Wood and Fiber Science (E-Journal)
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EFFECT OF TOOL TIP RADIUS ON RING DEBARKER PERFORMANCE OF FROZEN AND UNFROZEN BLACK SPRUCE LOGS
Full text linkThe effects of the tool tip radius on debarking quality of unfrozen and frozen black spruce logs were studied. The power, energy consumption and torque on frozen conditions were also studied. A proto-type one-arm ring debarker was used. The experiment consisted of debarking logs using three tool tip radii (40, 180, and 300 µm) for each temperature (-20°C and +20°C). The rotational and feed speeds, tip overlap, and rake angle were kept constants. Debarking quality was evaluated by two criteria: the proportion of bark remaining on log surfaces and the amount of wood in bark residues (WIB). Log characteristics, used as covariates, ie dimensions, eccentricity, bark thickness, knot features, bark/wood shear strength (BWSS), basic densities and moisture contents of sapwood and bark were measured, as well as total removed material after debarking. The results showed that tool tip radius had a significant effect on debarking quality of frozen and unfrozen logs. The proportion of bark on log surfaces increased and the amount of WIB decreased as tip radius increased. At the same applied radial force, a wider tip radius showed a shallower tip penetration leaving bigger regions of bark on the log surfaces. In contrast, a narrower tip radius showed a deeper tip penetration resulting in important wood fiber tear-out. The bark thickness and inner bark MC also affected debarking quality. The mean power, mean torque, and energy consumption increased as the tip radius decreased. However, this effect will depend on the choice of the applied radial force during debarking. Motor performance was also affected by the total removed material, log diameter, and BWSS. Overall, the results highlight the importance of choosing an adequate combination of tool tip radius and applied radial force to obtain the most profitable debarking quality with an efficient energy consumption
A CHARACTERIZATION AND ANALYSIS OF VERY VOLATILE ORGANIC COMPOUNDS AND ODORS FROM MEDIUM DENSITY FIBERBAORD COATED WITH DIFFERENT LACQUERS USING GAS CHROMATOGRAPHY COUPLED WITH MASS SPECTROMETRY AND OLFACTOMETRY : 80.300
No full textVolatile organic compounds (VOCs) from furniture and interior furnishing materials have been proven to pose adverse health effects. However, very VOCs (VVOCs) and odors were rarely taken into account. To bridge this gap, emissions of VVOCs and odors from medium density fiberboard (MDF) coated with different lacquers were characterized using gas chromatography coupled with mass spectrometry and olfactometry detection. The results demonstrated that the total VVOC AT THE 28th d (TVVOC28) from the control sample was higher than that of the other three lacquered samples. Alcohol VVOCs were the most abundant chemicals from the control MDF, followed by ketones, esters, and ethers, accounting for more than 90% of the total concentration. Also, they were the major odor-contributing substances with higher odor intensities. Nitrocellulose (NC), polyurethane (PU), and water-based (WB) lacquer paintings had a suppressive effect on the emission of certain VVOCs but promotion of the others. After the lacquer paintings, alcohols and ethers were the major components, accounting for 82.3% ~ 88.0% of the total VVOC. In addition, odors were affected by these three lacquer paintings. Fruity was the dominant odor impression of MDF, NC and PU decoration MDF, with an odor rating of 4.4, 7.1, and 4.9, respectively. A multiodor mixture was the major odor impression of WB decoration MDF, with an odor rating around 4.0. The odor may differ from one lacquer to another. Additionally, a newly added fishy-like odor arose in PU lacquer painting. From the data analysis of this study, PU and WB decoration MDF might be suitable for furniture or decorative materials due to their lower pollutants and odor emissions. Based on the comprehensive evaluation indices, the latter may be more preferred and was highly recommended for indoor applications
CHARACTERIZATION OF THERMOMECHANICAL PULP MADE FROM PINE TREES INFECTED WITH NEMATODES
Full text linkPine wilt is a lethal disease caused by the nematode Bursaphelenchus xylophilus. It causes tree death by blocking water and nutrient uptake in pine trees. Pine trees infected by these nematodes are used as fertilizer or fuel for thermal power plants, but their utilization is still only about 37%. To increase the utilization of the infected trees, this study investigated whether the shredded wood chips prepared from them could be used as raw materials for manufacturing thermomechanical pulp (TMP) and chemithermomechanical pulp (CTMP). TMP and CTMP prepared from the infected pine chips showed fewer pitch contents and better strength properties than those made from domestic pine. In conclusion, if the nematode-infected pine was used as raw materials for manufacturing TMP and CTMP, it is expected that it would contribute to the diversification of raw materials along with a high-temperature insecticidal effect.
