Volume 15 Issue 4

The accumulation of water inside wood creates a favorable environment not only for molds, but also for wood-decaying fungi and insects. Therefore, the ability to limit water adsorption and retention is key to the longevity and performance of wood. In this study, the effect of heat-treatment and Cu nanoparticle (CuNP) impregnation on surface contact angle, specific surface area, and hygroscopicity of Masson’s pine wood was examined. Heat-treatment caused thermal degradation of hydroxyl-rich biopolymers, leading to an increase in hydrophobicity; while the resulting breakdown and blockage of the interior cell cavity network caused a decrease in effective surface area. In turn, the hygroscopicity of the heat-treated wood was considerably lower than the untreated wood. Analysis of water adsorption isotherms enabled the differentiation between bound water and free water, where the latter was a prerequisite for mold growth. The research showed that the amount of free water was reduced by both impregnation with CuNP and heat-treatment, but the previously observed antimicrobial activity was shown to rely on the presence of CuNPs as opposed to the reduced free water content. This study presented a detailed methodology for the preparation and analysis of heat-treated, CuNP-impregnated wood, and provided further insight into the mechanism of antimicrobial action of treated woods.

A methodical approach to designing new furniture fasteners for lignocellulosic materials will uncover new sources of innovation. This paper presents an example of such a design procedure and its results. The outcomes are new concepts of mechanical fasteners for wood-based boards used in frameless furniture. At first, the requirements based on the furniture users, furniture manufacturers, and fastener manufacturers viewpoints were identified. These design criteria were analyzed, and as a result, seven ideas of fasteners with innovative features were created. The invented fasteners provided a starting point to generate prototypes. The prototypes were subjected to multi-dimensional methodical developed evaluations. The purpose of this paper is a detailed presentation of the pathway leading to solutions that are potentially beneficial in terms of product performance and of the identified design limitations. Two main conclusions were made. First, all mechanical furniture fasteners always are a combination of two functional subsystems, anchoring and drive. Secondly, there are a limited number of their design solutions. Despite the wide variety of market offerings, only four anchoring methods are used, and only two drive methods are used in all fasteners.

Bacterial cellulose, produced during fermentation of Kombucha tea, was investigated relative to its ability to modify the characteristics of pulp from recycled office wastepaper. The produced bacterial cellulose wet films were dispersed and added rates of 5%, 10%, and 15% to the recycled office wastepaper. The Fourier-transform infrared spectroscopy analyses, scanning electron microscopy images and thermogravimetric analysis values were determined in order to characterize the pulp samples. The results of these analyses showed similar changes as the amount of added bacterial cellulose increased, which also meant an increased amount of filler attaching to the fiber matrix. The burst index and tensile index values were protected while the tear index value partially decreased as the amount of added bacterial cellulose increased. The brightness values of the bacterial cellulose reinforced papers did not change after thermal aging, while the changes in the yellowness values were quite limited. Higher water absorption rates, and lower air permeability values were obtained from bacterial cellulose reinforced recycled office wastepaper sheets, which corresponded to the addition of increased bacterial cellulose amounts. Considering the mechanical and physical properties of the reinforced paper, bacterial cellulose represents a promising alternative for the reinforcement of office wastepaper.

Ethanol is an intermediate of the supercritical water decomposition of lignocellulosic biomass or biomass-derived compounds. In this study, experiments on ethanol decomposition in supercritical water were performed at different reaction temperatures (500 °C to 600 °C), residence times (6 s to 12 s), and initial ethanol concentrations (0.05 mol·L-1 to 0.20 mol·L-1). Temperature had larger impacts on the ethanol conversion than the other factors. Higher temperatures and feedstock concentrations facilitated gas production. In addition, the higher temperature promoted the scissions of C-C and C-O bonds of ethanol. However, longer residence times did not improve the yields of H2, CO, and C2. Because the H2-to-CO2 ratio was much greater than 1, the water-gas shift reaction was not the dominant route during the ethanol conversion process. Further, the mechanism and kinetic model of ethanol supercritical water decomposition were proposed. The kinetics revealed that ethanol gasification in supercritical water was mainly dominated by ethanol dehydrogenation, the hydrogenation of intermediates, and the coke formations of CO and CH4. In addition, H2 was mainly formed via ethanol dehydrogenation and consumed via the hydrogenation of intermediates. The rate of coke formation was relatively low during ethanol decomposition.

In this work, physical and chemical analyses of 28 sawdust samples (tropical woods, pine woods, and oak woods) derived from the primary process of wood transformation and 4 samples of citrus residues were performed, as an option to make densified biofuels. The study included the determination of initial moisture, particle size distribution, proximate analysis, ultimate analysis, calculation of the calorific value, and ash microanalysis. The initial moisture content of the biomass samples ranged from 6.04 to 75.21%. The biomass granulometry results indicate that the highest proportion corresponds to the 1.0-mm (33.10%) (Fraction retained in mesh 0.5 mm). Other results obtained indicate the following ranges: ash content (0.27 to 6.27%), volatile matter (78.90 to 90.50%), fixed carbon (9.10 to 20.44%), carbon (49.13 to 50.78%), oxygen (42.62 to 44.49%), and hydrogen (5.24 to 6.55%). The calculated calorific value ranged from 17.65 MJ/kg to 20.72 MJ/kg. The chemical elements with the highest concentration in the biomass samples were K and Ca, followed in some cases by Al and P. The biomass with the greatest possibilities for making densified biofuels of better quality is the group of pine woods because they have low mineral content, low nitrogen content, and high calorific value.

