Research Articles

Parallel strand bamboo (PSB), a processed bamboo composite, has been used as an alternative to wood products in building and engineering applications. Inelastic analysis of PSB members is important because of the evident nonlinearity of the material. The present work conducted experimental investigations on intermediately slender PSB columns subjected to biaxial eccentric loads. The bending failure, which underwent a pronounced nonlinear process, was the major characteristic of the intermediately slender PSB column that had a biaxial compressive load. The mid-height cross section of the columns can be divided into three parts over its depth: the plastic compressive zone, the elastic compressive zone, and the tensile zone. Both the secondary bending and material nonlinearity were important factors that impacted the nonlinear response of the columns. An analytical method was presented for evaluating the load-carrying capacity of intermediately slender PSB columns with rectangular cross sections under biaxial eccentric compression loads. There was good agreement between the results of the experiments and calculations.

Scots pine sapwood samples were pre-treated with a Lewis acid (AlCl₃) and a combination of Lewis and protonic acids (AlCl₃ and H₂SO₄), and were subsequently exposed to respective temperatures of 180 °C and 120 °C for establishing a comparable mass loss with those impregnated with demineralized water and solely thermally modified at 220 °C. Water impregnated samples dried at 120 °C also served as controls. The swelling behavior of all wood samples was examined with respect to maximum swelling in water, anti-swelling efficiency (ASE), shrinkage, and dynamic water vapor sorption at relative humidity ranges of 0% to 95%. The thermal modification at 220 °C diminished swelling and moisture adsorption, and also reduced moisture increment and decrement compared with the unmodified control. However, it was less obvious than both acid pre-treated samples. Excess surface work and Hailwood-Horrobin results calculated from water vapor sorption studies demonstrated that, at comparable mass loss, the available sorption sites were reduced to a greater extent by Lewis acid and combination of Lewis and protonic acids pre-treatment than the sole thermal treatment. This was attributed to more pronounced degradation of polysaccharides, mainly hemicelluloses and amorphous parts of cellulose, and to cross-linking of cell wall polymers due to the acid pre-treatments.

The use of cellulosic materials in the construction of low-rise housing in tropical climates has great potential. Bambusa blumeana (B. blumeana, J.A. and J.H. Schultes), the most abundantly available bamboo species in the Philippines, is a promising alternative material for the construction of cost-efficient buildings. However, to comply with municipal rules and regulations for construction, a comprehensive understanding of the organic raw material is needed to permit its application as a load-bearing structural member. In this study, the physical and mechanical properties of B. blumeana bamboo from a typical growth region of the Philippines were tested according to ISO 22157-1 (2004) and ISO 22157-2 (2004). The characteristic strength values of B. blumeana were as follows: compressive and tensile strengths parallel to the grain of 20 and 95 MPa, respectively; shear strength of 5 MPa, bending strength of 34.6 MPa, and the mean and fifth percentile modulus of elasticity of 13100 and 8600 MPa, respectively. Based on these results, a recommendation for permissible stresses for structural design was made in line with ISO 22156 (2004).

Load limit capacity, stiffness, and failure mechanisms were evaluated for the bending of two new types of furniture joints: one with an adhesive-bonded flat cross fastener, and the other with a frictional eccentric fastener. The results were compared with a commonly known direct thread connection used as a reference. For each of the three investigated types of joints, their strength-displacement curves and failure mechanisms were compared. The obtained results confirmed that the two new fasteners are suitable for making furniture joints with more advantageous load capacity and stiffness, as compared with the thread connection.

A new strategy is described to optimize multiple closely related parameters that are involved in the degradation of lignocellulose. Exo-β-1,4-glucanase, endo-β-1,4-glucanase, and β-glucosidase contained in the broth of Trichoderma viride 3.3711 cultures were used as enzyme solution. Corn stover (CS) pretreated by a combination of H2O2 and lignin peroxidase was used as raw feedstock. A comprehensive hydrolysis index (CHI) of three enzymatic activities was constructed by principal component analysis (PCA). Corn stover (CS) was pretreated with a combination of H2O2 and lignin peroxidase. The accuracy of the CHI was demonstrated by a quadratic regression using the CHI as an independent variable and the yield of the total reducing sugar (Ytrs) as a dependent variable. The results showed that the CHI was closely post-correlated with Ytrs and could be used to optimize the fermentation medium components for T. viride cultures due to a highly significant correlation between CHI and Ytrs. Based on the CHI at 96 h, an optimal medium contained 0.6% fructose, 0.6% xylose, 0.3% bean pulp, 0.15% yeast extract, 0.12% KH2PO4, 0.004% CaCl2, 0.008% FeSO4, 0.006% ZnSO4, 0.012% glycine betaine, and 0.004% polyethylene glycol. The maximum actual Ytrs was very near to the theoretical Ytrs.

