Preparation and applicability of polylactic acid/polyethylene glycol/ nanoclay composite films for smart steam release in microwave packaging

Smart materials are developed to serve additional functions in food packaging, including self-release features depending on temperature. Typically, phase change materials (PCMs) are used to impart smart functions to packaging materials. In this study, self-steam-releasing films were developed by compounding polylactic acid (PLA) with PCM derived from polyethylene glycol (PEG) and nanoclay using the melt-extrusion method. PEG as the PCM in the inner gallery of nanoclay endowed the nanocomposite film (PLA-G-C) with the steam-release behavior. The oxygen transmission rate of the nanocomposite films was strongly dependent on temperature, and a rapid increase in permeability was observed in the vicinity of the PEG melting point. In the microwave application test, the built-up steam inside the packaged container during microwave heating was safely released through the PLA-G-C nanocomposite films without bursting the package. Therefore, the as-developed temperature-responsive PLA-G-C nanocomposite films can be potentially used as smart steam-release materials for microwave food packaging.