Volume 13 Issue 3

The objective of this study was to investigate the mechanical and physical properties of bamboo-based fiber reinforced composites (BFRC) that were formed by using loose bamboo bundles (LBB) and phenol formaldehyde (PF) adhesive. Three resin content levels (10%, 14%, and 18%) and seven different assembly patterns were selected when the bundles were glued together. Board performance testing showed that the bond quality was improved by increasing the resin content. The board face layers impregnated with 18% resin content and core layers impregnated with 14% resin content had the best mechanical properties, and the boards impregnated with 18% resin content had the best dimensional stability properties. The mechanical and physical properties increased with increasing resin content and were affected by the assembly pattern. Various performance indices of the BFRC met the requirements of the China national standard GB/T 20241 (2006).

The effects of substrate Ca²⁺ concentration were studied relative to the anaerobic digestion and microbial community structure of anaerobic granular sludge. In the treatment of papermaking wastewater by anaerobic granular sludge, the cumulative gas production was maximum at a Ca²⁺ concentration in the substrate of 120 mg/L, whereas it was the lowest at a concentration of Ca²⁺ in the substrate of 4000 mg/L. A high Ca²⁺ concentration in the substrate (≥1200 mg/L) will cause the pH of the fermentation broth to decrease during the fermentation process, which is not conducive to the anaerobic fermentation of the methanogenic process, resulting in unsatisfactory anaerobic digestion of the granular sludge. In addition, when the Ca²⁺ concentration was below 200 mg/L, the abundance of the important bacterial family Ruminococcaceae (rumen bacteria) in the anaerobic fermentation hydrolysis stage was drastically reduced and methane gas production increased. When the Ca²⁺ concentration was above 200 mg/L, the abundance of Anaerolineaceae (Anaerobic Streptomyces), which supplies organic acids, was substantially reduced. The methane gas production decreased as the Ca²⁺ concentration increased. Thus, the results showed that when the concentration of Ca²⁺ was above 200 mg/L, the methanogenic activity of granular sludge decreased.

Carboxymethyl cellulose (CMC) was prepared from Gliricidia sepium and Cola gigantea cellulose with yields of 1.59 g/g and 1.76 g/g, respectively. The pH of the products were weakly acidic (6.47 and 6.54, respectively). The sodium chloride content was 0.22 for C. gigantea CMC and 0.27 for G. sepium CMC, while the degree of substitution was 0.46 and 0.51, respectively. The swelling capacity of G. sepium CMC was 802%, which was higher than the 519% of C gigantea CMC. Fourier transform infrared (FTIR) spectroscopy confirmed that the products were CMC, and a thermogravimetric analysis (TGA) confirmed that C. gigantea CMC was more stable than G. sepium CMC. Detergent fortified with G. sepium CMC had better performance than C. gigantea CMC in terms of cleaning action and emulsion index, and it competed favorably with a detergent fortified with commercial grade CMC.

The laser processing method was applied to wood processing, and the water-jet-guided laser processing was adopted to design a numerical control nanosecond water-jet-guided laser processing test bench, which will provide a new theory and method for laser-processing wood. The numerical control nanosecond water-jet-guided laser processing test bench was built. Pinus sylvestris was used as the test subject. Laser energy, cutting speed, and defocus amount were used as the experimental factors. The aspect ratio was used as a response indicator. A three-factor, three-level Box-Behnken design was studied. A regression model of the three factors and aspect ratio was established. The test results showed that laser energy and cutting speed were the significant effects (p < 0.001) and that defocus amount was the notable effect (p < 0.05). The interaction of laser energy × cutting speed and laser energy × defocus amount had a significant effect on the aspect ratio. The optimal processing parameters were as follows: laser energy of 195.24 mJ, cutting speed of 1.03 mm/s, and defocus amount of -0.69 mm. The authors compared the surface of nanosecond water-jet-guided laser processing with the surface of laser processing. The former had little slag, and the cutting processing was stable. Therefore, nanosecond water-jet-guided laser processing showed better processing quality.

A novel hydrogel was prepared starting with a 10-wt.% lignocellulose solution that was obtained by dissolution of Norway spruce wood (Picea abies) in the ionic liquid 1-butyl-3-methylimidazolium chloride. This ionic liquid was used to avoid traditional degradative and hazardous effects of solvents on the lignocellulose. Five alternate freezing and thawing cycles of the lignocellulose solution were employed as a means of physically crosslinking the hydrogels. The obtained hydrogel network was thermoreversible, with mesopores of 5 to 35 nm diameter, predominantly amorphous, and presenting distinct behaviors when immersed in aqueous solutions with different concentrations of organic electrolytes. The specific surface area of the hydrogel was 75.23 m²×g^-1.The hydrogels presented high uptake capacities for pollutant chemical species (Cu²⁺, Pb²⁺, and bemacid blue anionic dye) that spanned from 445 mg/L to 547 mg/L at a pH value of 6. This indicated that the hydrogels are promising materials for environmental applications.

