Volume 16 Issue 2

This study prepared compression-molded products from ball-milled wood by thermally plasticizing lignin without adhesives or resins. Wet ball milling for 120 min produced smooth, creamy slurries. The resultant products were hot-pressed at 180 °C and exhibited a plastic-like glossy surface and a high Young’s modulus (7.9 GPa), which was attributed to an increased bonding area. However, hydrogen bond formation occurs more predominantly during wood molding than thermoplasticization of lignin, because a hydrophilic surface was formed on wood fragments after wet ball milling in water. In contrast, when wood powder was ball-milled in toluene, drying aggregation due to hydrogen bond formation hardly occurred probably because the hydrophobic regions were preferentially cleaved. In this case, the hot-pressed product at 180 °C was formed mostly through the bonding owing to the thermoplasticization of lignin. These results suggest that the choice of the solvent for the mechanical disintegration of wood allows for control of the wood fragment surface and can affect the properties of the molded products.

The traditional method for the identification of paper from different origins relies on microscopy to observe the fiber morphology, which requires professional experience. In this paper, pyrolysis-gas chromatography-mass spectrometry was utilized to analyze five types of traditional Chinese handmade papers, e.g., ramie paper, bamboo paper, bark fiber paper (mulberry paper and kozo paper), and Langdu paper. The results demonstrated that this method can be used to differentiate the four types of handmade papers. A high phenolic compound content was detected in bamboo paper; macromolecular triterpenoids, e.g., β – amyrin, α – amyrin, and stigmastan- 3,5-diene were found in mulberry paper and kozo paper; while those compounds were not found in ramie paper. In particular, a large quantity of phytosterol compounds were found for the first time in Langdu paper. This not only can be used to differentiate Langdu paper from others, but also it helps to explain why Langdu paper can resist insect and mildew activities. Results of the study can provide experimental reference for characterization of traditional handmade Chinese papers via pyrolysis-gas chromatography-mass spectrometry.

Due to the increasing accumulation of wastes around the world, the demand for sustainable products is increasing. Paper is a commonly disposed of material that can pose problems even when it is recycled. The concept of using cardboard (CB) as a material for furniture production has been around for many years, but CB furniture does not last long. This study examined the feasibility of using post-consumer recycled paper to produce paper-based boards for furniture design. Cardboard (CB) and office paper (OP) were the main post-consumer materials that were used. The CB and OP were mixed with polylactic acid (PLA) and limestone. The boards were made at a temperature of 200 °C and pressed at a pressure of 3.5 N/mm2 using a single opening hydraulic press. The physical and mechanical properties were tested according to the European standards for wood-based panels. Tests that are critical for furniture parts, such as the modulus of rupture (MOR), the modulus of elasticity (MOE), the internal bond, the screw withdrawal resistance, the thickness swelling, and the water absorption were examined. The paperboard samples exceeded some of the requirements for the general use of boards for interior fitments (including furniture) for use in dry conditions (Type P2) and for non-load bearing boards for use in humid conditions (Type P3).

Solid carbon is an important raw material in industrial processes. Most of the charcoal produced today is via conventional carbonization, which suffers from huge carbon losses due to system inefficiency. Intermediate pyrolysis is principally similar to conventional carbonization and produces biocarbon while capturing the off gasses; among these off gasses is aqueous condensate, which is difficult to utilize due to the high water content and low energy content. This fraction can contain up to 25% of the carbon from feedstock, so utilization of this fraction is important for good overall carbon balance. Anaerobic digestion can be a promising tool for utilizing the carbon in the aqueous condensate by converting it into biomethane. Here, birch and spruce wood were pyrolyzed and the biomethane potential for the aqueous condensates was tested. The mass and carbon balances of the pyrolysis products of birch and spruce at two pyrolysis temperatures were performed, and biocarbon carbon yields ranging from 42% to 54% were obtained. Anaerobic digestion of the aqueous phases collected from the pyrolysis process was performed, with carbon recovery yields between 44% and 59%. A total carbon recovery of 77.8% to 85.7% was obtained, and the primary carbon losses were identified.

The thermogravimetric properties and chemical characterization of rice straw (RS) pretreated by mixed culture of white-rot fungi Phanerochaete chrysosporium (P. chrysosporium) and brown-rot fungi Gloeophyllum trabeum (G. trabeum) were investigated. The mixed fungal pretreatment showed a synergistic effect, which resulted in an energy-efficient pyrolysis of pretreated rice straw. The differences in thermochemical conversion of rice straw before and after fungal pretreatment were investigated using thermogravimetric analysis and the Flynn–Wall–Ozawa (FWO) method. Furthermore, the pretreated samples were also analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) to illuminate the changes in chemical composition and pyrolysis behavior. Compared to single fungal pretreatment, the mixed fungal pretreatment worked better and exhibited great potential in biomass pyrolysis.

