Intramolecular Reaction in Polycondensations. II. Ring-Chain Equilibrium in Polydecamethylene Adipate

Abstract

Decamethylene adipate polymers prepared in the absence of solvent undergo a reversible decrease in solution viscosity when heated for long times in chlorobenzene. This phenomenon is shown to be due to ester interchange reactions which establish equilibrium between ring and chain molecules. Quantitative agreement with the equilibrium theory of the previous paper is obtained if the effective length of a chain link is taken as 4.5±0.2A, which is of the order of magnitude to be expected from hindered rotation and steric effects. Measurements of ring‐chain equilibrium thus appear to offer a useful method for characterizing the stiffness of relatively short and flexible chains.