Volume 18 Issue 4

Due to the high viscosity of pure [Bmim]Cl, PEG was selected to be co-solvent to form the solvent system. The dissolution and plasticization ability of PEG-[Bmim]Cl to poplar veneer was completed with processes such as hot pressing and coagulation bath to achieve the in-situ modification of poplar veneers to develop an innovative wood composite, which are expected to be molded. At the same time, the effects of the solvent system on the properties of wood composites were studied. The results showed that both the [Bmim]Cl-treated group (B) and the PEG-treated group (C) had a certain degree of plasticity when compared with the untreated group (A). The PEG-[Bmim]Cl-treated group (D) had the greatest ductility. The main reason was that PEG and [Bmim]Cl synergistically in situ dissolve the components of the veneer, increasing the proportion of the matrix phase (dissolved part). The interface bonding between the matrix phase and the reinforced phase was enhanced and resulted in the best comprehensive mechanical properties. However, no other derivative reactions occurred in each group.

A huge rise in energy consumption has been observed in the past few decades because of population and economic growth. One of the renewable energy fuels that can be made from biomass is bioethanol. In Saudi Arabia, date palm provides tons of biomass waste each year, leading to serious problems. The current study aimed to use the date palm fibers (DPF) for bioethanol production via a saccharization step (by hydrochloric acid or by Trichoderma harzianum) for cellulose. This was followed by fermentation (by Saccharomyces cerevisiae). The maximum amount of total carbohydrates (95.55 ± 2.6 mg/dL) and reducing sugar (11.35 ± 0.35 mg/dL) were obtained on the 7^th day using T. harzianum. The optimum period of bioethanol production was at day 6 (12.52 ± 1.3 g/L), while at day 5 it became (12.76 ± 0.75 g/L) when the DPF were fortified with yeast extract. The bioethanol maximum yield (12.03 ± 1.10 g/L) was obtained at 30 °C. Moreover, 2 mL of S. cerevisiae inoculum gave maximum yield of bioethanol. Gas chromatographic analysis showed that bioethanol in the fermented broth represented the major constituent with a peak area of 75.01%. The findings indicate that the fortified DPF with yeast extract gave a promising bioethanol yield.

Volatile oil analysis, phenolic constituents, antioxidant capacity, antimicrobial activity, vitamin C, and enzyme activities of the fruits of Rhus coriaria L. were studied. The chemical with the highest percentage was sesquiterpene hydrocarbons with 40.4%. The major compound was detected as caryophyllene (36.9%). The main phenolic constituents of fruit samples were gallic acid, syringic acid, protocatechuic acid, and 4-hydroxybenzoic acid. The highest phenolic constituents of fruits were gallic acid. Ferric (III) ion reducing antioxidant power (FRAP) capacity (14.9 mg FeSO₄ eq./g), free radical scavenging (ABTS) capacity (68.8 mg AA eq./g), ABTS % inhibition rate (98.0%), free radical scavenging (DPPH) (53.1 mg AA eq./g), and DPPH % inhibition (79.6%) amounts were determined in antioxidant capacities of the samples. The bioactive component contents of the samples were total antioxidant amounts (TAC) (32.8 mg GA/g), total flavonoid substance amounts (TFC) (73.8 mg QE eq./g), and total phenolic substance amounts (TPC) (41.4 mg GA eq./g). The results of the antimicrobial activity analysis of R. coriaria fruit samples showed antimicrobial activity against Staphylococcus aureus and Listeria monocytogenes microorganisms. The amount of vitamin C and enzyme inhibitor activity in the fruits of R. coriaria were determined as 35.5 mg/100 g and 0.07 mg/mL, respectively.

Vitamin C, enzyme activities, phenolic compounds, antioxidant capacity, antimicrobial activity, and essential oil analyses of ripe and unripe fruits of P. terebinthus were investigated. Vitamin C amounts of ripe and unripe fruits were 63.2 and 15.4 mg/100g, respectively. The main phenolic compounds of unripe and ripe fruits are rutin, syringic acid, and gallic acid. It was determined that the enzyme inhibitor activities in the ripe and unripe fruits were 0.136 mg/mL and 2.14 mg/mL. In all of the free radical scavenging (DPPH and ABTS) activity, ferric (III) ion reducing antioxidant power (FRAP) capacity, total phenolic substance amounts (TPC), total flavonoid substance amounts (TFC), and total antioxidant activity (TAC) antioxidant methods analyzed with plant parts, the methanol extracts obtained from the ripe fruits of the P. terebinthus showed higher antioxidant properties than the methanol extracts obtained from the unripe fruits. Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 showed antimicrobial activity against microorganisms, while methanol extracts obtained from unripe fruit samples did not show antimicrobial activity against the microorganisms used. The chemical grade with the most compounds in the essential oils of P. terebinthus were monoterpenoids, sesquiterpenes, and monoterpenes in unripe and ripe fruits, respectively. The main components were α-pinene with 22.8% and 27.3% ratios in unripe and ripe fruits, respectively.

