As madeiras utilizadas para produção de polpa celulósica podem ser divididas em dois grupos em função da fibra: folhosas (fibra curta) e coníferas (fibra longas), as espécies de folhosas são destinadas especialmente a papéis de escrita e impressão. As principais espécies de folhosas utilizadas para produção de polpa de fibra curta em outros países são o Eucalyptus globulus (Península Ibérica e Chile), Eucalyptus nitens (Chile), Populus tremuloides (Canadá), Acacia mangium, Acacia crassicarpa (Indonésia). Este projeto tem por objetivo: avaliar e comparar o desempenho de madeiras utilizadas mundialmente para produção de polpa celulósica de fibra curta considerando parâmetros de qualidade da madeira tais como composição química, densidade básica, características anatômicas da madeira; com objetivo de fornecer informações estratégicas para o setor nacional de celulose e papel, visando o conhecimento e posicionamento em competitividade destas madeiras no mercado mundial. Para a realização deste trabalho foram coletadas 5 árvores de cada espécie as quais foram utilizados cavacos cortados manualmente obtidos de discos; com relação à madeira foram determinadas densidade básica, composição química e dimensões de fibras. Os resultados foram analisados estatisticamente sendo comparadas as diferentes espécies referentes à qualidade da madeira. / Wood used for pulp production may be divided in two major groups regarding fiber function: hardwood (short fiber) and softwood (long fibers). Hardwood species are mainly designated to writing and printing papers. Hardwood principal species used for production of short fiber pulp in other countries are Eucalyptus globulus (Iberian Peninsula and Chile), Eucalyptus nitens (Chile), Populus tremuloides (Canada), Acacia mangium and Acacia crassicarpa (Indonesia). This study aimed to evaluate and compare the performance of the main woods used worldwide for short fiber pulp production regarding wood quality parameters such as chemical composition, basic density and wood anatomical properties, in order to provide strategic information for national pulp and paper industry, aiming the knowledge and competitiveness of these woods at worldwide market. To accomplish this study, 5 trees from each species were collected and wood chips were manually cut. In relation to the wood, basic density, chemical composition and fiber lengths were determined. The results were statistically analyzed and the different species were compared regarding wood quality.

The effectiveness of using commercial polyethylene flashing and stainless-steel mesh in CLT wall systems as the termite barriers were evaluated in a short-term field test. American Wood Protection Association (AWPA) E21's visual ratings ranged from 10 to 9 in the specimens showing little damage when no physical barriers were used. Termites were able to crawl beyond the physical barriers in few specimens showing the necessity of further research on height and installation method of physical barriers. On the second part, the effect of decay caused due to Postia placenta, a brown-rot fungus, on the structural performance of hold-down brackets connected to CLT walls was evaluated using monotonic and cyclic loadings. An increase in moisture content reduced the strength of the connection system but increased the initial stiffness. Decay caused delamination of CLT laminate perpendicular to the grain, a different failure pattern, compared to the wet control and dry control specimens.

