Research Articles

Effects of nanofibrillated cellulose (NFC) and nano-silicon dioxide on dynamic mechanical thermal analysis and physical properties of nanocomposites films made of poly (vinyl alcohol) (PVOH) were investigated. For this purpose, the nanoparticles were mixed with PVOH at 0%, 5%, and 10% weight. Water absorption, dynamic mechanical thermal, transparency, and wettability properties were evaluated according to corresponding standard test methods. The morphology of nanocomposites was explored by using a field emission scanning electron microscope technique. The films became increasingly opaque with increasing nanoparticles contents, although the composites also retained moderate transparency. According to the results of the tests, the dynamic mechanical thermal (DMTA) properties of PVOH composite films were significantly improved with the increase of NFC and silica nanoparticles loading. The samples containing 20 wt% of nano-SiO2 exhibited higher hydrophobicity compared with that of 20 wt% NFC.

New experimental data is presented for the mechano-sorptive coefficient of Eucalyptus nitens wood analyzed in the longitudinal direction through the principle of total deformation superposition. The procedure was based on the determination of the partial strain components: elastic strain, free shrinkage strain, and mechano-sorptive strain. The methodology included the design of cantilever flexion tests of a wooden beam in an air-conditioned environment with variable relative humidity. These conditions made it possible to estimate each of the deformation components separately and then to determine the mechano-sorptive coefficient using the rheological stress-strain model. Deformations and displacements were evaluated with extensometers and displacement sensors, respectively, in conditions of 0 to 30% of the breaking load applied perpendicularly to beams oriented in the longitudinal direction. The cross-section was positioned according to the relation between the action line of the load applied and the growth rings orientation. The variation of moisture content was considered, decreasing from 22 to 12%. The results exposed a direct proportionality between the intensity of the applied load and the mechano-sorptive strains. The values determined for mechano-sorptive coefficients were 0.1224 and 0.1746 GPa-1 for loads applied to radial and tangential directions, respectively.

A novel Ru-modified composite catalyst, Ru-W/Sn-AlOx, was prepared, and the effects of the catalyst on lignin depolymerization were investigated in this study. The catalyst converted approximately 95% lignin into liquid product at 300 °C in 12 h and 2/3 of the liquid product could be soluble in petroleum ether. The petroleum ether (PE) soluble product was mainly composed of monomers, dimers and some trimmers. This indeed indicated that the catalyst could effectively depolymerize lignin into small-molecule products. 7.22% of monomers was obtained at 310 C for 12 h. Meanwhile, the catalyst effectively reduced the char formation to 2%. After the catalytic depolymerization, the higher heating value (HHV) of the liquid product increased from 25.7 to 32.4 MJ/kg. The product could be utilized as fuel additive or converted to biofuels. This catalysis system showed great potential in the conversion of lignin into biofuels.

The purpose of this study was to determine the anatomical and physical properties of three lesser-known Malaysian timber species, i.e., mahang (Macaranga hosei), medang (Litsea costalis), and terap (Artocarpus scortechinii). Correlation factors that influenced the density and shrinkage were also discussed. From the results obtained, terap wood had the longest fibre (1421 µm), followed by medang (1309 µm), and mahang (1161 µm). Terap, medang, and mahang were categorized as having very thin fibres. The density of terap, medang, and mahang had average values of 504 kg/m3, 485 kg/m3, and 474 kg/m3, respectively. In addition, terap wood also showed the highest tangential shrinkage (3.8%), followed by mahang (2.2%) and medang (1.5%) wood. This present study showed that the density was significantly influenced by the fibre length, fibre wall thickness, vessel diameter, and number of vessels. In addition, the shrinkage was highly correlated with the density. Based on the conducted research, mahang, medang, and terap show potential as alternative raw material to fulfill demand in wood-based industries.

Multivariate models with multiple linear regression (MLR), artificial neural network (ANN), and k-nearest neighbors (KNN) were developed to predict the modulus of rupture of Pinus sylvestris structural timber. The aim of this study was to develop and compare these models obtained from resonance and ultrasound tests, static modulus of elasticity tests, and different measured wood feature. Resonance tests were performed in the three vibration modes (edgewise, flatwise, and longitudinal) to obtain the fundamental resonant frequencies. To compare the goodness-of-fit of the different models, the 10-fold cross-validation method was used, which proved to be an adequate strategy to avoid overfitting. The variable with the best predictive capacity of the modulus of rupture was knottiness. The error was notably lower in the multivariate than the univariate models. The ANN and KNN algorithms showed no improvement over the MLR. The most suitable MLR for prediction of the modulus of rupture was the model with four variables: knottiness, edgewise dynamic modulus of elasticity, velocity of ultrasounds, and longitudinal resonant frequency.

