard performed better than gypsum, but worse than OSB and hardboard. In general, the performance indicators decreased when the walls were subjected to cyclic loading. The contribution of gypsum to walls with hold-downs was significant, but was not linearly additive. The use of hold-downs had a large effect on the performance of the walls. All shear wall performance indicators decreased when hold-downs were not included, with an average reduction of 66% in the peak load. / Master of Science

The static and dynamic flexural properties of a wood fiber matrix internally reinforced with continuous glass fibers were investigated. When modelled as a sandwich composite, the static flexural modulus of elasticity (MOE) of glass fiber reinforced hardboard could be successfully predicted from the static flexural MOE of the wood fiber matrix, and the tensile MOE and effective volume fraction of the glass fiber reinforcement. Under the same assumption, the composite modulus of rupture (MOR) is a function of the reinforcement tensile MOE and effective volume fraction, and the matrix stress at failure. The composite MOR was predicted on this basis with limited success. The static flexural modulus of elasticity, dynamic modulus of elasticity, and modulus of rupture of glass fiber reinforced hardboard increased with increasing effective reinforcement volume fraction. The logarithmic decrement of the composite decreased with increasing effective reinforcement volume fraction. Excellent linear correlation found among flexural properties determined in destructive static tests and nondestructive dynamic tests demonstrated the usefulness of dynamic test methods for flexural property evaluation. The short-term flexural creep behavior of glass fiber reinforced hardboard was accurately described by a 4-element linear viscoelastic model. Excellent agreement existed between predicted and observed creep deflections based on nonlinear regression estimates of model parameters. / Ph. D.

Wood and wood based composites such as hardboard have become very common materials for use in non-structural applications, which include pre-finished paneling, siding, exterior trim, furniture, and door skins. This thesis describes the results of a study of the failure of hardboard door skins. Forces applied during manufacture load the door skins in bending, and in some cases cause a split at the edge of the hardboard. A finite element model as well as a closed form solution based on mechanics of materials were developed to analyze the stresses and deformations of the door skin/stile assembly so that stresses could be predicted for various stile widths and loading conditions. The wood members that make up the frame along the perimeter of the doors, or stiles, were modeled as orthotropic and their properties were selected from available literature. The hardboard was modeled as transversely isotropic, and its properties were determined experimentally. The closed form solution developed can be used to determine the critical geometry for different combinations of hardboard thickness and adhesive joint stiffness. It predicts that as the stile width decreases, the point of maximum deflection, and greatest stresses, moves toward the outside edge of the panel. The ability to predict the critical stile width, or the stile width below which the maximum deflection and stress occurs at the outside edge of the panel, allows one to design the joint to be able to withstand specific loadings and prevent unwanted delamination of the hardboard during manufacture. / Master of Science

As usinas sucroalcooleiras aproveitam apenas a fração colmo da planta para a produção de açúcar e etanol restando o bagaço da cana-de-açúcar, composto das frações fibra e medula, é em grande parte usado para geração de energia elétrica. O resíduo agrícola da cana RAC, constituído pelas folhas, palha, e a ponteira da cana de açúcar são cortados durante a colheita e devolvidos ao campo para adubar o solo contribuindo para a lavoura da cana-de-açúcar. Os painéis hardboards são produzidos a partir da aplicação de calor e pressão a um colchão de fibras ou serragem de madeira, sendo aplicados como pisos na construção civil e como pranchetas e fundo de gavetas na indústria moveleira. Assim, a proposta desse trabalho foi o estudo da utilização dos materiais provenientes da cultura de cana-de-açúcar, em particular a fração