Wood and Fiber Science (E-Journal)
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Comparison of Methods for Preparation of Moisture Content Gradient Sections
Get PDFA comparison is made of the effect of sawing and slicing on the moisture content of wood sections used to assess moisture content gradients in lumber. Thin, small-diameter (0.020 inch x 2.75 inch and 0.031 inch x 4.00 inch) (0.508 mm x 6.98 cm and 0.794 x 10.2 cm), commercially available metal slitting saws and a modified commerical horizontal wood slicer were used to cut sections ranging in nominal thickness from 1/32 inch (0.79 mm) to 7/32 inch (5.56 mm) from air-dry Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and tanoak (Lithocarpus densiflorus (Hook. & Arn.) Rehd.). In both species, moisture content loss in cut sections increased with decreasing section thickness for both slicing and sawing. Above 3/32 inch (2.38 mm) section thickness, the larger diameter saw produced moisture content losses that were less than or equal to losses in sliced sections
Production Planning for Integrated Primary and Secondary Lumber Manufacturing
Get PDFThis paper describes two linear programming models that were developed for production planning in value-added lumber manufacturing facilities. One model is designed for nonintegrated value-added facilities; the other is designed for value-added facilities integrated with a sawmill. The models were then used to explore the financial benefits for a sawmill to integrate a value-added lumber manufacturing facility at the back end of the mill. Net revenues are compared from the sawmill's point of view for two experimental cases. In Case 1 the sawmill sells its entire lumber production to the market (including to an independent value-added facility). In Case 2, the sawmill sells only the lumber that it is not directed to the value-added facility for further processing. Net revenue for Case 2 exceeds the net revenue of Case 1 by 10%. Results shown demonstrate that production decisions in the value-added facility had a significant influence on production decisions in the sawmill
Determinant Attribute Analysis: A Tool for new Wood Product Development
Get PDFDeterminant attribute analysis was employed to identify the physical product characteristics most crucial in the purchase decision process for office furniture substrate materials. Fastener withdrawal strength, surface smoothness, flatness, stiffness (MOE), and edgebanding capability had the most effect on selection decisions. These results were then viewed in terms of the development of a new substrate product and the opportunities that could arise from achieving a superior competitive advantage based on those characteristics. The importance of recognizing customer needs in the new product development process is central to the analysis, and the potential of determinant attribute analysis as a powerful tool for this process is demonstrated
Effect of Precommercial Thinning on Residual Sawmill Chip Kraft Pulping and Pulp Quality in Balsam fir
Get PDFThis study examined the effects of precommercial thinning (PCT) on kraft pulping and pulp properties of balsam fir [Abies balsamea (L.) Mill.]. Heavy precommercial thinning of balsam fir stands results in detrimental effects on the kraft pulping and pulp properties of the residual stems. It was found that at a stand density of 1,500 stems per hectare, sawmill residual chips obtained from the stems are more difficult to cook and exhibit a corresponding reduction in pulp yield with concomitant increased cooking chemical consumption. Shorter, finer fibers were observed, and the kappa 30 kraft pulps exhibited improved sheet tensile strength. These results indicate that balsam fir stems from heavily precommercially thinned stands contain a higher proportion of juvenile wood, although a contribution from compression wood cannot be completely ruled out
Thermogravimetric Evaluation of Fungal Degradation of Wood
Get PDFYellow birch (Betula alleghaniensis Brit.) was degraded by a white rot fungus (Polyporus versicolor L. ex Fr.; now Coriolus versicolor (L.) Quél.) and a brown rot fungus (Poria monticola Murr.; now Poria placenta (Fr.) Cke.) under controlled conditions. Samples of known weight loss from fungi were milled to pass a 40-mesh screen, oven-dried, and then measured for rate of mass loss over selected temperature ranges. Rates of mass loss of nominal 4-mg samples were obtained isothermally in flowing oxygen using a thermo-gravimetric (TG) system containing a Cahn electrobalance. Activation energy (E) was found using zero-order kinetics for the initial mass loss. White-rotted birch (to 60% weight loss) had an E of 35 to 43 kcal/mole over the range of approximately 190 to 210 C. On the basis of TG data, the weight loss from fungal attack could be predicted within about 5%. Brown-rotted birch had more variation in E (30 to 44 kcal/mole), over a temperature range of 170 to 195 C. The rate of mass loss of brown-rotted birch (to 52% weight loss) was more sensitive to temperature because of the known nonlinear decrease in cellulose DP during fungal attack. Dynamic thermogravimetry, a much simpler method, indicated a similar degree of instability from fungal attack as did the isothermal tests. TG appears to be a viable research method to evaluate fungal attack of wood
An Evaluation of Analysis Methods to Eliminate the Effect of Density Variation in Property Comparisons of Wood Composites
