Myths prevail among the general public about wood, forest products, and the condition of the environment in the United States. Research shows that most people are unaware about the proliferation of products that they use in their daily lives that are made out of or are derived from wood, about the amount (and shortcomings) of paper recycling in America, and the degree of environmental "friendliness" that wood and non-wood substitutes inherently possess. Students surveyed on Virginia Tech's campus could not state the main purpose of the United States Forest Service, nor could they identify the primary reason rainforests in South America are disappearing. Survey results from undergraduate students enrolled in the Department of Wood Science and Forest Products showed that they have a much better understanding of the environment and use of wood in people's lives. Survey results from students enrolled in the wood curricula closely parallel those from employees in the wood products industry. An exhaustive literature review of current academic and popular journals is summarized, as are results from the Virginia Tech survey. The impact that public misperceptions have on the wood products industry and steps to remedy them are also examined. Research findings show that the forest products industry needs a coordinated and centralized public promotion campaign to inform the general public about wood's attributes and environmental advantages. / Master of Science

Drying of timber increases its durability and strength. Therefore, timber should be dried to a moisture content close to the equilibrium moisture content it will attain in service. The drying of timber from its natural green state to the required moisture content is thus an important part of the production cycle. Hardwood species, due to their macroscopic structures, are more difficult to dry as compared to softwood. A great deal of research has centred in recent years on developing a fast drying process for softwood; on the other hand, there is a need for a process to dry hardwood rapidly. A new drying technique, called Continuously Varying Schedule (CVS) was recently developed by the author for the purpose of rapidly drying the medium to high density hardwood. The investigation described herein was carried out to compare the CVS process with the conventional drying process. The factors compared were drying time, quality of timber produced and the energy consumed. It was found that the CVS process reduced the drying time by 34.5% and saved 30.7% of the energy. It produced also, a competitive dried timber quality. The process achieved highly efficient drying, as the rate of drying (MC%/h x 100) was 80.3% higher than the conventional process and also, the amount of water evaporated per unit of drying time (g/h) was 67.1% higher. The CVS drying performance has achieved a 71.9% increase in the amount of moisture content reduced per unit of energy (MC%/kWh x 100) and a 57.8% increase in the amount of water evaporated per unit of energy (g/kWh) as compared to the conventional process. Much emphasis was placed on energy saving in the drying plant and it was suggested that a heat exchanger be used to recover waste energy from the exhausted air of the kiln. A dehumidifier coupled to a solar-powered system, backed up with an electric or wood waste booster, was recommended as a low-cost energy drying plant. An alternative source to the petroleum-based energy was also discussed. The study of air flow through the timber stack in the kiln was a major part of this investigation as it is one of the principal features of the CVS process. A new technique was developed to measure the air velocity and the turbulence level %. The technique involves the integration of a hot wire anemometer, data logger, computer and computer peripherals. The air velocity profiles for twelve fan speeds, between 400 and 2200 rpm, were drawn by a computer graphical program, using data collected by the above circuit. It was obvious that the boundary layer which exists around the timber surface at the low air velocity protects the timber being processed against the high and continuously increasing temperature during the CVS drying process.

Dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. To obtain products of high quality, these so-called "special" pulps must fulfill certain requirements, such as high cellulose content, low hemicellulose content, a uniform molecular weight distribution and high cellulose reactivity. Most, if not all, of the commercial dissolving pulps accomplish these demands to a certain extent. Nevertheless, achieving high cellulose accessibility as well as solvent and reagent reactivity is not an easy task due to the compact and complex structure presented by the cellulose. In the first part of this work, three commercial monocomponent endoglucanases were investigated with the purpose of enhancing the cellulose accessibility and reactivity of a hardwood dissolving pulp. A monocomponent endoglucanase with a cellulose-binding domain (CBD) was shown to significantly improve the cellulose reactivity. The positive effect of this enzyme on dissolving-grade pulps was also observed on paper-grade pulps. The main focus of the forest industry is the production of paper-grade pulps. Paper-grade pulps are mostly produced by the kraft process. In contrast, dissolving-grade pulps are produced by the sulfite and prehydrolysis kraft processes due to the high purity required for these pulps. The kraft process is known for being the most efficient process in terms of energy and chemical recovery, which makes the production costs of paper-grade pulps lower than those of sulfite dissolving-grade pulps. Besides, the production of dissolving pulps present, among others, higher capital and chemical costs than paper-grade pulps. Therefore, the viability of converting paper-grade pulps into dissolving pulps is brought into a question. However, this task is not simple because paper-grade pulps contain a lower cellulose content and a higher hemicellulose content than dissolving pulps. They also present lower cellulose reactivity and an inhomogeneous molecular weight distribution. As a consequence, the second part of this work focused on the study of the feasibility of converting kraft pulps into dissolving pulps. Several sequences of treatments of hardwoods and non-wood pulps were investigated. The best sequence for each suitable pulp was developed, and the parameters involved were optimized. After several attempts, it was demonstrated that pulps from birch, eucalypt and sisal fulfill the requirements of a commercial dissolving pulp for the viscose process after being subjected to a sequence of treatments that included two commercial enzymes, a xylanase and a monocomponent endoglucanase, and alkali extraction steps. / QC 20101201

