Temperature dependence of strain-induced crystallization in natural rubber: On the presence of different crystallite populations

Nicolas Candau (1) , Rabia Laghmach (1) , Laurent Chazeau (1) , J.-M. Chenal (1) , Catherine Gauthier (2) , Thierry Biben (3) , Etienne Munch (4)

1 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
2 ICS - Institut Charles Sadron
3 ILM - Institut Lumière Matière [Villeurbanne]
4 Manufacture Française des Pneumatiques MICHELIN

The effect of the temperature on strain induced crystallization (SIC) of natural rubber (NR) is studied by in situ wide angle X-rays scattering (WAXS) experiments performed along different thermo-mechanical paths (cyclic deformation at different temperatures or crystallization and melting in the deformed state). The crystallinity index (CI), the average crystallite size (L200) and the average volume of the crystallites (V) increase (decrease) similarly if the sample is cooled (heated) in the deformed state or stretched (unstretched) at fixed temperature. These experiments are analyzed through a thermodynamic description assuming that SIC is controlled by successive nucleation of crystallite populations. Such description predicts that for a stretching ratio λ above (below) 4 and a temperature above (below) room temperature, crystallization first occurs in chains with the highest (lowest) network chain density, leading to the smallest (largest) crystallites.

Mots clés: Crystallite size; Chains; Rubber; Temperature; Temperature distribution; Crystallinity index; Cyclic deformations; Fixed temperature; Straininduced crystallization; Temperature dependence; Thermodynamic description; WAXS; Wide-angle x rays

Domaines: Matériaux

Nicolas Candau, Rabia Laghmach, Laurent Chazeau, J.-M. Chenal, Catherine Gauthier, et al.. Temperature dependence of strain-induced crystallization in natural rubber: On the presence of different crystallite populations. Polymer, 2015, 60, pp.115-124. ⟨10.1016/j.polymer.2015.01.029⟩. ⟨hal-01804713⟩