Due to increasing shortage of wood supply and higher environmental concerns with the depletion of forest resources, in recent years, there is a strong interest in using forest and agricultural residues for development of value added products. Bark is a mill-waste residue, available in plenty, having limited uses and causing disposal problems. Bark possesses a large amount of phenolic compounds, which can act as an adhesive in making panels, however only limited research has been done in this area. The main objective of this project is to develop bark-based environment-friendly panels with and without synthetic resins, using mountain pine beetle infested lodgepole pine barks. Analysis of bark constituents, barkboard development, mechanical properties evaluation, characterization and improvement tests were performed. Various results support the possibility of bark utilization for barkboards production; however, more research is required for further improvements and feasible commercial production process.

Due to increasing shortage of wood supply and higher environmental concerns with the depletion of forest resources, in recent years, there is a strong interest in using forest and agricultural residues for development of value added products. Bark is a mill-waste residue, available in plenty, having limited uses and causing disposal problems. Bark possesses a large amount of phenolic compounds, which can act as an adhesive in making panels, however only limited research has been done in this area. The main objective of this project is to develop bark-based environment-friendly panels with and without synthetic resins, using mountain pine beetle infested lodgepole pine barks. Analysis of bark constituents, barkboard development, mechanical properties evaluation, characterization and improvement tests were performed. Various results support the possibility of bark utilization for barkboards production; however, more research is required for further improvements and feasible commercial production process.

Borate can be a potential candidate to protect building envelope components from biodegradation as it has low toxicity and can penetrate wood without pressure treatment, even in the refractory species commonly used in construction industries as structural components. In this research, wood moisture content, grain direction, formulation and species that affect the diffusion of borate in refractory species were investigated. Two highly concentrated formulations were applied and a novel approach (borate bandage) was used to keep the preservative on the surface and enhance the diffusion by reducing surface drying. From ANOVA test for different diffusion periods and depths of penetration, it was found that grain directions and moisture content are significant factors. A mould test was performed, the diffusion co-efficients were calculated and some recommendations were made about the quantity required to protect a specific volume of wood considering the distance moved by diffusion and volume treated in different directions.

Borate can be a potential candidate to protect building envelope components from biodegradation as it has low toxicity and can penetrate wood without pressure treatment, even in the refractory species commonly used in construction industries as structural components. In this research, wood moisture content, grain direction, formulation and species that affect the diffusion of borate in refractory species were investigated. Two highly concentrated formulations were applied and a novel approach (borate bandage) was used to keep the preservative on the surface and enhance the diffusion by reducing surface drying. From ANOVA test for different diffusion periods and depths of penetration, it was found that grain directions and moisture content are significant factors. A mould test was performed, the diffusion co-efficients were calculated and some recommendations were made about the quantity required to protect a specific volume of wood considering the distance moved by diffusion and volume treated in different directions.

The preservative concentration difference in treated wood was investigated to understand the component distribution; a study of different chemical extractions of treated wood waste was carried out and certain reagents were realized to be feasible to the preservative component removal. During fixation, the preservative components redistributed between earlywood and latewood and concentration gradients at depths also developed. Different solvent extractions of CCA treated wood were tested and ion exchange, chelation and metal dissolving were all mechanisms for component extraction. The transition of Cr(III) to Cr(VI) by oxidizing reagents (NaClO and H2O2) can make possible the direct reuse of extracted chemicals as a preservative. Different reaction factors in the oxidant extractions were compared and higher pHs significantly improved the oxidizing capability of the reagents and CCA component removal. Fresh and aged CCA treated wood generally responsed similarly to the oxidant extractions. However, arsenic in aged wood was more difficult to be removed by NaClO, while, H2O2 was more efficient to extract CCA components from aged wood than fresh wood. Monoethanolamine (Mea) efficiently extracted copper (above 90%) from ACQ treated wood and the formation of stable neutral Cu(Mea)2 in sufficient Mea solution is the main mechanism for Mea extraction. Little wood structure degradation occurred during the process. Mea (10%~15%) extraction was fast and the effect of temperature was insignificant. Cu diffusion in the longitudinal direction was the most significant compared to other wood directions. To further promote Mea extraction, repeated extraction (batch-based and column-based) was performed and proved to be more efficient, feasible and economical than one-time extraction. Column-based continuous Mea extraction showed both high Cu removal (up to 99%) and Cu accumulation in the extract. After the preservative treated wood waste is decontaminated significantly, the extract solution can be reused by directly mixing with the preservative treating solution, which is the most straightforward procedure for the recycling of chemicals removed from the preservative treated wood.

