Wood and Fiber Science (E-Journal)
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Development of Biocomposite Concrete Panels for Low-Cost Housing
Get PDFThis study focused on the possibility of developing biocomposite concrete panels with coir fibers to be used as a low-cost construction alternative. Coir fibers were used to completely replace steel reinforcement and natural resin was the binding material. Two types of biocomposite panels with single and double layers of woven coir fiber were developed. The performance of the biocomposite for both wall and slab panels was evaluated under flexural and axial-compression loadings
Binderless Fiberboard Made from Primary and Secondary Pulp and Paper Sludge
Get PDFPulp and paper sludge is valuable in fiberboard manufacturing because primary sludge (PS) contains fibers and secondary sludge (SS) has adhesive properties. We evaluated properties of binderless fiberboard made from conventional pulp and paper mill sludge sources using a factorial design in which the factors were SS:PS ratio (1:9, 2:8, and 3:7) and pulping process (thermomechanical [TMP], chemical-thermomechanical [CTMP], and kraft). Sludge was collected, refined, dried, and characterized for chemical composition and fiber length. Internal bond strength of CTMP panels increased 90% and thickness swell of TMP panels improved 92% with increasing SS content from 10-30%. IR Fourier transform and X-ray photoelectron spectroscopy analyses were conducted to better understand these results. Increased bonding was attributed to presence of proteins and lignin on the sludge fiber surface, which enhanced adhesion during hot pressing, whereas surface contamination decreased bonding efficiency. The TMP formulation at SS:PS ratio 3:7 met the ANSI requirement for basic hardboard. All other formulations were not dimensionally stable enough to meet the standard. The CTMP source resulted in the highest mechanical properties, and thickness swell was similar for the TMP and CTMP pulping processes. The kraft source produced low-integrity and dimensionally unstable panels
Physicochemically Modifying Wood by Low Energy Hydrogen Ion Shower: An Alternative Plasma-Based Antitermite Method
Get PDFBlantocas et al (2007) reported that low-energy hydrogen ion shower (LEHIS) irradiation of wood produced inhibited flammability and surface inactivation of wood. In this study, pest control performance of LEHIS compared with conventional pesticide (pyrethroid toxin) was assessed. Subsequent statistical analyses indicated that LEHIS was equally as effective as pyrethroid toxin in arresting microcerotermes losbañosensis subterranean termite infestations. LEHIS functions not as a toxicant, but rather as a treatment that made wood unpalatable to infesters. LEHIS treatment smoothened wood exterior and decreased surface pore sizes restricting moisture penetration. The change rate constant k in the wetting model equation (dθ/dt = -kθ) fell two orders of magnitude from 0.25/s (initial θ = 25°) for the control to 0.001 9/s (initial θ = 60°) for the treated sample. Hydrophobization was attributed to molecular reorientation resulting in loss of bonding sites for polar molecules. Fourier transform IR spectra showed that LEHIS treatment decreased absorption intensities of hydroxyls (O-H at 3360 cm-1) and carbonyls (C=O at 1730 and 1647 cm-1) suggesting the breakdown of hydrophilic components, in particular that of hemicellulose. With less moisture absorptive capacity, wood became less palatable to termites, thus inhibiting further decimations
Improving Bagasse Pulp Paper Sheet Properties with Microfibrillated Cellulose Isolated from Xylanase-Treated Bagasse
Get PDFTo improve the properties of paper sheets, microfibrillated cellulose (MFC) was isolated from bleached bagasse pulp pretreated with xylanase enzymes and returned to the pulp in varying amounts. The standard hand sheet paper-making method was used. The effect of adding different amounts of MFC on tensile strength (wet and dry), tear resistance, burst strength, opacity, and porosity of paper sheets was studied. Adding MFC to bagasse pulp improved wet and dry tensile strength, but tear resistance and burst strength decreased with increasing amounts of MFC. Also, adding MFC to bagasse pulp did not significantly affect opacity, slightly decreased porosity, and tightened the texture of the paper sheets as observed from scanning electron microscopy images. The strength properties of paper sheets made from bagasse and MFC were compared with those of paper sheets made from bagasse and softwood fibers. Paper sheets containing MFC had higher tensile strength (wet and dry) than those containing softwood fibers, but the later had higher tear resistance and burst strength
Improving Photostability and Antifungal Performance of Bamboo with Nanostructured Zinc Oxide
