1967 Volume 24 Issue 270 Pages 715-720
The dissolved state of some syndiotactic-rich poly (vinyl alcohols) in water was studied with viscometry in order to clarify in detail the behavior of mechanical denaturation of aqueous PVA solutions.
In the case of atactic PVA Einstein's hydrodynamic equivalent spheres existed in the closest Packing at the critical concentration of apparent activation energy of flow (Eη). The syndiotactic-rich PVA which was derived from poly (vinyl formate) prepared at 0°C and had nearly the same syndiotactic (diad) % with the atactic PVA showed a similar result with that of the atactic PVA solution in Eη-concentration (C) relationship. Therefore, mechanical denaturation occurs to PVA slightly differing in stereoregurality. On the other hand, PVA which was derived from poly (vinyl formate) prepared at -40°C and had a higher syndiotactic (diad) % than the atactic PVA showed a different result from that of the atactic PVA solution.
PVA containing 5 mol % isopropenyl alcohol showed the different results from that of the atactic PVA solution in Eη-C relationship. Seemingly that the contact of methyl side chain with hydroxyl one takes the place of the contact between hydroxyl side chains.
The extent of polymer concentration effective to the mechanical denaturation ranged from the critical concentration to the concentration at which all the contacts changed into the entanglements.
