Structure–Property relationships of poly(vinyl alcohol). III. Relationships between stereo‐regularity, crystallinity, and water resistance in poly(vinyl alcohol)

Abstract

AbstractStructure–property relationships of poly(vinyl alcohol) have been studied by measuring the crystallinity and water resistance of films derived from samples of varying, known tacticity. Crystallinities of unannealed and annealed films were examined by means of density, infrared, and x‐ray measurements. Higher tacticity did not lead to higher crystallinity. The apparent order of crystallizability was atactic ≧ syndiotactic‐rich ≫ isotactic‐rich. Water resistance of these films was determined by measuring the swelling index at 30°C. and solubility at 70 and 130–140°C. Water resistance increases as tacticity increases, with syndiotactic‐rich PVA exhibiting the highest water resistance. Since water resistance also increases with crystallinity, both stereoregularity and crystallinity must be considered when evaluating structure–solubility relationships. Differential thermal and thermogravimetric analyses of these samples are also presented, together with a correlation of tacticity index as measured by an infrared technique with that of an NMR technique.