Volume 12 Issue 3

The radon absorption performance was determined and compared for different types of carbonized boards to establish effective carbonized boards. Moreover, the absorption mechanism of carbonized boards was investigated by specific surface area and pore size in each of the carbonized boards. The radon absorption performance was ranked in the following order: ash (87%), medium-density fiberboard (MDF, 83%), oriented strand board (OSB, 82%), particleboard (PB, 77%), and plywood (PW, 67%). The correlation between radon absorption capacity and surface area or pore volume showed that a higher surface area or pore volume had higher radon absorption performance. However, the highest surface area and pore volume was detected on carbonized MDF, which had a radon absorption performance that was 5% less than carbonized ash board. Therefore, the surface area and pore volume as well as other factors affected the absorption performance.

To achieve rapid bonding with desired adhesion properties, a combined treatment of sanding then coating with polyisocyanate, followed by plasma discharge was implemented on the surfaces of polyethylene wood-plastic composites (WPCs). The surface properties of polyethylene WPCs were studied by evaluating the contact angle and bonding strength, as well as analyzing it via Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results indicated that the shear strength and durability of the bonding joints of polyethylene WPCs increased considerably due to the synergetic effect from the surface treatment. Thus, a rapid bonding with desired adhesion properties of polyethylene WPCs was achieved. The roughness and the oxygen content on the composites’ surface increased after the combined treatment. Polar functional groups, such as –OH, –C=O, and –O–C=O, formed on the surface. At the same time, the presence of –NCO and –NH functionalities, generated during the combined treatment, showed that chemical bondings between polyisocyanate and the wood fibers of the composites occurred. The changes on the surface properties, such as roughness, wettability, as well as formation of chemical groups, substantially affected the adhesion properties of the bonding joint for polyethylene WPCs.

End-grain-to-end-grain welding has been the object of considerable study in the authors’ laboratory, but successful experiments have been hindered by wood defibration. End-grain butt joints obtained by friction welding with moso bamboo showed relatively good experimental results compared to beech, oak, and spruce. The average compression shear strength of the welded joints reached 5.81 MPa, and the departure of the bamboo fibers could not be observed during the welding process. A study of the microstructure of the welded surface revealed that during the welding process, hard vascular bundles within the fibers became prominent on the welded surface and acted similarly to a brush. These bundles dissipated lateral friction and protected the bamboo from cracking in the process.

Biomass has become a major source of renewable energy. The basic fuel properties of woody biomass from orchards were evaluated on the following fruit tree wood obtained from pruning operations: ‘Reliance’ peach, ‘Burlat’ cherry, ‘Packham’s Triumph’ pear, ‘Early Geneva’ apple, hazel (Polish variety Halle), ‘Hargrand’ apricot, walnut, domestic plum (Polish variety Węgierka), and sour cherry (variety Ujfehertoi fürtos). The research included the wood and bark of the trunk, whole limbs, and branches. Gross calorific value for the majority tested biomass ranged from 19.2 to 21.3 MJ / kg, which is typical for wood and bark of broadleaf species. The low content of chlorine and sulfur in the analyzed samples would contribute to low corrosion in boilers and a low atmospheric pollution factor for generated sulfur oxides and hydrogen chloride. Properties of fuel biomass obtained from pruning operations were not noticeably different from the typical properties of solid biofuels derived from woody forest biomass. Based on these results, biomass from orchards can be a substitute for raw forest material suitable for energy use.

The effects of a fire-retardant treatment and burl wood structure on the three-dimensional changes of aircraft sandwich panels were evaluated. Unvarnished and varnished panels with an outer decorative layer made from walnut burl (Juglans hindsii L.) were studied. Half of the samples from each type of panel received a fire-retardant treatment (phosphate-based) on all three layers of the decorative plywood. The other half had the two inner layers treated and the outer layer was left untreated. Three different wood areas formed by rotary peeling and by the grain orientation from the burl structure were identified and their veneer surfaces were separately studied. Samples pre-conditioned at 20 °C and 40% relative humidity (RH) underwent adsorption (25 °C, 90% RH) and then desorption (25 °C, 40% RH) treatments. Changes in the moisture content (MC), swelling, shrinkage, roughness, and waviness were measured after each moisture exposure condition. The results showed that the fire-retardant treatment significantly increased the MC, swelling, shrinkage, roughness, and waviness of the unvarnished and varnished panels. This treatment also affected the roughness and waviness of the burl wood structure for the unvarnished panels. The effect of this anatomical feature was not noticeable in the varnished panels.

