Impact of thermomechanical reprocessing conditions on polypropylene composites made from automotive waste parts: A path to a circular economy

Abstract

This work focused studying waste car bumper samples and their processing by re-extrusion-injection. Car bumpers are composed of crystalline phases of polypropylene (PP), talc, and amorphous ethylene propylene diene monomer (EPDM). The recycled material's thermal, mechanical, and structural properties depend strongly on the process used for extrusion and injection and the crystalline phases formed during the heating process. The FWHM of the x-ray diffraction patterns was used to study the recrystallization phenomenon in PP, and the result was in direct correlation with the Differential Scanning Calorimetry (DSC) results. The remaining micro paint particles from the bumpers involved in the recycled extrusion-injection process affect the mechanical properties, and their size and toughness could affect the injection. Removing these particles could improve the mechanical properties of the recycled PP. Car parts based on polypropylene can be recycled for the automotive industry to produce the same type of products and even for other areas. A methodology and metrology can be developed to understand the chemical composition and its relationship with the properties of PP-based materials. This could lead to finding new applications in different fields and promote the development of a circular economy.