Effect of pro-oxidant additive on physical, structural, mechanical and barrier properties of multilayer Polypropylene film used for food packaging application

Nowadays pro-oxidant additives represent a promising solution to the problem of environmental polymer waste. Its accelerate the photo- and thermo-oxidation of the materials and consequently, going throw a polymer chain cleavage, make the materials more susceptible to biodegradation. The aim of this work was to test an EVA prooxidant additive into a multilayer Polypropylene film usually used in the food packaging field, to understand the performance of the resulting material (degradation/stabilization). Thermal (DSC) and barrier properties to O2 and CO2 gas were evaluated, together with the biodegradation test. Further FTIR/ATR together with mechanical stress/strain analysis were performed in order to understand the material behaviour. Multilayer type films (Polymer/Al film/paper) used for biscuits packaging were analysed in the experimentation. In comparison a Polylactic acid (PLA) biodegradable polymer was used. Tests were performed before and after food contact, for several days, at different temperature (25, 35 and 45°C) and at 50% of relative humidity, during a thermo-oxidative degradation to monitor, at the same time, the food shelf-life. This work aims to give information on the behaviour of this new biodegradable polymer matrix in a real situation, comparing the data with those obtained using a standard polymer material, like PP, and a common biodegradable polymer like PLA. The degradation/stability of the polymer material was tested mimicking the shelf-life study of the food under analysis. The oxidation behaviour and hence degradation/biodegradation of the films containing pro-oxidant additives were evaluated. Was found that despite the addition of the pro-oxidant additive, the resulting performances of the multilayer polymer materials were good. PLA sample shows also excellent behaviour if coupled with paper, sometimes better or comparable to the standard polymer normally used in to the food packaging field.