The feasibility of using near infrared spectroscopy (NIR) to rapidly determine the cellulose content in pulp was investigated in this study. Partial least square regression analyses were performed to describe the relationships between the data sets of wet chemistry analysis and the NIR spectra. The selection of relevant wavenumbers combined with the appropriate data pre-processing methods produced satisfactory prediction models. The test statistics (R², RMSECV, and RPD) improved compared with the models over the wavenumber range 10000 cm⁻¹ to 4000 cm⁻¹. The predicted cellulose content models, using the cross validation in the appropriate wavenumber ranges coupled with the spectral data preprocessing methods of multiplicative scattering correction (MSC), standard normal variate (SNV), and first derivative (FD) normalization, were established. The highest R² value was found to be 0.92 with the lowest RMSECV values 0.60 using FD 19 normalization at the wavenumber range from 7250 to 6500 and 5500 to 4000 cm^-1. The highest RPD value was 2.45. NIR spectroscopy, combined with multivariate statistical analysis, could predict cellulose content in the pulp with efficient accuracy.

This paper examines the influence of technological parameters on electrical power in the plane milling of native and modified oak wood. Milling was performed under various cutting conditions, including cutting speeds of 20, 40, and 60 m s^-1, feed rates of 6, 10, and 15 m min^-1, and cutting edge angles of 15, 20, and 30° on five different samples of oak wood. The wood was native and heat-treated at temperatures of 160, 180, 210, and 240 °C. An analysis of variance and post-hoc Duncan test revealed the influence of the examined parameters on the energy consumption of milling, whereby the cutting speed was the most statistically significant parameter and was directly dependent on the speed of the asynchronous motor and the moment transmission to the miller spindle.

Sulfonation chemimechanical pulping (SCMP) of mulberry stalk was studied with different treatment concentrations. The resulting mulberry SCMP pulp contained different content of sulfonic acid groups depending on the concentrations. The brightness, tensile index, and folding resistance of mulberry SCMP pulp increased with the increasing concentration of sulfonation treatment, but the thickness decreased with increasing concentration. There was either a linear or a non-linear relationship between the content of sulfonic groups and the pulp physical properties. The mass average length of mulberry SCMP pulp was 0.66 mm, the fiber width was 16.4 μm, and the content of fine fibers was 20.6%.The mulberry extract and lignin dissolved, and part of soluble lignin may have been deposited on fiber surface in the process of SCMP pretreatment. There were almost no changes to the cellulose crystalline structure.

Serratene triterpenoids are considered chemotaxonomy compounds from the Pinaceae family, within the Pinus genus. However, no studies have been conducted on the constituents of serratene triterpenoids of Pinus merkusii. P. merkusii is the only pine species native to Southeast Asia, including Indonesia. This study aimed to investigate the use of triterpenoids and steroids from the bark of P. merkusii as chemotaxonomic biomarkers. Five lipophilic extractives, including three triterpenoids (3β-methoxyserratt-14-en-21-one (C1), 3α,21β- dimethoxy-D14-serratene (C3), serrate-14-en-3β,21β-diol (C5)), and two steroids (stigmast-4-en-3-one (C2) and β-sitosterol (C4)), were isolated from the n-hexane extract of the bark of P. merkusii using column chromatography and thin–layer chromatography. The structures of the triterpenoids and steroids were characterized on the basis of their spectroscopic data. The discovery of serratene triterpenoids and steroids in P. merkusii bark characterizes this species as being in chemical accordance with other species of the Pinus genus and Pinaceae family.

When offcut of wood is formed by shearing, Atkins’s analyses of sawing processes can be applied. Using this modern approach, it is possible to determine the fracture toughness and shear yield strength of wood. This model is only applicable for the axial-perpendicular cutting direction because both of these parameters are suitable for the given direction of cutting edge movement and cannot be considered material constants. Alternatively, these parameters can be recalculated for the perpendicular and axial directions of cutting when the parameters are considered non-variable quantities. The set of data necessary for calculation can be easily obtained while cutting wood with common circular saw blades. It is necessary to ensure a minimum of two levels of workpiece height and two diverse levels of feed speed. The main aim was to develop an alternative methodology for simultaneous determination of wood fracture toughness and shear yield strength for two principal directions regarding wood grains on the basis of cutting tests performed during circular saw blade cutting for two selected wood species of Central Europe provenance, such as spruce (Picea abies (L.) Karst.) and beech (Fagus sylvatica L.).