Mechanical Evaluation of Propylene Polymers under Static and Dynamic Loading Conditions

LAURA FASCE; VALERIA PETTARI´N; CELINA BERNAL; PATRICIA FRONTINI

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 1999 p. 2681 - 2693

0021-8995

The present investigation is concerned with the evaluation of the impacttoughness of commercial-grade Propylene polymers. Conventional impact static stress?strain and static fracture experiments were carried out. Static stress?strain experimentsrevealed different pattern behaviors among the materials that were reflected inthe fracture behavior. Under static conditions, all materials exhibited ductile behaviorand crack grew under J-controlled conditions displaying stress whitening through thewhole fracture surface with the sole exception of the homopolymer, which displayed aductile instability after some stable crack growth. Under dynamic conditions thehomopolymer exhibited brittle behavior, the block copolymer exhibited some plasticdeformation at the crack tip, and the random copolymer samples exhibited a whiteningeffect due to voiding and craze formation through the whole fracture surface, indicatingthat stable crack propagation was occurring. Fracture mechanics tests were analyzedby following different methods, depending on the mode of fracture presented by thepolymer. The Normalization J-method was used under static conditions. The elasticmethod, the corrected elastic method, and the essential work of fracture methodologywere used to characterize brittle, semibrittle, and ductile behavior, respectively. Fracturemechanics parameters arisen from both static and dynamic conditions are compared