Quantitative methods for sulphate and Na-base bisulphite micro-pulping and micro-analytical procedures were developed. Raw pulp and pulp carbohydrate yields were correlated with relative position within growth increments of black spruce and Douglas fir. Profiles varied at different pulp yield levels and with pulping process. No profiles were simply correlated with wood micro-specific gravities. Maximum raw pulp and pulp carbohydrate yields within growth increments shifted from earlywood to latewood as yield changed from high (80 ± 5%) to low (45 ± 5%) levels. Delignification rate differed within increments for both pulping processes. In the initial sulphate and Na-base bisulphite cooking stage, latewood lignin seemed to be more easily removed than that from earlywood. At high yield levels (80 ± 5%), the pulp residual lignin contents based on oven-dry pulp followed similar patterns in that maxima were found in early-wood, abruptly decreasing in the transition zone then slightly increasing in the latewood portion. At low yield levels (45 ± 5%), the residual lignin patterns varied slightly, or remained constant throughout the whole increment. Raw pulp yields, residual lignin contents and pulp carbohydrate yields (based on extractive-free water-free wood) were not significantly different for combined data of heartwood and sapwood, the two woods and two pulping processes, except for Na-base bisulphite pulp carbohydrate yields which showed significantly higher values for sapwood. Sulphate raw pulp yields and residual lignin contents obtained by combining data from all cooking levels and wood zones were not significantly different between the two species examined, except for Douglas fir carbohydrate yield which was significantly higher than that of black spruce. For Na-base bisulphite pulping, Douglas fir raw pulp yields and pulp carbohydrate yields were highly significantly greater than those from black spruce, whereas pulp residual lignin was not significantly different. / Forestry, Faculty of / Graduate

Initiation and maintenance of motion within a pulp suspension is necessary for effective mixing. This requires imposition of forces greater than the network strength and depends on suspension rheology once motion begins. As pulp suspensions display non-Newtonian and solid-like behaviour, studies were conducted using profiled rotors which imposed stress within the body of suspensions contained in cylindrical devices. A concentric cylinder device capable of high torques (85 N-m) and high rotational speeds (524 rad/s) was built to study pulp suspension dynamic behaviour. Most work used a profiled rotor 0.1 m in diameter with baffled housings 0.13 and 0.22 m in diamter. The yield stress of low consistency pulp suspensions were measured with a Haake RV12 Ro-tovisco concentric cylinder viscometer. Semi-bleached kraft pulp was used throughout the study. Some tests were made with stone groundwood and thermomechanical pulps. Yield stress measurements were made for nylon and Spectra-900 fibre suspensions. The yield stress of pulp suspensions, ty, have been measured and correlated with mass concentration (Cm) and volumetric concentration (Cv) over the range 0.4 ≤ Cm(%) ≤ 33. It was found that because of increasing gas content that correlations developed using the mass concentration were inaccurate above approximately 20% Cm. Correlations developed using the volumetric concentration were accurate over the full range tested. For a West-Coast semi-bleached kraft pulp, ty(Pa) = 1.40CV(%)²ֹ⁷². Once rotor motion was initiated, pulp suspensions exhibited two distinct regimes of behaviour. The first was a tangential-cavity regime in which predominantly tangential motion grew to fill the chamber as shear rate increased. When motion reached the outer housing wall a flow transition occurred, likely triggered by flow interaction with the housing baffles. The subsequent post-transition regime was characterized by radial and axial flow that effectively mixed the suspension on both the macroscale and fibre-scale. The flow transition appeared to be what earlier workers reported as the onset of "fluidization". During tangential-cavity flow, phase segregation occurred. Gas present in the suspension collected around the rotor and reduced momentum transfer from the rotor to the suspension. This caused the torque for the pulp suspension to fall below that for water at the same rotational speed, and the cessation of flow development in the chamber. If sufficient momentum transfer was attained to initiate post-transition flow, the chamber contents became effectively mixed. The torque could still fall below that of water depending on the effective density of the suspension in the rotor vicinity. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Indiana University-Purdue University Indianapolis (IUPUI) / The pulps of 112 permanent teeth of monkeys were surgically exposed and left open to the oral environment for 25 to 27 hours. Then one-third of the exposed, infected pulps were capped with a paste of calcium hydroxide and tap water; one-third were treated with an antibiotic paste compased of erythromycin estolate 10 per cent, streptomycin sulfate 10 per cent, and starch q.s. as the vehicle; and one-third were treated with a paste of zinc oxide powder, one drop of eugenol and one drop of formocresol. The teeth were extracted after one and two years post-operative intervals and were microscopically evaluated. The calcium hydroxide treated teeth had the highest percentage of satisfactory pulpal responses (91.6 per cent). The antibiotic treated teeth were considered to have had satisfactory pulpal responses in 87.5 per cent and the zinc oxide, eugenol and formocresol treated teeth showed satisfactory pulpal response in only 58.0 per cent of the teeth treated with this paste. After two years, several of the antibiotic teeth were considered to have had a satisfactory pulp response even though the calcific bridges were incomplete. The histologic findings were encouraging with calcium hydroxide and the antibiotic paste and warrant clinical investigations.

