Abstract

The comminuted bark of Acacia mangium was extracted with acetone solution, and the extract was then degreased with petroleum ether. The degreased solution was extracted by diethyl ether and ethyl acetate successively. In this way, the tannin of Acacia mangium was divided into the diethyl ether fraction, the ethyl acetate fraction, and the water fraction, respectively. The tannin molecular weight of these fractions was measured by gel permeation chromatography (GPC) and the particle sizes of tannin were examined by a Zetasizer ZS instrument. The results showed that the ether fraction consisted of the smallest molecules with an average molecular weight of 415Da possessing weak tanning ability but having a fast penetration rate. The molecular weight of the ethyl acetate fraction was 1788Da which showed significant tanning ability. The molecular weight of the water fraction was 2808Da with better tanning ability, and the biggest particle size was shown by this tannin. The thermal stability of the hide powder and cowhide tanned by these tannins was as follows: water fraction > ethyl acetate fraction > diethyl ether fraction; the order of penetration was: diethyl ether fraction > ethyl acetate fraction > water fraction. These results could provide a valuable reference for the use of the Acacia mangium tannin.