Volume 8 Issue 4

Those of us whose lives have been deeply touched by the technology of papermaking – and many others besides – are in for a real treat this coming fall when the book On Paper is scheduled to be published. The author, Nicholas Basbanes, employs an engaging, personalized approach as he brings to life the story of how paper has enabled the progress of civilization throughout two millennia. I first learned about Nick’s grand project, to capture the most intriguing aspects of paper’s story, during a re-broadcast of his hour-long interview that was presented on the CSPAN TV network. His enthusiasm is infectious, and it can be an uplifting experience to have him as a tour-guide to “all things paper”.

Bending wood dates back to antiquity in the form of baskets from willow branches. Fresh growth willow twigs are readily bent into practically any shape. When wood has been separated from the tree and dried it is more rigid, difficult to bend, and breakable. Bending drier wood with the help of heat and water is centuries old. Fishing hooks, barrel staves, and planks turned into boat hulls are examples. Steamed wood is less rigid, since adding moisture and heat to wood results in plasticization. Steaming at atmospheric pressure is common, wherein diffusion prevails as the predominant mechanism governing moisture movement. Applications using conventional atmospheric steaming can be time consuming, non-uniform, and can result in failures. Vacuum steam technology offers a promising method that utilizes pressure differentials to accelerate the addition of steam to wood due to water vapor bulk flow and subsequently an accelerated temperature rise. More uniform plasticization results in less breakage of the wood.

Crop straw-reinforced industrial materials can be effectively used as wood replacements, so the nondestructive evaluation of the dynamic performance and the realization of in-service testing are necessary for further quality control. Three nondestructive testing methods based on fast Fourier transform analysis were used to establish the dynamic modulus of elasticity of soybean stalk-reinforced materials. The results were compared to destructive measurements of the static modulus of elasticity and modulus of rupture using a regression analysis method. Significant correlations existed between the dynamic modulus of elasticity, static modulus of elasticity, and modulus of rupture. The highest degree of correlation was obtained from the flexural vibration method. The correlation degree is similar to that between the static modulus of elasticity and the modulus of rupture. Using the regression equation, a performance prediction model was established that will enable the prediction of the mechanical properties and quality evaluation of soybean stalk board.

Because of the increasing awareness of the environment and energy issues, as well as advances in technology, the areas of application for annual plant fiber functional materials are expanding. In this work, two chemical treatments, alkalization (2 h agitation with 5% NaOH) and furfurylation (graft furfuryl alcohol followed by oxidation with (1N) NaClO2 solution), were conducted on Luffa cylindrica fiber surfaces. The grafting of furfuryl alcohol followed by oxidation-generated quinines showed better results than alkaline treatment with respect to enhancement of surface area and hydrophobicity as well as wax, lignin, and hemicellulose extraction. The efficiency of chemical treatments was verified by elemental analysis and FTIR spectroscopy. Differential scanning calorimetry, thermo-gravimetric analysis, scanning electron microscopy, water absorption, and mechanical tests were performed to determine the thermal, mechanical, and morphological properties of untreated and chemically treated luffa fiber reinforced epoxy composites. Microstructures of the composites were examined to determine the mechanisms for the fiber-matrix interaction, which affects the thermal stability, water absorption, and mechanical behavior of the composites. The data from the water absorption process of composites at various temperatures were analyzed using a diffusion model based on Fick’s law.

The charge density of a bleached Kraft hardwood pulp, subjected to layer-by-layer adsorption of the oppositely charged cellulose derivative polyelectrolytes hydroxyethylcellulose ethoxylate, quaternised (HECE), and carboxymethyl cellulose (CMC), was studied by polyelectrolyte titration as a function of pH and ionic strength. The experimental design included a simultaneous variation of the experimental parameters, and the trends were evaluated with the help of partial least squares regression. As expected from the literature, the data indicate that both pH and ionic strength influence the charge of cationic fibers. It is also obvious that CMC as an outermost layer is more sensitive to changes in pH than the deprotonation of ≡COOH groups suggests. High ionic strength seems to be beneficial for the adsorption of HECE, while the pH dependence seems much more complicated. The non-linear pH dependence indicates that, in addition to electrostatic interactions, entropy factors and hydrogen bonding between OH groups on both the substrates and ligands are responsible for the adsorption, which is in agreement with literature on the subject.

