Volume 8 Issue 4

Tension tests of metal-plate connected (MPC) joints for Chinese larch (Larix gmelinii (Rupr.) Rupr.) were conducted in four orientations. Load-deflection curves were obtained for each MPC jointed specimen. Ultimate tension load, translation stiffness, stiffness at large slip, and failure modes for each specimen were obtained. A Foschi 3-parameter model was found to fit the load-deflection curves very well. Wood grain, and MPC length and loading directions had significant effects on elastic deformation and stiffness at large slip of the MPC joints. Load parallel to the grain with MPC length parallel to load (AA) represented the highest elastic deformation, while load perpendicular to the grain and MPC parallel to load (AE) showed the lowest. Load perpendicular to grain with MPC length perpendicular to load (EE) presented the highest stiffness at large slip, AA the second, load parallel to grain-MPC length perpendicular to load (EA) the third, and AE the lowest. The translation stiffness and tension load showed similar trends in terms of the effect of test orientations. The ultimate tension load was reduced by 18.9% from AA to EA, 34.2% from AA to AE, and 36.8% from AA to EE. Multiple failure modes occurred at the MPC joint, including MPC shear failure, tooth withdrawal, and wood failure.

Alpha cellulose was extracted from Bambusa rigida fibers by carrying out Soxhlet extraction and bleaching and alkali treatments with acidified sodium chlorite solution and sodium hydrate solution. Then, cellulose nanofibers were isolated from α-cellulose with the combination of (33 wt%) sulfuric acid and ultrasonic treatment. The nano-sized fibers were successfully isolated, and the average diameters were about 10 to 30 nm. FTIR showed that a majority of the hemicelluloses and lignin were removed from the raw fiber and that the chemical constituents of α-cellulose and cellulose nanofibers were similar. XRD showed that the obtained nano-fibers presented a cellulose I structure, and thus the crystallinity of cellulose nanofibers was significantly increased. TGA showed that the thermal stability of the cellulose nanofibers was significantly improved. The relative crystallinity and thermal degradation temperature of the cellulose nanofibers reached 61.21% and 315.2 °C, respectively.

Hot water extraction of hemicelluloses from aspen wood chips of different sizes and wood meal was performed, and the extracted hemicelluloses were characterized. With decreasing wood chip size, the total sugars and total poly- and oligosaccharides extracted with hot water increased. The dissolution of hemicelluloses was mainly limited by diffusion in the fiber wall and mass transfer from fiber to fiber during hot water extraction of the wood chips. The extraction yield of high molecular weight hemicelluloses was less than that of low molecular weight hemicelluloses, and the reduction of wood chip size benefited the extraction of high-molecular weight hemicelluloses. Compared to the wood chips, the high molecular weight hemicelluloses extracted from wood meal had a higher extraction yield and an increased average molecular weight.

Structural and mechanical aspects of the forming of paperboard have received attention in the literature; however, specific forming phenomena of the tray corner and rim area of paperboard packaging have not been researched widely. In light of the importance of the corner for packaging quality, and to enable improved process control of forming, this study considers the forming phenomena of the corner of a press-formed paperboard tray. Four different thicknesses of extrusion-coated paperboard were studied to research the effect of paperboard thickness and mould clearance on the final product of the press-forming process. Suitable mould clearance, i.e., the percentage of the mould cavity that is filled with paperboard, was found to be from 95% to 135% for the tested paperboard types.

The aim of this study was to investigate the decay resistance of wood- polypropylene composites (WPCs) treated with nano-zinc oxide against the white rot fungus Trametes versicolor and the brown rot fungus Coniophora puteana. WPCs containing different loadings of nano-zinc oxide, namely 0, 1, 2, and 3 percent (by weight), were made. The composites were subsequently exposed to a decay test according to a modified ASTM D1413 standard. Nano-zinc oxide distribution in the composite was studied by scanning electron microscopy (SEM) combined with energy dispersive analysis of X-rays (EDAX). No clear evidence of nano-zinc oxide agglomeration at a loading of 3% (w/w) was obtained using SEM-EDAX. The results showed that nano-zinc oxide improved the decay resistance of the composite against the fungi.

The effects of wollastonite nanofibers on the physical and mechanical properties of particleboard were studied. Nano-wollastonite (NW), with the size range of 30 to 110 nm, was applied at 5, 10, 15, and 20%, based on the dry weight of wood chips, and compared with control specimens. Two application methods of NW were used: surface application (SA) and internal application (IA). Density was kept constant at 0.68 g/cm³ for all treatments. Tests were carried out in accordance with ASTM D-1037 specifications. The obtained results showed that NW formed bonds between the wood chips and improved the physical and mechanical properties, both when applied internally and when applied superficially. However, formation of micro-cavities and decreased integration in the particleboard matrix caused by a reduction in wood chip content resulted in a decrease in the mechanical properties of IA-NW-treated specimens at higher NW consumption levels. It may be concluded that surface application of NW at a 1.5% consumption level can be recommended for use in particleboards.

