Volume 14 Issue 4

With the widespread use of wood-plastic composites, they are inevitably affected by aging during transportation and outdoor use. In this research, in order to improve the aging resistance of WPC, acrylate-styrene-acrylonitrile (ASA) was used as modifier (10 parts, 15 parts, and 20 parts). The effects of the ASA modification on the aging behavior of eucalyptus/polyvinyl chloride (PVC) composites was studied with simulated xenon lamp artificial aging conditions. Artificial aging caused the physical and mechanical properties of the composites to deteriorate. After 960 h of aging, the aging resistance of the ASA-modified WPC was better than unmodified WPC and the sample with 15% ASA added had the best performance.

Lignin/polyaniline composites were prepared by adding kraft lignin for the synthesis of polyaniline (PANI), a typical conductive polymer. The composites were utilized as an adsorbent for the removal of hexavalent chromium (Cr(VI)). When lignin alone was used as an adsorbent, the removal efficiency of Cr was low. However, when the lignin/PANI composite was used, lignin and PANI adsorbed Cr(III) together. The PANI reduced Cr(VI), which resulted in the efficient removal of Cr. In addition, as the dosage of the lignin/PANI composite decreased as an adsorbent, the Cr removal efficiency of the composite decreased considerably compared with pure PANI. However, the composite with a lignin-to-PANI ratio of 1:1 showed a Cr removal efficiency similar to that of pure PANI. The morphology of the lignin/PANI composite was observed to synthesize PANI around the lignin surface. Both Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses showed that an interaction between the carbonyl groups of lignin and the amine groups of PANI occurred. This study is expected to provide an opportunity to increase the utilization of lignin in the field of environmental science and provide several benefits.

Soybean-oil rosin-based polyester (SRP) has many uses in papermaking, but its performance as an internal sizing agent differs depending on the circumstances. In this study, a comprehensive laboratory approach was used to investigate the process variables affecting SRP application. Five levels of SRP (0.5%, 1.0%, 1.5%, 2.0%, and 2.5%), five levels of aluminum sulfate (0.5%, 1.0%, 1.5%, 2.0%, and 2.5%), and five levels of cationic polyacrylamide (0.05%, 0.1%, 0.15%, 0.2%, and 0.25%) were considered to determine the best process variables within a pH range of 5.0 to 9.0. Aspects that were considered included the mechanical properties (tensile, burst, and tear indices), water resistance (Cobb test, dynamic c9197ontact angle test, and scanning electron microscopy), and chemical usage (economical and environmentally friendly procedures). The optimum conditions based on these factors were 1.0% SRP, 1.0% aluminum sulfate, and 0.15% cationic polyacrylamide levels at a pH of 7.0. The results showed that in the optimal sizing system, 15% calcium carbonate can be tolerated.

The potential of organic and inorganic fillers at different loadings (ranging from 1% to 10%) was evaluated as a means to enhance the performance of Kappaphycus spp.-derived biopolymer films. The morphological properties of organic and inorganic fillers were characterized by scanning electron microscopy (SEM). The organic fillers displayed an irregular rod shape with sizes from 60 µm to 80 µm, while the inorganic fillers displayed spherical shapes with a much smaller size range (0.08 µm to 0.25 µm). The contact angle (CA) and mechanical properties of the fabricated biopolymer films were remarkably enhanced compared to the neat biopolymer films due to the incorporation of organic and inorganic fillers. The highest tensile strength (TS), CA, and water barrier properties were attained by biopolymer films that incorporated 5% organic and 1% inorganic fillers. Up to now, there has been no such report on the role of organic and inorganic fillers on tuning the performance of the Kappaphycus spp.-based biopolymer films. This work demonstrated that the biopolymer films containing inorganic fillers promoted better physical-mechanical performance compared to the biopolymer films with organic fillers, achieving desirable properties for various packaging applications.

The wood dowel pin is one of the common fasteners for connecting structural members in wooden furniture frame construction, such as chairs. The effects of dowel penetration depth, shear strengths of connection member and dowel materials, dowel surface texture, and member grain orientation on ultimate direct withdrawal loads of single dowels withdrawn from wooden materials were investigated. The main findings were that the connections using dowels and main members with low shear strength properties achieved the same ultimate direct withdrawal loads with connections using the materials with higher shear strength properties for dowels and main members. Additionally, the existing empirical equations, including shear strength properties for both dowel and main member materials used to construct dowel connections, tended to remarkably underestimate the ultimate direct withdrawal loads of the evaluated dowel connections withdrawn from the end and side grains of the tested wood species. The connection main members in this study when these two shear strength values were added together was less than 25 MPa. Both estimation expressions were modified to consider the lower shear strength effort on ultimate direct withdrawal loads of dowels evaluated in this experiment.

