A direct analytical test of the Flory-Schulz distribution in nylon-6-type equilibrium polymers

The validity of the Flory-Schulz distribution of chain length in equilibrium polymers produced from ¿-caprolactam and water (Nylon 6) over a DP range from ~14 to ~90 is tested by determination of the content of monomer (¿-aminocaproic acid, ACA) by means of a chromatographic technique. Experiments show general agreement with a simple theoretical relationship (P¯n1 = N, where P¯ = number average DP of chains, n1 = number of ACA molecules, and N = total number of chains), required for equilibrium if equal reactivity of all functional groups independent of chain length is assumed. Moderate deveiations from this relation, which seem to occur at higher DP values (P¯ ~ 90) require further investigation.