Mechanical properties of sawn timber are the most important characteristics in many applications, particularly for structural timber. The previous paper in this series reported on the physical properties of teak trees at different sites (Panggang, Playen, Nglipar)
Penelitian ini bertujuan untuk mengeksplorasi sifat kimia kayu jati dari hutan rakyat Kabupaten Gunungkidul. Pohon (dbh 28-37 cm) diambil dari tempat tumbuh berbeda yaitu Nglipar, Panggang, dan Playen. Setiap tempat diambil 3 pohon sebagai ulangan dan sampel yang digunakan adalah disk yang diambil dari bagian pangkal. Penampang radial disk dibagi menjadi 3 bagian, yaitu gubal, teras luar, dan teras dalam. Sifat kimia yang diuji adalah kadar holoselulosa, á-selulosa, hemiselulosa, lignin, ekstraktif etanol-toluena, kelarutan dalam air panas, kelarutan dalam NaOH 1%, dan abu. Sebagai pembanding, digunakan kayu jati dewasa dari tegakan Randublatung (Perhutani). Kisaran nilai kimia dari komponen dinding sel kayu jati Gunungkidul adalah kadar holoselulosa 75,76-79,74%, á-selulosa 46,72-50,90%, hemiselulosa 27,41-30,14%, lignin 29,22-32,80%, dan kelarutan dalam NaOH 1% sebesar 16,43-17,35%. Selanjutnya, kadar ekstraktif etanol-toluena, kelarutan dalam air panas, dan abu adalah 5,04-10,77%, 2,74-7,85%, dan 0,60-1,66%, secara berurutan. Interaksi antara kedua faktor berpengaruh nyata pada kadar holoselulosa, á-selulosa, hemiselulosa, dan ekstraktif etanol-toluena. Faktor tempat tumbuh berpengaruh nyata pada kadar abu sedangkan faktor radial berpengaruh nyata pada kadar kelarutan dalam air panas dan abu. Kayu jati dari Gunungkidul memberikan nilai rerata kadar ekstraktif etanol-toluena dan abu yang lebih rendah sedangkan nilai di parameter lainnya masih dalam kisaran nilai kayu jati dari Randublatung.Kata kunci: Tectona grandis, sifat kimia, hutan rakyat, arah radial, Gunungkidul AbstractThis study aimed to explore the chemical properties of teak wood grown in community forests from Gunungkidul Regency. Trees (dbh 28-37 cm) were selected from three different sites i.e. Nglipar, Panggang, and Playen. Three trees were cut from each site and disks were taken from the base of the trees. The disk in radial cross section was divided into 3 parts: sapwood, outer heartwood, and inner heartwood. Chemical properties tested were holocellulose, á-cellulose, hemicellulose, lignin, ethanol-toluene extractives, hot-water soluble extractives, solubility in NaOH 1%, and ash contents. Mature teakwoods from Randublatung (Perhutani plantation) were used for comparison purpose.The values range of chemical composition in the cell wall components of the Gunungkidul teak wood were holocellulose content 75.76-79.74%, , á-cellulose content 46.72-50.90%, hemicellulose content 27.41-30.14%, lignin content 29.22-32.80%, and solubility in NaOH 1% 16.43-17.35%. Further, the ethanol-toluene extractive, hot-water soluble, and ash content values ranged from 5.04 to 10.77%, 2.74-7.85%, and 0.60-1.66%, consecutively. Interaction between two factors affects significantly to holocellulose, á-cellulose, hemicellulose, and ethanol-toluene extractive contents. The growth-site significantly influence on the ash contents as radial factor has significantly affect on the levels of hot water soluble extractives and ash content. The amounts of ethanol-toluene extractive and ash contents of Gunungkidul teak wood showed the lower values than those of teak from Randublatung. The values of other parameters were remain in the range of value of teak from Randublatung.
A proposed method for assessing wood recovery involves application of a machining station approach with volume and mass measurements. A medium wood furniture company located in Jepara, Indonesia was selected to develop the method. Batch measurements of the inputs and outputs for different types of indoor-furniture products at every station were collected and analysed. For the volume method, three dimensions were measured on each specimen: the length, width, and thickness. For the mass method, the specimens were weighed before and after each processing station using a balance. Based on the mass method, the average total wood recovery rate was 26.2% ± 2.3%. For individual products and per station, the significant difference in the wood recovery rate occurred only at the resawing and edging, and trimming stations. The relationship between the teak quality, product dimensions, and type of finish was significantly different, where A-quality teak, large dimensions, and polyurethane finish resulted in a higher wood recovery rate. Both methods were reliable because of insignificant differences in the wood recovery rates. However, the mass method was more efficient and practical. The proposed protocol using the mass method is a suitable and effective system because the contribution of the variance component of the method was 2.71%.
The aim of this study was to evaluate the effects of radial growth on wood properties and anatomical characteristics and to clarify the xylem maturation process in Gmelina arborea. Stem diameter, tree height, and stress-wave velocity were investigated for 54 5-year-old G. arborea trees planted in Indonesia. In addition, radial variations of wood properties (basic density and compressive strength parallel to the grain in green condition) and anatomical characteristics (fiber and vessel morphologies) were investigated for nine trees selected from three different radial growth categories (fast, medium, and slow growing). Stem diameter was positively significantly correlated with stress-wave velocity and compressive strength parallel to the grain in green condition. In addition, compressive strength and anatomical characteristics, except for wood fiber diameter, differed significantly among the radial growth categories. Radial variations of the wood properties and anatomical characteristics gradually increased, and then they showed constant values toward the bark. It is thought that the xylem maturation of G. arborea begins at approximately 5 cm from the pith. In addition, in a fast-growing tree species, such as G. arborea, the trees with faster stem diameter do not always form wood with low strength properties.
Teak wood has been used for various uses because of its excellent natural
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