Wood and Fiber Science (E-Journal)
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AN INVESTIGATION ON THE EFFECTS OF WOODEN SPECIES OF DOWELS AND THE END DISTANCE OF CATCH CONNECTORS (CLAMEXP14) ON THE BENDING MOMENT OF L-TYPE CORNER JOINTS FOR RTA (READY TO ASSEMBLE) FURNITURE
No full textIn this study, the effects of the wood species of dowels and the end distance were examined relative to the moment resistance of L-type corner joints with catch connector (ClamexP14) and three different wood species of dowels were used as specimen (as used in the furniture industry). L-type joint specimens 297 mm long were tested under static diagonal compression loads for determining the bending moment capacity. The results showed that the Orientalis beech dowel had the highest bending moment resistance under compression. Regarding the end distance, the highest bending moment resistance was obtained from an end distance of 60 mm.
REPEATABILITY OF ADHESION FORCE MEASUREMENT ON WOOD LONGITUDINAL CUT CELL WALL USING ATOMIC FORCE MICROSCOPY
No full textAs a powerful tool to investigate the surface properties at a nano-scale resolution, the atomic force microscopy (AFM) encounters challenges in the measurement of plant materials such as wood surface. In particular, for rough and heterogeneous surfaces, a robust and easily performed positioning method is necessary for reproducible measurements. One of the critical issues is the ability to position the AFM tip after the specimens are removed for treatments from a device and repeatedly analyzed. If the tip is not repeatably positioned within the measured area, the natural variability of surface (such as surface roughness) can mask the effects of treatments of interest. In this paper, a positioning method using the bordered pit of the wood radial surface as a natural marker is proposed and a systematic measurement procedure is presented. The idea results from the uniqueness of the anatomical features of a natural material (wood in this case) and low probability of having exactly the same geometry of pit clusters in the vicinity of the area of interest. The results show that the anatomical features can be used as unique markers for precise positioning of the AFM tip. The process is demonstrated using an example of the effect of temperature on adhesion forces on the wood surface. After the heat treatment, the wood surface layers were investigated with Fourier transform infrared spectroscopy and attenuated total reflection (FTIR-ATR).
TECHNICAL NOTE: LIGHT FRAME WOOD TRUSS ROOF COLLAPSE IN MISSISSIPPI, A CASE STUDY
No full textIn or around 1972, an experimental building was constructed. One of the intents of the construction project was to demonstrate advancements in wood building construction design. In was value-engineered throughout. That is, its materials and systems were intended to function at or near design capacity. In 2019, part of the roof of the structure collapsed. This case study investigates two potential factors that led to the failure: stress concentration in excess of the allowable stress for 2 x 4 web members and insufficient plywood sheathing to support live loads caused by large rain events.
ROLE OF TYLOSES IN THE DURABILITY OF CHESTNUT OAK
No full textTyloses are extruded cell contents of adjoining parenchyma cells that result in the obstruction of vessels. The function of tyloses in live trees is uncertain, but it has been proposed that they increase the natural durability of the wood by limiting water movement and the probing of fungal hyphae. Chestnut oak (Quercus montana, aka Quercus prinus) is inconsistent in producing tyloses; an initial study indicated a wide variation in the frequency of tyloses within and between trees of chestnut oak from three different states: VA, TN, and PA. This naturally occurring variation in tylosis abundance provides an opportunity to evaluate the impact of tyloses on natural durability. In this study, samples were further examined for extractive content, rate of wetting, and natural durability, to determine if these properties were related to the prevalence of tyloses. Tylosis abundance was not related to the density or extractive content but appeared to reduce water uptake, and fungal decay in laboratory tests. The mechanism of tyloses’ role in reducing decay is unclear but may include
PREDICTION OF END SPLITTING IN LOG OF EUCALYPTUS NITENS (H. DEANE & MAIDEN) MAIDEN THROUGH REGRESSION MODELS USING LONGITUDINAL RESIDUAL STRAIN, PHYSICAL, AND DENDROMETRIC PROPERTIES
No full textThe objective of this research was to develop regression models, with the purpose of estimating the growth stresses and end splitting, in 12-yr-old Eucalyptus nitens trees located in the province of Valdivia, Chile. A total of 40 trees were samples. Their longitudinal residual strain (LRS) was measured using the CIRAD-Forêt method and compared with the Council of Scientific and Industrial (CSIR) index and with a new index proposed in this investigation, called the splitting index. Physical and dendrometric properties of each selected tree were measured to identify possible correlations between these variables. These predictors were analyzed statistically, allowing the development of regression models, which showed a coefficient of determination (r2) of 0.783 and 0.770 to predict the LRS and CSIR indexes, respectively. Finally, a relatively robust regression model was developed to predict end splitting in logs using LRS and physical and dendrometric parameters
