Self-Activatin Process to Fabricate Activated Carbon from Kenaf

Self-activation takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon, so that a high performance activated carbon is obtained. Kenaf fiber, one type of biomass, was self-activated into activated carbon. The Brunauer–Emmett–Teller (BET) specific surface area (SABET) of non-activation and self-activation pyrolyzed at 1100°C for 2 hours were analyzed and obtained as 252 m2/g and 1,280 m2/g, respectively, with 408% difference. The results showed that the highest SABET (1,616 m2/g) was achieved when a kenaf fiber was pyrolyzed at 1,000°C for 15 hours. A linear relationship was shown between the ln(SABET) and the yield of kenaf fiber based activated carbon through the self-activation process. The study also showed that a yield of 9.0% gave the highest surface area by gram kenaf fiber (80 m2 per gram kenaf fiber), and the yields between 7.2 – 13.8% produced a surface area per gram kenaf fiber that was higher than 95% of the maximum surface area by gram kenaf fiber

Dynamic Adhesive Wettability of Wood

Adhesive wettability of wood is usually evaluated by contact angle measurement. Because of liquid penetration and spreading on the wood surface, the contact angle changes as a function of time. In this study, a wetting model was developed to describe the dynamic contact angle process in which a parameter (K) can be used to quantify the adhesive penetration and spreading during the adhesive wetting process. By applying the wetting model, the adhesive wettability of sapwood and heartwood of southern pine and Douglas-fir was studied. Liquid wettability along and across the wood grain direction was also compared. Two resin systems, polymeric diphenylmethane diisocyanate (PMDI) and phenol-formaldehyde (PF), were evaluated. It was learned from this study that the wetting model could accurately describe the dynamic adhesive wetting process on wood surfaces. Through applying this model, it is shown that PMDI resin exhibited a better wettability on wood than PF resin. The adhesive is more easily wetted along the grain direction than across the grain direction. Species and drop location have no significant effect on the spreading and penetration rate (K-value). However, the interaction term between species and resin type shows a significant effect for the K-value. PMDI exhibits a greater K-value on the Douglas-fir surface, while PF resin shows a greater K-value on the southern pine surface. Heartwood shows a lower instantaneous contact angle than sapwood. Douglas-fir has a greater instantaneous contact angle than southern pine. The effect of species on the equilibrium contact angle is strongly dependent on the location of the drop on the wood surface. The equilibrium contact angle of Douglas-fir is smaller than that of southern pine for sapwood, but is greater for heartwood

An Evaluation of Analysis Methods to Eliminate the Effect of Density Variation in Property Comparisons of Wood Composites

The 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

Modal Analysis of Upright Piano Soundboards by Combining Finite Element Analysis and Computer-Aided Design

This study presents a visual model for analyzing the vibration modes of piano soundboards by combining the tools of finite element analysis and computer-aided design. Based on the predicted results from the model, changes of natural frequency and maximum displacement of the soundboard as a function of wood properties, structure, and rib size were discussed. Wood grain direction affected the mode shape of the soundboard. Among the 10 property factors investigated, density presented the greatest impact to the vibration mode of the soundboard followed by Young's modulus, shear modulus, and Poisson's ratio. Increasing the thickness of the resonance board and the use of ribs had positive impacts on the natural frequency of the soundboard. However, the amount of natural frequency was decreased for those that were lower than 100 Hz. Natural frequency increased as the intensity, density, and size of ribs increased. Rib height had a greater effect on the variation of natural frequency than the intensity, density, and rib width. In general, increases in rib intensity, density of wood species, and rib width presented negative effects on the maximum displacement

Evaluation of the Noah\u27s Ark: Wood Mechanical Properties Affected by Water Immersion

This study focuses on the mechanical properties of different wood types related to Noah’s Ark and their degradation over time as the ark experienced over a year in water. The objective of this research was to evaluate the wood mechanical properties affected by water immersion as a function of time to see if the strength and stiffness would be diminished. Wood specimens from white oak, teak, and pitch-coated and non-coated southern yellow pine were chosen, because they represent upper and lower bounds of the elastic moduli and strengths of different wood types found around the world. Teak is thought to best represent gopher (term used in the bible) wood, since it was prevalently used as a structural material in the Middle East. The different wood types were soaked in fresh water and salt water for one year (the total time of the flood event). The tensile, compressive and flexural properties of the wood specimens were tested every two months, and the results were statistically analyzed. Since all of the wood types gave similar degradation trends in their mechanical properties over time, one would expect that the mechanical behaviors of gopher wood would exhibit the same trends. Even pitch was used to coat some wood specimens for comparison to provide understanding of the corrosion protection by water-proofing. The bottom line is that the mechanical properties and consequential dimensional stability of gopher wood would not have changed significantly by water immersion (30% maximum), even if it was in salt water and even if there were no pitch to cover the wood. This 30% reduction is not enough to diminish the structural integrity of the ark