The demand for engineered wood products (EWPs) continues to rise internationally. However, for some important Australian commercial timbers such as plantation grown southern pine and native forest sourced spotted gum, a major impediment to achieving commercially viable EWP production is difficulties experienced in gluing – particularly for sawn laminate based EWPs such as glulam. Wettability and permeability have a major influence on wood adhesion. This study investigated the efficacy of different surface machining preparations on the wettability and permeability of southern pine and spotted gum. For both species, planing resulted in poor wettability, whereas face milling and sanding treatments post-planing improved wettability. Wettability increased in southern pine earlywood compared to latewood; and wettability decreased for both species with increased time post-surface machining. Planing resulted in the highest permeability for southern pine but the lowest permeability for spotted gum. Face milling resulted in higher permeability compared to sanding treatments.

Lignin has gained momentum as a renewable material because it is the largest natural source that can provide aromatic compounds in a wide range of applications. However, its heterogeneity in terms of high polydispersity molar mass distribution and variety of functional groups has limited the direct production of added-value lignin-derivatives. Among the alternatives to obtain more homogeneous lignin cuts is solvent fractionation. However, it is not well understood how different solvents influence lignin partition, and thus it is difficult to establish a rational solvent order to perform it. Thus, the purpose of this work was to understand Eucalyptus urograndis kraft lignin partition in organic solvents through the application of three solubility parameter theories: Hildebrand, Hansen (HSP), and Functional (FSP). Through the theories studied, FSP provided the best representation of lignin partition in organic solvents. In addition, the influence of solvents’ solubility parameters on lignin solubility was investigated by multiregression analyses, which revealed that only the polar solvent parameter showed statistical relevance to describe lignin solubility. The results of this work may contribute to the effective development of technical lignins’ fractionation, allowing the production of higher-value lignin derivatives, increasing the profitability of biorefineries, and establishing a sustainable bio-based economy.

Nanofibrillated cellulose (NFC) and a combined systems of NFC with cationic starch or cationic polyacrylamide were used in place of long-fiber chemical pulp in manufacturing currency paper from waste lint fibers from the textile industry. Handmade papers (60 g) were produced from each treatment, and the physical, mechanical, and optical characteristics of papers were compared. The results showed that increasing amounts of NFC by itself increased tensile strength, resistance to bursting, tearing, porosity, and opacity, and decreased the resistance to folding and brightness. Increasing NFC in combination with cationic starch reduced the need for chemical pulp, while improving porosity, opacity, and brightness and increased tensile strength, bursting strength, resistance to tearing, and folding in comparison to the use of long-fiber pulp. Increasing NFC in combination with cationic polyacrylamide, compared to long-fiber chemical pulp, increased opacity, tensile strength, and resistance to bursting and decreased the porosity, resistance to tearing, folding, and brightness. Field emission-scanning electron microscopy results showed that an enhanced percentage of NFC reduced porosity so that addition of 5% cellulosic nanofiber made the paper surface smoother and pores were relatively filled.

Effects of treating cotton stalks with a coupling agent (maleic anhydride polypropylene (MAPP), polymeric methylene diphenyl diisocyanate (PMDI), or vinyltrimethoxysilane (A171)) were investigated relative to the mechanical and water resistance properties of cotton stalk–polypropylene film boards. The interfacial morphology was investigated by scanning electron microscopy (SEM). The results showed that the properties of the boards increased with the incorporation of MAPP or PMDI up to 2 wt%, or with A171 up to 3 wt%, but further increases in the coupling agent contents decreased the properties. Boards treated with 2 wt% PMDI exhibited optimum properties, with a 39.0% increase in modulus of rupture, a 38.2% increase in modulus of elasticity, a 68.4% increase in internal bond, and a 57.4% decrease in thickness swelling, compared with untreated boards. The SEM micrographs further confirmed an efficient fiber-film adhesion in the coupling-agent-treated boards.

Poplar and pine wood were extracted with water, 1% NaOH (wt%) solution, and benzene:ethanol solution (V1 : V2, 2 : 1) to investigate the governing factors and mechanism by which extractives affect wood structure and mechanical properties. The structure, pore distribution, crystal structure, and mechanical properties of samples were analyzed by Fourier transform infrared spectroscopy (FTIR), adsorption of N2 gas, X-ray diffraction (XRD), and mechanical testing, respectively. The results demonstrated that cellulose, hemicellulose, and lignin were degraded to some extent in the course of the dissolution of the extractives. This degradation had a great influence on the structure and quantity of pores. The extraction treatment did not change the crystallization type of the wood, but it increased the crystallinity of the wood, and the length and width of the crystallization area changed. In addition, the mechanical properties of wood were changed when the content of the extractives was reduced.