Structure and properties of poly(vinyl alcohol) of different stereoregularity

Highly oriented films and fibers of PVA with different stereoregular struct ures, such as atactic PVA and syndiotactic enriched PVA were studied. For s amples with a different content of syndiotactic diads, a marked difference in their thermal and mechanical properties was revealed. As was shown by X- ray diffraction analysis, films and fibers based on PVA with an increased S -diad content are characterized by a more perfect crystalline structure. A significant difference in the temperature behavior of PVA samples with diff erent stereoregularity was found. It was concluded that, upon varying the s tereoregular character of PVA, the structure and properties of the polymer are primarily controlled by intermolecular hydrogen bonding.