medula do bagaço de cana-de-açúcar e do RAC para produção de hardboard (sem a utilização de adesivos) e particleboards (com a adição de resina fenol-formaldeído). Adicionalmente, estudou-se a adição da humina resultante de processos de hidrólise ácida do bagaço de cana-de-açúcar como coadjuvante na produção de painéis de medula de cana-de-açúcar. A utilização da resina fenol-formaldeído foi estudada no intervalo de 10% a 33%, sendo os melhores resultados obtidos quando do uso de 25% de resina, que apresentou tensão máxima de 29,9 MPa em ensaio de tração. Definido esse valor, realizou-se o estudo do efeito da quantidade de humina no intervalo de 12,5% a 75%, o qual revelou que a humina leva à produção de materiais frágeis com redução do desempenho mecânico. As frações RAC foram empregadas para a produção de amostras com teor de resina fenol-formaldeído igual a 25%. Todos os corpos de prova produzidos foram analisados por ensaios de tração (MOR e MOE), análise térmica, microscopia eletrônica de varredura (MEV) e análise dinâmico mecânica. A produção de hardboards a partir da fração medula do bagaço de cana-de-açúcar, nas condições empregadas neste estudo preliminar, resultou em materiais com baixo desempenho mecânico, revelado pelos resultados dos ensaios de tração que indicou tensão máxima de 4,7 MPa. Entretanto, a mesma matéria prima quando misturada com resina fenol-formaldeído resultou na produção de particleboards que, apesar da dispersão pouca efetiva da resina, apresentaram um melhor desempenho mecânico (tensão máxima no intervalo de 29,9 a 11,3 MPa). Finalmente, os materiais obtidos com as frações RAC da cana-de-açúcar e resina FF mostraram-se mais homogêneos e com desempenho mecânico igual ou superior (tensão máxima no intervalo de 36,1 a 27,7 MPa) aos observados para os materiais obtidos com Pinus sp (tensão máxima de 27,7 MPa). / Sugar and ethanol mills use only the stem fraction of sugarcane for the production of sugar and ethanol. The sugarcane bagasse, composed of fiber and pith fractions, is largely used to generate electricity. The sugarcane agricultural residues - RAC, made up of leaves, straw and the tip of sugarcane are cut during harvest and returned to the field to fertilize the soil. Hardboard panels are produced from the application of heat and pressure to a fiber or sawdust mat. Its commercial application includes floors in construction and clipboards and bottom drawers in the furniture industry. Thus the purpose of this work was to study the use of materials from sugarcane culture, in particular the core fraction of bagasse sugarcane and the sugarcane trash for the production of hardboard (without the use of adhesives) and particleboards (with the addition of phenol formaldehyde resin). In addition, he studied the addition of the resulting humin acid hydrolysis process of sugarcane bagasse as an adjunct in the production of sugarcane pith panels. The use of phenol formaldehyde resin was studied in the range of 10% to 33%, with best results obtained when using 25% resin, which had maximum stress of 29.9 MPa in tensile testing. Once established, the study of the effect of the amount of humin was held in the range of 12.5% to 75%, which revealed that the humin leads to the production of brittle materials with reduced mechanical performance. Sugarcane trash fractions were used for production of resin samples with phenol formaldehyde content equal to 25%. All produced samples were analyzed by tensile tests (MOR and MOE), thermal analysis, scanning electron microscopy (SEM) and dynamic mechanical analysis. The production of hardboards from the marrow fraction of sugarcane bagasse, under the conditions employed in this preliminary study, resulted in materials with low mechanical performance, revealed the results of tensile tests indicated that maximum voltage of 4.7 MPa. However, the same raw material when mixed with phenol-formaldehyde resin resulted in the production of particleboards that despite the low effective dispersion of the resin, had a better mechanical performance (maximum stress in the range from 29.9 to 11.3 MPa). Finally, materials obtained from the fractions of RAC sugarcane and PF resin proved to be more homogeneous and with equal or higher mechanical performance (maximum stress in the range from 36.1 to 27.7 MPa) to that observed for materials obtained with Pinus sp (maximum stress of 27.7 MPa).

