The following paper which describes the enzymatic degradation of PVA by starch may be helpful:
Polymer Degradation and Stability
Volume 93, Issue 10, October 2008, Pages 1884–1890
Enzymatic degradation of some nanocomposites of poly(vinyl alcohol) with starch
Iuliana Spiridon, Maria Cristina Popescu, Ruxanda Bodârlău, Cornelia Vasile,
Abstract
A study of the enzymatic degradation of some montmorillonite-containing nanocomposites of poly(vinyl alcohol) with starch was based on the determinations of mass loss and the reducing sugars. The degraded residues have been examined by FT-IR spectroscopy and optical microscopy. It has been established that the nanoparticles hinder degradation, while the susceptibility to enzymatic degradation varies in the order: PVA/starch/nanocore > PVA/starch/Bentonite > PVA/starch/Peruvian clay.