The major question after a flooding event is whether to remove or remediate the building materials so that potentially harmful mold growth and their by-products cannot cause serious health problems for susceptible individuals. The purpose of this study was to determine the growth of Stachybotrys chartarum and corresponding production of macrocyclic trichothecenes on different components of a residential wall up to 65 days after a simulated flood event. Small-scale residential walls constructed of fiberglass batt insulation, oriented strandboard, gypsum wallboard, and lumber were destructively sampled at four time points. All four building materials contained notable levels of macrocyclic trichothecenes on all collection days. The highest concentrations of macrocyclic trichothecenes were on the paper siding of the gypsum wallboard, followed by the paper siding of the batt insulation and wood lumber. There was a significant increase in trichothecene concentration over time, particularly on the gypsum. The DNA concentrations of the mold were significantly higher on the batt insulation than on the wood products, and the mold concentrations also increased over time on the batt insulation and gypsum, but not on the wood products. It was concluded that if a flooding event should occur, the insulation and gypsum should be removed from the home and the remaining materials should be remediated.

A response surface methodology (RSM) tool with the Box-Behnken design was used to determine the optimum pretreatment conditions of Helianthus tuberosus residue for the enzymatic production of fermentable sugar with aqueous ammonia and sulfuric acid solutions, for various parameters such as pretreatment solution concentration, temperature, and reaction time. The pretreatment of biomass was performed using these optimized parameters in aqueous ammonia and sulfuric acid solution, followed by hot water, under the same conditions. The process was then performed by changing the sequence.

The influence of the nano-zinc oxide amount was evaluated relative to the flammability behavior, as well as the morphological and mechanical properties of wood plastic composites (WPCs). The polymer amount was approximately 50 wt%, and the lignocellulose material was 50 wt%. Nano-zinc oxide was applied at six weight levels including, zero (control), 1, 2, 3, 4, and 5 phc. For all treatments, the maleic anhydride polyethylene (MAPE) amount was 2 phc. The WPCs were made using a mixture of nano zinc oxide, high-density polyethylene, and mixed hardwood flour injection molding method. The morphological and mechanical properties, such as flexural strength and modulus, were measured. Various tests were conducted with a cone calorimeter, including the amount of char residue, total smoke production, time to ignition, and heat release rate, according to ASTM E1354-92 (1992). The flexural strength and modulus of composites in samples with 5 phc nano-zinc oxide were 79.9% and 27.2% greater, respectively, than in samples without nano zinc oxide. Nano-zinc oxide enhancement to 5 phc increased the ignition time and char residue 105.1% and 121.7%, respectively, and decreased the burning rate and total amount of smoke production 20.3% and 46.0%, respectively. Scanning electron microscope results indicated the presence of nano-zinc oxide agglomerates in the sample.

Switchgrass harvested from saline soil was slowly pyrolyzed at 300, 500, and 700 °C in a fixed-bed reactor. The objective was to understand the characteristics and evaluate the potential values of the bio-oil, syngas, and biochar. The biochar yield (27.0% to 41.3%) decreased with increasing temperature, whereas the syngas yield (26.3% to 40.9%) increased. The bio-oil yield (30.8% to 34.1%) was highest when the switchgrass was pyrolyzed at 500 °C. Both the bio-oil and syngas had low value as direct fuels because of their low heating values. Compared with the biochars from the switchgrass grown in “sweet” soil, the biochars derived from the switchgrass grown in saline soil had higher values of ash (10.5% to 17.2%), mineral nutrients, and cation exchange capacity (CEC) (200.3 to 241.1 cmol/kg). These results suggested that the biochar generated in this study might have a better liming effect and improvement of soil fertility and crop growth as a soil conditioner, and lead to double wins in saline soil improvement and a new approach for switchgrass utilization.

Graphene was manufactured from commercial kraft lignin, and its forming mechanism, structure, and properties were investigated. A single factor test was employed to determine the optimum conditions of the production of graphene nanosheets. Kraft lignin was mixed with iron powders as catalyst with different weight ratios. The mixed carbon source and catalyst were thermally treated at 1000 °C and incubated for a period of time in a tubular furnace. The thermally treated carbon materials were analyzed by field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The preferable conditions for production of graphene nanosheets from kraft lignin were determined. The graphene fold structure was obtained after thermally treating for 90 min when the ratio of carbon source to iron was 3:1. The results revealed that folded lamellar graphene structure increased with greater holding time. Carbon nanotubes (CNTs) were observed after thermal treatment for 105 min. These results indicate the formation of graphite crystal structure and multi-layered graphene from kraft lignin in the presence of iron catalyst.