Abstract: The ring structures in the ketals obtained from the reactions of atactic PVA with acetone and butanone have ben studied by ¹³C NMR. It was found that PVAand acetone mainly formed six-member ketal ring. On the contrary, butanone formed eight-and ten-member rings boldes the six-member ring, moreover, the methyl groups were all in axial conformations while the ethyl groups were in equatorial conformations. The concentrations of different hotal rings and the reaction equilibrium constants were also calculated through the ¹³C NMR data.

Key words: ¹³C NMR, Polyvinyl alcohol, Ketalization