Technical Note: A Preliminary Study on the Bending Stiffness of Chemically Treated Wood Material for Structural Composite Lumber

This research explored the effect of a chemical treatment on the stiffness of three southern hardwoods, yellow-poplar, sweetgum, and red oak, with the aim of broadening the potential feedstocks for structural composite lumber. Water-saturated 3 × 15 × 150 mm samples from each species were heated at 150° C for 30 min in three solutions: 1.0% H2SO4, water, and 1.0% NaOH. The specimens were nondestructively tested by static bending before and after treatment, and the reduction in modulus of elasticity (MOE) was determined. A significant interaction was present between the species and solutions. The trend in mean response for each species was generally a quadratic function of the solution. MOE was reduced the least for each species exposed to water. Sweetgum had a higher reduction in MOE in all three solutions, being significantly greater in the alkaline solution

Estimating Maximum Water Absorption of Wood Fiber/Polymer Fluff Composites

The objective of this study was to develop a model to estimate the maximum water absorption (MWA) of wood fiber/polymer fluff composites as a function of polymer fluff content and board density. Polymeric diphenylmethane diisocyanate (PMDI) resin bonded dry-process wood fiber/polymer fluff composites were used in this study. Six polymer fluff contents (0, 15, 30, 45, 60, and 100%) and four target oven-dry board densities in the range of 0.50-1.00 g/cm3 were studied. A water immersion test was conducted on these boards. The effect of irreversible thickness swelling after water immersion (TSi) on the estimation of the maximum water absorption was evaluated. It was shown that the irreversible thickness swelling had a quadratic relationship with polymer fluff content and a linear relationship with oven-dry board density. The TSi of the composites used in this study was in the range of only 0.04-4.20%, which was negligible in the estimation of maximum water absorption. The prediction of maximum water absorption from the MWA model developed in this study was over 95% accuracy for most of the specimens. The maximum water absorption had a linear relationship with the polymer fluff content and a reciprocal relationship with board density

Investigation of OSB Thickness-Swell Based on a 3d Density Distribution. Part I. The Finite Element Model

A finite element model was developed for predicting thickness-swell of oriented strandboard. The model accounts for both vertical and horizontal density variations of the board, or the three-dimensional density distribution. Density variation, resulting from manufacturing processes such as strand orientation and pressing cycles, affects the uniformity of thickness-swell in OSB. The model uses nonlinear constitutive behavior in the through-the-thickness direction. Moisture changes were modeled using transient moisture transfer equations and coupled moisture-density-stress-strain relations. The model was used to predict thickness-swell during a 24-h soak test. The model was able to predict average thicknes-swell of commercial panels with an acceptable error, generally less than 10%

Technical Note: The Susceptibility of Chemically Treated Southern Hardwoods to Subterranean Termite Attack

Ongoing research into chemically treating southern hardwoods for producing structural composite lumber suggests that some improvements may be imparted by modifying the wood. How chemical treatment(s) affect modified wood durability, particularly resistance to Reticulitermes flavipes, was the objective of this study. Water-saturated samples of yellow-poplar, sweetgum, and red oak were heated at 150°C for 30 min in two solutions: water and 1.0% NaOH; controls were also included. Samples were subjected to the AWPA E1-09 no-choice termite test in which mass loss from R. flavipes was determined. The species and treatments independently and significantly affected the mass loss. Yellow-poplar, which had the lowest specific gravity, averaged significantly greater mass loss than sweetgum and red oak for all three exposures. All species treated in water or NaOH showed a higher degree of termite degradation as compared with the controls

Technical Note: The Susceptibility of Chemically Treated Southern Hardwoods to Subterranean Termite Attack

Ongoing research into chemically treating southern hardwoods for producing structural composite lumber suggests that some improvements may be imparted by modifying the wood. How chemical treatment(s) affect modified wood durability, particularly resistance to Reticulitermes flavipes, was the objective of this study. Water-saturated samples of yellow-poplar, sweetgum, and red oak were heated at 150°C for 30 min in two solutions: water and 1.0% NaOH; controls were also included. Samples were subjected to the AWPA E1-09 no-choice termite test in which mass loss from R. flavipes was determined. The species and treatments independently and significantly affected the mass loss. Yellow-poplar, which had the lowest specific gravity, averaged significantly greater mass loss than sweetgum and red oak for all three exposures. All species treated in water or NaOH showed a higher degree of termite degradation as compared with the controls