Abstract
Abstract The properties of the laminated veneer lumber (LVL) composed of the boiled veneer of Rubberwood (Hevea brasiliensis) using polyvinyl acetate (PVAc) adhesives in various cold-pressing time and various conditioned time with loaded and unloaded were studied. Five-ply LVL was produced by boiling veneer at 100°C for 90 min as pretreatment and cold-pressing time at 12 kgf cm−2 for 1.5, 6, 18, and 24 h then conditioned at 20°C and 65% relative humidity (RH) with loaded (12 kgf cm−2) and unloaded for 7 days as physical treatment. Especially for the delamination test, the specimens were immersed at 70 ± 3°C for 2 h and dried in the oven at 60 ± 3°C for 24 h; then, the specimens were solidified at room temperature (20°C and 65% RH) with loaded (12 kgf cm−2) and unloaded for 7, 10, 12, and 14 days. To determine the performance of LVL, the density, moisture content (MC), delamination, modulus of elasticity (MOE), modulus of rupture (MOR), horizontal shear strength, and formaldehyde emission tests were conducted according to the Japanese Agricultural Standard (JAS 2008) for structural LVL. The MOE and MOR values were significantly influenced by the physical treatment, however, neither to horizontal shear strength nor to formaldehyde emission. The best performance of LVL has resulted from unloaded LVL with cold-pressed time for 18 h; the MOE and MOR values were 9,345.05 ± 141.61 N mm−2 and 80.67 ± 1.77 N mm−2, respectively. The best value of the horizontal shear strength was obtained from the LVL with 18 h cold-pressing time and conditioned with loaded (13.10 ± 1.47 N mm−2) and unloaded (12.23 ± 1.36 N mm−2). The percentage of delamination values decreased with an increase in the cold-pressing time and conditioning time. The lowest value of delamination (19.06%) was obtained from the LVL with 24 h cold-pressing time and conditioned with loaded for 14 days. Except the delamination test, all other properties fulfilled the JAS.
Highlights
In Indonesia, the use of small-diameter logs produced from industrial forest estates has been studied since 1998 due to the decrease of large diameter logs from the natural forest as raw materials for composite wood industries (Kliwon and Iskandar 1998)
The purpose of this research was to improve the performance of polyvinyl acetate (PVAc) adhesives by using the above-mentioned physical treatments on the production of laminated veneer lumber (LVL) made from rubberwood, especially for interior use
That a delamination test of LVL produced from boiled veneer at the temperature of 100°C for 90 min, coldpressed at 12 kgf cm−2 for 24 h, and conditioned at 20°C and 65% relative humidity (RH) for 7 days before testing has the best result with the percentage of delamination 9% (Table 3)
Summary
In Indonesia, the use of small-diameter logs produced from industrial forest estates has been studied since 1998 due to the decrease of large diameter logs from the natural forest as raw materials for composite wood industries (Kliwon and Iskandar 1998). Rubberwood (Hevea brasilienis) produced from community rubber plantation can be used as a raw material for wood-based panel products because, in comparison with some commercial wood species, it has been shown to exhibit equal or better physical and mechanical properties (Boerhendhy et al 2003). Rubber plantation in Indonesia is still dominated by community rubber plantation (smallholders), which cover an area about 3,235,761 ha (88.13%) followed by government estate 189,576 ha (6.70%) and private estate 2,46,050 ha (5.16%) (Ministry of Agriculture of Indonesia 2019). By assuming that the rubber areas were rejuvenated every year about 2% of smallholders and 3% of government estate and private estate, respectively, and the average wood potential was about 50 m3/year (Boerhendhy et al 2003), the potential wood. Research to improve the properties of LVL manufactured from rubberwood using a cold-setting adhesive, namely PVAc, with physical treatment is very limited
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