Identification of caprolactam oligomers and related compounds in aqueous extracts of nylon-6

摘要

Cyclic oligomers of caprolactam were isolated from a multilayered polyolefin plastic film containing a nylon-6 layer and subsequently characterized. Nylon-6 was extracted with aqueous solutions and the levels of the oligomers were measured in the resulting extracts. Oligomers up to n = 5 were present at high and comparable levels in all the nylon-6 extracts. The levels of the oligomers dropped off rapidly with increased compound size after n = 5, with the heptamer being barely observable in the extract chromatograms. The effect of extracting solution pH on the compound's concentration in the extract was small, except for the monomer, whose accumulation was significantly decreased at low pH. (C) 2005 Wiley Periodicals, Inc.