Nanoclay based enhancers for microwaveable polymeric packaging

Polymeric materials are good candidates for microwaveable packaging thanks to their transparency to microwaves (MW). In addition, a great interest is devoted to developing innovative solutions based on systems that act as susceptors or heating enhancers to improving the characteristics of polymers in cooking/heating in MW ovens. This work was focused on design, production and characterization of nanocomposite multilayer poly(ethylene terephthalate) (PET) films suitable for microwaveable food packaging applications. The matrices used were two PET copolymers modified respectively with carbon black (ULTRA STD) and with titanium oxide (ULTRA NA). Nanocomposite co-extruded multilayer films were produced using different percentages of Cloisite® 20A (C20A). Films were analyzed in order to evaluate the effect of nanoclay on the morphology, the barrier properties and the effectiveness of the systems in reducing the cooking times of meat products. Morphological analyses showed that intercalation increases by increasing the clay percentage in ULTRA STD based systems. Gas and water vapor permeability analyses showed, for both ULTRA STD and ULTRA NA matrices, a more significant improvement in systems with the lowest concentration of nanofiller. The cooking tests have pointed out that the selected matrices are efficient in reducing cooking times and that even low concentration of C20A acts as heating enhancer of PET.