Literature shows that production of cottonseed adhesives is feasible to develop an environmentally friendly and competitive bio-based wood adhesive. Defatted cottonseed and water-washed cottonseed meals were prepared from glandless cottonseed and were used in adhesive formulations to produce three-ply yellow poplar (Liriodendron tulipifera) plywood panels as the first objective. These two cottonseed meals were compared with the properties of plywood panels made with an adhesive formulated from a commercial soybean meal, as a control. Adhesive resins were prepared from each protein meal with sodium metabisulfite (Na2S2O5) and one of two polyamido-amine-epichlorohydrin (PAE) wet strength agents, and the plywood panels were produced by hot pressing for 7, 8.5 and 10 minutes at 135°C with a constant pressure of 1.241 MPa. Panels prepared from three protein meals had comparable shear strengths. The combinations of the two cottonseed preparations and the two wet strength agents produced panels with acceptable wet resistant properties, whereas the soybean meal only produced acceptable panels with one of the wet strength agents. Because the panels prepared from the two cottonseed meals had comparable properties, there appears to be no benefit to including a water-washing step to increase the meal’s protein level. The second objective of this research was to reduce the hot press time and develop cottonseed meals into adhesives to become comparable to commercial soybean-based adhesives. New cottonseed, water-washed cottonseed, and commercial in-house soybean meals were separately prepared with deionized water, sodium metabisulfite, and PAE to produce three-ply yellow poplar plywood panels. The panels were hot pressed for 4, 5, and 6 minutes at 135°C with a constant pressure of 1.241 MPa. Panels prepared from the three meals and commercial soybean plywood panels had comparable mechanical shear strengths and water resistance properties. Results indicated that press time, meal types, and interactions were statistically significant. Shear strength results indicate that cottonseed could be used alternatively to soybean. The new cottonseed panels were more resistant to delamination than soybean. The cottonseed meals showed great promise for applicability as a formaldehyde-free, bio-based, and environmentally friendly hardwood plywood wood-based adhesives product for use in interior type applications.

Interest in the use of mass timber in building and construction is growing worldwide, this is due to the structural integrity and reduced environmental footprint of timber-based structures. Concerns associated with the biological and environmental degradation of mass timber necessitate the development of adequate protection strategies to ensure the durability of these products. Preservative treatment is a proven technique that increases the durability and performance of wood in-service and can also be applied to large-sized timber panels such as cross-laminated timber (CLT). Therefore, this study focused on investigating the feasibility of treating prefabricated 3- and 5-layer CLT panels with Copper-azole type C (CA-C) and micronized copper azole (MCA) preservatives. Further, we studied the effects of panel layup and thickness on the preservative impregnation in CLT. Based on the experimental results, we found adequate preservative penetration and retention in the treated 3- and 5-layer CLT panels, particularly in CA-C treated panels. Also, the lengthwise layup shows better treatment results in both CA-C and MCA-treated panels. In addition to the preservative-treatment of CLT panels, this dissertation covers the development of lignin-reinforced polyurethane adhesive (PUR) for bonding glue-laminated timber (Glulam). Herein, the glulam were fabricated and bonded using lignin-reinforced PUR at different wt% (1, 2, and 3) and tested for shear strength, wood failure and delamination. The lignin-treated PUR samples showed improved adhesion properties via high shear strength and reduced delamination compared to the control specimens. Thus, the lignin-reinforced PUR adhesive shows great potential as a bio-based and environment-friendly wood adhesive for producing glulam used in structural applications.

Greenhouse gas emissions are one of the critical factors that affect climate change, increasing flooding risk and threatening human life. The use of traditional construction materials is responsible for a higher percentage of global greenhouse gas emissions when compared to the use of sustainable materials in the construction industry. The substitution of current building materials with sustainable materials is essential to reduce greenhouse gas emissions and positively influence climate change when the current construction demand in the world is considered. Wood is one of the primary environmentally friendly construction materials in regard to high carbon storage and low carbon emissions. Cross-laminated timber (CLT) is prefabricated and this type of composite wood material is convenient for constructing middle to high rise buildings because materials are able to be cut to specific specifications which lowers onsite labor time. This research observed the hygrothermal behavior of partially submerged CLT wall panels during the wetting and drying period and simulated the flooding of the panels with a software tool, Wärme Und Feuchte Instationär (WUFI). The higher number of CLT layers caused a slower water penetration rate throughout the layers with a lower water absorption rate corresponding to the first layer than the other layers, so the water was primarily retained in the first layer. Also, water penetration through axial direction significantly decreased due to gravity impact when the height of CLT panels was increased. The visual assessment showed that the 3-day-wetted CLT panel configurations did not show any type of fungi growth through the wetting and drying period. However, both untreated and treated CLT panels with the envelope system did have fungi growth on the drywall after a 20-day-wetting period.