Keywords: Pine wilt, nematode disease, thermomechanical pulp, chemithermomechanical pulp, pulp strength, insecticidal effect
 
INVESTIGATION OF BIOGAS DIGESTATE AS FIBER MATERIALS FOR COMPOSITES
Full text linkFiber reinforced plastics with synthetic fibers are widely used. Plant fibers are also known to produce more sustainable composites. However, there is a great interest in finding alternatives to classical natural fibers. The digestate of biogas plants seems to be such an alternative. Biogas plants are fed with plant-based substrates and during the digestion, the biomass is degraded. In this study, the fiber quality of digestates from four biogas plants with different initial substrates is investigated. Therefore, typical fiber properties, such as slenderness ratio, cell wall components, and the potential fiber performance, are measured. According to the general definition, the solid part of the digestate is a fiber material. The slenderness ratio is 5 or higher and the density is 1.5 gcm23, which is typical for natural fibers. Fibers with similar properties are already used in composite materials
EFFECT OF POROUS TRAITS OF HARDWOODS CROSS-SECTION ON SOUND ABSORPTION PERFORMANCE - FOCUS ON 6 SPECIES OF KOREAN HARDWOODS
No full textAn investigation of sound absorption in 6 species of hardwoods according to the pore structure of cross-sections revealed that higher gas permeability was associated with greater sound absorption at high frequencies. In addition, diffuse-porous wood exhibited superior sound absorption performance compared with ring-porous wood. Through-pore porosity was associated with improved sound absorption in the cross-sections of hardwoods, while closed=pore porosity was associated with poor sound absorption
MOMENT RESISTANCE PERFORMANCE OF LARCH LAMINATED TIMBER BEAM-COLUMN JOINTS REINFORCED WITH CFRP
Full text linkThis study evaluates the moment resisting capacity of the drift pin larch beam-column joint with slotted-in steel plates of larch laminated timber. It is reinforced with carbon fiber reinforced plastic (CFRP) to suppress the brittle fracture of the beam-column joint and improve the joint capacity using larch laminated timber, a wood material manufactured by multi-layering of timber as a structural member of heavy timber.The average maximum moment capacity of the control specimen was 16.9 kN·m and the average maximum moments of the Type-A (volume ratio of joint reinforced with CFRP: 3.6%) and Type-B (volume ratio of joint reinforced with CFRP: 5.4%) were increased by 46% and 62%, respectively, compared to that of the control specimen. The capacity of the joint, such as the average yield capacity, ultimate moment capacity, and ductility ratio, of the control, Type-A, and Type-B specimens increased as the reinforcement ratio of the CFRP increased. For the failure mode of the control specimen, splitting failure occurred in both the column and beam members in the end distance direction. However, the splitting failure did not occur in the beam member due to the improvement of the joint and ductility of the specimens reinforced with the CFRP. The Type-A specimen had improved joint capacity and ductility compared to the control specimen; however, brittle failure occurred owing to the external force exceeding the joint capacity. However, in some of the Type-B specimens, the splitting failure did not occur in the column and beam members due to the CFRP reinforcement. Particularly, the Type-B3 specimen exhibited ductility
PERCEPTION AND EVALUATION OF (MODIFIED) WOOD BY OLDER ADULTS FROM SLOVENIA AND NORWAY
Full text linkBackground. Many building users prefer wood over other building materials, but it is unclear how modified wood is perceived compared to the unmodified wood. Additionally, it is unclear which material properties play a role in the general preference for wood, how tactile and tactile-visual perceptions of materials affect user preference for wood, and whether human preference for wood is consistent across countries and cultures with different wood use practices.
Method. 100 older adults from Slovenia and Norway rated and ranked wooden materials (i.e., handrails) made of either unmodified or modified wood and a stainless-steel control sample. The materials were rated on a semantic differential scale (capturing sensory and affective attributes) by each participant twice: first while only touching the materials and then while simultaneously touching and seeing the materials. Finally, each participant ranked the handrails in order of preference.
