Treatment of rubberwood (Hevea brasiliensis) with boron compounds using thermal process
1998
Zaidon, A. | Abang Idham, A. | Mohd Hamami, S. (Putra Malaysia Univ., Serdang 43400, Selangor (Malaysia). Faculty of Forestry. Dept. of Forest Production)
Rubberwood (Hevea brasiliensis) samples with dimension 51 mm x 51 mm x 152 mm at two moisture content (MC) conditions were immersed in hot boric acid equivalent (BAE, 5 percent w/v) solution at 80 decgree C for 1 hr and allowed to cool in the same solution for another 2 hr. The retention and distribution of BAE in the treated wood were analysed immediately after treatment or after the treated wood had undergone 1, 2 or 4 weeks of diffusion storage. The retention and concentration of BAE (od weight basis) of rubberwood regardless of their initial MC when treated by thermal process achieved the standard BAE retention (more than 5.13 kg per cubic m) and exceeded the treshold limit (more than 0.2 percent w per w BAE). Rubberwood which was previously air-dried (MC ca. 12 percent) retain less BAE (5.14 kg per cubic m) than partially-dried (MC 60-80 percent) wood (5.74 kg per cubic m). The distribution of boric acid in the treated material which did not undergo diffusion storage was confined near the outer layer. A combination of diffusion storage after thermal treatment improves penetration. The initial MC of the samples greatly influenced the penetration of boric acid. For samples which initially had higher NC, 1 to 2 weeks of diffusion storage was sufficient for complete penetration of boric acid, while drier wood took at least 2 weeks.
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