Zinc borates with different structures and morphologies were selectively prepared starting from zinc sulfate hydroxide (Zn4SO4(OH)(6)) and boric acid in aqueous solution. When the reaction temperatures were 80 and 90 degrees C, platelet-like and polyhedral zinc borates with the formula of 2ZnO center dot 3B(2)O(3)center dot 3H(2)O were formed, respectively. When the reaction temperature was less than 80 degrees C, rod-like heptahydrate zinc borates with the formula of 2ZnO center dot 3B(2)O(3)center dot 7H(2)O were formed. The morphology of zinc borates (2ZnO center dot 3B(2)O(3)center dot 3H(2)O) changed from platelet to polyhedron at the reaction temperature of 90 degrees C with increasing the water content in the reaction solution. The presence of polyethylene glycol and sodium dodecyl benzene sulfonate in the reaction solution favored the formation of small-sized polyhedral 2ZnO center dot 3B(2)O(3)center dot 3H(2)O particles. The presence of citric acid favored the formation of 2ZnO center dot 3B(2)O(3)center dot 3H(2)O platelets. The chemical structure and morphology of the zinc borates significantly affected their performances on improving the thermal and oxidative stability of polyvinyl alcohol. (c) 2012 Elsevier B.V. All rights reserved.