Compatibilization of PP/PET microfibrillar composites for the upcycling of mixed polymer waste streams

Microfibrillar composites are an interesting class of composites where a high melting fibrillated polymer reinforces a lower melting matrix polymer by applying a specific processing sequence. This paper focuses on the influence of a compatibilizer on the morphology and mechanical properties of the composites. Therefore, microfibrillar composites of polypropylene (PP) and poly(ethylene terephthalate) (PET) have been prepared by twin-screw extrusion, followed by cold drawing at a fixed draw ratio of 6 and injection moulding. Different amounts of compatibilizer were added at different points in the processing sequence, in order to quantify both the effect of the compatibilizer concentration and the compatibilizer activity during the different processing steps. Samples were subjected to extensive characterization after each step of MFC preparing. The influence of the compatibilizer on the morphology was investigated by using Scanning Electron Microscopy. The observations from the fracture surfaces were discussed and compared with mechanical properties (flexural and impact)