Thesis (Ph. D.)--Institute of Paper Chemistry, 1971. / Includes bibliographical references (p. 111-114).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1972. / Includes bibliographical references (p. 78-81).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1964. / Includes bibliographical references (p. 64-66).

Nano-cellulose fibers/suspension has very high viscosity, its viscosity has to be lower before it can be applied in the paper coating recipe. For this purpose the adsorption behaviour of polyvinyl alcohol on nano-cellulose fibers were investigated using method developed by Zwick in 1960, based on the formation of PVA-iodide blue complex in the presence of boric acid. The experiments showed that the maximum adsorbed amount i.e. 0.13 g PVA/g NFC was obtained in a dispersion with 0.2 % PVA concentration. It should be possible to further increase the PVA adsorption as the adsorbed amount didn’t reach a saturation point where the PVA adsorption attained a constant value. It was also found that adsorption of PVA on NFC is time dependent. The absorbance measurement after four days of mixing PVA/NFC suspension showed only partially adsorption of PVA on nano-cellulose surface.  An equilibrium time of 10-13 days was needed for PVA to fully adsorb on nano-cellulose fibers surface. Another important observation was that PVA adsorption also depends on the concentration of nano-cellulose fibers. A lower concentration of NFC easily allows PVA to adsorb on its surface, as compared to higher NFC concentration. An important finding during the methodology development was the method to get rid of formation of flocs in the blue iodide complex solution; by slowly addition of reactants, especially the KI/I2 solution under continuous stirring around 60oC the tendency to flocs formation was suppressed.

Sodium hydroxide can cause cellulose to swell and can even dissolve cellulose in a narrow range of the phase diagram. It was found that for cellulose with low to moderate degree of polymerization, the maximal solubility occurs with 8~10% soda solution. In recent years, researchers found that sodium hydroxide with urea at cold temperature can dissolve cellulose better than sodium hydroxide alone. However, the lack of sufficient understanding of the NaOH and NaOH/urea dissolution process significantly constrains its applications. In order to fully understand the cellulose dissolution in alkali system, there are several aspects of problems that need to be addressed. Our focus in this study is in the interaction of cellulose with alkali solution at low temperatures, the improvement of its solubility, and the effect of hemicellulose and lignin.

Low cost cellulosic wastes like paper sludge, municipal wastes, solid wastes from food, packing etc. contain a high amount of cellulose which can be converted to bioethanol by two steps: (1) solubilization of cellulosic fibers to monosaccharides (2) conversion of monosachharides to bioethanol via fermentation. At present the implementation of this technology has been deterred by high cost for enzymes. Enzymatic hydrolysis of cellulosic fibers shows a biphasic behavior with an initial fast step followed by a slow step leading to low cellulose conversion rates. Low hydrolytic conversion rates necessitate the use of a high enzyme dosage to obtain meaningful cellulose conversion rates which make the implementation of this entire technology economically infeasible. The objective of this study is to get a better understanding of the mechanism of enzymatic hydrolysis of fibers to glucose and to investigate the effect of cationic polymers on enzymatic hydrolysis rates. To achieve the first objective, we performed experiments so as to study changes in morphological and physiochemical properties like fiber length, percentage of fines, crystallinity index, kink angle, kink index, mean curl, total organic carbon and glucose production with time. We used bleached kraft softwood, hardwood, and unbleached softwood fiber as cellulosic substrate and pergalase as cellulase enzyme. All of the experiments were carried out at experimental conditions of a temperature of 50 .C and a pH of 5.0 which maximize enzymatic activity. We studied the impact of recycling and refining on hydrolysis rates by measuring total organic carbon and glucose production. We found that refining increases enzymatic conversion rates by about as much as 20 %, however refining being energy intensive makes its implementation economically unfavorable. We found a novel way of enhancing hydrolysis rates by the use of cationic polyacrylamides. The effect of cationic polacrylamides was studied on both hardwood and softwood fibers at similar experimental conditions. Cationic polyacrylamides produced a maximum rate increase of 20 % in hydrolytic conversion rates for hardwood fibers. Even though, the increase in hydrolysis rates for softwood fibers was smaller than hardwood fibers, it was still significant. We further studied the effect of parameters like polymer concentration, cationicity and molecular weight to find a relation between properties of polymers and the increase in enzymatic hydrolysis.

Thesis (M.S.)--University of Central Florida, 2008. / Adviser: Michael Sigman. Includes bibliographical references (p. 143-147).

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The thesis deals with the properties of epoxy resins, their reinforcing by thermoplastic modified epoxies, rubbers and cellulose fibers. The thesis also describes the production, properties and types of cellulose fibers. In the practical part of this thesis, there was executed reinforcement of epoxy matrix by different amounts of cellulose fibers. Mixing was performed in two ways – by a homogenizer or an ultrasonic homogenizer. There were also executed the tensile strength and shear strength tests to the manufactured conglomerates.

The subject of this project is to study spun cellulose fibers made by Spinnova Oy inFinland. The fibers are spun using an environmentally friendly spinning process withoutuse of harsh chemicals.The spun filaments and the yarn based on these filaments were characterized and usedas reinforcement in polylactic acid biopolymer (PLA) and in biobased epoxy resin. Acomprehensive mechanical and morphological characterization of the single filamentsand their yarn was conducted. It was found that the single filaments are flat with a largewidth/thickness ratio, they are porous especially on one side and some cellulosemicrofibril orientation is observed on the filament surface. The single filaments are stiffand strong if compared to commercial regenerated cellulose filaments but are difficultto handle as they are very small and extremely light. The yarn showed to have lowermechanical properties but is easier to handle during the process of compositemanufacturing. Unidirectional fiber-reinforced composites were made using theSpinnova-yarn and PLA polymer applying film-stacking processing method. Thecomposite mechanical properties were studied and the results showed that themechanical performance of the PLA was significantly improved. The strength improvedfrom 54 MPa of the neat PLA to 95 MPa and the stiffness from 3.4 to 8.6 GPa withaddition of 22 wt% Spinnova-yarn.The main challenge of the project was handling the single filaments and their yarn todevelop a suitable manufacturing process which allows to exploit the potential of themto obtain a homogeneous fiber “preform” and to achieve good impregnation with the PLA matrix.