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Toughness profile in injection-molded polypropylene: The effect of the β-modification

✍ Scribed by Miroslav Raab; Jiří Kotek; Josef Baldrian; Wolfgang Grellmann

Publisher
John Wiley and Sons
Year
1998
Tongue
English
Weight
171 KB
Volume
69
Category
Article
ISSN
0021-8995

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✦ Synopsis

Fracture toughness characterized by the J-integral method has been evaluated along injection-molded bars of isotactic polypropylene. A significant increase in toughness with decreasing distance from the specimen gate has been observed with maximum steepness of the dependence in the central part of the specimen length. Parallel analysis of wide-angle X-ray diffraction patterns has shown a similar dependence of the crystalline b-phase concentration. It is suggested that polypropylene with b-crystallites has better structural continuity in the amorphous phase and, consequently, higher inherent ductility and superior macroscopic toughness than the related material containing only a-crystallites. Consequences of b-phase gradients for practical toughness testing are also discussed.

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