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( Deded Sarip Nawawi ),( Andita Maria ),( Rizal Danang Firdaus ),( Istie Sekartining Rahayu ),( Adesna Fatrawana ),( Fadlan Pramatana ),( Pamona Silvia Sinaga ),( Widya Fatriasari ) 한국목재공학회 2023 목재공학 Vol.51 No.2
Densification is an effective method for improving the physical and mechanical properties of low-density wood. However, the set-recovery of dimensions was found to be the problem of densified wood due to low fixation during the densification process. Alkali pretreatment before densification is thought to be a modification process to improve the dimensional stability of densified wood. In this research, the wood samples used were boiled in a 1.25 N sodium hydroxide (NaOH) solution at different times, followed by densification for 5 h at 100℃. The alkali pretreatment for 1, 3, and 5 h of boiling increased the dimensional stability of densified woods and anti-swelling efficiency values were 8.52%, 63.24%, and 48.94%, respectively. The boiling of wood in NaOH solution decreased the holocellulose content, as well as lignin to a lesser degree, and a lower crystallinity index was observed. The lower hydroxyl groups and a higher proportion of lignin in treated samples seem to have contributed to the high dimensional stability detected.
General Tendency of Lignin Chemical Structure and its Relation to Reactivity
Yuji Matsumoto,Deded Sarip Nawawi,Satoko Shimizu,Pattaraporn Posoknistakul,Iori Tomoda,Takuya Akiyama,Tomoya Yokoyama 한국펄프·종이공학회 2016 한국펄프·종이공학회 학술발표논문집 Vol.2016 No.10
Hardwood lignins are different from softwood lignins by the presence of syringyl type aromatic nuclei. In addition, there are wide varieties in the structure and amount of hardwood lignins depending on wood species, environment of growing site, portion in the wood, portion in the cell wall, and so on. We have shown that the wide variety of lignin structure and amount can be sorted out by taking the syringyl/guaiacyl ratio as an index. Furthermore, we have also shown that lignin structure can be quantitatively related to the chemical reactivity such as delignification during chemical pulping by taking the syringyl/guaiacyl ratio as an index. In this report, we review our recent achievements about the quantitative relationships between lignin structure and reactivity.
Anatomical Structures and Fiber Quality of Four Lesser-Used Wood Species Grown in Indonesia
( Sari Delviana MARBUN ),( Imam WAHYUDI ),( Jajang SURYANA ),( Deded Sarip NAWAWI ) 한국목재공학회 2019 목재공학 Vol.47 No.5
This study aimed to investigate the anatomical structure and fiber quality of four lesser-used wood species namely Benuang (O. sumatrana), Duabanga (D. moluccana), Pisang Merah (H. hellwigii), and Terap (A. odoratissimus). This study evaluated its suitability for raw material in pulp and paper manufacturing. The anatomical structure was observed macro- and microscopically. Macroscopic structures were observed directly to the wood samples, while microscopic characteristics were observed through microtome specimens. Fiber dimension was measured through macerated specimens and fiber quality was analyzed following the Rachman and Siagian’s method. Results showed that these four timber species have similarity in the indistinct growth ring, diffuse porous in a radial pattern, rounded solitary vessel outline, 1 to 3 cells of ray width, deposits within the rays, fiber length, and cell wall thickness. Differences were found on vessel diameter, vessel grouping, vessel frequency, tyloses existence, type of axial parenchyma, and ray height. Based on fiber length and its derived values, the wood fibers of all species studied are suitable for pulp and paper manufacturing. They belong to the II quality class. The produced pulp and paper would have good quality, especially in tensile, folding, and tear strength. To promote their utilization, silviculture aspect of these four species has to be well understood.
( Muhammad Iqbal Maulana ),( Rio Ardiansyah Murda ),( Byantara Darsan Purusatama ),( Rita Kartika Sari ),( Deded Sarip Nawawi ),( Siti Nikmatin ),( Wahyu Hidayat ),( Seung Hwan Lee ),( Fauzi Febrianto 한국목재공학회 2021 목재공학 Vol.49 No.1
The objective of this study was to investigate the effect of alkali-washing with different sodium hydroxide concentrations on the chemical compositions of steam-treated Betung bamboo strand. Strands were subjected to steam treatment at 126 ºC for 1 h under 0.14 MPa pressure and followed by washing with 1-5% sodium hydroxide solution for 30 sec. The alteration of structural and non-structural chemical components content of bamboo strands was evaluated. Steam and washing treatments with various concentrations of sodium hydroxide solution considerably reduced the extractive content of bamboo strands, and the cell wall chemical components of the strand in the small degree. FTIR analysis showed noticeable changes in peaks related to hemicellulose and lignin. The relative crystallinity increased significantly after steam and washing treatment with sodium hydroxide up to 3% concentration. SEM Images showed smooth and clean strands surface after washing with 3% sodium hydroxide.
( Fauzi Febrianto ),( Dini Lestari ),( Adesna Fatrawana ),( Sena Maulana ),( Rita Kartikasari ),( I Nyoman Jaya Wistara ),( Deded Sarip Nawawi ),( Nam Hun Kim ) 韓國木材工學會 2017 한국목재공학회 학술발표논문집 Vol.2017 No.1
Dimensional stability and strength of bamboo oriented strand board (BOSB) were much improved when bamboo strands were steamed pre-treated prior to be mixed with adhesive. However, the treatment is still needs to be improved due to some extractives were still accumulated on the surfaces of strands. The objectives of this research were to evaluate physical, mechanical and durability properties of BOSB prepared from modified steam treatment of betung bamboo strand (Dendrocalamus asper) and chemical composition change during the treatment. Three layers of BOSB were prepared and the ratio of surface, core and back layer was set 1:1:1. The strands were steamed at closed tank at certain condition. Some strands were washed with distilled and NaOH 1% solution. Paraffin in amount of 1 % was added. A rotary drum blender was used for mixing the strands and 8% PF adhesive. The mat-form was hot-pressed at 135 ℃ for 10 min at a pressure of 2.5 MPa to fabricate BOSBs. The board was then conditioned for two weeks in a room condition. For comparison, BOSB prepared from strands preserved with 3% borax preservative was also developed. Steam treatment greatly improved dimensional stabilization i.e. water absorption (WA) and thickness swelling (TS) and mechanical properties i.e. MOE, MOR and internal bond (IB) of BOSB. Washing strands with NaOH 1% solution after steamed treatment resulted in better improvement of those parameters than washing with distilled water. BOSB resulted from the above modified steam processes also improved its durability against termite attacked. Extractives, holocellulose and lignin of bamboo reduced and pH value and alpha cellulose increased after applying steam. Durability class of BOSB obtained in this experiment was equal with using 3% borax preservative.