Structure–property–migration relationships in polyethylene food packaging: FTIR classification, DSC crystallinity, and UV-absorbing contaminants in ethanol simulants

Abstract

Polyethylene films are widely used as food-contact packaging materials, yet migration behaviour can vary depending on polymer structure, thermal properties, and food simulant conditions. This study evaluated the migration of UV-absorbing contaminants from commercially available polyethylene packaging films, using an integrated structure–property–migration approach. Fourteen polyethylene films collected from the local market were classified as LDPE-like or HDPE-like based on FTIR spectral features associated with chain structure, while thermal behaviour and degree of crystallinity were determined using differential scanning calorimetry. Preliminary migration screening was conducted using ethanol-based food simulants under controlled conditions, with 20 % ethanol applied as a more aggressive simulant relative to the earlier screening performed using 8 % ethanol. Migration responses were assessed using UV–VIS spectrophotometry as a comparative screening tool. FTIR and DSC analyses revealed substantial structural and thermal variability among the films, with crystallinity values ranging from approximately 10 % to 50 %. Migration screening responses showed broader variability among some lower-crystallinity films, however, exploratory analysis indicated that crystallinity alone did not fully explain the observed responses. Overall, the findings demonstrate the complexity of structure–property–migration relationships in commercial polyethylene packaging films, and highlight the value of integrating spectroscopic, thermal, and screening-based analytical approaches for comparative migration evaluation.