Wood adhesives based on tannin extracts from barks of some pine and spruce species

Characterization of Pinus pinaster bark and its alkaline extracts by diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy

“…The Stiasny number is a parameter that indicates the capacity of the extracts to react with formaldehyde in the preparation of adhesives. In this sense, Yazaki and Collins (1994) have found that extracts with Stiasny numbers higher than 65 can be used with guarantee in the formulation of adhesives. Thus, it is interesting to ®nd a relationship which enables the quick estimation of the Stiasny number by means of the characteristic DRIFT spectra bands of the extracts.…”

Characteristics of Pinus pinaster bark extracts obtained under various extraction conditions

“…Alkaline extracting solutions gave yields of 15±31%, and in all cases the Stiasny number of the spraydried extract was greater than 65, the lowest value allowing formulation of adhesives of acceptable quality according to Yazaki and Collins (1994a). In all cases, the presence of a 7±12% reducing sugars content derived from the hydrolysis of polysaccharides lowered the potential formaldehyde-condensable polyphenols content and would doubtless somewhat reduce the strength and water-resistance of adhesives formulated with the tannin extracts (Pizzi and Mittal 1994).…”

“…7 shows the results for a rotational velocity of 30 min À1 (it was not possible to prepare solutions of F1 and B/4 extracts with solids contents greater than 25% and 35% respectively). Like the extracts of other barks (Weissman 1983, SuomiLindberg 1985, Yazaki and Collins 1994aand b, Grigoriou 1997, those of Pinus pinaster thus have quite high viscosities at the solids contents commonly used in adhesive formulations. However, this does not necessarily rule out their utility, since a) satisfactory results have been obtained with tannin-based adhesives with relatively low solids contents (Pizzi and Stephanou 1994), and b) the viscosity of the extracts can be reduced by sulphitation (Yazaki and Hillis 1980, Weissmann 1983, Yazaki and Collins 1994a or the addition of hydrogen bond breakers (Ayla andWeissmann 1981, Grigoriou 1997).…”

Sintesis Perekat Tanin Resorsinol Formaldehida Dari Ekstrak Kulit Pohon Mangium Untuk Peningkatan Kualitas Batang Sawit

“…Jumlah bilangan Stiasny sangat penting untuk menghasilkan perekat berkualitas tinggi yaitu minimum sebesar 65,00% (Feng et al, 2013;Yazaki & Collins, 1994). Pada Tabel 2 bilangan Stiasny yang diperolah dalam ekstrak cair dari kulit kayu pohon A. mangium nilainya 65,82%.…”