Volume 17 Issue 1

The aim of this study was to evaluate the differences between juvenile and mature woods of Populus alba trees in the axial and radial directions of the stem. For this purpose, three stands of P. alba trees were randomly chosen and cut from at their diameter at breast height. Three disks with a thickness of 5 cm were taken at three different height levels along the tree stems. The specimens were sequentially cut in the radial position according to the ISO standards method. The results indicated that there are significant differences in the physical and biometric features of P. alba trees in the longitudinal and radial axes of the stem. As the height from the base of the tree to the top of the stem increased, the oven-dry density, basic density, and fiber biometric factors decreased. Moreover, as the distance from the pith to the bark increased, the oven-dry density, basic density, and fiber biometric factors increased. The microscopic study represented that the P. alba is a semi-ring-porous hardwood with distinct growth ring boundaries, simple perforation, homogenous rays, and alternative inter-vessel pits.

This study investigated the effect of cutting conditions effects on sound level and surface quality in softwood and hardwood. The sound emission level caused by cutting process (band saw) as well as the surface roughness and topography of the wood samples were evaluated. A direct relationship was found between sound emission level and density, moisture content, feeding rate, and dimensions of the samples. Straight cutting of the samples caused less sound emission than cutting in a curved direction. The protective effect of the earmuffs was very significant, reducing the sound emission level from 88 dB to 38 dB. The results showed that with increasing the density and dimensions of the samples, the surface roughness decreased, while with increasing the moisture content and feeding rate, changing the cutting direction from straight to curved, the surface roughness of the samples increased.

Before timber is used for engineering and structural purposes, it is necessary to grade the strength of the timber. In order to obtain the static modulus of elasticity value of timber quickly and accurately, this study used ultrasonic waves and continuous mechanical stress rating equipment and two non-destructive test methods to analyze the correlation between the non-destructive test measured value and the static modulus of elasticity value. It also evaluated the influence of the feeding orientation of the boards, the forward and reverse feed directions, feeding speed, and break area ratio. The analysis results indicated that the modulus of elasticity value determined through continuous mechanical stress rating equipment had the highest correlation with the static modulus of elasticity value. Moreover, according to the results, the feeding orientation of the boards, the forward and reverse feed directions, and the feeding speed did not influence the prediction of the continuous mechanical stress rating equipment modulus of elasticity value. Meanwhile, to ensure the accuracy and uniformity of the continuous mechanical stress rating equipment modulus of elasticity detection value, it is necessary to avoid an excessively high break area ratio in Cunninghamia lanceolata timber during the preparation process.

The flange of press-formed paperboard trays was reshaped in this work with a developed folding method to increase the rigidity of the trays. The tray rigidity was evaluated with compression, torsion, and storing tests. The rigidity of the folded trays and the reference trays was compared, and the quality of the trays was investigated with an optical analysis. The folding temperature was altered to 23, 60, and 90 °C to compare the effects of heat input on the tray rigidity. The compression and torsion test results linked the increased tray rigidity to the additional heat input and surface pressure induced to the material in the folding phase. The trays that were folded at 90 °C showed a 43% higher compression force and a 12% smaller torsion angle compared to the reference trays. The storing tests showed an unclear effect on the tray rigidity to the dimensional stability, and the optical analysis depicted similar quality between the folded and the reference trays. The folding method was found to enhance the stacking and end use capabilities of paperboard tray packages, and the use of higher folding temperatures was suggested to increase the strength and stiffness of the trays.

The anatomical characteristics in the culms of the four promising Indonesian bamboo species, including Dendrocalamus asper, Dendrocalamus giganteus, Bambusa vulgaris var. vulgaris, and Bambusa vulgaris var. striata, were investigated to produce an identification key and quality indices for further effective utilization. The crystalline properties of the bamboo culm were determined using X-ray diffraction analysis. Dendrocalamus asper and Bambusa vulgaris var. striata showed vascular bundle type IV, while Dendrocalamus giganteus and Bambusa vulgaris var. vulgaris displayed vascular bundle type III. The vascular bundle density in the bamboo culms increased from the bottom to the top part and was higher in the outer part than in the inner part. The fiber portion and length in the outer part were higher than those in the inner part, opposite of those in the parenchyma portion. Dendrocalamus giganteus had the largest vessel and parenchyma diameter, while Bambusa vulgaris var. vulgaris had the smallest. Bambusa vulgaris var. vulgaris had the longest parenchyma, while Bambusa vulgaris var. striata and Dendrocalamus giganteus had the shortest. The outer part of the four bamboo culms showed higher relative crystallinity than the inner part. All anatomical parameters, except for crystallite width, showed a variation in the radial direction of the four bamboo culms but did not show a consistent tendency vertically. This study revealed that the anatomical properties were different between bamboo species and could be used for species identification and quality evaluation indices of the culms.

