Research Articles

Nanocrystalline cellulose (NCC) was prepared from Agave tequilana Weber blue variety via acid hydrolysis. The NCC was used in forming acrylic acid/acrylamide hydrogels (AA/AM), (80/20 w/w), crosslinked with N-N-methylene bisacrylamide (MBA) at addition levels of 1, 2, 4, and 8 wt% of the monomeric phase. The NCC was dosed at 0.1, 0.5, and 1.0 wt%. Two synthesis routes were used. In the first route, polymerization was performed immediately after mixing the components. In the second route, the mixture of the components was kept at 2 °C ± 1 °C for 24 h before the polymerization (thermal treatment). All the hydrogels were characterized by nuclear magnetic resonance (NMR), water absorption tests, scanning electron microscope (SEM) analysis, and rheology tests. The NCC particles had a diameter of approximately 75 nm. The hydrogels that were subjected to the thermal treatment reached the equilibrium after approximately 72 h. The un-treated hydrogels reached the equilibrium after approximately 58 h. The thermally treated samples had a lower swelling degree and the swelling degree decreased as the crosslinking degree and the NCC concentration increased. The swelling kinetics followed the Schott´s pseudo-second-order.

Raw bio-oil was pretreated and tested for hydrodeoxygenation (HDO) using three types of the commercial catalysts (HT-36, HT2300, and HT951T) to improve physio-chemical properties and enhance hydrocarbon yields. The three catalysts prompted different levels of hydrodeoxygenation, and the organic phase products (OLPs) yields were 25.30, 27.83, and 13.05 wt%, respectively. Moreover, OLPs had lower water content, total acid numbers (TAN), and O content as well as higher heating value (HHV), C, and H contents. For the three catalysts, HT-36 had the best HDO effects, resulting in 34.8% hydrocarbon production with improved HHV, water content value and TAN as well as element contents. The different level of HDO depended on the catalyst components, structure, and morphology. This research is beneficial for the selection and preparation of effective catalysts for bio-oil upgrading.

Rice straw, which is considered an excellent insulation material, can be filled into the hollows of concrete block after being pressed, thereby improving the thermal performance of the concrete block. This new type of straw-concrete composite block will have good mechanical and thermal properties. In this study, to explore the feasibility of this new type of block, the response surface method was introduced. The goal was to find the effects of processing parameters on the forming quality of straw blocks. The quadratic regression model was established, and the processing parameters were optimized. It was found that the forming density, vertical pressure, pressure-holding time, and the interaction between the forming density and pressure-holding time had significant effects on the forming quality of the straw blocks. The optimal conditions obtained by RSM optimization were a forming density, a vertical pressure, and a pressure-holding time of 319.7 kg/m2, 2.5 kN, 33.68 s, respectively. Under these conditions, the volumetric contractivity of straw blocks was 11.17%, the horizontal failure strength was 21.74 kPa, and the natural moisture content was 16.37%. The parameters calculated via the prediction model were highly consistent with the results produced via the actual measurements, which showed that the prediction model was reliable and potentially useful in guiding industrial production.

To efficiently and economically utilize a wood-plastic biocomposite, an eco-friendly biocomposite was prepared using modified poplar fiber and polylactic acid (PLA) via 3D printing technology for the first time. First, the effects of poplar fiber (0, 1, 3, 5, 7, and 9%) on the mechanical and rheological properties of the printed biocomposites were investigated. Subsequently, the printing parameters, including printing temperature, speed, and layer thickness, were optimized to obtain the biocomposite with superior properties. Finally, four printing orientations were applied to the biocomposite based on the optimized printing parameters to study the effect of filament orientation on the properties of the biocomposite. Favorable printability and mechanical properties of the biocomposite were obtained at 5% poplar fiber. The optimal printing temperature of 220 °C, speed of 40 mm/s, and layer thickness of 0.2 mm were obtained to produce the desired mechanical properties of the biocomposite with the printing orientation in a longitudinal stripe. However, the printing parameters should be chosen according to the applications, where different physical and mechanical properties are needed to achieve efficient and economical utilization of the biocomposites.

Wood sapstain is a serious problem caused by the wood stain fungus, and it has a great influence on the international wood industry. The utilization of biological methods has good prospects for wood conservation. The objective of this study was to systematically estimate the antagonistic effect and influencing factors of Bacillus subtilis against wood stain fungus by using meta-analysis of literature data. Through report retrieval, a total of 992 references on B. subtilis related to wood were obtained. After strict screening, 163 data items from 7 articles were integrated. Estimated by the random-effects model, the combined effect Odds Ratio of the overall antagonistic effect was 0.15 (95% confidence interval [0.06, 0.34]). The results showed that B. subtilis could produce significant antagonistic effects against wood stain fungi. The inhibitory effect of wood stain fungi was affected by the strains of B. subtilis, species of wood stain fungi, the B. subtilis dosage, the type of mixed reagent, and the amount of mixed reagent on different wood stain fungi. The results of this study may provide a reference for biological control experiments, field tests, and practical applications of wood conservation.

