Impact behaviour of polypropylene/polyethylene blends

Due to the large volume consumption of polyolefins, the treatment of the re sulting solid waste is becoming a major concern. One possible utilization o f the polyolefin wastes is to form blends from recycled polypropylene (PP) and polyethylene (PE). This study is a preliminary investigation on the imp act fracture behaviour for the PP/PE blends. The impact testing method empl oyed in this study includes the conventional and instrumented Izod impact t ests, the instrumented Charpy impact test, and the instrumented drop weight plate impact test (IDWPIT). In both conventional and instrumented Izod imp act testing, PP homopolymer and PP/LDPE blend have similar impact strengths , while PP/HDPE blend exhibits slightly lower impact strength. However, the instrumented Charpy impact test indicates that both PP/LDPE and PP/HDPE ha ve similar impact strengths, and both are slightly lower than PP homopolyme r. This suggests that the type of impact test employed is playing an import ant role in the impact fracture behaviour of the PP/PE blends. The effect o f temperature on the impact fracture behaviour for the PP/PE blends was eva luated by means of the Charpy and drop weight plate impact tests. During th e tests, impact strengths reduced with decreasing testing temperature. In t he Charpy impact test, the impact strength for PP homopolymer was higher th an those of the two PP/PE blends at both 20 and 0 degrees C. The E-total me asured from the IDWPIT indicated PP/LDPE has the highest impact strength at both 20 and 0 degrees C. (C) 1999 Elsevier Science Ltd. All rights reserve d.