The potential of sulfurous acid prehydrolysis followed by chemical pulping was examined at the laboratory scale using radiata pine. The residue obtained by sulfurous acid prehydrolysis with base addition was sufficiently delignified in a subsequent soda pulping stage, while the delignification of the residue was completely insufficient in subsequent kraft pulping. The residues prepared by prehydrolyses of hydrochloric and sulfuric acids were not delignified sufficiently regardless of the pulping method. The yield of hemicellulose-derived monosaccharides was about 90% on a theoretical basis in the optimal sulfurous acid prehydrolysis. In subsequent soda pulping under various conditions, pulps with kappa number 21 to 34, pulp yield 37 to 41%, and high cellulose content could be prepared from the residue obtained by sulfurous acid prehydrolysis with base addition. It was suggested from these results that sulfurous acid prehydrolysis with base addition in combination with subsequent soda pulping is an effective method for the utilization of wood hemicelluloses.

Some pretreatments that swell and/or open the structure of wood fibers could increase the effectiveness of a biobleaching process, allowing for an industrial application. To this end, a chemical pretreatment (urea, U), a physical pretreatment (refining, R), and their combinations (RU and UR) were optimized to evaluate and compare their enhancement of the LE biobleaching sequence (laccase-mediator treatment plus alkali extraction). The urea pretreatment before biobleaching (ULE) provided the highest delignification (37.5%) and the highest increase in brightness (6.1 points % ISO). As expected, adding a refining process before or after the urea pretreatment increased paper strength. However, when the refining was applied after the urea pretreatment (URLE), the delignification was higher than that obtained after RULE. Thus, URLE provided a similar Kappa number and an increase of 97%, 149%, and 98% in the tensile, tear, and burst indexes, respectively, compared with ULE treatment, but it had a reduction of 2.8 points (% ISO) in brightness, caused by the action of refining. Therefore, depending on the final use of the paper (which can require high optical properties or high strength), either ULE or URLE would be the optimal sequence.

This study was carried out to determine the thickness swelling of three-layered hybrid particleboard composed of sawdust and Acacia mangium under two different testing conditions. The experimental particleboards, composed of mixed sawdust and Acacia mangium, were fabricated with different resin contents and densities within the face and back (both composed of sawdust) and the core (composed of Acacia mangium particles). Particleboards consisting of only Acacia mangium particles were used as the control. Three different resin ratios (8:10:8, 10:10:10, and 12:10:12) were tested in combination with three different board densities (500, 600, and 700 kg/m3). Urea formaldehyde (UF), with the addition of wax, was used as a binder. The thickness swelling was evaluated using two tests: water immersion, and change in relative humidity, specifically between 10 and 90%, in accordance with the ASTM D 3502-76 (ASTM 1999) standard. The results indicated that there were significant interactions between the resin contents and the densities, which had an impact on the percentage of thickness swelling of the mixed sawdust-Acacia mangium composites in both test conditions.

This study focuses on the use of demountable furniture joints in combination with 38-mm-thick honeycomb panels. These fittings were incorporated into L-shaped corner joints and then tested to determine their bending moment capacity. Overall, seven combinations of demountable fittings were tested. These groups of connectors consisted of solution non-glued, partly-glued connectors, and fully-glued connectors. All of the connectors were positioned in the test samples as they are commonly located in furniture construction. The highest capacities were obtained with glued connectors, followed by partly glued and then non-glued connectors. The difference in capacity between the inside and outside positions was insignificant for the non-glued and fully-glued connectors. A large difference between connectors in different positions was found for the partly glued connectors and for the second type of unglued connectors. The modes of failure were analyzed for each connector, and the possibilities for use in construction are described.

Poplar (Populuseuramericanacv.) is one of the most important fast-growing tree species in China, but so far its utilization has been limited to nonstructural wood-based panels. The objective of this work was to develop a good understanding of how to improve the mechanical properties of poplar laminated veneer lumber (LVL) with carbon fiber reinforced polymer (CFRP). A theoretical model was successfully developed to predict the bending modulus of elasticity (MOE) of LVL reinforced by CFRP. To validate the model, two different configurations of LVL were made in the laboratory: LVL reinforced with a single layer of CFRP on one side (LVL-SR) and LVL reinforced with a single layer of CFRP on each side (LVL-DR). It was found that the model prediction of the LVL MOE agreed well with the experimental results. LVL reinforced with CFRP had a greater MOE and modulus of rupture (MOR) than the control LVL. The MOE of the LVL-SR and LVL-DR increased by 40% and 67%, respectively.