Volume 16 Issue 2

The growing interest in wood accessories has focused scientific research attention on wood cutting with small diameter tools. A problem that may arise when drilling wood is the phenomenon of wandering – when the hole is not made in the designed place. The difficulty in studying small diameter drill holes (0.5 mm to 0.9 mm) is due to the difficulty of automatic measurement. The development of an appropriate methodology may allow for the observation of this phenomenon without the need for high-class hardware and expensive software. This article presents the results of tests carried out on nearly 500 samples made of various wood-based materials (high-density fiberboard (HDF), medium-density fiberboard (MDF), chipboard, and plywood) in terms of the usefulness of the OpenCV computer vision library for the determination of wandering.

The interrelationships among specific gravity (SG), modulus of elasticity (MOE), and strength (modulus of rupture, MOR) are largely the foundational basis for non-destructive evaluation and testing. Resource monitoring and commercial structural lumber production often rely upon such non-destructive evaluation to predict the bending and/or tension strength of individual members. These technologies require routine calibration. In addition, it is important to know the extent to which a given resource may change over time. To that end, this study investigated the relationship among SG, MOE, and MOR of small clear specimens from three samples taken across an approximate 50-year period; 1965 to 2018. Coefficients of determination among these variables are presented along with the prediction equations. These findings can be used to gain insight into the reliability and stability of these relationships over time.

Straw mulch mat is a promising alternative to petroleum-based plastic mulching film. The straw pretreatment process parameters influence the mechanical properties of the mat. To explore the effect of pretreatment process parameters on physical properties of wheat straw mulch mat, a five-factor and five-level central composite design (CCD) methodology was studied. With response surface methodology (RSM) analysis, the effects of parameters (soaking water temperature, soaking time, processing speed, manufacturing temperature, and manufacturing pressure) on dry tensile index and wet tensile index of original film, and initial beating degree of the straw pulp were reported. The optimal technical parameters were optimized as soaking water temperature 90 °C, soaking time 1.5 h, manufacturing pressure 1.5 MPa, processing speed 83.5 to 87.8 r/min, and manufacturing temperature 95 to 100 °C. With the optimal condition, the dry tensile index, wet tensile index, and initial beating degree were higher than 8 N·m/g, 4 N·m/g, and 17 °SR, respectively. With this pretreatment of raw materials, the wheat straw mulch mat would meet the demands of mechanical properties for agriculture mulching after adding chemical additives.

In recent years, circular saw blades with thinner kerfs have been in high demand for improvement of the production yield of wood-based materials and the reduction of sawdust. In the case of ripping of solid wood, the number of teeth of a circular saw blade is normally set to 40 or 50, with a diameter of 305 mm, which allows less cutting resistance and smooth exhausting of sawdust. However, at certain rotational speeds, self-excited alternate-tooth vibration can easily occur in circular saw blades with such thin kerfs and so few teeth. Therefore, the cutting surface quality tends to be worse. In this study, the mechanism of this self-excited alternate-tooth vibration was clarified. The vibration mode and frequency were predicted by the finite element method. In addition, a circular saw blade with a body thickness 1.5 mm and 50 teeth was employed for wood-cutting experiments. The rotational speed range of the self-excited alternate-tooth vibration modes and their frequencies were investigated. When a double of the tooth passage frequency was slightly higher than the frequencies of the alternate-tooth vibration modes, an alternate-tooth vibration of the regenerative chatter type was excited, owing to the forces on the sides of the tooth.

The bark of Pteroceltis tatarinowii is one of the main raw materials for the manufacturing of Xuan paper. In order to guide the production of Xuan paper, the anatomical properties and chemical compositions of the bark and branch wood from P. tatarinowii at different years of age were analyzed in this study. The results from a variation analysis of the anatomical properties indicated that the ratio of the length to width of the bark and branch wood was greater than 30, while the ratio of the lumen diameter to the wall thickness was less than 1. Furthermore, there were significant differences in the length and the ratio of length to width of the bark and branch wood. The results from a variation analysis of the chemical composition indicated that the lignin content of branch wood at various ages (years) was greater than the lignin content of bark. Additionally, the cellulose extractive and pentosan contents of the branch wood was less than the contents in the bark. Based on the analysis of the anatomical and chemical composition, barks that were 2 to 3 years old were the most suitable raw materials for the manufacturing of Xuan paper.

