Polyvinyl butyral (PVB) was prepared by condensation reaction of butyral with polyvinyl alcohol (PVA) in aqueous phase containing an acid as a catalyst and an emulsifying agent. Properties of the polymer were a function of the relative amounts of the three randomly distributed units of acetal, acetate and vinyl alcohol groups, and the molecular weight. In this work, some effective factors in synthesis of PVB have been investigated by Taguchi method. The percent of the acetalization has been determined according to the ASTM D1396, and the polymer was characterized by IR, TG, and DTG techniques. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 3592-3597, 2010