Basic dyeability and acid content of high‐conversion polyacrylonitrile

Abstract

AbstractPrevious data have shown that the basic dyeability of acrylic polymers increases at a given specific viscosity as the peroxydisulfate‐to‐bisulfite ratio, that is, the catalyst‐toactivator (C/A) ratio, is increased. This study represents an effort to understand better the role of the initiator system on the basic dyeability, the acid group composition, and the chain composition of acrylic polymers by preparing model polymers with radioactive initiators. As the C/A ratio is increased, the molecular weight distribution broadens as measured by the M̄v/M̄n ratio, the latter obtained by osmometry. There is also a significant effect of both C/A ratio and molecular weight on the sulfate group content per molecule, but there is no effect of C/A ratio on the number of basic dye sites per molecule, the number of sulfonate groups per molecule, or the weak acid groups per molecule. These effects can be explained by invoking a chain transfer to activator reaction in addition to the usual method of chain termination by recombination. The basic dyeability is found to correlate with the number‐average molecular weight and with the number of strong acid groups plus the nonchromophoric weak acid groups.