A study into the distribution of thermophilic and thermotolerant fungi in a spruce-pine wood chip pile in Prince George was carried out. Five treatments consisting of pine, spruce, incorporation of wood fines into spruce, sterilized spruce and sterilized spruce inoculated with a Ptychogaster sp. were examined. Samples of wood chips buried at six different locations in the chip pile were examined after 3, 6 and 12 months storage periods. From 100 randomly selected chips from each sample the fungi were isolated on 2% malt, 0.5% malic acid and 2% agar at 25° and 45°C. Data on temperature during storage and acidity of wood chips, moisture content and weight loss at the time of sampling were recorded for the six positions in the wood chip pile. Thermophilic fungi colonized the inner regions while thermotolerant fungi inhabited the outer regions of the wood chip pile. Among the thermophilic fungi, listed according to frequency of isolation were Byssochlamys emersonii Stolk-Apinis, Allescheria terrestris Apinis, Sporotrichum thermophile Apinis, Thermoascus aurantiacus Miehe and Humicola lanuginosa (Griffonand Maublanc) Bunce. The most common thermotolerant fungi were Aspergillus fumigatus. Fresenius and Chrysosporium pruinosum (Gilman and Abbot) Comb. Nov. Fungal distribution was generally related to position in the wood chip pile. Of the associated factors temperature (17°-45°C) was most strongly related to fungal distribution, whereas acidity of wood chips and moisture content did not vary greatly between positions. Incubation of wood samples on cultures demonstrated the ability of all the common thermophilic and thermotolerant fungi to cause weight loss of lodge pole pine Pinus contorta Dougl. varlatifolia, ponderosa pine Pinus ponderosa Laws. and spruce Picea glanca (Moench) Voss sap wood samples. These weight losses varied from 0.65% to 25% after six weeks incubation. Temperature, medium and type of wood affected the ability of the fungi to cause weight loss. No synergistic or antagonistic effects' existed between the thermophilic fungi. Chemical analysis of degraded wood indicated that the thermophilic fungi utilized the arabinose fraction of the hemicellulose preferentially. / Forestry, Faculty of / Graduate

The application of high velocity liquid jets for corrugated board cutting was investigated as a possible new method of slitting operations. Eleven types of corrugated board ranging from 91 pounds per 1,000 square feet board weight (125 psi - nominal burst test) to 297 pounds per 1,000 square feet (350 psi - burst test) were selected for the study. Plain water or water with polymer additive were used as the cutting fluids. The conditions under which cutting of corrugated boards was carried out were as follows: nozzle diameters 0.0082 and 0.0102 in., pressure levels 20,000, 30,000 and 40,000 psi; feed rates 300, 500 and 700 fpm. The obtained results indicate that slitting speeds with high velocity liquid jets are well above those achievable by the existing conventional methods. It has also been shown that the use of a low concentration of polyethylene oxide (Polyox WSR - 301) resulted in a marked increase in cutting efficiency as compared with plain water. Measurements of liquid retention after cutting.-have shown that wetting of corrugated boards during the cutting operation is insignificant and as such can be neglected. It has been demonstrated that the edgewise compression strength of corrugated board, cut with the liquid jet, is almost twice that cut with the typical conventional slitter. Based on the analysis of scanning electron micrographs it has been observed that the principal failure mechanism during cutting with high velocity liquid jet involves breaking of the interfibre bond with resulting separation of fibres. Corrugated board cutting with high velocity liquid jets has been found to eliminate crushing and tearing of the board as well as dust generation. The concept provides a means to reduce trim waste and particle contamination. Jet cutting is ideally suited for numerically controlled systems and appears to lend itself for adaptation to commercial application. / Forestry, Faculty of / Graduate

Nitrogen, argon and oxygen adsorption isotherms at 78 °K have been determined on samples of solvent exchange dried, fully bleached, kraft pulp of western hemlock and Douglas fir. The solvent exchange drying sequence used was water-methanol-n-pentane with the n-pentane removed at room temperature. The pulp samples were in two groups: one group was beaten to various levels on a P.F.I. mill and solvent exchange dried from a water swollen state; the second group was air dried to different moisture contents and then solvent exchange dried. The presence of micropores (Dubinin definition) in solvent exchange dried cellulose has been shown. This finding was suggested by the results of Harris, who noted that adsorbents having an average pore radius of less than 18 Å indicated an average Kelvin pore radius of 18 Å. The finding of micropores in solvent exchange dried cellulose was substantiated by the pore volume distribution which indicated a very large volume of pores at 18 Å radius, and by the Dubinin plot technique for the measurement of micropore volume. Some solvent exchange dried wood pulp samples indicated that up to 70 percent of their total pore volume was present as micropores. The presence of micropores with the associated enhanced adsorption and restricted adsorption space complicates the analysis of isotherms so that the B. E. T. surface area and Kelvin type pore analysis cannot be considered reliable. An investigation into the effects of errors