This study investigated the effect of pressurized temperature on the thermal, mechanical, and morphological properties of nanocomposites made from recycled polyethylene with the weight ratio of 50%. Nanosilica was applied at 3 levels (0, 4, 8 %) and wood flour had a weight ratio of 50%. High-density polyethylene (HDPE) went through multiple procedures. It was found that by increasing the nanosilica content, the tensile and flexural strength properties, the residual ash content, and the thermal stability increased along with a reduction in the tensile and flexural modulus and impact resistance. As the temperature increased, the tensile and flexural strength and modulus and the impact resistance decreased. Scanning electron microscopy (SEM) images revealed that samples with 8% nanosilica showed different polymerization than the wood flour particles.

Naturally durable wood species such as western juniper (Juniperus occidentalis) are a potential source of bio-based wood preservatives for the improvement of non-durable timber species. This research investigated the durability of southern yellow pine (Pinus sp.) and western juniper lumber or strandboard. Single layer panels were made with six different types of wood or wood treatments: southern yellow pine, mixed juniper sapwood and heartwood, sapwood, heartwood, sapwood strands impregnated with juniper oil prior to and after panel manufacturing. Panels were fabricated with 560 kg/m3 oven-dry density with 5% of PF resin and 0.5% of wax. Durability testing was performed with the brown rot fungi Gloeophyllum trabeum and Rhodonia placenta and the white rot fungus Trametes versicolor. Internal bond as a crucial parameter of OSB was measured. Tests revealed that juniper heartwood and juniper heartwood strandboards were highly decay resistant, and juniper oil pre- and post-impregnation strandboard manufacture imparted increased resistance to decay against one brown rot fungus, Gloeophyllum trabeum. Juniper strandboard manufactured from non-impregnated strands showed significantly higher internal bond than pine. These results suggest there is excellent potential for manufacturing highly decay-resistant OSB from juniper, especially from heartwood and that juniper oil can increase the durability of juniper sapwood strandboard.

In the flow forming technique of wood, a wood block is flowed into metal dies to mold the material into a three-dimensional complex shape. The purpose of this study was to investigate the effect of molding load and the mechanical properties of the molded material in the case that wood as a raw material was irradiated with electron beam (EB). The EB-irradiated wood board was impregnated with thermosetting resin and was subsequently molded into the material by adding pressure and heating in a closed metal die. It was found that the molding load of the impregnated wood was decreased with increasing the EB absorbed dose. The mechanical properties of the molded material were evaluated using modulus of elasticity (MOE) and modulus of rupture (MOR) in a three-point bending test. With increasing EB dose, MOR decreased greatly, while MOE decreased slightly. The EB irradiation on raw wood made it possible to mold the material at low load, though higher dose irradiation caused larger decreases in the mechanical properties.

A green composite was fabricated using bamboo fiber and 9,9′-bis(aryl)fluorene-modified cellulose nanofiber (FCNF). Cellulose nanofiber (CNF) and finely crushed bamboo fiber (CBF) were also used as binders. The mechanical properties of the composites were compared. It was found that the FCNF-bamboo fiber composite had the maximum flexural strength among these binders. This result was likely due to strong bonding by chemical reactions among fibers and the FCNF. The effect of fiber orientation accuracy on the mechanical properties of the composites was also investigated. When the bamboo fibers were carefully aligned, without fibers crossing each other, the mechanical properties increased by two times, compared to the composites with fibers crossing each other. In the accurately aligned bamboo composites, the cross sections of the fibers were largely deformed by compression stress during hot-press forming. Thus, the gaps among fibers decreased, and interfacial adherence was improved. The effect of fabrication temperature on the mechanical properties of the FCNF-bamboo composite was also examined. It was found that the maximum flexural modulus and strength of the composites were at approximately 250 °C, and the mechanical properties rapidly decreased above 270 °C due to thermal degradation of the bamboo fiber.

The use of screen-printed electrodes in different monitoring applications, e.g., polluted water, biotechnology, agriculture, industrial process control, and other applications, are continuously being developed. New cheap and open-source potentiostats have been recently emerging, in addition to the commercial and proprietary solutions on the market. In this study, paper-based, screen-printed electrodes were utilised as an alternative solution for ceramic-based electrodes and were tested with two potentiostats (proprietary and low-cost open-source running on wireless 64 bit Linux system installed on Raspberry Pi 3+). Unique paper substrates made from invasive plant papers and one commercial product were used for screen electrode printing. Ink layer thicknesses variations and mechanical grinding were applied, and cyclic voltammetry measurements were conducted. The variation in cyclic voltammetry measurements could be attributed to two sources: the potentiostats showed differences in their sensibility and signal values, and paper surface and structure also contributed to differences. Simultaneously, the additional processing steps, e.g., mechanical grinding, introduced additional measurement variations and differences in the measurement process.