PRODUCTION OF YELLOW POPLAR INTERIOR PLYWOOD WITH COTTONSEED-BASED PROTEIN ADHESIVES
No full textDefatted cottonseed (CS) and water-washed CS meals were prepared from glandless CS and were used in adhesive formulations to produce three-ply yellow poplar plywood panels. Adhesive resins were prepared from each protein meal with sodium bisulfite and one of two polyamido-amine-epichlorohydrin (PAE) wet strength agents, and the plywood panels were produced by hot pressing. Shear strength and water resistance were determined by American Society of Testing and Materials (ASTM) and American National Standards Institute for Hardwood and Decorative Plywood/Hardwood Plywood and Veneer Association (ANSI/HPVA) methods and were compared with the properties of plywood panels made with an adhesive formulated from a commercial soybean meal. Panels prepared from three protein meals had comparable shear strengths. The combinations of the two CS preparations and the two wet strength agents produced panels with acceptable wet resistant properties, whereas the soybean meal only produced acceptable panels with one of the wet strength agents. Because the panels prepared from the two CS meals had comparable properties, there appears to be no benefit to including a water-washing step to increase the meal’s protein level. In contrast with recent literature reports suggesting the addition of alkali to elevate the formulation pH was necessary with CS meal, suitable panels were prepared herein without the addition of the base. This difference may have been due to the slightly higher pressing temperature and longer press times used in this work compared with earlier results. The CS meals showed promise as formaldehyde-free hardwood-plywood wood-based adhesives for interior applications.
PROPERTIES OF REINFORCED POLYMER COMPOSITE PRODUCED FROM COCONUT FIBER
No full textThis study aimed at the production of reinforced polymer composites from coconut fibers and plastics. Coir Fiber (CF) sheets with dimensions of 200 x 200 x 12 mm (+ 3mm) were used as the natural fiber, whereas a thermosetting plastic or an elastomer (unsaturated polyester [UPE] or silicon rubber [SIR]) was used as the binder in the matrix. Processing was performed using the vacuum infiltration method, wherein the liquid polymer was made to infiltrate the cellulose of the natural structure of the CFs and disperse within the CF matrix. The effect of production variables on thermal, sound, and flexural properties was evaluated. Material characterization tests revealed that the addition of the UPE and SIR as reinforcing materials enhanced the thermal conductivity of the CFs. UPE improved the modulus of rupture of the CFs. The study further revealed that CF/SIR composites showed high ductility. Analysis of the sound absorption properties of the composites revealed that the noise reduction coefficient (NRC) of the CF/400 wt% SIR composite was the highest. Moreover, the CF/SIR composites showed higher sound absorption efficiency (α) values at high frequencies than those of the CF/UPE composites. However, the polymers had no effect on the NRC of the neat CFs when added in a low concentration (200 wt%). This study shows that coconut husk waste can be used to produce reinforced polymer composites with desirable thermal conductivity and sound absorption characteristics
TECHNICAL NOTE: A METHOD TO DETERMINE THE WETTING OF WOOD FIBERS WITH THERMOPLASTIC
No full textThis paper presents a method which allows to assess the wettability of thermomechanical pulp (TMP) with thermoplastic. The method is based on the usage of laboratory sheets made of TMP and plastic granules which form drops under heat. The contact angle of the drops after re-solidification on the surface of the laboratory sheets serves as the wetting characteristic. This method enables a direct and evaluable testing of wood fiber thermoplastic combinations. The exemplary results indicate that wood species, pulping temperature and mercerization influence the wettability of TMP with thermoplastic
SOUND ABSORBING SYSTEMS MADE OF WOOD CROSS SECTIONS PAIRED WITH VOID CAVITIES - A FIRST INVESTIGATION
No full textThis study investigates the possibility of exploiting the porous structure of wood for absorbing sound. With this aim, the following system is proposed: 1) the cross section of wood should be exposed to sound waves so that these can activate the vibration of air inside the wood pores; 2) the cross section should be cut to have small thickness to realize a thorough open cell absorber; 3) a void cavity should be left on the back to activate the absorption effect. This setup has been conceived to absorb sound by Helmoltz resonance. To preliminary assess the effectiveness of the system, cross sections of poplar wood were cut 1 mm thick and paired with rear void cavities 15, 30 and 50 mm thick. The normal sound absorption coefficient α was determined through the impedance tube method. Multiple absorption peaks and several α values higher than 0.6-0.7 (αmax=0.99) were measured in the medium-low frequency range. Building on these results, further studies are envisaged to model the acoustic behavior of the system and to set the technical aspects relevant to its feasibility in practice