Volume 15 Issue 3

Effects of bamboo species, adhesives, and steam-heating treatment (SHT) were examined relative to mechanical properties and dimensional stability of oriented bamboo scrimber board (OBSB) made from makino bamboo (Phyllostachys makinoi Hayata) and moso bamboo (P. pubescens (Mazel)) strips. Results indicated that OBSB produced using makino bamboo culms bonded with water-soluble phenol formaldehyde resin (PF) had significantly higher ultrasonic wave velocity (Vu (//)), tap tone sound velocity (Vt (//)), dynamic modulus of elasticity (DMOEu (//)), and DMOEt (//) than that produced using moso bamboo bonded with water-soluble urea formaldehyde resin (UF) (p < 0.05). The two types of OBSB showed the same trend of DMOEu > DMOEt > modulus of elasticity (MOE). In addition, OBSB made using steam-heated makino bamboo and PF had the largest modulus of rupture (MOR) (210.5 MPa), exceeding that of OBSB made using laminated bamboo timber and wood-plastic composite (WPC). However, OBSB made using steam-heated moso bamboo and UF exhibited the highest screw holding strength (SHS). Improvement in dimensional stability was observed in OBSB manufactured using steam-heated culms. Finally, OBSB glued with UF had lower water absorption, thickness swelling, and volumetric swelling than that glued with PF.

The development of the global economy is accompanied by growing environmental pollution, which has led to a change in attitudes and a need to promote sustainability. Modern innovation policy is becoming increasingly environmentally oriented. The purpose of this paper was to estimate the current situation of eco-innovation’s development in Slovakia. Eco-innovation Index analysis results showed that, in general, Slovakia is in the group of countries that are moderate innovators, with an innovation performance below the European Union average. Eco-innovation generally positively influences the environmental, economic, and social growth of companies that gradually adopt sustainable development. Therefore, it is convenient to identify the eco-innovative performance of Slovakia as well as to analyze the critical issues, which may also influence the desired positive development of eco-innovation in the future.

Unsupported combustion nitrogen (N2) and flame-retardant helium (He) were used to facilitate laser-cutting of cherry wood, and the effects of process parameters, gas flow, and gas reactivity on the surface quality of thin wood were studied. Using identical processing parameters, the cherry wood was laser-cut with and without the added gases. Through comparing the cutting width, heat affected zone (HAZ), and surface burning conditions under different gas-assistance conditions, the influence of the added gases on the gasification and combustion of cherry wood was analyzed. When N2 gas was used, the cutting width was less than that of laser direct cutting, but the surface of the burning area did not remarkably improve. Under the same conditions, when He gas was added, the burning areas on both sides of the kerf were remarkably reduced and the consistency of kerf was good. This indicated that He gas had good oxygen isolation and flame-retardant effects. The surface of the kerf was observed with a scanning electron microscope, and addition of He gas remarkably improved the burning that occurred when cutting kerf. This study combined gas processing and laser technology, and it provided technical references for reducing post treatment improving the surface quality of laser-processed wood.

The fiber saturation point (FSP) is an important parameter of wood material, related to dimensional stability and variations of mechanical performance. This paper investigated the FSP values of 15 tropical Brazilian wood species covering all strength classes of the Brazilian standard code. An additional goal was to estimate FSP value based on the wood’s apparent density. The FSP values were determined by measuring the wood specimen dimensions during moisture content reduction from the saturated state. Wood densities at 0% and 12% moisture contents and basic density were determined according to the Brazilian standard code. The average FSP for all wood species was 21.6% moisture content. Among density values, good correlations were observed, and a multivariate regression model for FSP estimation based on wood densities presented a coefficient of determination equal to 13.07%. There was no correlation between FSP and wood densities, suggesting that this parameter is almost constant regardless of the wood species.

This study examined the effect of applying cellulose nanoparticles as a filling material for phenol-formaldehyde (PF) resin in the process of manufacturing water-resistant plywood. Based on investigations that concerned the rheological behavior of resin mixture containing various amounts of nanofiller, the modification of resin resulted in a major increase of viscosity. Although Fourier transform infrared spectroscopy did not fully explain the effect of modification on the chemical structure of the adhesive, there was a noticeable improvement in the morphology of cured nanocellulose-reinforced resin. Based on the bonding quality results, the optimum amount of nanocellulose was 3 PBW (parts by weight) per 100 PBW of resin and it allowed the achievement of a notable increase in shear strength values. Moreover, introduction of cellulosic nanoparticles had a positive effect on mechanical properties such as bending strength and modulus of elasticity. In summary, the research showed that it is possible to apply nanocellulose as a modifier for the adhesives in the process of manufacturing water-resistant plywood.