The design practice has shifted from permissible stress design to limit state design using Eurocode 5 (EC5), which introduces design strength optimization. However, the adoption of EC5 in Malaysia cannot be done directly due to the absence of design strength data for Malaysian timber species. This paper presents a study that evaluates the bending strength properties, moisture content, and density of kekatong (Cynometra malaccensis) timber specimens using the Weibull theory to produce 1/k values for the local timber species. The depth impact adjustment factors for kekatong timber had a value of 0.23, which is not far from the well-established 1/k value of 0.2 for softwood and temperate hardwood with characteristic densities below 700 kg/m³ in EC5. The study shows that the bending strength of local timber is affected by its volume, and the variation of bending strength at several probabilities is in close agreement with theoretical predictions. Overall, the study provides important insights for the design of timber structures using Malaysian timber species, which can be used to improve the safety and sustainability of timber structures.

Effective separation of cellulose and hemicellulose from lignocellulosic biomass is an essential step for creating high-value products. In this study, a modified treatment process was proposed for cellulose purification via microwave-assisted formic acid catalytic hydrolysis followed by cold caustic extraction. The sugar content in the extract was determined using UV spectrophotometer and dual-wavelength visible spectrophotometry. Combined microwave-assisted formic acid (M-FA) with cold caustic extraction (CCE) treatments achieved rapid separation and removal of hemicelluloses from waste hardwood pulp fibers. The hemicelluloses content decreased from 28.6% to 2.3%, and the lignin content changed from 27.8% to 6.1%, which resulted in a maximal cellulose content of 91.5% under the optimal M-FA/CCE treatment conditions. In addition, the crystallinity index of pulp fibers increased from 54.3% to 67.1%, and the initial decomposition temperature decreased from 335.4 to 270.2 °C with the decrease of hemicellulose and lignin content. The modified process provided a sustainable and effective method for hemicellulose separation and lignin removal from cellulosic fibers.

Cellulose nanocrystals (CNC) were prepared from delignified kenaf bast fiber by using alkaline pulping, based on soda anthraquinone, hydrogen peroxide bleaching, and acid hydrolysis treatment with H₂SO₄. The size and morphology of the fibers were characterized by scanning electron microscopy (SEM), and the isolated fiber from unbleached and bleached pulp had a diameter between 9 to 30 µm. Fourier transform infrared (FTIR) spectroscopy exhibited that the content of lignin decreased in the pulping process, and the lignin was almost completely removed during hydrogen peroxide bleaching. Moreover, fibers were characterized for crystallinity using X-ray diffraction (XRD). The fiber crystallinity gradually increased at each stage of the process (raw kenaf bast, unbleached pulp, bleached pulp, and acid hydrolysis). The fiber was characterized by atomic force microscopy (AFM), which showed that the isolated pulp nanofibers had diameters of approximately 30 nm.

Conventional electrothermal floors suffer from low heating efficiency, uneven temperature distribution across the floor surface, local overheating, and severe heat accumulation. In order to improve the heating performance, an electrothermal composite floor with graphene as the heating layer was fabricated. The relationship between time and temperature rise, the relationship between power density and temperature rise, running stability, and surface temperature distribution were investigated and analyzed after heating, and the surface temperature profiles were simulated in two and three dimensions. The results were compared with the carbon fiber electrothermal composite floor and the resistance wire electrothermal composite floor. The results indicated that the temperature of the graphene electrothermal composite floor rose to 27.1 °C, the electrothermal conversion efficiency reached 90.1% after 40 min of electrification, and the temperature distribution unevenness was 4.4 °C, which were better than the carbon fiber electrothermal composite floor and the resistance wire electrothermal composite floor. The graphene electrothermal composite floor exhibited high heating performance, thus aiding the development and manufacture of such composite flooring.

Tetra Pak® paper and PE (polyethylene) wastes were evaluated to obtain a new composite material with awareness of environmental responsibility.  Fillers and coupling agents were used for this joining process. Calcite (CaCO₃), boric acid (H₃BO₃), SPT (Sodium Perborate Tetrahydrate / NaBO₃.4H₂O), titanate, MAPE (maleic anhydride grafted polyethylene, and vinyltriethoxysilane (C₈H₁₈O) composites were produced in 30 × 30 cm plates. A total of 30 samples were prepared as 5 mg flour for thermogravimetric analysis (TGA). Samples were observed in a thermal analyzer at 10, 15, or 20 °C/min heating rate in nitrogen atmosphere. Graphs were obtained as a result of TGA, and the activation energies were calculated using these graphs. The activation energy was calculated using the Flynn-Wall-Ozawa method. The determined activation energies of the composites were close to each other for each temperature group. In the samples using calcite and vinyltriethoxysilane, relatively higher activation energies were observed in comparison to the samples with boric acid and MAPE.

The Dou-Gong bracket is a key transition component between the roof and the column in ancient Chinese wooden structures. In this paper, the static structural behavior of Qing-style ‘one bucket three liters’ Column-cap Dou-Gong Bracket (third-class material) full-scale test model was studied by simulation. The simulation of monotonic static loading was carried out in the vertical (Z-axis) direction, and the simulation of quasi-static loading under horizontal low-cycle reciprocating load was carried out in the horizontal direction (Y-axis, X-axis). The material of the simulation was P. sylvestris, and the setting of its material parameters referred to the results obtained from the material property tests. An anisotropic constitutive model suitable for the properties of wood materials was selected, and the elastoplasticity of wood in the simulation was defined by the Hill yield rule. The static structural behavior of the component in the Z-axis could be described by the variable stiffness linear elastic mechanical model. The static structural behavior of the component in the Y-axis and X-axis could be described by a multi-linear restoring force model. According to the simulation results, the key mechanical indexes of Dou-Gong bracket component in the Z, Y, and X axes were calculated from three aspects of strength, deformation, and energy.