Research Articles

In order to compare the effect of vinyl acetate modification (VA) at different levels of weight percentage gain, Scots pine wood flour was modified with VA to three different wt% gains (10%, 16%, and 21% WPGs). Acetic anhydride (AA) modification at 24% WPG was also studied. Modified Scots pine wood flour reinforced HDPE composites (WPCs) were produced at 30 wt% wood flour loading by using extrusion-injection molding process and the mechanical properties of WPCs were determined. The thermal and morphological properties of WPG were characterised by using TGA and SEM techniques. The increase in tensile strength was significant for VA modified WPCs in comparison to the AA modified, unmodified or neat HDPE composites. Thermal stability was also significantly improved with increasing the WPG levels of VA modification.

Ultralong cellulose nanofibers with extremely high aspect ratio were successfully manufactured from waste corrugated paper pulp through a series of chemical treatments combined with grinding, ultrasonication, and centrifugation. SEM images revealed that the prepared cellulose nanofibers exhibited a uniform width ranging from 30 to 100 nm and a web-like network structure. The nanopaper was produced by filtration and oven drying using the obtained cellulose nanofibrils suspension. An interesting phenomenon occurred, namely that the nanopaper formed ​​in multilayered nanofibrous flakes, which can be seen in the SEM image of the nanopaper cross section. The nanopaper derived from waste corrugated paper presented high tensile properties, with a tensile strength of 135 MPa and a tensile modulus of 6.67 GPa, which was approximately 10 times higher than the untreated waste corrugated paper. The obtained nanopaper also exhibited high transmittance of 85.2% at 600 nm wavelength and low thermal expansion of 16.2 ppm/K. The high performance nanopaper seems to be a strong candidate for fabricating optical electronics, solar cells, and panel sensors.

A wood-rot fungus was isolated and investigated for its laccase production in submerged cultures. Based on sequence comparison and phylogenetic analysis of the 18S rDNA genes with reference taxa, the wild-type strain HLS-2 with high laccase production was identified as Psathyrella candolleana with GenBank Accession no. HQ215597. The production of laccase by P. candolleana HLS-2 can be enhanced by adding several agricultural wastes to the medium. Among them, wheat bran had the most significant effect and the highest laccase activity of nearly 12000 U/L. Extracellular laccase formations by this fungus can also be induced by veratryl alcohol, guaiacol, vanillic acid, coumaric acid, 2-2’-azinobis(3-ethyl- benzthiazoline-6-sulfonate) (ABTS), and copper sulfate. The maximal laccase activity, approximately 23000 U/L, was obtained from the shake-flask culture containing 1 mM Cu2+ without phenolic or aromatic inducers. Laccase activity of the extracellular liquid was stable at pH 8.0 and retained over 90% activity at 4 °C after 40 days.

This paper considers the modification of wood-derived cellulose assisted by supercritical carbon dioxide (SC-CO2). Cellulose carbamate derivatives were successfully prepared from softwood pulp at 150 °C and 3000 psi for 6 hours. Compared with conventional methods, SC-CO2 was shown to be more efficient in the modification of wood-derived cellulose. The modified cellulose had a considerable increase in nitrogen content. During the characterization Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetry (TG), and Field Emission Scanning Electron Microscopy (FE-SEM) were employed to investigate the structural and morphological changes in modified cellulose from wood.

The performance of veneer joints is known to affect the quality of laminated veneer lumber (LVL), so experimental research and simulation analysis of the tensile properties of lap joints were performed and reported in this paper. The lap length, specimen thickness, and specimen width were selected as the experimental factors. The maximum tensile load increased with the increase of each factor; the tensile strength increased with the increase of lap length, whereas it decreased with the increase of specimen thickness. Specimen width had significant effect on the maximum tensile load, but had little influence on the tensile strength. A response surface model of tensile strength was obtained using Matlab software, and it was used to predict the tensile properties for lap joints. The results of ANSYS simulation analysis showed that the stress peaks were concentrated in the joint ends; the peak shear stress and peak stripping stress all decreased with the increase of lap length and increased with the increase of specimen thickness; the result was consistent with the experimental results; therefore, the finite element simulation results can be used for the optimized selection of size parameters of joints.