associated with assuming values for the physical properties of adsorbed molecules led to the conclusion that gas adsorption is useful for indicating trends or for use as a parameter for correlations of some pulp and paper properties but should not be used to postulate models of specified dimensions. The Kelvin type pore analysis and the Dubinin pore analysis have been shown to be very sensitive to the model assumed to describe the physical structure.of the wood pulp fibre. While gas adsorption techniques are of doubtful validity for solvent exchange dried pulp samples, the B.E.T. analysis, was found to be quite reliable on air dried paper sheets. The existence of the large volume of pores of approximately 18 Å radius (cylindrical pore model) or 25 Å wall separation (parallel sided fissure model) in solvent exchange dried cellulosic materials which have been found by other workers has been shown to be doubtful. This finding is substantiated by the accessibility data of Stone and Scallan which does not indicate a large volume of pores near the most common pore sizes found by gas adsorption. P. F. I. mill beating of the pulp was found to lower the surface area slightly, to shift the pore size distribution slightly to larger pore sizes and to substantially lower the volume of pores at the most common pore size. The Dubinin micropore volume analysis also indicated lowering of micropore volume with beating. These results led to the conclusion that beating affected the structure of the pulp fibre even in structural elements of the smallest size measured. Partial drying of the pulp handsheets prior to solvent exchange drying was found to lower the surface area by nearly two orders of magnitude and to shift the pore volume distribution strongly to the smaller pore sizes. The effects of .beating and drying were easily interpreted on the basis of the Stone and Scallan parallel sided fissure model of the structure of cellulose. Comparisons between isotherm shapes indicated solvent exchange dried wood pulp may have a structure similar to montmorillonite, which is known to have a flat plate structure. The Kaganer and "t"-plot analytical techniques were applied to the solvent exchange dried wood pulp as additional methods of obtaining estimates of the surface area. The surface areas determined by these methods were significantly larger than those found by the B. E. T. equation, however, the trends were found to be the same. Handsheets were made from the pulp samples and these sheets were subjected to physical tests. The surface areas of these sheets were determined and the bonded areas estimated. The bonded area was found to increase with the level of beating. Sheet density increased as bonded area increased, so did the breaking length and burst. Tear factor decreased as the bonded area increased. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

A new approach to the problem of failure prediction of wood components and structures is that of fracture mechanics. In order to implement this approach knowledge of flaw growth (or crack propagation) in wood subjected to various stress systems and environmental conditions is required. The extension of flaws is accompanied by the release of energy in the form of acoustic or stress wave emissions, which can be detected and have been found to be reliable indicators of crack growth. Using acoustic emissions as a measure, flaw growth was investigated in stressed bending specimens of three species. The test pieces contained a variety of knot configurations, seasoning checks and resin pockets. Three wood moisture contents were used; specimen size was 2-by-4-inch (nominal) cross section and 50-inch length. A detailed description of the system used for detecting, measuring and recording acoustic emissions is given. Emission activity was measured using an electronic counter. Simultaneous count, load and deflection measurements were recorded and count-deflection and load-deflection curves plotted. The association between acoustic emissions and crack growth is discussed. Four types of integrated count- deflection patterns were found, which generally exhibited two common features. Firstly, a rate change point, where the count rate increased rapidly, and secondly a count increase just prior to failure. The rate change point was approximately coincident with the proportional limit in the load-deflection curve, suggesting an association between elastic behaviour and microfailure development. Several qualitative relationships between the count and load curves are presented. A correlation between stable crack growth and the entire load-deflection curve is postulated. The presence of checks and resin pockets affected the microfailure pattern, shown by increased acoustical activity, without appreciably influencing modulus of rupture. Green specimens for the most part produced lower counts than drier ones. Also clear or essentially clear boards exhibited lower emission counts. Species differences were not apparent. The estimation of modulus of rupture employing parameters from the count-deflection curves is discussed and compared to that using modulus of elasticity. Precision of the prediction was not improved using count parameters. A method for determining the direction of crack propagation in a fractured bending member is described. / Forestry, Faculty of / Graduate