Indiana University-Purdue University Indianapolis (IUPUI) / The study compared pulp reactions to a synthetic hydroxyapatite and to calcium hydroxide with either one percent chlorhexidine or distilled water as a mixing vehicle. Forty-seven permanent teeth of two monkeys were mechanically exposed under aseptic conditions. The pulps were then capped with one of the following: synthetic hydroxyapatite mixed with chlorhexidine; synthetic hydroxyapatite mixed with water; calcium hydroxide mixed with chlorhexidine; calcium hydroxide mixed with water. Small square sheets of gold foil were then placed over the capping material. A base of IRM was placed and the cavities were restored with amalgam. The teeth were extracted at 14 and 90 days after pulp capping. The specimens were fixed in 10% formalin and decalcified in 5% formic acid. Serial sections 7 microns thick were prepared and stained with hematoxylin and eosin. The synthetic hydroxyapatite mixed with one percent chlorhexidine or water was well tolerated by the dental pulp. Complete bridging occurred infrequently in the specimens capped with the hydroxyapatite, compared to those capped with calcium hydroxide, which usually showed complete bridging of the exposure.

Indiana University-Purdue University Indianapolis (IUPUI)

Indiana University-Purdue University Indianapolis (IUPUI)

Indiana University-Purdue University Indianapolis (IUPUI) / A study was made to develop a method for investigating the quantity and location of vascular leakage during acute inflammation of the dental pulp. Use was made of the method of "vascular labelling" by which carbon particles placed in the blood are deposited in the walls of leaking vessels. Three dogs were used, with cavities of varying depth being cut in their permanent teeth. Vascular leakage was induced in the skin and in some of the teeth by applying histamine phosphate solution. The tissues were studied in normal histologic sections and as cleared specimens. It was found that the number of leaking vessels was much less in the dental pulp than in the skin and that leakage was confined to the area immediately below the cavity preparation unless histamine had been applied to the cavity, when the labelled vessels were found further apically. The number of leaking vessels depended on the depth of the cavity, becoming greater as the cavity depth increased. These findings would support the common finding that the degree of inflammation beneath cavity preparations increases with cavity depth. The conclusion was that the method developed held promise as a tool in investigating vascular changes in the dental pulp.

No description available.

The thesis proposed technology to graft polymers to wood pulps. / The value and performance of Canadian premium NBSK pulps can be enhanced by attaching copolymers of maleic anhydride (MA) to the fiber surfaces, thus leading them to new applications. Kraft pulps can be treated with MA copolymers as it enters the pulp drying machine, where drying and heating results in polymer fixation. However, polymers capable of forming covalent linkages with cellulose tend to be good adhesives, dried market pulps usually cannot be redispersed (repulped). By carefully controlling the curing conditions (i.e., the time, temperature, and pH of the polymer solution) it is possible to fix MA copolymers to pulp fibers, while also maintaining repulpability. The impact of curing on repulpability can be probed by measuring the wet tensile indices of impregnated, cured pulp sheets. We have shown that the curing conditions can be condensed into a single parameter, the product  , where  is the estimated conversion of succinic acid moieties to the corresponding anhydrides during curing, and  is the amount of added MA copolymers. A survey of the common commercial MA copolymers identified high molecular weight (Mw) PEMA (100-500 kDa) as the most promising option, as it is possible to graft 1 and 29 kg of PEMA to each tonne of dried untreated pulp in high yield while still maintaining repulpability. PEMA grafting enhances the properties of pulp and paper in many ways, including increasing fiber swelling, increasing adsorption capacity of cationic additives, and increasing wet and dry paper strength. / Thesis / Candidate in Philosophy / Canada is home to 9% of the world’s forests, and a forestry industry that accounts for approximately $23.7 billion of its gross domestic product (GDP) in 2019. Pulp and paper manufacturing is an important subsector in the forestry industry, contributing roughly $7 billion to Canada’s real GDP each year. In 2019, 15.4 million tonnes of wood pulp were produced, with pulp and paper exports totalling $17.7 billion. Clearly, the pulp and papermaking industry is an integral part of the Canadian economy. Canada is a leading global supplier of wood pulp, and the largest producer of northern bleached softwood kraft (NBSK) market pulp. NBSK pulp has become the industry’s benchmark grade pulp due to its long fibers, which makes them ideal for reinforcing paper. The core objective of this research is to expand the properties of NBSK pulp by attaching polymers to the fiber surfaces, thus making them suitable for completely new high-value-added applications. This thesis describes a completely new technology that I have developed for grafting functional polymers onto market pulps. The resulting novel market pulps are characterized by high carboxyl group content that can give stronger products and a “clickable” surface suitable for biomedical and other novel applications.

Indiana University-Purdue University Indianapolis (IUPUI) / This was a histologic study of continued apical development in the pulpless permanent teeth of dogs. The vital pulps were exposed to the oral fluids for one week. The root canals were filled with either calcium hydroxide and camphorated parachlorophenol (CMCP) or calcium hydroxide and distilled water. A vital dye, Procion red was injected to demonstrate the formation of calcified tissue. After four months, the animals were sacrificed. Decalcified semi-serial sections were studied. In 31 of 61 pulpless permanent teeth, with incompletely developed roots, continued apical development occurred. Apical calcified tissue resembling cementum was observed in 55 per cent of the specimens treated with calcium hydroxide and CMCP and in 42 per cent of those, with calcium hydroxide and distilled water. Complete closure of the apical foramen was observed in 29 and 11 per cent of the specimens respectively. Inflammation of the periapical tissues was present in 48 per cent of the calcium hydroxide and CMCP group and in 79 per cent of the other group. A significant association was found between the degree of inflammation and apical closure, (P<.001) for the calcium hydroxide-CMCP group, (P<.005) for the calcium hydroxide-distilled water group. The results suggest that calcium hydroxide and CMCP was superior to calcium hydroxide and distilled water and that the addition of CMCP to the paste reduced inflammation. Procion dye was shown to be an effective in vivo dental hard tissue marker.