Results. Wooden handrails were generally more preferred than the steel sample. Preference ratings and rankings of modified wood were comparable to those of unmodified wood. Results were relatively consistent across both countries. Materials rated as liked were perceived as somewhat less cold, less damp, more usual, less artificial, more expensive, and less unpleasant. The ratings were fairly consistent between the tactile and tactile-visual task.
Conclusions. In at least some indoor applications, certain types of modified wood could be used in place of unmodified wood, while meeting human aesthetical preferences. Certain visual and tactile properties can predict material preference and could be considered in the material design phase. Tactile experience is important in overall material perception and should not be overlooked. These findings seem to be stable across countries with different wood use practices
WOOD PROPERTIES OF NINE ACETYLATED TROPICAL HARDWOODS FROM FAST-GROWTH PLANTATIONS IN COSTA RICA
Full text linkThe treatment of acetylation on tropical woods is influenced by their different levels of permeability and how these affect the weight percentage gain (WPG) in acetylated wood. The objective of the current study was to identify the effect of acetylation on the thermal stability, color, physical properties, hygroscopic and dimensional stability, wetting rate, and durability of nine tropical species of woods used for the commercial reforestation in Costa Rica. Study results showed that WPG varied from 2.2% to 16.8%. Positive significant correlations were observed between WPG and pre-exponential factors in TGA analysis and two parameters of dimensional and hygroscopic stability, whereas a negative correlation was observed with water absorption. In species with a WPG of over 10% (Vochysia ferruginea, V. guatemalensis, Cordia alliodora, and Enterolobium cyclocarpum) the thermal stability, wetting rate, hygroscopic stability, and resistance to biological attack showed an increase while swelling, and water absorption decreased. For these species, the best behaviors were obtained with an acetylation time of 2.5 hours and WPG values of over 10%. The same properties of wood in species with a WPG under 5% were found to be less affected by the different acetylation times and showed little difference in relation to untreated wood. Finally, the analysis showed that the dimensional stability obtained was attributed to the reduction of the absorptive capacity of the acetylated wood
EFFECT OF EXPOSURE TO ELEVATED TEMPERATURE ON DOWEL BEARING STRENGTH OF MASS PLYWOOD PANELS
No full textDesign of connections in mass timber are critical. Mass plywood panels (MPP) are a relatively new mass timber product, therefore, only a few studies characterizing their mechanical and connection properties exist. Dowel bearing strength is a critical parameter required in connection design regardless of the complexity of the connection. This study investigated the dowel bearing strength of MPP under the effect of exposure to elevated temperature. Thirty-two exposure duration-temperature combination was tested along with control group. Two analytical models are developed to explain the thermal degradation, one assuming a mechanism based on first-order kinetics and the second using a statistical regression. The degradation in the dowel bearing strength with respect to the increase in time and temperature exposure was characterized. In general, the kinetics model seemed to explain the data better than MLR using one less parameter
MOE DISTRIBUTION IN VISUALLY GRADED PONDEROSA PINE LUMBER HARVESTED FROM RESTORATION PROGRAMS IN SOUTHERN OREGON AND NORTHERN CALIFORNIA
Full text linkEvery year, restoration programs in Southern Oregon and Northern California produce large amounts of low-value Ponderosa pine (PP) lumber, which has limited market in the US. Engineered wood products, such as CLT and glulam, are expected to provide a value-added market to offset the high costs of restoration programs. However, restoration program lumber has larger amounts of juvenile wood and visual grades are reported to show lower mechanical properties compared to commercially harvested material, on which the National Design Specification (NDS) design values are based. This research addresses a knowledge gap on the impact of juvenile wood and visual, strength-affecting characteristics on the mechanical performance of PP lumber generated in the region of interest. The purpose of this study was to assess this impact based on measured moduli of elasticity (MOE) of samples of visually graded and ungraded restoration program PP lumber. The results were compared to previous studies and published values for commercially harvested PP as reflected in the NDS Western Woods (WW) species group. The results show that characteristic MOE values of visual grades No. 1 and 2. of PP from restoration programs were lower than respective design values for NDS WW group. However, the mean MOE values of all groups considered individually as well as pooled together were higher than NDS WW grade No. 3. MOE distributions for all groups, except for the visual grade No. 1, were remarkably similar showing negligible differences at 5th percentile, which may indicate negligible differences in correlated strength design values, not measured in this study. The average MOE of PP harvested in Southern Oregon and Northern California were higher than those reported for Columbia PP harvested in North Idaho