Thesis (Ph. D.)--Institute of Paper Chemistry, 1966. / Bibliography: leaves 98-101.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1944. / Bibliography: leaves 88-92.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1946. / Bibliography: leaves 68-69.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1953. / Bibliography: leaves 67-69.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1967. / Bibliography: leaves 66-68.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1948. / Bibliography: leaves 78-80.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1955. / Bibliography: leaves 83-85.

Lignocellulose can become the best opportunity for the society to reduce its dependency on the harmful petroleum based products as well as to produce clean energy. In each part of the production cycle, biomass based products have a better environmental profiles than their petroleum based counterparts. Woody biomass has a vast availability, but it suffers from recalcitrance that is mostly caused by lignin that is functioning as a matrix, surrounding and binding the carbohydrates that are currently the most valuable of the wood components. Lignin-carbohydrate (LC) bonds are believed to be a key element in this recalcitrance and research has shown that these types of bonds are common in wood. These bonds are important in an economical point of view as well, as e.g. residual lignin structures in pulp (lignins bonded to the cellulose and hemicelluloses) require expensive bleaching sequences for their removal. The LC-structures can also be exploited technically as we now have demonstrated. We developed a method that utilizes phenolic end groups that are bonded to different hemicelluloses for cross-linking. The enzyme laccase was used for the cross-linking to create a cost-efficient processing scheme to both isolate and increase the molecular weight of the hemicelluloses. Membrane filtration was used as the key separation technique, which enables the establishment of industrial scale production. The final product had improved mechanical and thermal properties and could be used e.g. as barrier film component in renewable packaging. Nanocomposite formation with nanofibrillated cellulose was also studied. This improved the film properties further. The complexes are also possible to use as model compounds for lignin-carbohydrate complexes in wood. This technique can also be seen to mimick the lignification and lignin-carbohydrate network formation phenomena in plants enabling the formation of entire networks of wood components. Our results suggests that the side chains of hemicellulose might play an important role in network formation and that hemicellulose molecules can carry more than one lignin phenolic end group to fulfill this capability. / <p>QC 20140825</p>

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.

Given the volatile, generally high price of crude oil, as well as environmental concerns associated with its use as a fuel, development of alternative energy sources is currently of considerable interest. Lignocellulose-derived energy has the potential to supplant traditional fossil fuels in the future because of its economic and environmental advantages. Lignocellulosic biomass is abundant and renewable. Lignocellulose is primarily composed of cellulose, hemicellulose and lignin, which can be converted by acid hydrolysis to simple sugars used in fermentation to produce biofuels. In this study, hemicellulose was hydrolyzed with different concentrations of hydrochloric acid at different temperatures. The resulting components were analyzed by high performance liquid chromatography (HPLC). The hydrolysis of cellulose was similarly characterized, with two additional parameters, the degree of polymerization (DP) and the crystallinity index (CrI), which were analyzed by Ubbelohde viscometer and X-ray diffraction respectively. The experimental results indicate that the hydrolysis rate of hemicellulose and the generation rate of furfural and 5-hydroxymethylfurfural (HMF) increased with increasing hydrochloric acid concentrations and reaction temperatures. In the selected five monosaccharides, xylose, glucose, mannose, arabinose and galactose, xylose has the highest hydrolysis rate and the accumulation of furfural during xylose hydrolysis is also the highest. Moreover, the hydrolysis rate of cellulose and the generation rate of glucose also increased with increasing hydrochloric acid concentrations and reaction temperatures. DP and CrI, both decreased when the cellulose was treated in concentrated hydrochloric acid. The rate of change of DP increased with the concentrations of acid and the reaction temperatures. The change rate of CrI increases by increasing concentration of acid and the temperature when it is above 0℃, while the CrI index decrease sharply when the reaction temperature was kept below 0℃. Experimental results also show that the hydrolysis rate of cellulose is much lower than that of hemicellulose.