Kinetics of strain-induced crystallization in natural rubber: A diffusion-controlled rate law

- The crystallization rate in NR after a strain jump was studied at various temperatures by synchrotron WAXD.
- A diffusion-limited rate law is suggested, in contrast to nucleation and growth models for quiescent crystallization.
- Based on chain dynamics, the model predicts crystallization rates as function of temperature and equilibrium crystallinity.

The kinetics of strain-induced crystallization in natural rubber were studied by synchrotron wide-angle X-ray diffraction (WAXD) in a strain jump setup over a broad temperature range. The increase of crystallinity after a strain jump was observed on a millisecond time scale, until a steady state plateau was approached. A novel model, based on chain dynamics scaling laws for diffusion in polymer networks was developed to interpret the time and temperature dependence of the strain-induced crystallization. In contrast to established thermal crystallization models, this model for the strain-induced crystallization proposes that the formation of stretched crystallizable chain segments takes place before the attachment to a growing crystallite.

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