A Plackett-Burman design was used to pre-optimize the medium composition for biobutanol production using a unique isolate of solvent-producing Clostridium YM1. Various nutrient factors affecting biobutanol production were screened using the Plackett-Burman design. These factors included: glucose, tryptone, yeast extract, peptone, ammonium acetate, KH2PO4, K2HPO4, MgSO4, FeSO4, Na2CO3, and NaCl. The results were analyzed by an analysis of variance (ANOVA), which showed that glucose, tryptone, yeast extract, peptone, K2HPO4, Na2CO3, and MgSO4 had significant effects on biobutanol production. However, ammonium acetate, KH2PO4, and FeSO4 had insignificant effects. The established model from the ANOVA analysis had a significant value of Pmodel > F = 0.0245 and an R2 value of 0.999. The estimated maximum biobutanol production was 9.01 g/L, whereas the optimized medium produced 10.93 g/L of biobutanol.

Greenhouse carbon dioxide (CO2) enrichment from biomass residues was investigated using exhaust gas from the combustion of syngas produced by gasification. Near complete syngas combustion is essential to achieve CO2 levels which increase plant yields while maintaining a safe environment for workers. Wood pellets were supplied to a downdraft gasifier to produce syngas fed to a steel swirl burner. The preliminary results were encouraging and represented a first step toward a successful development of this technology. The burner required an equivalence ratio (the actual air to fuel ratio relative to the stoichiometric air to fuel requirements) of 2.6 for near complete combustion. Concentrations of sulphur dioxide (SO2) and ethylene (C2H4) emissions were either below critical concentrations or negligible. In 60% of the trials, carbon monoxide (CO) emissions were below ASHRAE standards for indoor air quality. However, the average nitrogen oxide (NOx) emission was 23.6 ppm, and it would need to be reduced below the 0.05 ppm to meet ASHRAE standards. Proposed improvements to the syngas burner design to lower NOx emissions and increase efficiency are: integration of a low swirl design, mesh catalysers, a higher quality refractory material, and a more efficient heat exchanger. Theoretically, combustion or gasification of biomass could provide more CO2 for greenhouse enrichment than propane or natural gas per unit of energy.

Hybrid composites are characterized by a variety of properties that are of interest to automotive applications, including strength, mechanical, and thermal properties. In this work, palm kernel shell-filled maleated polypropylene composites and palm kernel shell/nanosilica-filled maleated polypropylene hybrid composites were produced using a Brabender Internal Mixer. The results showed that the usage of the two types of filler in the PP matrix enhanced the tensile strength, elongation at break, and impact strength but reduced the tensile modulus of the PP composites. Thermal studies confirmed that the improved nucleating ability of the hybrid fillers contributed to the superb mechanical properties of the hybrid composites. A lower percentage of water absorption was observed in hybrid composites compared to the palm kernel shell/PP composite system.

A simple strategy is reported for catalytic conversion of glucose to 5-hydroxymethylfurfural (HMF) over AlI3 in N,N-dimethylacetamide (DMAC). When the reaction was conducted in DMAC at 120°C for 15 min over AlI3 catalyst, HMF was obtained with a yield of 52%. The reaction course was monitored by 13C NMR spectroscopy and HPLC analysis. The results suggest that AlI3 catalyzes the three consecutive reactions consisting of mutarotation of α-glucopyranose to β-glucopyranose, isomerization of glucose to fructose, and dehydration of fructose to HMF.

The feasibility of co-producing activated carbon and bio-oil from rice stalk through molten salt pyrolysis is reported in this work. The results indicated that: (1) mixed ZnCl2-KCl molten salt could considerably improve the solid and liquid yield as well as the ratio of H2 and CH4 selectively (compared to the traditional ZnCl2 method), (2) an increase of pyrolysis temperature had the same impact on the yield as mixed molten salt, except for a decrease of the liquid yield, which may have a negative effect on the adsorption ability of activated carbon, and (3) the adsorption capability of activated carbon varied significantly with the activation temperature and, to a lesser degree, with the pyrolysis temperature. The conclusion can be drawn that pyrolysis in molten salt is a potential technology for agricultural residue utilization because of its capability of co-production, especially in activated carbon and bio-oil.