ABSTRACT
The phenomenon of Strain-Induced Crystallization (SIC) in Natural Rubber (NR) has been the subject of a large number of studies since its discovery by Katz in 1925. This is due to the improvement of the mechanical and ultimate properties SIC is supposed to impart to NR samples. Substantial progresses in X-ray techniques have led to the publication of a significant real-time diffraction studies during the last decade: for an overview, see for instance (Huneau 2011). A particular interest has been recently given to the kinetics of SIC at higher elongations where the rapidity of the process becomes an experimental challenge. This is indeed an important aspect as NR-based materials are essentially used in dynamic conditions. However, we have the feeling that other fundamental questions remain open like the one already raised by P. Flory in its well-known publication dealing with the theory of SIC (Flory 1947): why is SIC in dynamic condition accompanied by stress hardening while stress softening is observed in static conditions? Different effects have been evoked: the fact that crystallites should act as giant cross-linker and as filler, or the percolation of them, that is crystallite networking. We have recently shown that it is possible to easily evaluate a quantity proportional
example of measurement in oscillation conditions will be given and discussed.
