Investigations on aromatic polyesters with polynaphthalene systems in the main chain—X. Studies on the determination of chemical inhomogeneity of aromatic copolyester chains

The turbidimetric titration technique was applied to determine, for a number of solvent-nonsolvent systems, the relation between the parameter $\text{γ}{}^1$ and the content of 2,2 bis(4-hydroxyphenyl) propane in the terephthalic copolyester of 4,4′ dihydroxydinaphthyl 1,1′ and 2,2 bis(4-hydroxyphenyl) propane. A system most sensitive to differences in the chemical composition of the copolyester was found and then used to fractionate two copolyesters obtained in different reaction conditions and having the same composition but differing in the arrangement of comonomer units in the chain. Fractionation results have been presented in the form of MWD curves and also as a relation between the content of 2,2 bis(4-hydroxyphenyl) propane and the intrinsic viscosity [η] of individual fractions.