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In situ SEM study of fatigue crack growth mechanism in carbon black‐filled natural rubber
Author(s) -
Beurrot Stéphanie,
Huneau Bertrand,
Verron Erwan
Publication year - 2010
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.31707
Subject(s) - natural rubber , materials science , crack closure , composite material , scanning electron microscope , fracture mechanics , breakage , crack growth resistance curve , ultimate tensile strength , crack tip opening displacement
Abstract A micro‐tensile testing machine placed in the chamber of a scanning electron microscope is used to perform in situ fatigue tests on a 43 phr carbon black‐filled cis ‐1,4‐polyisoprene rubber; the crack tip is observed in real‐time during crack propagation. These observations lead to a detailed description of the crack tip morphology; the crack front is a regular pattern of diamond‐shaped zones delimited by extended straight ligaments. Fatigue crack growth is driven by the ligaments breakage, which occurs in all the zones of the crack front surface continuously in time but at different velocities. This phenomenon of nonlocalized damage explains initiation and limited propagation of branches which deviate from the main crack. All those mechanisms are sources of energy dissipation which explains the great fatigue properties of NR. Finally, from similar experiments conducted on styrene butadiene rubber, it is established that the peculiar morphology of the crack tip and mechanism of crack propagation in NR are due to strain‐induced crystallization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010