Tannin extraction and utilization from Bakauan [Rhizophora apiculata (Blume)] barks [from Real, Quezon, Philippines]
1982
Manas, A.E. (Forest Products Research and Industries Development Commission, College, Laguna (Philippines))
Tannins from bakauan Rhizophora apiculata (Blume) barks were extracted by a six-stage counter current process at 63 C with 1:8 bark to water ratio. The yield of extract obtained was 81% based on the oven-dry weight of raw material. The combined extracts were spray dried in the Bowen laboratory spray dryer. Tannin formaldehydes adhesives, prepared from the extract, were used to bond three ply bagtikan (Parashorea plicata) veneers. The resultant plywood panels did not delaminate in the cyclic boil test. Maximum dry and wet-shear strengths were obtained with bakauan-tannin formaldehyde adhesive, fortified with 25% resorcinol-phenol formaldehyde resin. The bakauan-tannin-formaldehyde adhesive had lower wet-shear strength compared to commercial phenol-formaldehyde adhesive, but is superior in water resistance to commercial urea-formaldehyde adhesive.
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