The thesis studies the relationship between inter-fiber forces present within a cellulose fiber web under varying external conditions. It particularly concentrates on the degree of fiber to fiber bonding and fiber entanglement as a function of moisture content. Finite element analysis of the fiber bonding is used in conjunction with the experimental results to analyze and explain the inter-fiber behaviors taking place within a sheet.

Office waste paper is one of the fastest growing segments of the recycled fiber industry. Toner particles are rigid, insoluble and difficult to disperse and detach from fibers. Therefore papers made from recycled office waste having high toner content will contain noticeable ink particles. This work will consider an alternative way of efficient de-inking using plasma polymers which will not affect the fibers chemically or mechanically. The focus is development and characterization of plasma-deposited films to serve as a barrier film for the adhesion of ink toner to the paper fibers and thereby enhance ink lift off from the fibers. The plasma treated paper is coated with fluorocarbon (PFE) and polyethylene glycol (PFE) films, with constant thickness of PFE and varying the thickness of PEG by 1500, from 1500 to 4500, for the three cases studied (PFE greater than PEG, PFE=PEG, PFE less than PEG). Handsheets were made using virgin fibers to eliminate effects of fillers. Once the sheets were coated and printing performed, they were re-pulped and both the slurry and the de-inking surfactant were placed in a flotation cell. Handsheets were made from the collected foam and stock and were scanned for particle count. The results indicated higher ink loss for the cases with increased thickness of polymer films. A handsheet with a 7500 film (PFE = 3000 and PEG = 4500) showed 61% ink removal compared to 38% for handsheets with no film deposited. There was also less material loss for the cases with higher polymer film thickness.

The paper industry utilizes fillers either to reduce the cost or to provide desired functional or end-use properties of paper products. However, there are disadvantages associated with higher filler loadings beyond a certain level, which reduces paper strength. The present study focused on improving the physical property of filled papers. Three methods of structuring fillers were designed; precipitation with starch, complexation with starch and fatty acid, and regeneration with cellulose. Because cellulose and starch have hydroxyl groups on the chemical structure, the hydrogen bonding between fillers and wood fibers is assumed to be occurred by structuring fillers. For starch application, we used two different approaches; salt precipitation and fatty acid complexation. The cooked starch can be precipitated by certain salt solutions such as (NH4)2SO4. Also, the cooked starch can be complexed with fatty acid to produce an insoluble crystalline structure. When starch composites with clay made by both methods were put into the furnish as fillers, dramatic strength improvement was achieved such as 100-200% gains in tensile strength. This is due to the strong bonding between clay fillers and wood fibers, which is determined by Z-directional tensile strength. One of advantages is that using the starch-fatty acid complex has an inherent water repellent property, sizing effect. For cellulose as a bonding material, N-methylmorpholine-N-oxide was used as a solvent to dissolve the cellulose. The advantage of using this method is that we can use the low grade cellulose. The physical properties of the cellulose coated clay handsheets were significantly improved, but optical properties such as brightness and opacity were inferior to the hadnsheets filled with starch-clay composites due to relatively large particle size. In order to model the strength improvement by the composite filler, BDT theory, which is a modified Pages Equation, was used. After calculating the factors such as surface area and specific bond strength, the model matched well with the experimental results. Using this model, the tensile strength improvement could be predicted in terms of the change of bond strength and composite size.

The most common strategy for handling paper mill solid waste is typically disposal in landfills. However, several drawbacks are associated with this type of solid waste management, such as increasing costs due to oil price rise, governmental restrictions on land use, and environmental concerns such as leaching of disposed contaminants into groundwater, as well as methane generation of and release to the atmosphere, thus contributing to global warming. An alternative to reduce solids prior to disposal and to recover methane as a renewable fuel is anaerobic digestion, but it is not yet clear whether such an approach is feasible in paper mills. In this study, the anaerobic digestion of paper mill waste streams was evaluated for a paper plant located in Belen, Costa Rica, to investigate up to what extent certain waste streams can be anaerobically digested, to what extent energy can be produced in the form of methane for implementation in a wastewater treatment plant and to evaluate the conditions that will favor methane generation from select waste streams. Batch assays were performed to evaluate the biodegradability of single and combined waste samples under ideal, laboratory conditions. Samples were obtained from the manufacturing plant as well as the wastewater treatment plant at the paper mill under study. The ultimate biodegradability ranged 25 to 85% in terms of volatile solids destruction, corresponding to the waste activated sludge (WAS) and Flotation Cell rejects, respectively. The COD destruction of single samples ranged from 45 to 63%, corresponding to WAS and wastewater treatment plant (WWTP) dissolved air flotation (DAF) skimmings, respectively. Methane generation ranged from 80 to 190 ml at 35oC/g COD added for all single samples (excluding underflows). In combination Feed 1 was reduced by 46 and 52% and Feed 2 by 27 and 38%, respectively. Two combinations of two single samples each (Feed 1 and 2), formulated according to plant operational data, and their solids and COD destruction as well as methane generation in semicontinuous flow anaerobic digesters were evaluated at different solids retention times (30, 20, 15, and 7 days). Nutrients (N, and P) availability as well as alkalinity in the plant waste streams were evaluated and minimum supplements were used to support an efficient anaerobic digestion process. The reactors reached stable operation at all retention times evaluated. Methanogenesis was the predominant, terminal metabolic process under anaerobic, mesophilic conditions, but the overall process rate was determined by the hydrolysis of the particulate substrate. Reactors fed with Feed 1 achieved the highest level of destruction, which amounted to 85% of phosphorus that is typically present in paper mill wastes. Alkalinity addition to the feed (3.5 mg NaHCO3/L) was necessary to maintain the reactors pH above 6.9.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1942. / Includes bibliographical references (p. 106-107).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1981. / Includes bibliographical references (p. 63-65).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1981. / Includes bibliographical references (p. 67-69).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1959. / Includes bibliographical references (p. 92-95).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1961. / Includes bibliographical references (p. 161-162).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1964. / Includes bibliographical references (p. 42-44).