Cracking behavior of carbon black filled elastomers
Résumé
The study of crack propagation in rubber has a very high economic significance but is still not well understood. For this purpose the main objective of this work is to study the fracture behavior of two types of rubber: the NR, which crystallizes under stress and the noncrystallizing SBR. To study the cracking behavior of materials we have made tests of cracking follow-up. The mode of crack propagation has been studied in terms of fillers ratio and traction speed. The unfilled SBR and NR showed simple lateral propagation independently of the test speed, whereas the mode of cracking of filled materials was very influenced by the parameters mentioned previously. The filled SBR can present important deviations of the crack when the fillers ratio is sufficiently high; this deviation is even more pronounced when the speed increases. On the other hand, the natural rubber which crystallizes under stress showed particular mode of propagation characterized by the appearance of longitudinal cracks. This mode of cracking is much more important at low speeds than at the high speeds. It is proposed that the fillers increase the breaking strength of a noncrystallizing material and allows that the crack takes a deviated way if the fillers ratio is sufficiently high. But if it is a material which crystallize like the NR, crystallization and fillers will act simultaneously and the material will be much more resistant which gives rise to a particular mechanism which is the appearance of the longitudinal cracks before the catastrophic rupture. © 2010 World Scientific Publishing Company.
Mots clés
Breaking strength
Catastrophic rupture
composites
Cracking behavior
Filled elastomers
Fracture behavior
Lateral propagation
Longitudinal cracks
Low speed
Natural Rubber
Speed increase
Test speed
Behavioral research
Carbon black
Crack propagation
Elastomers
Fillers
Fracture
Plastics
Rubber
Speed
Cracks