Recycling of Polypropylene Based Car Bumpers: Mechanical and Morphological Analysis

Abstract

The recycling of new and ten years old bumpers either painted or unpainted have been investigated. They were made by a polypropylene matrix and an ethylene-propylene rubber copolymer as dispersed phase. Mechanical testing carried out before reprocessing showed a dramatic loss in the tensile and impact properties of aged bumpers with respect to the new items. The recycling further reduces the mechanical performances of these items while it has only a little effect on the properties of new bumpers. The addition of appropriate stabilising agents, during the recycling process of aged bumpers, produced an enhancement of the whole mechanical parameters. In particular the impact strength reached values typical of very tough materials and close to those of new items. Scanning electron microscopy of the fracture surfaces showed a considerable enhancement of matrix plasticity when stabilisers were used.