A technique is described for improving wood fibre web strength by copolymerization of a hydrocarbon drying oil (CTLA Polymer) within hand-sheets made from pure and admixed forms of high yield chemical (sulfite and sulfate) and groundwood fibres. Oil polymerization can be initiated successfully by prolonged thermal treatment at 145°C, as well as by the novel method of low dosage gamma-ray irradiation. The treatment strengthens inter-fibre bonding. Evidence for copolymerization was sought through assessment of tensile and related strength data on variously treated standard handsheets. Effectiveness of the polymerization on pulp types investigated as initiated by heat and low dosage irradiation is strongly related to surface colloidal and basic physical and mechanical properties of the fibres. Maximum strength parameters were obtained with oil saturated sulfite and groundwood handsheets following polymerization by thermal treatment. Copolymerization efficiency by irradiation, on the other hand, is estimated as 73% for sulfite, 65% for groundwood and 50% for kraft handsheets. Effectiveness of oil polymerization by irradiation was found to be proportional to dosages up to 10⁵rad. As anticipated, limit of strength improvement was not set entirely by intrinsic fibre strength, but was also influenced by surface colloidal properties of the fibres. Blends made from chemical-groundwood fibre mixtures behaved more or less proportional to individual pulp strengths and extent of blending. Copolymerized sulfite-groundwood blends at equal proportions approximated the tensile strength of similar kraft papers suggesting better economy with kraft fibres when papers of limited strength are produced. All other strength parameters (elastic modulus, tensile strain and tensile energy absorption) followed similar trends, or if different were of aid in explaining certain phenomena characteristic to treated fibre webs. The presence of graft copolymer could not be conclusively proven, since both the copolymer and oil homopolymer are insoluble in the usual organic solvents. A dual character of the oil polymer was demonstrated with glass filterpaper and highly purified commercial cellulose fibres. Effectiveness of oil polymerization in highly lignified mechanical pulps was greatly depressed by mild sodium chlorite treatment, although the strength and bonding capacity of such fibres increased considerably. This was taken as direct evidence for the possibility of a lignin-CTLA Polymer copolymer system. Site of chemical reaction has not been described, although means for assessment of such information are suggested. The study proves the usefulness of gamma irradiation as energy source for the copolyerization of drying oils in handsheets as replacement for the prolonged thermal treatment hitherto used by the hardboard industry. Added advantages of irradiation processed copolymerized papers are less discoloration, especially with high lignin content pulps, and lower elastic modulus, a factor clearly objectionable for some paper uses. / Forestry, Faculty of / Graduate

The hypothesis is examined that short-term creep response of earlywood and latewood tissues of some coniferous species, stressed in tension parallel to the grain, is a function of microfibril angle of the S 2 layer of and relative degree of crystallinity in the tracheid cell wall, along with specific gravity of that wood tissue and its extractives content. A new technique was developed to measure the total creep that occurred over a 60-minute period of time for small specimens (nominally 0.010 in, thick) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) (normal and compression wood), Sitka spruce (Picea sitchensis (Bong.) Carr.) and western hemlock (Tsuga heterophylla (Raf.) Sarg.), taken from earlywood and latewood zones of the same increment. Total creep was determined at two initial deformation levels, 3,000 microin.per in. (strain level No. 1) and 6,000 microin. per in. (strain level No. 2). Microfibril angle was measured by a modified mercury impregnation method, while cell wall crystallinity was determined on small, unoriented pellets by the X-ray diffraction technique. Air-dry specific gravity (oven-dry weight) and alcohol-benzene plus hot water extractives were also determined by conventional methods. Multiple regression analyses were carried out and prediction equations, based on the experimental results, have been constructed. It is shown that the variability in total creep response can best be explained by using the prediction equation which contains microfibril angle of the S2 layer, specific gravity and extractives content. The multiple coefficients of determination (R²) using this subset of variables are 0.7680 and 0.8550 for initial strain Numbers 1 and 2, respectively. Cell wall crystallinity was eliminated from the prediction equations as the least important variable due to its high inverse correlation with the microfibril angle of the S2 layer (r=0.9284). Two possible reasons are suggested to explain this correlation. First, in the case of a small angle, the scatter around the mean microfibril angle is smaller and the microfibrils probably lie almost parallel to each other. As a result, the relative degree of amorphous material required to fill the micro-spaces between microfibrils would be smaller. Considering the case of a large microfibril angle, the microfibrils are probably not parallel to each other; consequently, relatively large micro-spaces would be occupied by the amorphous material. A second possible reason for this relationship may be that cellulose chain molecules, in the case of a small microfibril angle, will have a better chance for increased frequency of cross links (bonding between neighbouring chains) along their unit length. Consequently, a tendency of improved geometric order should be observed with better chain coherence in the resulting cellulose as compared