Migration study of caprolactam from polyamide 6 sheets into food simulants

Abstract

Caprolactam, used in manufacturing polyamide (PA) 6, may threaten human health. Here, PA 6 sheets were produced by using a twin-screw extruder to evaluate its safety. Caprolactam migration concentrations from the PA 6 sheets into food simulants were evaluated according to the standard migration test conditions under the Korean Food Standards Codex (KFSC). Concentrations were investigated under various food simulants (distilled water, 4% acetic acid, 20 and 50% ethanol, and heptane) and storage conditions (at 25, 60, and 95 °C). Caprolactam migration concentrations into food simulants were determined as follows: 4% acetic acid (0.982 mg/L), distilled water (0.851 mg/L), 50% ethanol (0.624 mg/L), 20% ethanol (0.328 mg/L), and n-heptane (not detected). Migrations were determined to be under the regulatory concentration (15 mg/L) according to the KFSC test conditions. Taken together, these results verified that the standard migration test conditions by KFSC were reliable to evaluate the safety of PA 6.

Nanoscale analysis of plastic contaminants migration in packaging materials and potential leaching into model food systems

“…Figure 6 shows that monomer interphase crossing is greatly facilitated by the presence of ethanol as an adjacent solvent, most likely due to the penetration of this solvent into the polymers' core and the consequent swelling it induces in their matrices, allowing trapped monomer molecules more easiness to diffuse. It is important to stress that the ethanol-induced polymer swelling observed in polyamide-6 (Figure S2A) and PMMA (Figure S4A) are frequently reported experimentally 20,65 , however not in such extreme degree as in our calculations, which is to be expected given the limited size of our polymer slab.…”

“…At this point, the reader might be justifiably wondering how these migration predictions compare with experimental measurements. To start answering this question, we compared our results for polyamide-6 with the values of caprolactam migration observed from Song et al 20 . They reported the following order of solvents in terms of monomer leaching promotion: water > 50% ethanol/water > n-heptane.…”

“…3,4 The dependence of monomer leaching on the external media is another complicating factor. Considering that the standard experimental determination of monomer leaching is a relatively wearying, time-consuming process, 5,6 it is impractical to experimentally analyze the myriad of different components contained by or exposed to polymers. Therefore, relying on predictive methods to analyze monomer, and other potential contaminant, migration is critical to product developers, regulatory agencies, and manufacturers.…”

“…19 PA 6 is formed from the ring-opening polymerization of (ε-)caprolactam (azepan-2-one) with typical yield less than 100%, resulting in residual monomers remaining inside the material. [20][21][22] Caprolactam is of mild toxicity in humans and its acute or chronic exposure is controlled. 20,23 PC is a thermoplastic polymer with a wide range of applications including food packaging, electronic insulation, and building materials.…”

“…[20][21][22] Caprolactam is of mild toxicity in humans and its acute or chronic exposure is controlled. 20,23 PC is a thermoplastic polymer with a wide range of applications including food packaging, electronic insulation, and building materials. 24 PC is typically formed by condensation polymerization between BPA (2,2-(4,4dihydroxydiphenyl)) and carbonyl chloride or diphenyl carbonate.…”