Volume 9 Issue 3

Bonding processes play a significant role in the wood and furniture industry. They allow for the creation of fixed joining of construction elements, creation of new materials and, last but not least, aesthetic appreciation of parts. However, the quality of bonded joints is affected by many factors, one of which is the moisture of the bonded material – wood. The main objective of this research was to determine the influence of wood moisture on the strength of bonded joints formed by polyvinyl acetate (PVAc) and polyurethane (PUR) adhesives. In current practice these adhesives are being increasingly used for their properties and zero formaldehyde content. The procedure for determining the bond strength (tensile shear strength of lap joints) corresponded to standard EN 205. It was ascertained that in addition to actual moisture of bonded wood, the quality of the joint is also affected by the environment to which the glued joint is subsequently subjected. In a normal environment, the strength of the tested joint PVAc adhesive decreases with increasing wood moisture, but it still meets the requirement of the standard. In a humid environment, the strength falls below the limit of the standardized value. In a normal environment the joint strength bonded with PUR adhesive is similar, but the decrease in strength is lower. In a humid environment it shows the highest strength at 20% wood moisture and meets the specified standard minimum strength (4 MPa). Graphs ​​were created from the measured values that clearly show the influence of wood moisture on the final bond strength of a joint.

Bio-oil obtained from hydrothermal liquefaction of Salix psammophila is a very complicated mixture with some highly valued chemicals. In order to separate the chemicals from bio-oil, solvent extraction using nine solvents with different polarities were investigated in detail. The bio-oil extraction yield of the nine solvents were from high to low: tetrahydrofuran > toluene > ethyl acetate > acetone > ether > methylene chloride > methanol > petroleum ether > n-hexane. Based on their extraction yield, an efficient solvent combination of n-hexane, ethyl acetate, and tetrahydrofuran was used to separate the bio-oil through multistep extraction into three parts: light oil (26.13%), mid-weight oil (54.19%), and heavy oil (19.68%). These fractions were characterized by gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. The results showed that most of the highly valued chemicals were contained in the light oil; the mid-weight oil consisted of aromatic oligomer derived from the decomposition of lignin, which could be a promising candidate for partial substitute for petroleum-asphalt binder; the heavy oil was rich in alkanes.

Biomass pyrolysis or gasification can convert low-energy density biomass into a high-energy density gaseous fuel. In this paper, pyrolysis of pine sawdust with and without the addition of a catalyst was investigated using a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TGA-FTIR). The effects of modified SBA-15 catalysts on the formation characteristics of CO, CO2, and CH4 were studied. The two prepared catalysts, La/SBA-15 and Fe/La/SBA-15, retained the hexagonal order of the SBA-15 material and showed high thermal stability in the temperature range of the TGA-FTIR experiments. The results showed that the pyrolysis behavior of biomass is remarkably improved in the presence of La/SBA-15 and Fe/La/SBA-15 catalysts. The modified SBA-15 materials favored thermal cracking of macromolecular substances, resulting in an apparent decrease in the tar and coke fraction, an increase in the yield of light gases, and much higher gas production. Meanwhile, a significant increase in CH4 led to a much higher energy density gaseous product.

The present study is aimed at evaluating the use of plant-based polymers and fibres for the production of sustainable biocomposites. For the first time, plasticiser/solvent-free hemp fibre-reinforced wheat gluten and hemp-gliadin and glutenin composites were obtained by compression moulding at different temperatures. The plasticiser/solvent-free sample preparation method developed in this study facilitated the use of a powdered protein matrix with a mat of randomly oriented hemp fibres. The tensile and protein cross-linking properties, as well as the biodegradability, were investigated. The addition of hemp fibre to the protein matrix increased the E-modulus by 20 to 60% at 130 °C. An increase in moulding temperature from 110 to 130 °C resulted in an increase in maximum stress due to the formation of intermolecular bonds between protein chains. The gliadin composites had higher E-modulus and maximum stress and showed a larger increase in protein polymerisation with increased temperature compared to the glutenin composites. A comparison of tensile properties revealed that the composites were stiffer and stronger compared to several similarly produced biobased composites. The composites were found to be fully biodegradable under a simulated soil environment after 180 days. Biocomposites produced in the present study were found to be environmentally friendly with fairly good mechanical properties.

The chemical components of essential oil of Toona sinensis leaf blades and their petioles from China were extracted by simultaneous distillation solvent extraction (SDE) and were analyzed by GC-MS. The antimicrobial and DPPH scavenging activity of the essential oil were evaluated. The results showed that there were differences in chemical compositions and content among essential oils extracted from T. sinensis in different parts and different geographical areas in China, but the main components of essential oils were sesquiterpene and sesquiterpene oxygenated compounds, accounting for 90.1% (No. 1), 92.6% (No. 2), and 80.9% (No. 3) of the relative mass fraction, respectively. T. sinensis essential oil exhibited noticeable growth inhibitory activity against the tested microorganisms. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of different essential oils against microorganisms were different. For all essential oil samples, MIC and MBC against Escherichia coli and Bacillus subtiliswere less than 25 μg·mL−1, MIC and MBC against Penicillium citrinum were 200 and 400 μg·mL−1, respectively, and MIC and MBC against Colletotrichum gloeosporioides were 50 and 200 μg·mL−1, respectively. The IM50 of DPPH scavenging for T. sinensis essential oil was less than 0.3 g DPPH per g essential oil. The results indicated that T. sinensis essential oil may be a useful natural antiseptic source from forest products.

