Journal article

Effect of inclusions and blending on the mechanical performance of recycled multilayer PP/PET/SiOx Films

Extending the useful life of materials through recycling has proven to be an efficient means of reducing natural resource use and limiting the production of waste. In the case of polymer-based materials, in general, and of packaging materials, in particular, material recovery is complicated by the presence of incompatible polymers, as well as a priori undesirable contaminants such as inorganic inclusions. This article investigated the recycling of multilayer packaging material systems, based on polypropylene and silicon oxide-coated poly(ethylene terephthalate). In particular, the effect of a compatibilization of the blend using maleic anhydride-grafted polypropylene on the mechanical properties of the recycled material was examined. Without a compatibilizer, and at low compatibilizer concentrations, the blend exhibits a coarse morphology and is brittle. At a concentration of 5% wt of the compatibilizer, a fine morphology is obtained, and the blend shows excellent ductility. Beyond this concentration, a brittle interphase forms between the blend constituents, with a corresponding decrease in ductility. These results were confirmed by a study of strain-induced crystallization in the blend. Furthermore, the size of the SiOx inclusions, resulting from the fragmentation of the oxide coating during reprocessing, had no detectable influence on the mechanical properties of the recycled blend, providing that their concentration is lower than 2 × 10-3. This study showed that a control of both the microstructure and interface properties considerably improves the mechanical properties of the recycled material, leading to high added-value applications.


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