Effect of α- and β-nucleating agents on the fracture behavior of polypropylene-co-ethylene

The effect of alpha- and beta-nucleating agents (NA) of various amounts on the fracture behavior of polypropylene-co-ethylene (CPP) was evaluated using the essential work of fracture (EWF) method. The specific EWF values of CPPs incorporated with alpha-NA of different amount were all lower than that of pure CPP, while the specific nonessential work of fracture was the highest at relative low alpha-NA loading (0.1 wt%), and then decreased with further increasing amount of alpha-NA. Similar trend of variation was observed with increasing amount of beta-NA in CPP, and it was found that the variation of K-beta for beta-NA nucleated CPP versus NA content accorded well with the EWF versus NA content, which indicated that the addition of beta-NA could lead to effectively increased beta-crystal content and consequently improved fracture resistance of CPP. (C) 2008 Wiley Periodicals, Inc.