The preservative concentration difference in treated wood was investigated to understand the component distribution; a study of different chemical extractions of treated wood waste was carried out and certain reagents were realized to be feasible to the preservative component removal. During fixation, the preservative components redistributed between earlywood and latewood and concentration gradients at depths also developed. Different solvent extractions of CCA treated wood were tested and ion exchange, chelation and metal dissolving were all mechanisms for component extraction. The transition of Cr(III) to Cr(VI) by oxidizing reagents (NaClO and H2O2) can make possible the direct reuse of extracted chemicals as a preservative. Different reaction factors in the oxidant extractions were compared and higher pHs significantly improved the oxidizing capability of the reagents and CCA component removal. Fresh and aged CCA treated wood generally responsed similarly to the oxidant extractions. However, arsenic in aged wood was more difficult to be removed by NaClO, while, H2O2 was more efficient to extract CCA components from aged wood than fresh wood. Monoethanolamine (Mea) efficiently extracted copper (above 90%) from ACQ treated wood and the formation of stable neutral Cu(Mea)2 in sufficient Mea solution is the main mechanism for Mea extraction. Little wood structure degradation occurred during the process. Mea (10%~15%) extraction was fast and the effect of temperature was insignificant. Cu diffusion in the longitudinal direction was the most significant compared to other wood directions. To further promote Mea extraction, repeated extraction (batch-based and column-based) was performed and proved to be more efficient, feasible and economical than one-time extraction. Column-based continuous Mea extraction showed both high Cu removal (up to 99%) and Cu accumulation in the extract. After the preservative treated wood waste is decontaminated significantly, the extract solution can be reused by directly mixing with the preservative treating solution, which is the most straightforward procedure for the recycling of chemicals removed from the preservative treated wood.

Xylan is one of the major hemicelluloses present in plant cell wall matrix, where it is closely associated with other cell wall components, cellulose and lignin. Xylan has enormous potential as a renewable biopolymer and recently, research in the direction of isolation and utilization of xylan is gaining lot of research attention. Extraction of xylan from the plant cell walls involves the hydrolysis of xylan and its transfer from the plant cell wall matrix to the hydrolyzing media. Current process of extraction involves prolonged heating of the biomass with the hydrolysis media at high temperature and/or pressure that leads to molecular degradation of xylan and limits its high potential polymeric applications. In this research, microwave assisted alkaline extraction of polymeric xylan from birch wood is investigated as an alternative to the time intensive conventional extraction. The hypothesis to be tested is that the microwave’s selective heating ability leads to the generation of hot spots through its interaction with the alkali present in the fibers and the resulting "explosion effect" loosen the recalcitrant fiber structure network thereby facilitating the hydrolysis of xylan and its dissolution before undergoing significant degradation. Effect of microwave extraction on the yield of xylan and wood solubilization, physico-chemical properties of wood fibers and of isolated xylan were investigated in comparison with conventional extraction. Low power input microwave (110 W) alkaline extraction was found to be an efficient alternative to the conventional extraction. FTIR and chemical composition of wood fibers after extraction demonstrated an increased removal of xylan from the wood fibre using microwave extraction. SEM, X-ray microtomography, and X-ray crystallinity studies of wood fibers demonstrated a porous and loosened fibre structure after microwave extraction confirming the hypothesis. Molecular weight of the isolated xylan using microwave extraction was found to be higher compared to the xylan isolated using conventional extraction indicating less molecular degradation. About 75% of xylan present in birch wood could be extracted using a low power input microwave heating under optimized extraction conditions of 8wt% NaOH solution, 1:8 (g:mL) solid to liquid ratio, and 25 minutes of extraction time.

Modern biorefineries provide a framework for the sustainable conversion of biomass to biofuels and biochemicals. In light of the recalcitrance of lignin in woody feedstocks, the native shrub eastern leatherwood is proposed as a model hypolignified species. Xylem tissue of this low-lignin plant contained syringyl-rich lignin that was more easily hydrolysed and did not appear to be localised in the middle lamellae. Also, leatherwood cellulose was less crystalline and the xylan was highly acetylated. While viable low-lignin plants will enable the sustainable utilisation of woody feedstocks, high-value bioproducts are needed to economise future biorefineries. The carbohydrate oxidoreductases galactose oxidase and glucooligosaccharide oxidase were studied for use in the oxidation and derivatisation of plant-derived polysaccharides for the production of such high-value bioproducts. The carbohydrate-binding module of galactose oxidase was necessary for recombinant protein production. Also, a mutant library of glucooligosaccharide oxidase variants was produced to generate enzymes with novel activity.

Modern biorefineries provide a framework for the sustainable conversion of biomass to biofuels and biochemicals. In light of the recalcitrance of lignin in woody feedstocks, the native shrub eastern leatherwood is proposed as a model hypolignified species. Xylem tissue of this low-lignin plant contained syringyl-rich lignin that was more easily hydrolysed and did not appear to be localised in the middle lamellae. Also, leatherwood cellulose was less crystalline and the xylan was highly acetylated. While viable low-lignin plants will enable the sustainable utilisation of woody feedstocks, high-value bioproducts are needed to economise future biorefineries. The carbohydrate oxidoreductases galactose oxidase and glucooligosaccharide oxidase were studied for use in the oxidation and derivatisation of plant-derived polysaccharides for the production of such high-value bioproducts. The carbohydrate-binding module of galactose oxidase was necessary for recombinant protein production. Also, a mutant library of glucooligosaccharide oxidase variants was produced to generate enzymes with novel activity.

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.