Production of fumaric acid and xylooligosaccharides from corncob was investigated using a combined process. Corncob was fractionated into a cellulose-rich fraction and a hemicellulose-rich fraction by an alkali pretreatment. The cellulose-rich fraction was converted into fumaric acid by Rhizopus oryzae in fed-batch simultaneous saccharification and fermentation (SSF). Maximal fumaric acid concentration reached 35.22 g/L at a final 15% (w/v) solid loading in the fed-batch SSF. The hemicellulose-rich fraction was converted into xylooligosaccharides (XOSs) by endo-β-1,4-xylanase. The yield of XOSs was 62.35% after 24 h of xylanase hydrolysis. Xylobiose, xylotriose, and xylotetraose were the three major components in the XOSs. A mass balance analysis demonstrated that 100.6 g of fumaric acid and 148.1 g of XOSs were produced from 1000 g of dry corncob matter. The production of fumaric acid and XOSs by the combined process could make the utilization of corncob more efficient and more promising.

The catalytic effects of various acids (sulfuric acid, hydrochloric acid, phosphoric acid, and formic acid) on the depolymerization of organosolv lignin under mild microwave heating (approximately 100 W, 160 °C for 30 min) were investigated. The liquid product was separated from the solid residue and analyzed by gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). The solid residue was analyzed with thermogravimetric analysis (TG-DTG) and observed by scanning electron microscopy (SEM). The experimental results showed that sulfuric acid exhibited a better catalytic effect than the other acids. The SEM and TG-DTG results showed that the solid residue from sulfuric acid-catalyzed depolymerization was not only remarkably smaller than that of the other groups, but also presented a faster thermal decomposition rate. The molecular weight (Mw, weight-average) of the liquid product (Mw = 1020) from sulfuric acid-catalyzed depolymerization was also lower than that of the other groups.

Ozone is a non-chlorine bleaching agent that can reduce pollution in the pulp bleaching stage. In this work the ozone bleaching of eucalyptus kraft pulp was performed as part of a kinetics study to explain factors affecting the properties of bleached pulp. The bleaching efficiency was closely related to the rates of mass transfer and self-decomposition, as well as the intensity of ozonation. For ozone bleaching of 3% consistency pulp, a brightness of 68% ISO, viscosity of 579 mL/g, and kappa values of 7.9 were achieved under an optimal condition with pH 2 and organic reagent NP-10 supplied. In this condition, the ozone mass transfer and intensity of ozonation were promoted, while self-decomposition declined.

The electrosorption capacity of an electrode strongly depends on the surface properties of the electrode material, such as the surface area, pore microstructure, and pore size distribution. Carbon-based electrode materials for capacitive deionization (CDI) or electrosorption processes suffer from problems with high manufacturing costs, poor electrical conductivity, and poor wettability. The thin-film coating of SiO₂ on porous biomass carbon may provide an alternative electrode material for double-layer applications. In this paper, the activated porous biomass carbon (AWSC) was first obtained through a simple potassium hydroxide (KOH) activation of wheat straw carbon (WSC) as the precursor, and then thin-film SiO₂ coated AWSC (SiO₂@AWSC) was prepared by a sol-gel coating process. Scanning electron microscope (SEM) imaging of SiO₂@AWSC demonstrated that a SiO₂ thin-film was deposited on the surface of AWSC without changing the opening structure. Compared to WSC, the Brunauer-Emmett-Teller (BET) surface area of SiO₂@AWSC was greatly increased, and presented obvious micropore and mesopore distributions. Further electrochemical analyses were performed via cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance. The electrochemical results showed that SiO₂@AWSC electrodes showed increased electrosorption capacitance, which were attributed to a large specific surface area, a porous structure, and enhanced wettability.

The bleaching of pulp prepared by a displacement digester system (DDS) for displacement cooking of bamboo (Neosinocalamus) was established by comparing the results from elemental chlorine-free (ECF) bleaching and totally chlorine-free (TCF) bleaching. This process produced the optimal performance of obtained pulp via O-D₀-E_OP-D₁ bleaching, where the Kappa number of DDS pulp was 18 to 22, and the Kappa number of oxygen delignified pulp was 10 to 12. The brightness of the obtained pulp was over 86% ISO, the yield was up to 46%, and the viscosity was approximately 800 mL·g^-1. In contrast, O-Q-P₁-P₂ bleaching was advantageous for pulp with kappa number less than 5 after oxygen delignification. The brightness of obtained pulp was up to 81% ISO, the yield was over 40%, and the viscosity was about 650 mL·g^-1. In TCF bleaching, the water consumption was 20 m³·t^-1, the chemical oxygen demand (COD) content was 30 kg·t^-1, and the absorbable organic halogen (AOX) content was zero. The water consumption of ECF bleaching was 4 times that of TCF bleaching, while the COD content was 16 kg·t^-1 and the AOX content was 2 kg·t^-1.