Ring-chain equilibration reactions of poly(decamethylene adipate) (PDA) were carried out in the presence of large amounts of diluent. Good yields of cyclics [CO(CH 2) 4COO(CH 2) 10O] x were obtained virtually free of linear species. The individual cyclics with 18–198 skeletal bonds were completely resolved using PL-gel mixed-E gel permeation chromatographic columns and their molar cyclization equilibrium constants were compared with the corresponding theoretical values predicted by the Jacobson-Stockmayer theory as well as those obtained previously for undiluted PDA ring-chain equilibrates.