Viscosity-Molecular Weight Relationships of Poly -(Vinyl Acetate) and Poly-(Vinyl Alcohol)

Relationships between limiting viscosity number and molecular weight for poly-(vinyl acetate)(PVAc) were determined from measurements of light scattering, osmotic pressure, end group determination and viscosity. Mostly the techniques employed was as same as mentioned in Part I and II. The range of molecular weight of the samples used was from 2×104 to 120×104 by weight average. From the data of light scattering and the measurement of end carbonyl group, the heterogeneity of the low conversion samples expressed by MwMn, was found to be 2 as expected by theory. The obtained relationships between limiting viscosity number [η] and molecular weights for unfractionated low conversion PVAc were renresented by the following eauationsin acetone:=in methyl ethyl ketone: in methanol: in θ solvent, (a mixture of methyl isopropyl ketone 72.7vol % and n-heptane 27.3vol % at 30°C):were Mw and Mn are weight and number average molecular weight, respectively, and [η] is represented in ml/g. The values obtained in acetone solution was corrected to the perfectly homogeneous specimens as follows: or, Where P is degree of polymerization.