Sulfited tannin from the bark of Acacia Mangium for bio-based adhesive
2009
Hoong, Y. B., Putra Malaysia Univ. (UPM), 43400 UPM Serdang, Selangor (Malaysia). Faculty of Forestry (Malaysia). Dept. of Forest Production | Paridah M. T. | Koh, M. P., Forest Research Institute of Malaysia (FRIM), 52109 Kepong, Selangor (Malaysia) | Luqman C. A, (eds.), Putra Malaysia Univ. (UPM), 43400 UPM Serdang, Selangor (Malaysia). Faculty of Engineering
The current increase in oil price has intensified the efforts to seek renewable resources to be converted into biopolymers. Phenol, a petroleum-based chemical, is one of the most sought-after chemicals which can be synthesized from the bark of trees. This study evaluates the properties of tannin extracted from Acacia mangium tree bark. Acacia tree contains 10% bark (v/v), of which about 20% are extractives. Extraction of this bark using water and sulfite medium can produce 15-25% tannin (dry weight). In this work, several extraction conditions such as bark size, site, extraction time and extraction medium were studied. The results show that the optimum method for extracting tannin from tree bark to generate acceptable amount of tannin yield is using either hot water or sulfite medium. Bark size of less than 1-mm mesh size gave relatively high tannin yield irrespective of the extraction medium used. By using a 600:100:2:0.5 (w/w) ratio of water: bark: sodium sulfite: sodium carbonate respectively, and reacted at 75 DC for 3 h improved the tannin yield by at least 30%. The extracts were reasonably reactive towards formaldehyde as shown by their high Stiasny numbers (SN). The study has showed that the bark of A. mangium trees can generate tannin (polyphenols) of high reactivity towards formaldehyde which can be used as biobased phenolic adhesive for bonding wood.
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