Polypropylene Modified with Elastomeric Metallocene- Catalyzed Polyolefin Blends: Fracture Behavior and Development of Damage Mechanisms

LAURA A. FASCE; PATRICIA M. FRONTINI; SHING-CHUNG WONG; YIU-WING MAI

JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS

JOHN WILEY & SONS INC

Lugar: New York; Año: 2004 p. 1075 - 1089

0887-6266

ABSTRACT: The fracture behavior and deformation mechanisms of polypropylene modifiedby elastomeric metallocene-catalyzed polyolefin blends were investigated underboth static and dynamic loading conditions. The fracture toughness was evaluated withthe J integral approach. The development of damage mechanisms was studied by theexamination of fracture surfaces with scanning electron microscopy and by the examinationof single-edge, double-notch, four-point-bending or low-impact-energy fracturedsamples with optical microscopy. In addition, tensile dilatometry measurements werecarried out to determine the nature of the deformation micromechanisms. The fracturebehavior and the size and shape of the damage zones were drastically influenced by theelastomeric particles and the imposed constraint. The role of the elastomeric particleswas different, depending on the strain rate. Under impact loading, particle pullout andcrazing were responsible for the increased fracture toughness of polypropylene. Underquasistatic loading, stable fracture growth was caused by particle cavitation, whichpromoted ductile tearing of polypropylene before failure continued in an unstablefashion via crazing. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42:1075?1089, 2004Keywords: poly(