As usinas sucroalcooleiras aproveitam apenas a fração colmo da planta para a produção de açúcar e etanol restando o bagaço da cana-de-açúcar, composto das frações fibra e medula, é em grande parte usado para geração de energia elétrica. O resíduo agrícola da cana RAC, constituído pelas folhas, palha, e a ponteira da cana de açúcar são cortados durante a colheita e devolvidos ao campo para adubar o solo contribuindo para a lavoura da cana-de-açúcar. Os painéis hardboards são produzidos a partir da aplicação de calor e pressão a um colchão de fibras ou serragem de madeira, sendo aplicados como pisos na construção civil e como pranchetas e fundo de gavetas na indústria moveleira. Assim, a proposta desse trabalho foi o estudo da utilização dos materiais provenientes da cultura de cana-de-açúcar, em particular a fração medula do bagaço de cana-de-açúcar e do RAC para produção de hardboard (sem a utilização de adesivos) e particleboards (com a adição de resina fenol-formaldeído). Adicionalmente, estudou-se a adição da humina resultante de processos de hidrólise ácida do bagaço de cana-de-açúcar como coadjuvante na produção de painéis de medula de cana-de-açúcar. A utilização da resina fenol-formaldeído foi estudada no intervalo de 10% a 33%, sendo os melhores resultados obtidos quando do uso de 25% de resina, que apresentou tensão máxima de 29,9 MPa em ensaio de tração. Definido esse valor, realizou-se o estudo do efeito da quantidade de humina no intervalo de 12,5% a 75%, o qual revelou que a humina leva à produção de materiais frágeis com redução do desempenho mecânico. As frações RAC foram empregadas para a produção de amostras com teor de resina fenol-formaldeído igual a 25%. Todos os corpos de prova produzidos foram analisados por ensaios de tração (MOR e MOE), análise térmica, microscopia eletrônica de varredura (MEV) e análise dinâmico mecânica. A produção de hardboards a partir da fração medula do bagaço de cana-de-açúcar, nas condições empregadas neste estudo preliminar, resultou em materiais com baixo desempenho mecânico, revelado pelos resultados dos ensaios de tração que indicou tensão máxima de 4,7 MPa. Entretanto, a mesma matéria prima quando misturada com resina fenol-formaldeído resultou na produção de particleboards que, apesar da dispersão pouca efetiva da resina, apresentaram um melhor desempenho mecânico (tensão máxima no intervalo de 29,9 a 11,3 MPa). Finalmente, os materiais obtidos com as frações RAC da cana-de-açúcar e resina FF mostraram-se mais homogêneos e com desempenho mecânico igual ou superior (tensão máxima no intervalo de 36,1 a 27,7 MPa) aos observados para os materiais obtidos com Pinus sp (tensão máxima de 27,7 MPa). / Sugar and ethanol mills use only the stem fraction of sugarcane for the production of sugar and ethanol. The sugarcane bagasse, composed of fiber and pith fractions, is largely used to generate electricity. The sugarcane agricultural residues - RAC, made up of leaves, straw and the tip of sugarcane are cut during harvest and returned to the field to fertilize the soil. Hardboard panels are produced from the application of heat and pressure to a fiber or sawdust mat. Its commercial application includes floors in construction and clipboards and bottom drawers in the furniture industry. Thus the purpose of this work was to study the use of materials from sugarcane culture, in particular the core fraction of bagasse sugarcane and the sugarcane trash for the production of hardboard (without the use of adhesives) and particleboards (with the addition of phenol formaldehyde resin). In addition, he studied the addition of the resulting humin acid hydrolysis process of sugarcane bagasse as an adjunct in the production of sugarcane pith panels. The use of phenol formaldehyde resin was studied in the range of 10% to 33%, with best results obtained when using 25% resin, which had maximum stress of 29.9 MPa in tensile testing. Once established, the study of the effect of the amount of humin was held in the range of 12.5% to 75%, which revealed that the humin leads to the production of brittle materials with reduced mechanical performance. Sugarcane trash fractions were used for production of resin samples with phenol formaldehyde content equal to 25%. All produced samples were analyzed by tensile tests (MOR and MOE), thermal analysis, scanning electron microscopy (SEM) and dynamic mechanical analysis. The production of hardboards from the marrow fraction of sugarcane bagasse, under the conditions employed in this preliminary study, resulted in materials with low mechanical performance, revealed the results of tensile tests indicated that maximum voltage of 4.7 MPa. However, the same raw material when mixed with phenol-formaldehyde resin resulted in the production of particleboards that despite the low effective dispersion of the resin, had a better mechanical performance (maximum stress in the range from 29.9 to 11.3 MPa). Finally, materials obtained from the fractions of RAC sugarcane and PF resin proved to be more homogeneous and with equal or higher mechanical performance (maximum stress in the range from 36.1 to 27.7 MPa) to that observed for materials obtained with Pinus sp (maximum stress of 27.7 MPa).