Research Articles

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.).

9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) graft γ-amino propyltriethoxy silane (APS), γ-glycidoxy propyltrimethoxy silane (GPS), and methacryloyl propyltrimethoxysilane (MPS) were synthesized and introduced on the surface of wood fiber. DOPO-g-APS (GPS and MPS) treated wood fibers (DAWF, DGWF, and DMWF) were used to prepare composite phenolic foams (DAWFCPF, DGWFCPF, and DMWFCPF). The chemical structures of DOPO-g-APS (GPS and MPS) were confirmed by Fourier transform infrared (FT-IR) spectra and nuclear magnetic resonance. The structures of DAWF, DGWF, and DMWF were confirmed by FT-IR. The diffraction peak positions were basically unchanged, but the crystallinity was slightly increased. Compared with WF, thermal stabilities were increased. The residue (800 °C) was slightly reduced. Compared with phenolic foam, the properties of DAWFCPF and DGWFCPF were better than others. Besides compression strength, the mechanical properties were increased dramatically, limited oxygen index was slightly enhanced, the cellular pore distribution was more regular, and the size of bubble cell was smaller and more uniform. By comprehensive analysis, the properties of DAWFCPF were best in all samples. The interfacial compatibility was significantly improved between DAWF and phenolic resin. These results confirmed that DOPO-g-APS is a suitable material for treating wood fibers and preparing composite phenolic foams.

Processes of extracting hemicellulose from annual plants usually neglect the cellulose fraction. This study explored the possibility of obtaining both a hemicellulose and a cellulose fraction of sufficient quality for further use, with barley husks used as the raw material. An alkaline extraction was used to isolate the biopolymers by a process in which sodium dithionite replaced the traditional sodium borohydride as the reducing agent. The cellulose fraction was successfully transformed into nanocellulose by sulfuric acid hydrolysis, and the obtained hemicellulose (i.e., arabinoxylan) displayed carbohydrate composition characteristics similar to those previously reported in the literature for processes of extracting hemicellulose from barley husks. Using this methodology, both the cellulose and hemicellulose can be isolated in high quantities of dry material and used for transformation into new bio-based materials.

In this study, a bamboo-derived magnetic carbonaceous solid acid catalyst (BC@Fe3O4@SO3H) was synthesized by FeCl3 impregnation, which was followed by incomplete carbonization and -SO3H group functionalization. FT-IR, XRD, and TGA results showed that the prepared catalyst contained -SO3H, -COOH, and phenolic -OH groups. It exhibited poor adsorption ability for the dominating sugars released during the catalytic conversion process. The prepared bamboo-derived magnetic carbonaceous solid acid presented high catalytic activity for depolymerization and conversion of corncob hemicellulose. Warm water immersion under 60 °C was able to destroy the complex corncob cell wall structure and accelerated the dissolution of carbohydrates. The highest furfural yield of 54.1 mg/g was obtained from 40 °C water-immersed corncob after reacting at 180 °C for 30 min. Up to 96.1% of the corncob hemicellulosic backbone sugars were depolymerized to monosaccharides and oligosaccharides in the hydrolysates. The prepared catalyst exhibited a simple magnetic recovery process and high stability. This work provides promising strategies for biomass utilization via renewable materials.

The effect of sugar palm fiber (SPF) loading was studied relative to the mechanical properties of roselle (RF)/SPF/thermoplastic polyurethane (TPU) hybrid composites. RF/SPF/TPU hybrid composites were fabricated at different weight ratios (100:0, 75:25, 50:50, 25:75, and 0:100) by melt mixing and hot compression. The mechanical (tensile, flexural, and impact test) and morphological properties of tensile fractured samples were examined using a universal testing machine, impact machine, and scanning electron microscope. It was found that the hybridization of RF/SPF increased its impact strength corresponding to the increases in the SPF content of the composites. The tensile and flexural properties of the hybrid composites decreased due to poor interfacial bonding between the fiber and matrix. Scanning electron micrographs of the tensile fractured surface of the RF/SPF hybrid composites revealed fiber pullouts and poor adhesion bonding. In conclusion, the hybridization of SPF with RF/TPU composites enhanced its impact strength while decreasing the tensile and flexural strength.