Every year, millions of tonnes of dead biomass from algae and seagrasses are collected on the Mediterranean coasts. Posidonia oceanica is one of the most abundant species. In this work, leaves and rhizomes from this plant were pulped, alkalized, and cationized to make a value-added product. The main effects of five separate pulping variables, namely temperature, time, NaOH concentration, anthraquinone, and liquid-to-solid ratio were studied. The total procedure to produce cationic fibers took only 3 h (approximately), which made it a feasible process. A pseudo-second-order rate equation was used to fit the results of chemical modification via incorporation of quaternary ammonium ions. Characterization involved X-ray diffraction, scanning electron microscopy, and elemental analysis. The authors found that mild conditions were enough to achieve good results, reaching degrees of substitution of 0.20 for leaves and 0.12 for rhizomes.

In the biomedicine field, three-dimensional (3-D) printing of biomaterials can construct complex 3-D biological structures such as personalized implants, biodegradable tissue scaffolds, artificial organs, etc. Therefore, nanocellulose/gelatin composite hydrogels are often selected as bio-printing materials in the 3-D printing of biological scaffolds. Process parameters of 3-D printed bio-scaffolds were studied in this work because formation accuracy of scaffolds is an important part of the molding process. Firstly, the mixing proportion of nanocellulose and gelatin was explored, and the optimum proportion was selected. Then, the printing effects of different printing pressures, temperatures, speeds, and nozzle diameters were used in the 3-D printing. The filament widths were used to evaluate the molding effects. Finally, through the calculation and analysis of the grey correlation coefficient and grey correlation degree, the multi-objective optimization of the parameters was carried out. The combined effects of the process parameters and the influence degree order on the evaluation index were obtained. Using these parameters, the 3-D porous biological scaffolds were printed with high precision. Furthermore, using a microscope, the morphologies of CCK-8 cells were observed and the cell proliferation were analyzed. The results demonstrated that the printed bio-scaffolds had good biocompatibility.

The effects of cross-sectional geometry and force direction on bending strength (MOR) and modulus of elasticity (MOE) were investigated in selected softwoods. The specimens were constructed of Scots pine (Pinus sylvestris), Black pine (Pinus nigra), Siberian pine (Pinus sibirica), Stone pine (Pinus pinea), Nordmann fir (Abies nordmanniana), Oriental spruce (Picea orientalis), and Lebanon cedar (Cedrus libani). A total of 280 specimens were prepared from these seven species in two different cross-sectional geometries (circular and square, equal in area) and tested in two characteristic force directions (tangential and radial) by 10 replications. They were subjected to three-point bending tests according to TS 2474 (2005) and TS 2478 (2005) to obtain the MOR and MOE. The results showed that the type of cross-sectional area and direction of applied force, individually or together, had considerable effects on the MOR and MOE. The MOR values of the circular-sectioned specimens were 5% greater than those of the square-sectioned specimens. The MOE values of the circular-sectioned specimens were on average 19% greater than those of the square-sectioned specimens. The MOR and MOE values were on average 7% and 17% greater, respectively, for the force applied in the tangential direction.

The cutting power value, the surface quality of the machined surfaces, and the cutting edge wear were determined in the planar milling of oak wood (Quercus robur L.). The experimental tool was a milling head with two interchangeable blades. The basic material of the three milling cutters was HS 18-0-2-5 high-speed steel (ISO 4957 2018). Two milling blades were treated with different coatings: a multilayer AlTiCrN coating of thickness 1 μm to 4 μm (knife B) and a multilayer MoC coating of thickness 1 μm (knife C). Parameters for the experiment were as follows: tool angular geometry: α = 30°, β = 45°, γ = 15°, and δ = 75°; spindle speed: 3000 min-1, 4000 min-1, and 5000 min-1; feed rate: 6 m/min, 8 m/min, 10 m/min, 12 m/min, and 14 m/min; cutting depth: 1 mm and 2 mm. The results showed that the cutting power for face milling increased with milling length for all three blades. The greatest power was measured at milling using the knife C (mean value of 209.3 W). The wedge wear parameter WBW increased with milling length; knife C reached the greatest value (WBW = 54.0 μm at length of 270 m). The surface quality parameter (Ra) of the machined surfaces was almost unchanged with increasing milling length beyond 90 m for all knives.

This study analyzed how the quality class (A, B, C) of pine logs (Pinus sylvestris L.) from the Silesian Forestry Region influences the mechanical properties of timber produced from those logs. The study utilized 210 pieces of timber with nominal cross section dimensions of 40 × 138 mm that were 3500 mm long and made of logs from a specific quality class. From these timber pieces, the density (with the stereometric method), the dynamic modulus of elasticity (using the Mobile Timber Grader device), the global modulus of elasticity, and static bending strength (EN-408 2012) was determined. On the basis of the conducted analyses, the log quality class influenced the physical and mechanical parameters of structural timber to a limited degree. However, statistically significant differences were not found for the density, dynamic and global modulus of elasticity, and bending strength between timber elements made of logs from A and B quality classes (Anova analysis with significance level p < 0.05).