to situations associated with tracheids characterized by larger microfibril angle. It must be indicated that reasons for this high degree of correlation, as noted above, remain conjectural. Among the structural features studied, microfibril angle was shown to control creep response to the greatest extent. As it increases, total creep increases, the reason being that with a small angle, microfibrils are in a position to bear most of the applied load and therefore their relative movement towards a smaller angle would be less. This results in a small plastic deformation. In the case of a large angle, there is a possibility that the microfibrils have a large tendency to move to a smaller angle causing a large creep response. Wood samples of low specific gravity creep more than those with high specific gravity. This behavior is explained by the higher relative per cent of the S2 layer in the latter. Extractives are shown to contribute significantly to the variation in total creep. They probably act as plasticizers causing a reduction in the primary and secondary bonding between microfibrils. This would facilitate the movement of the stiff inextensible microfibrils to accommodate the creep-inducing stresses. Results obtained in this study were compatible with the proposed hypothesis. / Forestry, Faculty of / Graduate

Residential construction has been a focus of attention in North America in recent years. Rising construction costs, and growing social pressures to meet housing needs have resulted in a concentrated effort by government and industry to develop new and improved building methods. Wood frame construction techniques, although traditional in Canada, are not guaranteed a dominant position in the future. With the high volume of wood products consumed in residential construction, the forest industries have a large stake in this market. Two aspects of declining wood use in housing have been investigated in this thesis: (1) changing methods of construction; and (2) substitution of non-wood building materials for wood. Although recent projections indicate a strong housing demand to 1980, the types of dwellings constructed are equally important, single-family units consuming the greatest volume of wood products, and high-rise apartments the least. A strong trend toward apartment construction has been evident since 1950, fostered by rapid urban population growth, mortgage investment preferences, the high cost of urban land, and the lower cost of rental accommodation. It is estimated that the loss of wood products markets from 1960 to 1969 due to this trend was 1,355 million bd. ft. of lumber, 245,075,000 sq. ft. of plywood and veneer, and 151,068,000 sq. ft. of building board. Functional suitability is probably the most important determinant of materials choice. Tradition, a factor which has favoured wood frame building, is losing its influence. Availability of materials and vertical integration are not significant factors in Canada. Upward trends in the price of wood products, price instability, and the much higher research and development expenditures in competing industries can be expected to result in an accelerated rate of substitution of other materials for wood. Although wood performs well in many applications, its combustibility has been a great disadvantage for construction uses. Building codes have significantly limited its use, but have also hindered the introduction of new building techniques, and products made of substitute materials. Products made of aluminum, plastics, steel, and non-metallic minerals have had varying degrees of success in the housing market. Numerous developments such as aluminum and steel structural systems, plastic and metal sandwich panels, and precast concrete building systems, offer potential competition to wood frame methods. Vertical integration with the building industry, and more active promotion of, and technical assistance in wood frame methods may help curb the trend to apartment construction. Greater efforts to reduce costs, higher research and development expenditures, increased activity in market research, and greater efforts to reduce price fluctuations are necessary to prevent higher rates of substitution. More effort should be concentrated on the development of foreign markets, both to help reduce price fluctuations, and to provide alternate markets for those lost through substitution. / Forestry, Faculty of / Graduate

Samples of sawdust from poplar, alder and Douglas fir, were ground past screens ranging in size from 2.21 mm to 0.25 mm (60 mesh). A reduction in particle size significantly increased the in vitro rumen digestibility of poplar, but had little effect on the digestibility of alder or fir. The above woods, plus sludge (a by-product of the pulping process) were treated with NaOH solutions of 2, 4 and 6%. These solutions were used at three treatment periods of 0.5, 1.0 and 1.5 hours, and all treatments were carried out at 1.05 kg/sq cm and 121° C. NaOH treatment significantly increased the in vitro cellulose digestibility of all woods except fir. The optimum treatment conditions for increasing the in vitro cellulose digestibility of all woods were 4% NaOH at the 1.5 hour treatment period, except in the case of alder which was most digestible when treated with 2% NaOH for 1.5 hours. Gamma irradiation increased the in vitro cellulose digestibility of all woods. Alder and fir were most digestible when treated with 2 x 10⁸ rads, but poplar and sludge reached their peak digestibility when exposed to 1 x 10⁸ rads. Irradiation was found to decrease the cellulose and acid detergent fibre (ADF) content of all the woods studied. Acid detergent lignin (ADL) also decreased in response to irradiation in all woods except sludge. Irradiation had no effect on the ash content of any of the samples. Three methods of cellulose analysis were used on both untreated and irradiated wood, and there was a significant difference shown among the methods. The lowest values were obtained using Van Soests' KMnO₄ method, next were the results from Van Soests' 72% Hg₂SO₄ method, and the highest values were obtained using the Crampton and Maynard procedure for cellulose. Two lignin methods were also compared and it was found that the KMnO₄ lignin values were significantly higher than those obtained using the 72% H₂S0₄ method for lignin. / Land and Food Systems, Faculty of / Graduate