Low mole ratio urea-melamine-formaldehyde (UMF) resins synthesized with 2.5% and 5.0% melamine levels added at the beginning, middle, and end points of the first alkaline step of the typical urea-formaldehyde (UF) resin synthesis procedure were compared with typical UMF resins synthesized with melamine additions made at the final alkaline step. Various resin analysis, particleboard preparation, physical performance, and formaldehyde emission level tests were carried out. UMF resins synthesized with melamine additions at the beginning of the first alkaline step showed adequate storage lives of 2 to 3 weeks, and their particleboard bonding tests showed small but significant improvements in water soak test values, while formaldehyde content values were slightly higher in comparison with typical UMF resins. The particleboards showed adequate board strength and the formaldehyde contents were relatively low to qualify for the E1 Class of European Standards. UMF resins synthesized with melamine addition made at the middle and end of the first alkaline step were highly turbid and showed chemical structure differences and very short storage lives and the resin synthesis procedures were concluded to be of little practical value.

Japanese pine sawyer beetle, pine shoot beetle, and Formosan subterranean termite were selected to investigate the inhibitory abilities of solid wood and wood-based composites (MDF and WPCs) made with Eucalyptus urograndis and Melaleuca leucadendra. The chemical components in the extractives of the two types of wood were also analyzed by GC-MS. The results indicated that the inhibitory ability can generally be listed in descending order as WPCs, MDF, and solid wood when made by the same wood filler. However, samples in each group made using Melaleuca leucadendra exhibited a higher inhibitory level than samples made using Eucalyptus urograndis. 2,3-dihydro-2,2-dimethyl-3,7-benzofurandiol, which was identified in the extractives of both woods (14.169% in Eucalyptus urograndis and 12.686% in Melaleuca leucadendra), was a significant factor for inhibition due to its high toxicity to insects. The chemical components with greatest potential for inhibition were stigmast-4-en-3-one (8.656%) in Eucalyptus urograndis andboth 3-demethyl-colchicine (2.642%) and squalene (1.649%) in Melaleuca leucadendra. Additionally, perlite-based MDF showed the best inhibitory ability, possibly because the alimentary of the insects are prone to injury by perlite. PVC-based WPCs had a greater inhibitory level than HDPE-based WPCs due to the presence of the Cl element in PVC, as well as the addition of calcium zinc stabilizer and inorganic filler.

The catalytic conversion of lignocellulosic biomass to levulinic acid in ionic liquid, [EMIM][Cl] was conducted using a hybrid catalyst. The hybrid catalyst (1:1 ratio) with equal CrCl3 and HY zeolite weight ratios was synthesized using a wet impregnation method. Initially, optimization of cellulose as a model compound was carried out using two-level full factorial design (23) with two centre points. Under optimum process conditions, 46.0% of levulinic acid yield was produced from cellulose. Subsequently, utilization of lignocellulosic biomass demonstrated 15.5% and 15.0% of levulinic acid yield from empty fruit bunch (EFB) and kenaf, respectively, at the optimum conditions. Meanwhile, in the presence of ionic liquid under the same process conditions, 20.0% and 17.0% of levulinic acid were obtained for EFB and kenaf, respectively. The results indicated that ionic liquid could disrupt the covalent linkages between the biomass structures and dissolved the hollocellulose. This allowed the hollocellulose chains, accessible to the chemical transformation, to react and produce levulinic acid in presence of the hybrid catalyst. This study demonstrated that the combination of hybrid catalyst and ionic liquid has the potential to be applied for biomass conversion to levulinic acid under adequate process conditions.

To achieve a desired ethanol concentration and maximize substrate concentration, the fed-batch simultaneous saccharification and fermentation (SSF) process was performed on steam-exploded corn stover using the yeast strain Saccharomyces cerevisiae Y5. The fed-batch SSF experiments were conducted with feed loading and scheduled feed time conditions that were optimized with response surface methodology (RSM). The overall ethanol yield (based on the raw material cellulose content) in 48 h was as high as 64.0%, which was achieved with a final substrate loading of 26%(w/w), enzyme loading of 7 FPU/g cellulose, and dry yeast loading weight of 2.0 g/L. No additional yeast cells or enzymes were added during solid substrate fermentation.