Dodi Nandika

Tartaric acid catalyzed furfurylation of beech wood

European beech (Fagus sylvatica L.) is a major tree species of European forest which is underexploited because of its low dimensional stability and durability. Similarly to what has been developed with radiata pine, furfurylation might be the answer to optimize the utilization of local beech wood. Beech wood furfurylation process was studied using five different catalysts: maleic anhydride, maleic acid, citric acid, itaconic acid, and tartaric acid. Optimization of the furfurylation process was investigated for different catalyst and furfuryl alcohol (FA) contents, and different duration of polymerization. The following properties were studied: weight percent gain (WPG), leachability, anti-swelling efficiency (ASE), wettability, modulus of elasticity, modulus of rupture, Brinell hardness, and decay durability. Tartaric acid, never investigated up to now, was retained as catalyst to perform furfurylation due to its efficacy compared to other catalysts and its novelty. Wood modification with FA and tartaric acid as catalyst led to samples with high WPG even after leaching, improved ASE, and lower wettability with water. Increasing the polymerization duration increased the fixation of FA in treated wood. Most of all, treatment gave a significant improvement in mechanical properties and resistance to wood decaying fungi.

Juvenile and mature wood characteristics of short and long rotation teak in Java

Teak wood ( Tectona grandis ) as an important forest resource in Indonesia has been processed to wood furniture in large quantities to fulfill an increasing need of both local and international consumers. To satisfy the increasing demand for wood products, teak wood has been supplied from the State forests (Perhutani) and Community teak plantations. Community teak has been harvested at shorter age rotations (7–10 years) than Perhutani teak (40–60 years). This paper discusses the occurrence and characteristics of juvenile wood in Perhutani and Community teak based on density, shrinkage, bending strength (modulus of rupture - MOR, modulus of elasticity - MOE), fiber length, and microfibril angle (MFA). A segmented modeling approach was used to find the juvenile mature transition. Fiber length and MFA appear to be good anatomical indicators of radial increment demarcation between juvenile and mature wood, although maturation radial increment varies slightly between the fiber length and MFA. The use of radial increment density, shrinkage, MOR, and MOE were not appropriate, because of low coefficients of determination and a large range of radial increment for transition from juvenile to mature wood. The maturations were estimated to start at radial increments 10 and 14 cm from the pith by fiber length, and 11 and 15 cm from the pith by MFA for Perhutani and Community teak, respectively. The projected figures for the proportion of juvenile wood at breast height for Perhutani and Community teak were 65% and 100%, respectively. The results also indicate that short-rotation Community teak was not remarkably inferior in shrinkage, MOE and MOR compared to Perhutani teak, although it was less dense, less attractive and less durable due to lower heartwood content. Therefore, careful attention should be given to the use of the Community teak in some wood-processing technologies.

Wettability and bonding quality of exterior coatings on jabon and sengon wood surfaces

Wettability and bonding quality of exterior coatings on fast-growing wood surfaces were studied. Samples of air-dried flat-grained (tangential surface) and edge-grained (radial surface) pattern of jabon (Anthocephalus cadamba) and sengon (Paraserianthes falcataria) woods were used. Before application of exterior coatings, the surfaces of the lumber samples were sanded. To provide wood surfaces with various degrees of roughness, abrasive papers of 120, 240, and 360 grits were used for the surface preparation. The wettability of two exterior coatings (water-based acrylic and oil-based alkyd varnishes) on the sanded wood surfaces was measured using a sessile drop contact angle method. The Shi and Gardner (S/G) model was used to evaluate and compare the wettability of the surface coatings on the wood. The sanded wood samples were coated with the two coatings (two layers each). Bonding quality of the coating layers was measured using a crosscut tape test method. Experimental results show that constant contact angle change rate (K value) of the S/G model decreased as the grit number of abrasive paper increased. This indicates that the wettability decreased as the roughness of the surface decreased (surface becomes smoother). There was no evidence of differences in wettability between tangential and radial wood surfaces. The oil-based alkyd coating generated better wettability compared to the water-based acrylic. The crosscut tests showed that the bonding quality of the coating films on both jabon and sengon wood decreased as the surface became smoother. The sengon wood compared to jabon wood provided better coating wettability and bonding quality. Wettability in terms of the K values was a good indication for determining the bonding quality of the two varnish layers.

A Comparison Study of Kernel Functions in the Support Vector Machine and Its Application for Termite Detection

Termites are the most destructive pests and their attacks significantly impact the quality of wooden buildings. Due to their cryptic behavior, it is rarely apparent from visual observation that a termite infestation is active and that wood damage is occurring. Based on the phenomenon of acoustic signals generated by termites when attacking wood, we proposed a practical framework to detect termites nondestructively, i.e., by using the acoustic signals extraction. This method has the pros to maintain the quality of wood products and prevent higher termite attacks. In this work, we inserted 220 subterranean termites into a pine wood for feeding activity and monitored its acoustic signal. The two acoustic features (i.e., energy and entropy) derived from the time domain were used for this study’s analysis. Furthermore, the support vector machine (SVM) algorithm with different kernel functions (i.e., linear, radial basis function, sigmoid and polynomial) were employed to recognize the termites’ acoustic signal. In addition, the area under a receiver operating characteristic curve (AUC) was also adopted to analyze and improve the performance results. Based on the numerical analysis, the SVM with polynomial kernel function achieves the best classification accuracy of 0.9188.

Acoustic-Based Technology for Agarwood Detection in Aquilaria Trees

Agarwood is a non-timber forest product with high economic value. This incense wood is produced in the living stem of Aquilaria tree species after exposure to several stress factors and is not profoundly visible. Traditionally, agarwood hunters or collectors predict the existence of agarwood in the tree by relying on their visual assessment and experience, which may not be accurate at all times. To overcome this uncertainty, new technologies such as the nondestructive testing (NDT) technology are more reliable at providing valuable information for managing an agarwood plantation. In this study, an acoustic-based NDT has been applied on wounded and inoculated Aquilaria trees from which a reduction in sound velocity has been recorded. When coupled with PiCUS® sonic tomograph device, the tomogram results displayed progressing stages of decays consistent with that caused by fungal attack. The technology has been successful in detecting the existence of the agarwood in the target tree and can be improved for estimating the quantity and quality of agarwood in live trees periodically, before the final harvesting.