A piezo-ceramic sensor was developed to measure normal and tangential shear forces applied to a bar at one location in the refining zone of a Sunds Defibrator Conflo® JC-00 refiner. Testing was completed at the Pulp and Paper Research Institute of Canada in Vancouver. BC using CTMP pulp with a stock consistency of 3.15%. Distributions have been determined for peak normal and shear forces. peak coefficient of friction. shear work. and shear lead. These distributions were analysed to assess possible correlations with specific edge load. Force magnitudes were found to increase with an increase in specific edge load. The peak coefficient of friction was calculated that ranged from 0.13 to 0.16. Both the normal and shear force magnitudes varied by as much as a factor of 3, due to rotor out-of-tram of only 0.06 mm. These distributions could provide greater insight to the mechanisms responsible for fibre development in papermaking and thus "In Process" control of various refiner conditions.

Thesis (Ph.D) -- McMaster University, 1997. / Includes bibliographical references. Also available via World Wide Web.

Thesis (MSc (Forest and Wood Science))—University of Stellenbosch, 2005. / In this study the mechanical pulping characteristics of Solanum mauritianum (Bugweed) were investigated using Thermomechanical (TMP), Chemithermomechanical (CTMP) and Biothermomechanical (BTMP) methods. Results were compared with those obtained from Pinus patula pulps treated under similar conditions. In the TMP pulping trials, the pretreatment of wood chips involved soaking of chips in water overnight prior to refining. The CTMP pulping trials involved first the impregnation of wood chips with 3% sodium sulfite and 2% sodium carbonate solution for 24 hours before refining. Coculture of hemicellulolytic Aspergillus flavipes and ligninolytic Pycnoporus sanguineus were inoculated to the wood chips in BTMP trials, to enhance wood chip breakdown. Solanum mauritianum (Bugweed) wood chips produced the highest pulp yields and less shive content compared to Pinus patula treated under similar pulping conditions. This could be ascribed to easier fibre separation and lesser fibre damage, as well as its lower extractive content. Results showed that the pretreatment of wood chips prior to TMP pulping increased paper strength properties compared to the pulp prepared from the untreated wood chips. Chemically pretreated wood chips consumed a larger amount of refining energy. With regard to brightness levels, handsheets from Pinus patula pulps recorded lower brightness values than those from Bugweed pulps. This was related to the lighter colour of the Bugweed wood chips and the higher extractive content of Pinus patula. The high brightness level of the CTMP pulps could be attributed to a modification of the lignin chromophores and the extractive removal, which contributed to a lower absorption coefficient of the pulp. Handsheets from BTMP pulps showed a reduction in brightness compared to the TMP and CTMP pulps. This was caused by the darkening of the wood chips during the fungal incubation period. Pulp and paper properties of Bugweed compared favourably to those results published for other hardwoods. The results of this study suggest possibilities for using Bugweed in high yield pulping processes.

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