A lignin-containing adhesion enhancer, a water-soluble polyelectrolyte complex (LPEC) composed of soda hardwood lignin (HASL) and polyethylenimine (PEI), and the effect of the treatment of hydrolyzed and ammoxidized aspen sawdust with the LPEC nanoparticles were studied relative to the properties of wood-plastic composites (WPCs) based on recycled polypropylene (rPP). The presence of the excess of free amine groups and salt bonds between PEI and soda lignin, forming hydrophobic sites in the LPEC structure, caused the enhanced surface activity of the LPEC. The treatment with the LPEC nanoparticles increased the content of the fixed nitrogen in the modified sawdust samples and was accompanied by decreasing their water sorption and increasing contact angles that favored the decrease in the polar part of their surface free energy. The decreasing wetting ability enhanced the mechanical and water sorption properties of the obtained WPC samples. The improvement of the interfacial adhesion between the nitrogen-containing groups of the treated sawdust and the oxygen-containing groups of rPP was explained by the formation of both covalent and physicochemical bonds.

Branch wood possesses unique properties that may affect biochar characteristics. Despite the abundance of broad studies on biochar, the correlation between feedstock properties and biochar hydrological characteristics has yet to be elucidated. Therefore, in this work the tree branch wood properties of three feedstocks (Acacia gerrardii Benth., Tamarix aphylla (L.) H. Karst., and Eucalyptus camaldulensis Dehn.) were investigated and compared with the characteristics of biochar produced by pyrolysis at 300 °C, 400 °C, and 500 °C. It was found that a higher lumen fraction resulted in a more porous structure, thus increasing the ability of biochar to absorb and retain water. Acacia gerrardii absorbed 403% and retained 73.6% water, whereas T. aphylla and E. camaldulensis held 396% and 342%, and then retained 71.5% and 68.1% water, respectively. The water holding capacity and water retention ability were lower in biochars pyrolyzed at 300 °C than 500 °C. The present findings demonstrate that fiber lumen diameter and parenchyma properties provide indicators of biochar hydrological characteristics generated from tree branch wood.

A feasible procedure was proposed to convert agriculture mulching film wastes into functional flame-retarded cotton stalk particles-polyethylene-sandy soil composites (CS-PE-SSx) by simple compounding and injection molding. Due to the uniform dispersion of solid particles in polymer matrix and the promising interfacial combination and the potential interacting forces between cotton stalk and sandy soil particles, the resultant composites showed promising mechanical strength (a flexural strength of approximately 29.0 MPa, a tensile strength of approximately 15.8 MPa, and an impact strength of approximately 3.17 kJ/m2) and improved thermal stabilities. The addition of sandy soil particles endowed materials with favorable flame-retarded properties, which can be resistant to fire ignition and flame out within 55 s. Moreover, the actual agriculture wastes containing mulching film residues, cotton stalk, and soil from different areas of China were also successfully transformed into functional composites, which exhibited promising mechanical, thermal, and flame-retarding properties. This study provided a simple, green, and low-cost strategy to convert agriculture mulching film wastes into functional materials, which can be recommended as a viable option to solve the problem of agriculture mulching film wastes.

This work investigated the feasibility of using western juniper (Juniperus occidentalis) as a material to manufacture oriented strandboard (OSB) panels. Four different material combinations of juniper sapwood, heartwood, and fibrous bark were compared with regular southern yellow pine (Pinus sp.) strands. The OSB panels were made at an oven-dry density of 560 kg/m3. One pine control panel was also made at a higher density of 650 kg/m3 with a 5% addition of phenol formaldehyde (PF) resin and a 0.5% addition of wax. The single-layer panels were formed with a hot press, and the physical and mechanical properties were tested according to the ASTM standard D1037 (2020). The testing indicated that western juniper is a potential material for manufacturing of OSB panels. The properties of the juniper panels were equivalent or slightly better than those of the southern yellow pine panels at the same density level, except for the modulus of elasticity (MOE). The lower density of the juniper OSB panels may have benefits in construction applications and can decrease transportation costs.

The purpose of the study was to inspect the mechanical and thermal properties of four kinds of core-shell structured bamboo-plastic composites (BPCs). The materials that were used for the fabrication of the BPCs were high density polyethylene (HDPE), bamboo pulp fibers (BPF)/HDPE, nano-CaCO3/HDPE, and white mud (WM)/HDPE. As verified by flexural properties and impact properties, the dispersion of the BPF, nano-CaCO3, and WM in the HDPE matrix was inhomogeneous. The fracture surface of the scanning electron microscope (SEM) images showed that some aggregates existed in the HDPE. Additionally, X-ray diffraction (XRD) was used to corroborate the results. The thermogravimetric analysis (TGA) showed that the samples with the WM/HDPE shell has little effect on the thermal stability. However, the apparent activation energy (Ea) values of the nano-CaCO3/HDPE shell were higher than those of the other samples, which indicated better thermal stability. The thermal stability had no remarkable changes with the addition of the WM and BPF. The differential scanning calorimeter (DSC) curves revealed that the relative crystallinity of the BPCs increased with the addition fillers, which suggested that the fillers can act as nucleating agents.