A type of conductive graphite/cellulose composite film used for chemical vapor-sensing material was prepared at room temperature in the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIm]Cl). Graphite was pretreated with both oxidation and reduction processes. Due to the use of N,N-carbonyldiimidazole (CDI), as a covalent cross-linking agent in [BMIm]Cl, there were limited chemical bonds between the graphite and cellulose. The composite film was analyzed using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XRD). When these conducting films were exposed to certain organic vapors, their electrical resistances quickly changed, showing gas sensitivity. The percolation threshold of the conducting film was about 5 wt%. The gas-sensing behavior of these films in solvent were the opposite of those gas-sensing materials based on a non-polar polymer matrix. A typical negative vapor coefficient (NVC) was observed when the film was placed in polar organic solvents such as methanol, ethanol, and acetone.

In this study, the effects of chemical modifications of oil palm mesocarp fiber (OPMF) via bleaching, silane coupling agents, and combinations of the two on the composition and morphology of OPMF were investigated. The chemically modified OPMF was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The FTIR spectra showed that bleached OPMF became more hydrophilic, while silanized unbleached and silanized bleached OPMF became less hydrophilic. The TGA thermograms indicated that bleaching successfully removed hemicellulose from the OPMF, while TGA analysis showed that silanized unbleached and silanized bleached OPMF had higher thermal stabilities than unbleached or bleached OPMF. The SEM micrographs revealed that the modified OPMF surface was rougher and more porous than that of the unbleached OPMF, further indicating that OPMF was successfully modified.

Chemical modification of wood with the aim of improving its dimensional stability can also influence the mechanical behavior of the timber when assembled into a structure. Hence, in this study, the stress-carrying capacity of mitred and butted L-type joints constructed from furfurylated wood samples with two weight percentage gains (WPGs), i.e., 20 and 60% (low and high levels, respectively), was investigated by subjecting the specimen to a diagonal tension load. Results indicated that the bending moment resistance of both L-type joints depends on the WPG. The L-type joints’ bonded stress value with poly-vinyl acetate (PVAc) adhesive decreased with increasing WPGs. Likewise, in the case where epoxy adhesive was used for jointing, the stress capacity increased for both joints constructed with furfurylated wood. Values of tension stress in the butted joint were higher compared to the mitred one. Evaluation of shear stress parallel (׀׀ ) and perpendicular () to the grain of members jointed with PVAc adhesive demonstrated that the shear stress-carrying capacity decreases as furfurylation level increases. However, by applying epoxy adhesive for jointing, τ׀׀ and τ┴ were increased by raising the furfurylation levels.

Pineapple agro-waste, the residue produced during harvesting or processing activities, is widely available around the world. After harvesting, most pineapple residue is disposed of and serves as fertilizer, or is burnt in an open field. However, these methods are not only ineffective, but also contribute to air pollution. The main objective of this study is to determine the physicochemical properties (i.e., cellulose, hemicellulose, lignin, proximate composition, dry matter, and nitrogen content), of leaves and stems in different varieties (MD2, Moris, and Josapine) of the pineapple plant waste. The data obtained were analyzed using thermogravimetry analysis and proximate analysis. The results showed that the stems and leaves of different varieties exhibit different percentages in lignocellulosic content (hemicellulose, cellulose, and lignin). Proximate analysis showed that nutrient contents were available in the leaves and stems of pineapple plant of different varieties.

Palm kernel cake (PKC), a by-product of palm oil industry, contains glucose and mannose as hexose sugars. This study was performed to determine the feasibility of using PKC as a lignocellulosic substrate for biobutanol production by Clostridium saccharoperbutylacetonicum N1-4 in an acetone-butanol-ethanol (ABE) fermentation process. Moreover, the effect of tryptone-yeast extract-acetate (TYA) medium and P2 medium on biobutanol production was evaluated. Experimental results showed that butanol production of 3.05 g/L was obtained using mannose sugar, which was comparable to 3.61 g/L butanol production measured using glucose. Moreover, the maximum production of biobutanol (0.38 g/L) was obtained at a PKC concentration of 30%, indicating the possibility of PKC utilization in butanol production. ABE fermentation of PKC using distilled water, TYA medium, and P2 medium showed that the highest butanol production (0.26 g/L) with ABE production of 0.38 g/L was obtained when ABE fermentation was conducted in P2 medium.