The Study on the Foam Stability of Aqueous Poly(vinyl alcohol) Solution

Abstract

Relationships between defoaming rate of aqueous poly(vinyl alcohol) solution and preparation methods of poly(vinyl alcohol) were studied.
Poly(vinyl acetate) prepared by emulsion or suspension polymerization is more superior in the defoaming properties than that prepared by solution polymerization in methanol. Poly(vinyl alcohol)s which have the broader composition distribution of residual acetoxyl groups and/or block copolymers of vinyl acetate and vinyl alcohol had low foaming stability. Defoamation rate of aqueous poly(vinyl alcohol) solutions increased greatly by adding a small amount of less hydrolyzed poly(vinyl alcohol). It is concluded that, to increase the defoaming ability of aqueous poly(vinyl alcohol) solutions, it is necessary to lower the crystllinity of poly (vinyl alcohol) s.