Influence of molecular mass, thermal treatment and nucleating agent on structure and fracture toughness of isotactic polypropylene

The influence of processing, crystallization conditions and molecular characteristics on the fracture behaviour of isotactic polypropylene obtained by a new catalyst system was investigated. The sample specimens were prepared by using two extreme crystallization conditions -- quenching or slow crystallization -- in order to obtain crystals and amorphous phases with different structure. Interesting correlations between fracture parameters and some morphological parameters such as long spacing and lamellar thickness of the samples were found. The SEM fractographic analysis provides useful information on the influence of factors such as molecular weight, spherulite size and undercooling. Nucleating agents were used to tailor the dimensions of spherulites.