Strain-induced self-assembly of crystallites in elastomers

We propose a model of strain-induced crystallization in elastomers, combining Flory's original work with a description of crystallization adopted from the theory of micellar solutions. The experimentally observed hysteresis appears in the model due to a continuous, unidirectional change of the free energy difference between straightened polymer sections which occur isolated and those which are aggregated. The model yields good qualitative and even semiquantitative agreement with measurements of crystallization in natural rubber at variable cross-link density, strain amplitude, and temperature. The attendant description of the stress hysteresis is less good but still qualitatively correct.