Volume 16 Issue 3

The successful manufacturing of glulam from several important Australian commercial timbers is quite challenging due to difficulties in gluing. Improvements in adhesive bond performance of spotted gum, Darwin stringybark, and southern pine timber have been achieved using alternative pre-gluing surface machining methods, e.g., face milling and sanding-post planing, when compared to conventional planing methods. In order to improve the understanding of the effects that different surface machining methods have on adhesive bond performance, this study used micro X-ray computed tomography and microscopy to assess key adhesive bond criteria. There was a considerable loss in the amount of adhesive after the wet and dry test cycles for all species. There was also an extremely high frequency of voids in the glue lines for all species, which would negatively impact bond strength and durability. Face mill prepared timber boards resulted in thicker glue lines and greater resistance to adhesion loss, compared to boards prepared via planing. For the two hardwood species, face milling also resulted in greater adhesive penetration; however, for southern pine, there were no significant differences in adhesive penetration between the three surface machining treatments. Adhesive penetration was much deeper in southern pine compared to spotted gum and Darwin stringybark.

Sawdust specimens of two Paulownia species, namely Paulownia tomentosa and Paulownia elongata, were evaluated in order to obtain briquettes and pellets. Briquettes and pellets were manufactured from the sawdust, and their physical properties (density), mechanical properties (the resistance of the briquettes to breaking, and the shear resistance of the pellets), and energetic properties (caloric value, black ash content, and calcined ash content) were determined. The densities of the P. elongata and P. tomentosa briquettes were 790 kg/m3 and 934 kg/m3, respectively, while the pellets had densities of 1268 kg/m3 and 1266 kg/m3, respectively. These values were within the standardized limits, and the ash content had good values. The high calorific value of 16815 kJ/kg and the low calorific value of 16669 kJ/kg was acceptable, since they were greater than other vegetable resources. In conclusion, it was found that the two types of wood biomass are suitable for the production of briquettes and pellets, due to their good physical, mechanical, and energetic properties.

The purpose of this work was to investigate the effect of 5%, 10%, 15%, and 20% additions of sea buckthorn biomass to cereal biscuits and analyze the oxidation stability and sensory attractiveness. The oxidation stability of the biscuits was evaluated with an Oxitest reactor under 6.0 bar oxygen pressure at 110 °C, and the increase in the induction period with increasing addition of sea buckthorn biomass up to 15% level was found. An increase in the induction period was observed with increasing addition of sea buckthorn biomass up to 15% level. In contrast, 20% addition of biomass caused a decrease in the induction period by 30 h compared to the induction period with 15% biomass addition. Sensory analysis revealed that brittleness and hardness of the biscuits decreased with increasing addition of sea buckthorn biomass. Overall, the most sensory acceptable from the point of view of assessors were biscuits with 15% addition. It was concluded that 15% addition of sea buckthorn biomass to cereal biscuits was the most optimal content in terms of oxidation stability and sensory attractiveness. The results of this study pointed out the excellent possibilities of fortification of cereal products with sea buckthorn biomass.

To improve the connecting strength of larch timbers, tensile shear test specimens were fabricated, and their connecting shear strength performance was examined. The control specimens consisted of larch timber reinforced with steel plate. These were compared with similar specimens in which the wood had been reinforced with carbon fiber reinforced polymer (CFRP). The reinforced specimens were fabricated in three types depending on the position of the CFRP reinforcement in the wooden part. All specimens were fabricated in two end distance types, depending on the bolt insertion position. The end distances examined were 60 mm (5D) and 84 mm (7D). The maximum connecting strength and the yield shear strength of each type were not different according to the CFRP reinforcement position. The reinforced specimens had an average connecting strength and yield shear strength that was 24% to 29% higher than the control specimens. The CFRP-reinforced specimens with an end distance of 5D had an average connecting strength and an average yield shear strength that that was 70% and 26% higher, respectively, than non-reinforced 7D specimens. The yield shear strength was predicted by measuring the bearing strengths of the larch timber samples and CFRP-reinforced timber samples. The predicted yield shear strength matched the measured yield shear strength.

In recent times, the indiscriminate disposal of post-consumer plastic packaging material has received global attention. There is a need to develop an alternative packaging material from bio-based polymers to reduce plastic waste pollution. This work studied the effects of loading seaweed nanoparticles into an agar matrix by analyzing the physical, mechanical, water vapor barrier, and biodegradation properties, as well as the surface morphological properties of biopolymer composite. The results showed that the addition of seaweed nanoparticles in the biopolymer matrix improved the properties of the agar-based biopolymer composite, except for the water vapor barrier properties of the biopolymer composite. The biopolymer composite film loaded with 6 w/w% seaweed nanoparticles appeared to achieve the highest mechanical strength. In addition, scanning electron microscopy analysis verified that the 6% w/w% seaweed nanoparticles biopolymer composite showed a homogenous surface morphology and had a strong adhesion on the interfaces of the filler and matrix. The samples had a desirable density of 0.0131 cm-1g-1 and a desirable biodegradability when 8 w/w% nanoparticles was used. This study verified that seaweed nanoparticles are compatible with agar matrix in terms of the enhancement of biopolymer composite properties.

