Polymerization of vinyl acetate in fatty acids and properties of poly (vinyl alcohols) derived from the poly (vinyl acetates)

摘要

Polymerization of vinyl acetate (VAc) in various fatty acids (carbon numbers 4-18) was carried out.Chain transfer constants to the acids were determined to be 20-35x10~(-4),from which the constant to a methylene group was obtained to be 0.73x10~(-4).Viscometry in aqueous solution of derived poly (vinyl alcohol) (PVA) showed the usual behavior in terms of Huggins' constant obtained by the Schulz-Blas-chke's equation for PVAs derived from fatty acid systems lower than hexadecanoic acid.PVA derived from octadecanoic acid system showed abnormality,indicating association of alkyl groups.Contact angles on surfaces of PVAs cast from aqueous solutions were measured.While those of PVA derived from lower acid systems were 62°,those of PVAs derived from higher aids were higher and increased to 92° with increase in carbon number to octadecanoic acid.Alkyl groups in the PVAs were estimated to appear on the surfaces.Surface tension of aqueous solution of the PVA derived from octadecanoic acid showed high surface activity,and depended on pH of the solution,indicating the presence and cleavage of lactone ring at the combined portion between PVA and the acid.