The carbohydrate composition (glucose, xylose, mannose, galactose, and arabinose) of lignocellulosic biomass Liriodendron tulipifera, Populus nigra × Populus maximowiczii, Populus alba × Populus glandulosa, Populus euramericana, Salix alba, Quercus variabilis, Robinia pseudoacacia, Zelkova serrata, Abies holophylla, Pinus rigida, rice straw, and peanut hull was investigated based on high-performance liquid chromatography (HPLC) and gas chromatography (GC) analyses derived from ASTM and NREL methods. The glucose content was higher in HPLC than in GC analysis, and the xylose, mannose, galactose, and arabinose contents were higher in GC than in HPLC analysis. The difference in carbohydrate composition was noticeable in the glucose, mannose, and arabinose contents of Abies holophylla and Pinus rigida, and this was affected by the species. A decision tree, as a data mining and artificial intelligence method, is a reliable and simple variable selection tool. This technique was used for carbohydrate analysis classification. Accordingly, 432 monosaccharide content reading data and analysis methods were used for model checking. It was found that arabinose was the most important splitting variable in carbohydrate analysis, and other monosaccharides did not influence the assay decision. However, the selection of a determination method for each sample should be considered comprehensively in future studies.

During the simulation analysis of the discrete element method (DEM) for the alfalfa compression process, the input parameters in DEM software had a significant effect on simulation results. To obtain simulation parameters of the alfalfa with different moisture contents, a combination of angle of repose tests and simulation optimization design are presented in this paper. The repose angle of the alfalfa with moisture contents of 2.7%, 13.4%, 19.9%, 33.1%, and 74.5% was measured, and the results were 41.99˚, 38.30˚, 47.47˚, 56.31˚, and 63.09˚, respectively. Inclinometer tests, shear test, and restitution test were performed to evaluate the contact parameters. Taking contact parameters as the calibration object, the Plackett-Burman test was used to screen out which parameters had significant influence on the repose angle. The results of variance analysis showed the surface energy was the most significant parameter in the alfalfa repose angle test for each moisture content. Based on the Box-Behnken test, a second-order regression model of repose angle was obtained and the significance parameters were optimized and calibrated. The parameters calibrated in this paper can provide a reference for other simulations of alfalfa utilization.

This study was conducted to propose an accurate measurement method of charred thickness in structural glued laminated timber (glulam) exposed to standardized fire temperature conditions for evaluation of the fire resistance of Japanese larch (Larix kaempferi) structural glulam. The compressive strength of the test piece collected from the structural glulam exposed to the standardized fire temperature for two hours was analyzed. The results showed that there was residual strength of 14% in the boundary area between sound and charred part. Therefore, the thickness of charred part should be calculated as approximately 4.5 mm less than what is measured visually. The cell wall thickness between sound-, boundary-, and charred-part exposed to high temperature was observed under a microscope. Higher temperature resulted in a thinner tracheid cell wall, and the radial tissue was broken down. The transformation of the boundary part of these microstructures progressed gradually until full carbonization of wood occurred. Based on compressive strength tests and microscopic observation in the boundary part of specimens exposed to high temperature, the current visual assessment of charred thickness measurement is safe in terms of structural aspect but not efficient in terms of wood utilization point of view due to exception of load carrying area of the member.

Hardness, surface roughness, and adhesion strength were determined for water-based opaque paints applied to heat-treated wood material surfaces. For this purpose, Scotch pine (Pinus sylvestris L.) and beech (Fagus orientalis Lipsky) woods were used as experimental material. Specimens were subjected to heat treatment at 3 different temperatures (150, 180, and 210 °C) and 2 different periods (2 and 4 h) under laboratory conditions. Two-component water-based paints with commercial codes D17 and D45 were applied to the surfaces. The hardness, surface roughness, and adhesion strength values of painted samples were determined according to the applicable standards. The results showed that there were higher values of hardness and surface roughness of water-based paints in short-term heat treatment compared with long-term heat treatment. A general decrease in pine with D17 and D45 paints applied to the surfaces and in beech with D45 in adhesion strength was detected depending on the increasing heat treatment temperature and duration. An increase was observed in beech samples with D17 paint applied.

Environmental and economic concerns are driving tissue paper manufacturers to improve understanding of the relationships between fibres, the networks they form, the forming process, and the final tissue paper properties. This work investigated how pulp fractionation, refining, or addition of microfibrillated cellulose (MFC) affect the compromise between absorbency and strength of 33 ± 2 g/m² model papers made of bleached eucalyptus kraft pulp. The results showed that the compromise of properties was better when fibres were refined than when MFC was added. The absorbency capacity of 2%wt MFC-paper was almost 20% lower than the capacity of the refined paper at the same dry strength. The calculated additional storage capacity due to water-induced deformations of the fibre network was 40% lower in the same range of bulk. By forming a high viscosity gel at inter-fibre contacts, MFC could limit the occurrence of major fibre and network deformation mechanisms when water was imbibing the paper.