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Thesis (Ph. D.)--Institute of Paper Chemistry, 1952. / Includes bibliographical references (p. 154-157).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1984. / Includes bibliographical references (p. 83-86).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1979. / Includes bibliographical references (leaves 81-82).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1976. / Bibliography: leaves 93-95.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1966. / Bibliography: leaves 82-84.

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

A unique penetration instrument has been developed to evaluate the role of surfactants in kraft pulping process. This instrument can screen surfactants which can improve the wood impregnation more effectively and much faster than pilot-plant experiment. The role of surfactants in wood penetration has been explored. Surfactants can improve wood impregnation by dispersing the extractives in the wood structure and optimizing the interfacial properties between wood surface and kraft liquor. The addition of two blends of anionic and nonionic surfactants into kraft pulping process results in a significant reduction of the screen rejects and an increase of screened yield at the same delignification rate. / Six wood species were tested in this study including both non-resinous and resinous wood species. Both sapwood and heartwood of these species were tested. Surfactants were found to have no improvement on sapwood, but a significant improvement on heartwood. The critical micelle concentrations (CMC) of surfactants in kraft liquor were determined. The best dosages of surfactants based on CMC were also determined in this study.

Xylanase production from a Bacillus subtilis gene cloned into a strain of Escherichia coli was measured. Although this gene was expressed in E. coli at several temperatures, efficient normal xylanase secretion did not occur, the observed protein release apparently depending on cell leakage or lysis. Screening for a better microbial protein secretor free of cellulase selected B. cereus #259. The strain had wild plasmids that were hard to eliminate using acridine orange and elevated temperature curing techniques. While still bearing 5 wild plasmids, attempts to transform B. cereus #259 were unsuccessful using conventional methods and electroporation. Another strain, B. cereus #518, found to be free of wild plasmids, was then used. A bidirectional vector shuttle plasmid (pMK3) was employed to carry the cloned gene into this B. cereus strain. Transformation was carried out by high voltage electroporation. Xylanase production by the new B. cereus clone was similar to that from E. coli, but was shown to be continuously and normally secreted. The xylanase gene products from the E. coli and B. cereus hosts were shown to function identically. Both xylanases improved the delignification of unbleached softwood and hardwood kraft pulps, thus reducing the Cl$ sb2$ required to achieve a given degree of bleaching, without altering the physical properties of the fibers. Using a target kappa number lignin content) of 5, xylanase pretreatment of aspen kraft pulp led to a 22% saving of chlorine. Adsorbable organic halogens in the bleachery effluent were also lowered by more than 50%.

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