The stress distribution near the centerline apex of pitch-cambered glulam beams is analysed. The analysis is done with an orthotropic trapezoidal finite element utilizing the stiffness approach. The element is tested with various grid sizes against known solutions and shown to give an overall accuracy to within five percent. Radial tension stresses perpendicular to grain due to moment, were calculated for various geometries and plotted as a design aid. These stresses can be several times those found in a uniform curved beam. The effect of changing the elastic moduli of the whole beam or individual laminations was investigated and found to be unimportant. Radial stress due to shear forces was found to be unimportant. Radial stress for one typical geometry due to moisture change was investigated in detail. This showed that ten pounds per square inch tensile stress was generated for a one percent change in moisture content. Twenty two tests were performed on tension perpendicular to grain to indicate that the allowable stress would be near thirty five pounds per square inch. A numerical example and design recommendations are included. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Orangutans are the only great ape to live an almost completely arboreal lifestyle, spending the majority of their time in the canopy of the tropical forest. The orangutans’ large size and habitual arboreal lifestyle means they are uniquely constrained by the mechanical properties of their canopy habitat. It is therefore necessary to have knowledge of the mechanics of trees and the wood material of which they are made in order to gain a greater understanding of orangutan ecology. This thesis begins with an investigation into the bending failure of three temperate tree species. Observations and electron microscopy of the fractures of hand bent branches were coupled with mechanical tests of the branch structures and the wood material. It was shown that the fracture mechanisms observed were related to the anatomy and consequent mechanical properties of the wood material. Light woods buckled due to their low transverse compressive strength, whilst denser woods tend to break in greenstick fracture, in which the fracture is diverted longitudinally at the midline, due to the low tangential tensile strength of the wood material. Three neotropical tree species were investigated in the same way and it was shown that all species tested failed in greenstick fracture with the modes of failure explained, at least in part by the differences in their wood anatomy and mechanical properties. These results were used to inform an investigation of orangutan nest architecture. The compliance of the nest structures was measured and the morphology, mechanical properties and modes of fracture of the nest elements were recorded. It was shown that nests were slightly more compliant where the orangutans’ weight was situated. Orangutans built the structural part of the nest by selecting, half breaking and weaving together thicker more rigid branches. However, the nest lining was generally made from completely detached narrower and less rigid branches. This suggests orangutans have a degree of technical knowledge, selecting the correct material for a certain construction role. In order to achieve a greater understanding of the mechanically complex canopy substrate that the orangutan inhabits, a study in to the mechanics of the canopy substrate was performed. Direct measurements of compliance and frequency of oscillation were taken from a range of tropical branches used by orangutans. It was shown that compliance increases dramatically towards the tip of branch and that branch diameter is the most effective branch morphological trait for predicting compliance levels. This study allowed a greater understanding of how these properties may affect orangutan ecology. To address whether conditions are present for energy storage and return during bouts of orangutan bipedalism, measurements of compliance and branch oscillation times were used in conjunction with analysis of video footage of orangutans. It was found that long step times of orangutans fall between the minimum and optimum step times for energy return, calculated from mechanical properties of bipedal supports. These results were supported by videos demonstrating in-phase branch movement and step kinematics. These results suggest that local diameter is the single most useful trait to predict the strength and rigidity of tropical branches, and their compliance and oscillatory frequency. This suggests that this is the cue used by the apes, and helps validate the assumptions made by previous researchers investigating arboreal primate locomotion. They also suggest that the conditions do exist in the natural environment that may facilitate energy storage and return on compliant branches during bipedal locomotion.