| Abstract: | Melting point, the iodine color reaction, and foam fractionation were studied on model poly(vinyl alcohol) (PVA) having short branches of one or two monomer units in length. An increase in the amount of short branching units caused a marked decrease in color intensity of the PVA–iodine reaction and in the melting point. These tendencies were more remarkable when the short branching was two monomer units in length than when it was one monomer unit. It was also found that foam fractionation of an aqueous PVA solution produced PVA fractions with different degree of short branching, the degree increasing with increase in the fraction number. The color intensity of the PVA–iodine reaction has been confirmed to decrease with increase in the fraction number, but this result cannot be explained solely in terms of the short branching. It is concluded that the phenomenon of foam fractionation of PVA and the iodine color reaction of the fraction appear to be governed by many factors such as molecular weight, stereoregularity, and short branching. |