Get PDFWe report on the formation of zinc oxide (ZnO) films with various morphologies on bamboo to simultaneously furnish it with excellent photostability and antifungal properties. A simple two-step process was adopted, consisting of generation of ZnO seeds on the bamboo surface followed by solution treatment to promote crystal growth. Effect of reaction conditions on film morphologies was systematically investigated. Results indicate morphologies of ZnO films can be tailored from nanoparticles to nanostructured networks and irregular aggregates at the micron scale with different crystallinities through specific combinations of reaction conditions. The photostability and antifungal performances of coated bamboo were greatly improved and highly dependent on both crystallinity and morphologies of ZnO films
Ultrasonic-Assisted Dyeing of Poplar Veneer
Get PDFThis study introduces poplar veneer ultrasonic-assisted dyeing. Response-surface methodology was adopted to perform optimum analysis of effects of ultrasonic dyeing on poplar veneer. Results demonstrated that ultrasound increased dye uptake under optimal conditions (210-W ultrasonic power, 57-min assisted dyeing time, and 30-kHz ultrasonic frequency using a dye concentration with mass fraction of 0.52% at 72°C). Under these optimal conditions, dye uptake can reach 42.4%. Compared with nonultrasonic dyeing technologies, ultrasonic dyeing technology for poplar veneer developed in this study increased dye uptake 11.2%
Predicting Tensile and Compressive Moduli of Structural Lumber
Get PDFNondestructive bending modulus of elasticity (MOE) of lumber is commonly used as input data to estimate mechanical properties of glued lumber or laminated timber components. Many standard and nonstandard test methods exist to determine MOE. However, when glued components are loaded, the stresses imposed on the lumber subcomponents are quite different from stresses used in determining MOE of the lumber. It is well known that the bending MOE of lumber is somewhat different from its tensile and compressive moduli. Therefore, defining the differences and relationships between bending MOE and tensile and compressive moduli is important. This study predicted the tensile and compressive modulus from dynamic and static bending MOE of major softwood structural lumber in Korea. The measured MOE and tensile and compressive moduli from the same specimens by various test methods were found to differ. In particular, the tensile modulus was twice the compressive modulus for the same specimen. Edgewise bending MOE, which showed the highest correlation with tensile and compressive moduli, was suggested as a suitable input parameter for predicting tensile and compressive moduli. Predicting tensile and compressive moduli from dynamic or flatwise bending MOE of structural lumber is also possible, although with a different relationship. With better prediction of tensile and compression moduli, it is expected that the properties of engineered wood or timber structures can be more accurately estimated
Cell Wall Porosity in Norway Spruce Wood as Affected by High-Temperature Drying
Get PDFIn this study, pore size distribution in wood after high-temperature drying followed by rewetting was investigated by differential scanning calorimetry. Nonfreezing water content of wood was lower than previously indicated considering the effect of phase change on specific heat capacity of water. High-temperature drying appeared to close cavities of the largest size in earlywood, particularly with increasing drying temperature and time. Pore closure by irreversible hydrogen bonding dominated the eventual creation of cavities by degradation of wood structural components. Stress relaxation within wood elements, favored by slow high-temperature drying, decreased the extent of drying microcracks in earlywood, manifested in lower nonfreezing water content
Concerns About a Variance Approach to X-Ray Diffractometric Estimation of Microfibril Angle in Wood
Get PDFIn this article, we raise three technical concerns about Evans' 1999 Appita Journal "variance approach" to estimating microfibril angle (MFA). The first concern is associated with the approximation of the variance of an X-ray intensity half-profile by a function of the MFA and the natural variability of the MFA. The second concern is associated with the approximation of the natural variability of the MFA by a function of the MFA. The third concern is associated with the fact that the variance approach was not designed to handle tilt in the fiber orientation. All three concerns are associated with potential biases in MFA estimates. We raise these three concerns so that other researchers interested in understanding, implementing, or extending the variance approach or in comparing the approach to other methods of estimating MFA will be aware of them