Pipes (outer diameter 40 mm, wall thickness 4 mm) which have been extruded from either a β-nucleated isotactic polypropylene homopolymer (β-iPP) or a poly(propylene-co-ethylene) random copolymer (RCPP) were subjected to instrumented falling weight impact tests at room temperature. The impact energy of the dart was set to achieve single or double wall perforation of the pipes. It was found that the impact behaviour of β-iPP is superior to that of RCPP from the viewpoint of both stiffness and toughness characteristics. The former result is explained by the higher Young's modulus of β-iPP compared with RCPP. The loading induced β-α transition (phase transformation toughening) was responsible for the outstanding toughness of β-iPP. The onset of the β-α transformation was demonstrated by differential scanning calorimetry on samples taken from the perforation site of β-iPP pipes.
|Number of pages||4|
|Journal||Plastics, Rubber and Composites Processing and Applications|
|Publication status||Published - Dec 1 1997|
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