Abstract
Laboratory investigation of bark extract from different age groups of Rhizophora mucronata (bakau kurap) showed that the tannin extract of barks of 40 years old trees had high reactivity towards formaldehyde as indicated by its stiasny number of 72. The bark also possessed high tannin and extractives'contents. Plywood manufactured from mersawa veneers using this tannin extract met the minimum knife test value of 5 and gave satisfactory strength properties as its failing load met the minimum failing load (45.4 kgf) for boiling resistant type of adhesive, stipulated in the British Standards.
Zusammenfassung
Die Untersuchung der Rindenextrakte unterschiedlicher Altersgruppen von Rhizophora Mucronata zeigen, daß der Tanninextrakt der 40jährigen Bäume eine hohe Reaktivität gegenüber Formaldehyd aufweist. Dies ergibt sich aus der Stiasny Zahl von 72. Die Rinde enthält hohe Anteile an extrahierbarem Tannin und anderen Extraktstoffen. Sperrholz aus Mersawa-Furnier, das u. a. mit diesem Tanninextrakt verleimt war, entsprach dem unteren Wert von 5 beim Aufstechversuch und hatte zufriedenstellende Festigkeitseigenschaften, da die Bruchlast der Mindestanforderung des British Standards (45,4 kgf) für kochfeste Leimtypen genügte.
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Nurulhuda, M.N., Chew, L.T., Mohd, N.M.Y. et al. Tannin properties of rhizophora mucronata barks of different ages. Holz als Roh-und Werkstoff 48, 381–383 (1990). https://doi.org/10.1007/BF02634528
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DOI: https://doi.org/10.1007/BF02634528