Effect of pre-treatment and compression ratio on specific gravity (SG) and dimensional stability improvement of three lesser-used wood species from natural forest area of North Kalimantan Province, Indonesia had been investigated. Hot soaking at 80 C for 3 hours within 2 and 5% of boron solution was applied as pre-treatment, while compression ratio applied was 20 and 40% from the initial thickness. Densification was conducted using hot pressing machine at 30 kg/cm 2 of pressure and 160 C of temperature for 15 minutes. Specific gravity was measured gravimetrically, while dimensional stability was evaluated through thickness swelling and water absorption as the indicator. Results show that SG of densified wood was influenced by wood species and compression ratio, but not by pre-treatment applied; while dimensional stability was influenced by wood species, compression ratio, and pre-treatment. Specific gravity and water absorption of densified wood was improved significantly. Specific gravity increased 28.86-63.03%, while water absorption decreased 12.80-15.89%. Thickness swelling of 20% densified wood was lower than that of 40% densified wood.
The aim of this study was to investigate the effect of impregnating materials (low molecular weight phenol formaldehyde or LmwPF and succinic anhydride or SA), their concentrations (5and 10%), and compression ratios (20 and 40% from initial thickness)on improvement of specific gravity (SG) and dimensional stability on nyatoh, sepetir, and pisang putih wood; and then compared them to control and densified wood. The results showed that SG and dimensional stability of compregnated wood were affected by all parameters studied. Higher compression ratio and concentration will result in a greater improvement.In general, SG and dimensional stability of compregnated wood were better than the control.SG of LmwPF-and SA-compregnated wood increased by 10.69‒22.31% and 6.96‒23.09%, respectively. Utilization of LmwPF and SA has significantly reduced the spring-back, butthe latter is better. Thecompression-set recovery after compregnation was 18.34‒33.99%, while after densification was 47.86‒71.49%.
The purpose of this study was to analyze anatomical characteristics, fiber morphology, and several important physical properties of nyatoh (Palaquium lanceolatum), pisang putih (Sindora walichii), and sepetir (Mezzettia leptopoda) wood from North Kalimantan in order to support the proper utilization of each wood species. All parameters were analyzed using their standard procedures. Results showed that anatomical characteristics of nyatoh wood are the vessels predominantly are in radial multiples and contained tyloses, ray parenchyma is mostly uniseriate and even, while axial parenchyma is in narrow tangential line with irregularly spaced. For pisang putih wood, the vessels are exclusively solitary, ray parenchyma of two distinct sizes, while axial parenchyma are in continuous tangential bands with irregularly spaced. In case of sepetir wood, the vessel is in radial and diagonal patterns, rays tend to have two different sizes, axial parenchyma is vasicentric to aliform, and has the axial resin canals in continuous tangential bands. Average values of fiber length and fiber wall thickness are 1904 and 3.61 µm (nyatoh), 1708 and 4.51 µm (pisang putih), and 1337 and 3.39 µm (sepetir), respectively; while the mean values of specific gravity and T/R-ratio are 0.42 and 1.41 (nyatoh), 0.37 and 2.34 (pisang putih), and 0.32 and 1.40 (sepetir), respectively. Nyatoh wood is categorized as the Strength Class of III, while pisang putih and sepetir woods are categorized as the Strength Class of IV. Compared to pisang putih and sepetir woods, nyatoh wood is more potential for pulp, paper, and furniture manufacturing. Keywords: anatomical characteristics, fiber morphology, lesser-used wood species, physical properties
The effect of NaOH, succinic acid and their combination used as pretreatments on selected properties of densified wood samples of pisang putih (Mezzettia spp.), nyatoh (Palaquium spp.) and sepetir (Sindora spp.) has been studied. The properties of these samples were then compared with those of untreated wood (control) and densified wood samples without any pretreatment (HD wood). For alkali-pretreatment, after immersion in 10% NaOH (w/w) for 1, 2 and 3 h, the samples were immediately compressed; for acid-pretreatment, the sample was impregnated with 10% succinic acid (w/w) using a vacuum of −50 kPa for 30 min and a pressure of 7 bar for 2 h before pressing; while for the combination-pretreatment, the sample was initially immersed in 10% NaOH then impregnated with 10% succinic acid (w/w) and finally densified/compressed. Compression was applied in a radial direction and carried out in an open system using a hot press machine at 180 °C and 7 MPa specific pressure for 30 min with a 40% compression ratio. The results showed that densified wood with or without pretreatment had a higher specific gravity (SG) than the control, whereas sepetir wood showed the greatest increase in SG. The alkali- and combination-pretreatments resulted in a higher C-set value than in the control, HD and acid-pretreated samples. Acid-pretreatment resulted in the best improvement in dimensional stability compared to the other pretreatments. Increasing the immersion time in NaOH solution was proven to be able to increase dimensional stability both in alkali- and combination-pretreatments, although water absorption values varied.
Betung bamboo (Dendrocalamus Asper) has recently attracted interest as a sustainable reinforcement fiber in (polymer) composite materials. Utilization of bamboo has an advantages and disadvantages. It has a short growth cycle, lightweight, and good mechanical properties, but with poor wettability, dimensional instability, and low resistance againts biodeterioration agent. Some efforts have been devoted to alter and enhance its properties, especially wettability properties. Heat treatment under various temperature can enhance wettability properties due to chemical changes and migration of extractives, but also can induce color changes. Therefore, this study aims to investigate wettability properties and color changes of heat-treated Betung bamboo strand. The 1/3 middle of Betung bamboo was used as main material and converted into strand. Heat treatment temperatures applied were 140oC and 160oC for 3 hours. The wettability of Phenol Formaldehyde (PF) adhesive on heat treated Betung bamboo strand was measured using a sessile drop contact angle method. Constant contact angle and K-value were used as parameter of wettability. Color change of heat-treated Betung bamboo strand was measured by portable color difference meter model CDX 105 and characterized by CIE Lab. Results showed that the increasing temperature of heat treatment affected wettability and color properties. Contact angle tended to increase with an increase of temperature which is indicated an enhancement of wettability by making wood more hydrophobic. Increasing of temperature made Betung bamboo strand to be darker than that of control sample. Total color change (AE) values were 21.06 and 29.23 at 140 and 160 oC, respectively.
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