Get PDFThe objective of this research was to evaluate commonly used data analysis methods in property comparisons of wood composites to eliminate the effect of the density variation among board test specimens and to suggest a more reasonable and robust method. The methods reviewed included average, specific strength, and analysis of covariance. The indicator variable method was also applied to the property comparison and compared to the other methods. The modulus of rupture of wood fiber/polymer fluff composites manufactured with different material combinations and press temperatures was tested in the experiment for evaluation of the different analysis methods. The results of this study indicated that the statistical analysis method employed was very important in the study of the physical and mechanical properties of wood composites. The specific strength method is limited to the analysis of strength comparison for the high density composites. The analysis of covariance can be applied to all the property comparisons for either high or low density composites in eliminating the density variation effect. However, error exists in the property comparison using the analysis of covariance method when the slopes of the regression lines of property vs. specific gravity (SG) are different for the different composites being tested. The indicator variable method is shown to be more reliable than the specific strength and analysis of covariance methods because it compares the linear regression lines of property vs. SG by testing both the intercept and slope based on the data in the whole specific gravity range of test specimens
Appearance Wood Products and Psychological Well-Being
Get PDFThe study of how people's psychological health and well-being can be connected to wood used in appearance applications is a new and relatively unexplored area of inquiry, despite strong theoretical support, intuitive reasoning, and a growing recognition of the importance of healthful living. This research attempted to better understand this phenomenon by mapping out people's perceptions of wood used in interior applications. Specifically, the aim of this exploratory study was to determine what types of environments appearance wood products can create and to gauge whether or not the use of these types of products could have positive impacts on people's emotional states. To that end, a total of 119 respondents from the Greater Vancouver Regional Area were asked to partake in a three-part experimental study, consisting of a q-sort exercise, personal interviews, and a self-administered survey. The findings suggest that people's response to wood is, for the most part, extremely positive, with subjects generally showing a strong preference for rooms containing many wood details. There also appears to be a strong belief that the use of wood can help to create healthful environments, and commonly evoked descriptors for wood rooms include "warm," "comfortable," "relaxing," "natural," and "inviting." The reasons underlying these findings are complex and further exploration rooted in the field of environmental psychology is warranted. However, the results of this study could have potentially far-reaching implications for manufacturers of appearance wood products seeking to differentiate themselves in an increasingly competitive marketplace. Specifically, these findings point to an opportunity to market wood in an entirely new and innovative manner with the inclusion of potential psychological benefits into the total product concept
Properties of Transfer-Molded Wood-Fiber/Polystyrene Composites
Get PDFTransfer-molded composites combining polystyrene, wood particles, and three bi-functional coupling agents were prepared and evaluated for physical and mechanical properties. Pure 685D polystyrene (PS) (75-100% by weight) was combined with 100-mesh (0.15-mm sieve opening) particles prepared from thermomechanically pulped quaking aspen (Populus tremuloides) (0-25% by weight). Three coupling agents, polystyrene/poly(methacrylic) (both low and high molecular weight) and polystyrene/poly(vinyl acetate) developed at Michigan Technological University, were added in an effort to promote compatibility between the hygroscopic wood fiber and the non-polar hydrophobic polystyrene. Mechanical tensile testing was used to assess the respective composite's tensile elastic modulus and tensile strength. A polystyrene/poly(methacrylic) acid (PS-PMAA) coupling agent was found to be the most effective with regard to enhanced tensile elastic modulus at higher fiber-loading levels (enhancement levels of 11.3-23.8% over pure PS). A fiber/PS composite using low molecular weight PMAA (PS-PMAAL) as a coupling agent demonstrated the best tensile strength retention characteristics at higher fiber-loading levels. Initial results show high variability in material properties over the range of fiber-loading levels, and between coupling agent type. It is clear, however, that certain coupling agents do have a positive effect on composite properties
Fiber Surface Structure and Fiber Liberation in Soda-anthraquinone Kraft and Soda Pulps as Determined by Conventional Electron Microscopy
Get PDFComparative studies on the surface structure of defibrated fibers and fiber liberation in nondefibrated chips from three different pulping processes, soda-anthraquinone (soda/AQ), kraft and soda pulping, were performed via conventional electron microscopy. By comparing the exposed fiber surface structure with the degree of fiber liberation, delignification processes in middle lamella regions were elucidated for these pulping systems. Soda/AQ pulping resulted in fiber liberation with less lignin removal than for either kraft or soda pulping process
Three-Dimensional Modeling and Visualization of Whole Norway Spruce Latewood Tracheids
Get PDFThe three-dimensional morphology of four whole Norway spruce latewood tracheids is described in this work. Tracheids are shown to have a characteristic shape composed of five different morphological zones. Visualization of the different morphological zones was accomplished with the use of computerized three-dimensional (3D) reconstruction. 3D reconstructions were generated from stacks of micrographs obtained from serial sections of a wood block. The micrographs were processed and integrated in a CAD-based computerized modeling system using Non-Uniform Rational B-Splines (NURBS), which produces 3D reconstructions consisting of surfaces or volumetric bodies. Volumetric changes in relation to hydration state of latewood tracheid segments were studied. It was found that tracheid tips swell less than central regions, and that as a consequence of swelling, the cell walls of Norway spruce latewood tracheids expand inward towards the lumen