Paper is comprised of quasi-randomly distributed fibres, fines and different additives. The properties of paper depend on the type of fibres used, their uniformity of distribution, the amount and type of fines and fillers. It is difficult to predict how a particular component will behave in a mixture. This will depend on the form of material introduced (flocculated or dispersed) and on what kind of interactions will take place. These factors can be controlled by various wet-end strategies based on known colloidal behaviour of various additives. Thus, applying this knowledge to papermaking, one should be able to predict and control final structures of paper, which will be reflected in optical and mechanical properties. / A thorough understanding of the effects of different materials, such as fines and fillers, on optical and mechanical properties of paper can only be obtained from a systematic study. Therefore, this research focused on elucidating the relationship between the nature and amount of fines and fillers and paper properties. The studies were mainly limited to papers made from thermomechanical pulps (TMP), although occasionally comparisons with other pulps were made as well.

Oxygen-alkaline pulping is a sulphur-free chemical pulping process, which has a potential to replace the kraft process as an environmentally more viable alternative. However, there are some drawbacks to the process, which have so far prevented it from commercialization. The penetration of oxygen into the structure of wood chips and rather severe degradation of carbohydrates are the main problems that result in high reject contents and low pulp strengths. In this study, wood chips, after presoaking in a 0.2% solution of alkali, were mechanically treated in a compression screw feeder with the aim to facilitate the penetration of oxygen. Mechanically pretreated wood chips produced oxygen alkali pulps with screened yields that were almost 13% higher than those without mechanical treatment. At the same time, the total yields of both pulps were comparable. To improve the strength of the oxygen-alkaline pulps, the pH of the pulping liquor was kept constant between 7 and 8 throughout the pulping process. This resulted in a pulp that has a viscosity 3 times greater than that of the control oxygen-alkaline cook, thus indicating an improvement in strength properties.

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Drying Doctor, a multiple technique simulator of the paper drying process, has been developed at the Pulp and Paper Research Centre, McGill University. This thesis examines the different approaches to the modeling of this process, provides a rigorous validation of the simulation program and demonstrates its utility with four containerboard machines of Norampac Inc. / Several features differentiate this simulator from others. When heavy grades of paper are produced or when high intensity drying processes are used even with thin sheets, substantial thickness direction gradients of moisture content and temperature develop across the sheet, demonstrating the necessity of a fully microscale model such as employed by Drying Doctor. / Using industrial and laboratory data for a variety of paper grades and drying processes, 31 uncalibrated simulations for machine speed showed a standard deviation of only 3.4% from known speeds. Through simulation of modified operating conditions such as steam pressure, spoiler bars, pocket air conditions and addition of the high intensity drying process, Yankee air impingement dryers, substantial production rate increases for the industrial partner's papermachines through use of the Drying Doctor simulator were shown possible.

The effects of agricultural development on wood turtles (Clemmys insculpta) were investigated in Quebec during 1994 and 1995. Age structures, growth, and mutilation rates were compared between an agricultural population and a reference site in an undisturbed forest. Turtles in the 0-4 year age class were absent from samples taken at the agricultural site. Overall, 23% less juveniles were encountered at the agricultural site. In addition, relatively fewer adults were captured from the 20+ age class. Shell injuries were twice as common at the agricultural site when compared to the forest site; whereas, limb amputations were twice as frequent at the forest site. Although shell injuries inflicted by predators occurred with similar frequencies at both sites, there were 2.7 times more fractures resulting from anthropogenic sources at the agricultural site. Multiple limb loss occurred only at the forest site. Tail amputations occurred with similar frequencies at both sites. Casts of pleural scute annuli revealed that turtles at the agricultural site had significantly lower growth rates during their second decade of life. Females at the forest site were significantly larger for all measurements recorded; whereas, males differed only with respect to carapace and plastron lengths. Agricultural development may have resulted in reduced growth, recruitment, and predation rates, as well as increased adult mortality.

Air drying of paper by pure impingement, pure through flow and by combination of impingement and through flow was studied. For the combined process the inlet and both outlet air flow rates were held constant throughout drying, thereby providing results appropriate for analysis of the complex and interacting kinetics. / Pure impingement drying rate curves were quantified with three parameters which were related to drying process conditions: constant drying rate, critical moisture content and the exponent for a power law relationship over the falling rate period. The Churchill - Usagi asymptotic approach model was tested and found not applicable. / For pure through drying the constant drying rate period disappears at higher drying intensities leaving two drying rate periods, the increasing rate and falling rate periods. A theoretically based exponential relationship was obtained for the increasing rate period, where up to 47% of the drying may occur. Drying rate curves were quantified with no subjective judgements, using five parameters: moisture contents at the end of the increasing rate and constant rate periods, constant drying rate, and exponents for the increasing and falling rate period relations. A universal normalized drying rate curve was obtained. Through drying rates are the same with or without impinging jets. / In combined impingement and through air drying, an adiabatic process, removal of impingement boundary layer humidity by through flow makes both components of the process nonadiabatic. Relative to pure impingement drying, impingement water removal rates are sensitively reduced by through flow. Because critical moisture content is intrinsically lower for through drying than impingement drying, through flow water removal rate curves can be strikingly different from pure through drying, with addition of a unique feature, a secondary increasing rate period when paper temperature is driven up by the falling rate period of impingement water removal. Parameters for quantitative representation were determined, analyzed and related to drying process conditions. / Of two prior models for the combined impingement and through air drying of paper, trends assumed by Randall (1984) are now found contrary to actual rates while the Crotogino and Allenger (1979) model has the trends correct but over predicts the drying rates now measured. Results of the pilot plant work of Burgess et al. (1972) are consistent with the comprehensive model now developed to predict drying time and drying rate for combined impingement and through flow air drying of paper.