Innovative films with tunable permeability for fresh vegetable packaging applications

Blends of a commercial polypropylene (PP), typically used as food contact material, with increasing amounts of poly(4-methyl-1-pentene) (PMP) are prepared in a twin-screw extruder to obtain thin films with improved gas permeation for fresh vegetable packaging. Permeability, haze, and transparency of monolayer films produced by casting are investigated under conditions mimicking the industrial ones. O2 and CO2 permeability can be tuned by increasing PMP content in the blends from 5 to 20 wt %. Transparency and haze are practically unchanged in the presence of low content of PMP. Moreover, tensile and rheological tests show that PMP does not significantly affect the related properties of blends compared to the neat PP matrix, thus allowing for the industrial applicability of these new formulations.