Jorge, Fernando CaldeiraBrito, PauloPepino, LinaPortugal, AntónioGil, Maria HelenaIrle, Mark A.Costa, Rui Pereira da2010-01-142010-01-141999Jorge, Fernando Caldeira; Pepino, Lina; Portugal, António; Gil, Maria Helena; Irle, Mark A.; Costa, Rui Pereira da (1999). Improved extraction of pine bark for wood adhesives. In 3rd European Panel Products Symposium. Llandudno. p.301-307http://hdl.handle.net/10198/1288Pine bark tannins must be subjected to sulphonation to have an acceptable solubility in water for the preparation of wood adhesives. In this study, several extraction variables (sodium sulphite and urea concentrations in the extraction white liquor, extraction time, bark/liquor ratio and temperature) were assessed for their effect on extraction yield, and on the phenol, sulphur and ash content of extracts. Temperature had the highest positive effect on extraction yield and on the yield of total phenols in the extract. Sulphur content (i.e., the degree of sulphonation) was influenced mostly by sulphite concentration in white liquor, as was ash content.engconference paper