A biosorbent was prepared from the cellulose fibers found in rice straw through cationic modification. The effects of the dosage, pH, contact time, and initial concentration of lemon yellow dye were explored. The static adsorption results showed that cationic modification drastically improved the adsorption capacity of straw cellulose fiber. The maximum equilibrium adsorption capacity value was 137.6 mg/g and the highest removal reached 99%. The pseudo-second-order kinetic model was a good fit for the adsorption process, together with the Langmuir isotherm model. The adsorption reaction was spontaneous, and the adsorption process was an exothermic reaction, which was shown by the thermodynamic model. As the adsorption time became longer, the effluent concentration became larger until reaching equilibrium. The time was 420 min. After desorption using a dilute NaOH solution, the maximum adsorption capacity was still 36.1 mg/g and the maximum removal still reached 36.2%. The parameters calculated from the Yoon-Nelson model have a good fit with the experimental data. In short, cationic straw cellulose fiber is an effective and easy to prepare biosorbent. This work offers a new method for dye wastewater purification and solves the effective utilization of rice straw resources.

The effects of different activation temperatures (Ta), ranging from 300 to 750 °C, on the ash content, yield, ignition point, microcrystalline structure, surface functional group, pore structure, and adsorption performance of activated carbon in preparing activated carbon by phosphoric acid (H3PO4) were systematically studied. The yield and volatile content of activated carbon decreased with the increase of Ta, while the ash content, ignition point, and graphitization degree showed the opposite results. The turning point of ash content increasing rate of activated carbon occurred at 500 °C. The thermal decomposition temperature of phosphonate compounds was approximately 450 °C. With increased Ta, micropores were generated first, followed by mesopores. The ignition point of activated carbon was related to the volatile content and the degree of graphitization. Activated carbon with low ash content, high yield, well-developed pore structure and good adsorption performance was prepared at 350 to 425 °C. With increased Ta, the volatile content decreased, and the ignition point of activated carbon increased. At Ta higher than 500 °C, the aromatic and condensed ring structure, graphitization degree, and mesopore ratio of the activated carbon increased, yielding decreased adsorption performance.

Solid wood is an important engineering material. Solid wood has superior properties, such as being renewable, easily processed, relatively inexpensive, and having higher mechanical properties relative to its density than any other engineering materials. Density, moisture content, tree species, knots, cracks, and some other variables influence the mechanical properties of wood. In this study, the effect of span length on the impact bending strength (IBS) of wood was investigated. Poplar and pine wood samples were used as test materials in the experiments. The IBS measurements were carried out following TS 2477 (1976) using a pendulum impact bending machine. Tests were conducted for various span lengths of 10, 15, 20, 25, 30, and 35 cm. The results indicated that there is a relationship between IBS and span length. The highest impact bending strength was obtained with a span length of 10 cm for poplar and pine wood. The relationship between IBS and span length was parabolic. The coefficients of determination were 0.94 and 0.99 for poplar and pine wood, respectively.

The increasing demand for sustainable architecture has led to a growing interest in wood structures. Hence, ensuring their structural stability and strength performance is an imperative. This study investigated the nail bearing strength and withdrawal resistance of mixed cross-laminated timber (CLT) using Japanese larch and yellow poplar layers. The mixed CLT was composed of three larch laminas (major) and two yellow poplar laminas (minor). The bearing strength of the mixed CLT decreased as the ratio of the thickness of the minor lamina to nail depth increased. The nail withdrawal resistance differed in the penetration and axial directions of the laminas. In the direction perpendicular to the grain, the withdrawal resistance load of the yellow poplar lamina was measured to be 1.45-times that of the larch lamina. The withdrawal resistance of the mixed CLT with the yellow poplar layer was 17% higher than that with larch. Therefore, the length of the nail used for the mixed CLT should be selected based on the thickness of the minor lamina to achieve efficient bearing and withdrawal resistance of the nail connection.

In order to study the lateral resistance of reinforced traditional Chinese timber frames with mortise-tenon connections, three cyclic tests were conducted on one-bay mortise-tenon jointed traditional timber frames. Three reinforcement methods, i.e., steel angle strengthening, wood brace, and Timu, were studied. Seismic performances were evaluated according to the experimental phenomena and the test results. The failure mode, hysteresis curves, skeleton curves, curves of stiffness degradation, and energy dissipation capacity of the three specimens were analyzed based on the tests. The test results showed that the wood frames had good deformability. The stiffness degradation of the timber frame was severe at the initial loading stage; however, the degradation rate tended to decrease after the initial stage. In addition, the energy dissipation increased as the lateral displacement increased. The wooden frames with mortise tenon joints strengthened by steel angle, wood brace, and Timu can achieve good aseismic results. The study can provide a theoretical basis for seismic design and reinforcing methods of traditional timber structures.