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<p>Syftet med den här avhandlingen var att undersöka mekaniska egenskaper hos olika arter av lövträd, och koppla egenskaperna till cell- och cellväggsstrukturen i materialet. Arterna som omfattades av undersökningen var Europeisk asp (<i>Populus tremula</i>), hybridasp (<i>Populus tremula x Populus tremuloides</i>) och ek (<i>Quercus robur</i>). Arterna inom familjen<i> Populus</i>, inklusive den snabbväxande hybridaspen, har på senare tid kommit att användas inom ett stort antal projekt inom genforskningen. Det har i sin tur ökat behovet av noggrannare bestämning av mekaniska egenskaper hos dessa arter. Ek har sedan tusentals år tillbaka varit ett populärt konstruktionsmaterial; något som har resulterat i ett stort antal arkeologiska ekfynd. Konservering av dessa inkluderar ofta dimensionsstabilisering med hjälp av polyetylen-glykol (PEG); en kemikalie som man vet påverkar de mekaniska egenskaperna. I vilken utstäckning detta sker är däremot inte helt klarlagt. Studien på euoropeisk asp och hybridasp inkluderade utveckling av en ny metod för provning av små juvenila prov i grönt tillstånd. Töjningsmätningar gjordes med hjälp av digital speckelfotografering (DSP). Axiell dragstyvhet och draghållfasthet var av speciellt intresse. Sämre mekaniska egenskaper hos hybridaspen korrelerade med medelvärden på densitet, som var lägre för hybriden än för den Europeiska aspen.</p><p> Ek undersöktes i svällt tillstånd, där svällningen inducerades med hjälp av PEG (molekylvikt 600). Axiell dragstyvhet och draghållfasthet samt radiell tryckstyvhet och ytspänning undersöktes. Töjningsmätningar i axiell riktning gjordes med hjälp av videoextensiometer, medan töjning i radiell riktning gjordes med hjälp av DSP. Övrig karakterisering av materialet inkluderade scanning electron microscopy (SEM), röntgenmikrotomografi och wide angle X-ray scattering (WAXS) för bestämning av mikrofibrillvinkel. Axiell dragstyvhet och draghållfasthet påverkades bara marginellt av PEG-behandlingen. WAXS-mätningarna visade att mikrofibrillvinkeln i materialet var mycket liten. Därigenom blir de mekaniska egenskaperna i axiell riktning till stor del beroende av mikrofibrillerna, vilket samtidigt minimerar den mjukningseffekt som PEG-impregneringen har på cellväggsmatrisen. De mekaniska egenskaperna i radiell kompression påverkades däremot starkt negativt av impregneringen. Detta antogs bero på den försvagande och uppmjukande effekt som PEG:en har på de radiellt orienterade märgstrålarna i veden.</p> / <p>The aim of this work was to investigate the mechanical properties of different hardwood species and relate the properties to the structure at the cellular and cell wall level. The species examined were European aspen (<i>Populus tremula</i>), hybrid aspen (<i>Populus tremula x Populus</i> <i>tremuloides</i>) and European oak (<i>Quercus robur</i>). The <i>Populus</i> species, including the fast-growing hybrid aspen, are used in a large number of projects using transgene technology, which also has raised the demand for a more extensive determination of mechanical properties of the species. Oak have been a popular construction material for thousands of years, esulting in a vast number of archaeological findings. Preservation of these often includes dimensional stabilization by polyethylene glycol (PEG), an impregnation agent which affects the mechanical properties. To which extent is not properly investigated, however. The study on European and hybrid aspen included development of a method for tensile testing of small, juvenile specimens in the green condition, where strain was measured using the digital speckle photography (DSP) technique. Mechanical performance of the species in terms of longitudinal tensile stiffness and strength were of special interest. Inferior mechanical properties of hybrid aspen corresponded well to mean values of density, which were lower for the hybrid aspen compared to European aspen.</p><p> Oak was examined in the swollen state, where swelling was induced by PEG with molecular weight 600. Longitudinal tensile stiffness and strength as well as radial stiffness and yield strength in compression were compared. Longitudinal and radial strain was measured using video extensiometry and DSP, respectively. Additional characterization of the material included imaging from scanning electron microscopy (SEM), X-ray microtomography and determination of microfibril angle using wide angle X-ray scattering (WAXS). Tensile stiffness and strength in the axial direction were only slightly affected by PEG-impregnation. WAXS measurements showed that microfibril angles were close to zero which implicates that cell wall properties are strongly dependent on the microfibrils, and only marginally influenced by the plasticization effects from PEG on the lignin/hemicellulose matrix. In the radial direction, on the other hand, mechanical performance was strongly decreased by PEG-impregnation. This was believed to originate from softening of rays.</p>

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Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 89-96). Also available on the World Wide Web.

Thesis (M.A.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains vi, 18 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 18).

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