An eco-friendly time indicator (TI) was developed using cellulose-based materials. The TI comprises a dye, copy paper, nanofibrillated cellulose (NFC) film, and filter papers coated with NFC slurry and/or paraffin-free biowax. A suitable dye and its conditions were determined by observing the dye solutions and the migration pattern at the different concentrations. Commercial filter papers were prepared, and the dye migration rate, depending on physical properties, was evaluated. NFC was coated to control the dye migration rate of filter paper. In addition, biowax was used to impart hydrophobicity to filter papers used for supporting NFC films, storing the dye, and allowing the migration of dye. Finally, a TI was fabricated using those components. Methylene blue was selected as a dye for the TI due to its deep color and high solubility. The results showed that the key property of filter paper affecting the dye migration rate was the pore size. The migration rate could be reduced when NFC was coated on both sides of the filter paper. Since biowax modified the hydrophobicity of filter paper surface, it was used to make the NFC film-supporting paper, location for dye storage, and bottom-layer. In conclusion, a multilayered TI could be assembled using cellulose-based materials.

Recently, there has been considerable interest in establishing tree-rearing methods for breeding nursery trees, which are similar to the methods employed in plant factories to produce vegetables. Studies have shown that the efficiency of tree cultivation can be improved by changing the wavelength of the lighting that is used to raise young plants and that light emitting diodes (LEDs) are effective for this purpose. In this study, the effect of blue (450 nm), red (660 nm), and white (combination of blue and yellow (525 nm) LED lights was investigated for rearing Cryptomeria japonica saplings. 7 saplings with each LED were prepared and reared for 52 weeks in a constant environment chamber (Temperature: 23 ± 2 °C, relative humidity 50% ± 10%), and their growth rates and root system morphology were compared. After 52 weeks of breeding, red light induced slightly more stem growth than white light. Blue light was nearly three times more effective in stem growth than white light. Furthermore, the wavelength of light affected the root system morphology. Many root branches were observed in saplings reared under red light, while marked taproot growth was observed in saplings reared under blue light. There was a possibility that saplings could be produced more efficiently by using LED.

Aerobic composting and vermicomposting processes were compared in the co-composting of durian shells and citrus peels. For decomposers, the microorganism catalyst from the Land Development Department, i.e., the LDD1 catalyst, and earthworms were used. The moisture contents of the durian shells and citrus peels were 84.6% and 77.3%, respectively, and the pH of the shells and peels were relatively low, as these are sources of potassium. The experiments utilized four different reactors: durian shells (100%) in reactor 1; durian shells and citrus peels (50% to 50% ratio) in reactors 2 through 4; with the LDD1 catalysts in reactor 3 and the earthworms in reactor 4. The temperature, pH, moisture content, electrical conductivity, NaCl, organic matter, organic carbon, C to N ratio, nutrients (nitrogen, phosphorus, and potassium), germination index, and size of the compost were analyzed according to the standards of the Land Development department (2013). Throughout the composting process, the pH tended to increase, although citrus peels, with a low pH of 3.95, were used as a raw material. At the end of the composting process, reactor 4, which used earthworms as decomposers, passed the standard criteria, yielding a germination index of 90%.

Mechanical, thermal, and water absorption properties of the composites have been studied as a function of sawdust content, using different weight percentage. The characteristics properties of the composites were studied using differential scanning calorimetry and Fourier-transform infrared spectroscopy. Field emission scanning electron microscopy was used to understand the interfacial bonding. The obtained results showed that the 15 wt% composites exhibited the highest tensile strength (7.5 MPa) and flexural strength (8.9 MPa) compared with the 5 wt%, 30 wt%, 40 wt%, and 50 wt% composites. A good interfacial combination was formed between 15 wt% of sawdust and epoxy resin. In terms of the tensile and flexural strength, the differential scanning calorimetry analysis confirmed that matrix modification could improve the mechanical properties and thermal stability of the composites compared to neat resin. The Fourier-transform infrared spectroscopy spectrum showed the presence of functional groups pertaining to composites. The absorption data of the composite showed that the water uptake increased as the amount of sawdust in the composite increased. The 5 wt%, 15 wt%, 30 wt%, and 40 wt% sawdust composites also displayed less water absorption behavior (1.534%, 1.871%, 2.492%, and 4.127%, respectively) compared to the 50 wt% composite.

A combination of semipermeable membrane-covered composting systems and greenhouses was used to investigate the effects of different insulation systems on the aerobic fermentation of mixed raw materials and changes in the characteristics of fermentation feedstock. The combination of semipermeable membrane-covered and greenhouse systems increased the peak temperature by 6.53 °C, the average fermentation temperature by 28.2%, and extended the duration of the effective high-temperature stage of fermentation (temperature ≥ 50 °C) by 14 days. The decomposition percentage of solid organic matter in the enhanced group was 11.8% higher than that in the normal group, and the fermentation cycle was shortened by 5 days. The duplication provided by using both the semipermeable membrane-covered and greenhouse systems was conducive to the harmless treatment of raw materials, promoted the maturity and efficiency of composting, and reduced the content of biologically toxic substances. This study provides a theoretical basis for improving the efficiency of aerobic fermentation and the safe treatment of solid waste.