The effects of different machining parameters on surface roughness values of thermally treated pine, beech, and linden woods cut in a computer numerical control (CNC) router machine were examined. Wood specimens were thermally treated at 170, 190, and 210 °C for 2 h. Then, specimens were cut in the radial and tangential directions with three different spindle speeds (12000, 15000, and 18000 rpm) and three different feed rates (3000, 4000, and 6000 mm/min) using two different end mill tools (spiral and straight) on the CNC machine. The end mill type significantly affected the roughness values of the untreated and thermally treated specimens in both directions. Lower roughness values were found in the specimens (especially pine) machined with the straight end mill compared to those machined with the spiral end mill. Roughness generally decreased in the thermally treated specimens. However, thermal treatment temperature did not have a notable effect on roughness. As the spindle speed increased, the roughness values of all specimens decreased. In contrast, as the feed rate increased, the roughness values increased. Therefore, the end mill type, feed rate, and spindle speed were the most influential parameters on the roughness.

Foam forming technology has attracted much attention during the past few years in the paper industry. Its advantages compared to conventional water forming are a new product portfolio and increased process efficiency. To support the paper industry in pushing foam forming technology forward, process simulation is needed to provide supporting data for strategic decision-making and as a basis for equipment dimensioning. This study examined the conversion of an existing wallpaper machine from water to foam forming technology using process simulation. To determine the required process configuration and parameter changes in the existing process, both published and unpublished data on the foam forming process were collected. This paper also describes modeling of the foam phase in the selected simulation software. The suitability of existing paper process equipment for foam was analyzed. Simulations revealed that undisturbed operation with foam requires some equipment modifications and re-arrangements in water circuits. With foam forming, the water balance in both short and long circulation changes remarkably compared to conventional water forming, leading to a large increase in the long circulation volume flows.

A novel flattened bamboo-wood composite cross-laminated timber (CCLT) made from flattened bamboo and hemlock lumber was developed, and its mechanical performance was investigated and quantified in this work. The results demonstrated that the CCLT columns and control hemlock CLT counterparts had nearly equal axial compression strength, but the CCLT yielded a higher compression modulus of elasticity (MOE). Additionally, the CCLT compression behaviors were not significantly affected by the height. Compared with hemlock CLT, the CCLT exhibited a slightly higher flatwise bending MOE and strength in the major strength direction. Furthermore, the MOE and strength of the CCLT under edgewise bending were 17.3% less and 16.2% greater than those under flatwise bending, respectively. The load-carrying capacity of the CCLT was mainly governed by the interfacial failure between the bamboo and wood, in which no rolling shear failure was observed. Those features are unique for the new CCLT for engineered applications.

The microbiological diversity of cultivable bacteria was analyzed in an aerated facultative lagoon. The removal of specific compounds and measures of pollutant load was evaluated with isolated native bacteria, selected and identified in kraft cellulose effluent. The system was operated with an organic loading rate of 0.2 kgCODm-3d-1 for 60 days. Analyses of the fluorescence excitation-emission matrix, acute ecotoxicity, and microbiology were performed. Bioaugmentation tests were done to emphasize the removal of color, using promising species. The removals of biochemical oxygen demand, chemical oxygen demand, and total organic carbon in AFL were 94%, 51%, and 41%, respectively. Regarding color, removal was up to 4%, and the total phenolic compounds were not removed through biological treatment. The treatment also decreased turbidity by 94% and lignin derivatives by 12%. The bacteria identified through NCBI-BLAST and statistical similarity totaled 9 species in the cellulose effluent, three of which have the potential for color treatment: Bacillus cereus, Bacillus thuringiensis, and Paenibacillus sp. The Bacillus cereus combined with biomass removed color (69%), total phenolic compounds (37%), and compounds derived from lignin (53%). These species are promising for removing specific parameters combined with biomass from biological AFL treatment systems.

Due to great advantages, such as simple operation, high porosity, and good fiber continuity, the working principle and research progress of electrospinning technology was studied and polyvinyl alcohol (PVOH) nanofibers were prepared via this process. Air filter paper was used as the receiving substrate to prepare electrospun nano air filter paper (NAFP). The PVOH concentration, static voltage, and receiving distance, were tested to explore the influence of spinning parameters on the filtration performance. Further, the microfiber morphology of the electrospun NAFP was observed. The performance of filter paper, including air permeability, pore size, initial resistance, filtration efficiency, and dust retention, were tested. The results showed that the electrospun NAFP had better filtration performance compared to the air filter paper, and simultaneously they had lower initial resistance and higher precision filtration efficiency. The nanofiber influenced the surface of the air filter paper, as it sharply reduced the pore size. When the spinning condition was 10%, 21 kV, and 15 cm, the pore size decreased approximately 0.6 times of the original, which meant the electrospun NAFP could capture particles ≥ 0.2 μm in size. Finally, after three repeated uses, the good filtration performance was maintained.