Annual growth ring width was considered relative to the mechanical properties of timber from the Silesian Forestry Region in Poland. The timber was acquired from raw wood aged approximately 120 years old, with log quality A, B, and C. The study was conducted on 210 pieces of timber; 70 of them were from each part of the log: butt, middle, and top. The tested parameters, modulus of elasticity (MOE) and modulus of rupture (MOR), were measured on fully dimensional timber (40 × 138 × 3500 mm3) that had been dried and planed in industrial conditions. The density of wood (stereometric method) and annual rings width were calculated after MOR and MOE determination on samples including the entire cross-section cut near the failure zone. The tests revealed that the correlation between the width of growth rings and MOE or MOR depended on the log area: it was the highest for timber from butt logs and the lowest for timber from top logs. Moreover, the correlation between growth ring width and MOE or MOR depended also on the quality class of the logs from which the samples were obtained: it was the highest for timber from class A, and the lowest for class C.

To explore the overall mechanical properties of bamboo-wood composite cross-laminated timber (BCLT), a simulation model of BCLT mechanical behavior based on the solid element was established using the finite element software ABAQUS. The actual four-point bending experiment was compared and analyzed with the finite element numerical simulation. The total curve error coefficient of the BCLT specimen at 18-mm displacement was 0.2988 while the interval was 0.5 mm. The error coefficient was 0.0178 when the maximum load was reached, and the minimum error coefficient was 0.0015 at 12 mm of displacement. Analysis of the influence of material parameters, meshing density, and material arrangement on the final stress distribution indicate that the difference in the elastic parameters of the material greatly influence the final stress distribution, and the arrangement and combination of materials also have an effect on the overall mechanical properties of the BCLT board. The combination CLT1-2-1 (i.e., the upper and lower layers of the bamboo are Arrangement 1 and the hemlock is Arrangement 2) have a maximum load of 57682 Ν and a maximum stress of 103.9 MPa.

The co-liquefaction of Shengli lignite and Salix psammophila was used to produce the bio-oil with sub/super-critical water-ethanol as the reaction medium in a WHF-0.1 stainless steel autoclave. The effects of experimental conditions including reaction temperature, holding time, the ratio of S. lignite to S. psammophila, and addition of catalyst were investigated. NaOH is most beneficial to co-liquefaction of S. lignite and S. psammophila. The characteristics of bio-oil and solid residue under the best conditions were determined, and the chemical compositional analysis of bio-oil was done using Fourier transform infrared (FTIR) spectroscopy. Scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were used to characterize the solid residue after the liquefaction. The melting degree of S. lignite in co-liquefaction residue was deeper than that in L-residue, which showed there is a synergic effect between S. lignite and S. psammophila in co-liquefaction.

Chemical contaminants from wood-based panels, such as volatile organic compounds (VOCs) and formaldehyde, are the main sources of indoor air pollution. The particleboards were used as the substrate and five common finishing methods, including melamine-impregnated paper, high-density polyethylene decorative film, wood veneer, polypropylene water borne paintings coatings, and polyurethane water borne paintings coatings, were selected for this study. The emission curves in the first 6 h and the equilibrium concentrations of the total volatile organic compounds (TVOC) and formaldehyde processed with the finishing wood-based panel method for 24 h were obtained and measured using an airtight environmental chamber. The ingredients of the VOCs were investigated using the small chamber method and gas chromatography and mass spectrometry (GC/MS). The results indicated that the finishing methods were effective for reducing the emissions of TVOC (except the water borne coating) and formaldehyde of the particleboards. High density polyethylene film was the best finishing material to reduce the release of TVOC. The concentration of the veneered particleboard from the third to the tenth hour was higher than the unfinished particleboards. The veneered particleboard released six volatile ingredients to a lesser extent than the unfinished particleboard.

Lignin is a by-product of the pulp and paper industry that can be precipitated by acidification from black liquor as a potential feedstock for valuable green materials. Precipitation and quantification of lignin from softwood black liquors have been documented and commercialized with well-established methods; however, applying those methods to the precipitation of lignin from hardwood black liquors has produced low lignin yields. A need to understand the main differences between hardwood and softwood lignin precipitation prompted the current investigation. Multiple black liquor samples from sweetgum and pine pulping were obtained at different times of standard kraft cooks. Two lignin fractions were precipitated from each of these black liquors, one at pH 9.5 and one at pH 2.5. Detailed lignin and carbohydrate material balances were performed around each of the sample sets, starting with the wood and ending with precipitated lignin fractions. For all conditions tested, the amount and purity of pine lignin precipitated were superior to sweetgum lignin. The maximum recovery for sweetgum lignin was 69.7%, while for pine lignin, it was 90.9%.