Fracture behaviour of virgin and recycled isotactic polypropylene

Fracture behaviour of virgin and six times recycled isotactic polypropylene (PP) has been studied. Instrumented Charpy impact tests have been carried out to characterise the fracture parameters and scanning electron microscopy was used to study the fracture surfaces. Recycled PP presents slightly smaller spherulites and lower fracture toughness than virgin one. Fractography analysis reveals that crazing is the dominant fracture micromechanism for both materials, and that the difference in fracture toughness is a consequence of the smaller plastically deformed volume at the notch tip of the recycled polypropylene. (C) 2001 Kluwer Academic Publishers.