Characterization of the fracture toughness of rubber-toughened polypropylene thin plates

The fracture toughness of PP-EP (Polypropylene-Ethylene-Propylene) blends i s studied at room temperature using the "essential work of fracture" (EWF) method. The results obtained by applying this method are compared with thos e of puncture and tensile tests. Whereas the classical puncture tests do no t allow classifying the rubber-toughened PP-EP blends, the EWF method prove s to be a sensitive technique to monitor the effect of composition and morp hology of the blend on fracture toughness. Moreover, the application of the EWF method allows monitoring how the fracture toughness of a material depe nds on its ability to deform extensively before fracturing and on its capac ity to bear some load. A good combination of these two properties thus yiel ds materials presenting an optimal fracture toughness.