Sifat-Sifat Bagian Dalam Batang Kelapa Sawit (Elaeis guineensis Jacq.) Terkompregnasi Methylene Diphenyl Diisocyanate dan Aplikasinya sebagai Papan Blok
Date
2022-03-17Author
Mangurai, Silvia Uthari Nuzaverra Mayang
Hermawan, Dede
Hadi, Yusuf Sudo
Sulastiningsih, Ignasia Maria
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Inner part of oil palm (Elaeis guineensis Jacq.) trunk (IOPT) is still not optimally utilized. The IOPT can be used as raw material for wood and composite products such as blockboards to increase its added value. However, the IOPT has low density, strength, and dimensional stability. The physical and mechanical properties of the IOPT can be improved by wood modification techniques such as densification, impregnation, and compregnation. Densification has drawbacks such as the occurring of a spring-back so that the modification results are not fixed. Meanwhile, impregnation is a technique of filling wood voids with thermosetting resin to increase density. The combination of impregnation and densification is called compregnation. Compregnation has a lower spring-back than densification due to the presence of impregnants. So far, the impregnants used in the impregnation or compregnation techniques are formaldehyde-based resins which are not environmentally friendly. Therefore, research on impregnation using materials that are more environmentally friendly is important.
This study aims to improve the properties of IOPT through impregnation, densification, and compregnation methods and its application as a blockboard core. The research was divided into three stages, that is (1) determination of methylene diphenyl diisocyanate (MDI) concentration as an impregnant in the IOPT (2) determination of the optimum compression ratio in the densification and compregnation of IOPT, and (3) characterization of physical and mechanical properties of blockboard with a compregnated IOPT as a core.
The impregnation of IOPT was carried out by the vacuum-pressing method. The impregnation process was initiated with a 7.6 MPa vacuum process for 15 minutes. Impregnation using MDI resin with concentrations of 10% and 20% were carried out at a pressure of 1.2 MPa for 60 minutes. Densification with a target thickness of 1.5 cm and compression ratios of 20% and 30% was carried out using hot pressing at a temperature of 150 °C and a pressure of 8 MPa for 30 minutes. Compregnation is carried out by a combination of impregnation and densification as described above. The physical and mechanical properties of the modified IOPT were carried out according to the ASTM D 143-2000 standard. The resistance of the MDI impregnated IOPT against subterranean termites was tested based on the SNI 7207-2014 standard. The blockboards were made from the compregnated IOPT as the core and the mangium wood (Acacia mangium Willd.) veneer as the face layers. Total blockboards layers are three and seven layers. The IOPT and mangium wood veneers were glued with MDI resin with a spread rate of 200 g·m-2 and hot- pressed at 100 °C and a pressure of 0.5 MPa for 4 minutes for three-ply blockboard and 8 minutes for seven-ply blockboard. Physical and mechanical properties of blockboards were tested based on Japanese Industrial Standard (JIS) A 5908-2003 and Japanese Agricultural Standard (JAS) 232-2003.
The results showed that the impregnation using MDI improved the physical and mechanical properties of the IOPT at the bottom, middle, and top parts. The increase in the physical and mechanical properties of the IOPT was higher by increasing MDI concentration. The MDI impregnated IOPT had a higher density values and a lower moisture content. Dimensional stability and mechanical properties of untreated and impregnated IOPT tend to increase from the top to the bottom of the trunk. Despite the mechanical properties being increased, the impregnated IOPT with 10% and 20% MDI were still classified as strength class V. Meanwhile, the resistance to subterranean termites at the bottom of the IOPT increased from very poorly resistant (resistance class V) to poorly resistant (resistance class IV) at 10% MDI concentration and became moderately resistant (resistance class III) at 20% MDI concentration. Impregnation with a higher concentration of MDI increased termite mortality and reduced feeding rate and weight percent loss of the IOPT against subterranean termites.
The densified IOPT without the impregnation process had a lower compression set and a higher recovery set than the compregnated IOPT. The compregnated IOPT has the highest density, dimensional stability, and mechanical properties compared to the other modified IOPT. Densification and compregnation with a compression ratio of 30% resulted in a higher density and mechanical properties of the IOPT than the compression ratio of 20%. Modification through compregnation with MDI provides the best improvement compared to impregnation and densification.
The number of layers of the blockboard and the treatment of the IOPT affect the physical and mechanical properties of the blockboard. Seven-ply blockboards tend to have better physical and mechanical properties than three-ply blockboards. The blockboard with compregnated IOPT core has higher mechanical properties than the untreated IOPT core blockboard. The thickness swelling of blockboard with compregnated IOPT core was higher than that of blockboard with untreated IOPT core, but still complied with JIS A 5908-2003 standard. Three-ply and seven- ply blockboards with IOPT core for all treatments had MOE values below the JAS 232-2003 standard. MOR values of three-ply and seven-ply blockboards with IOPT core have fulfilled JAS 232-2003 and classified as strength grade E65-F205. The seven-ply blockboard with compregnated IOPT core has a higher hardness value than the three-ply blockboard.
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