ABSTRACT
Upon stretching a natural rubber sample, polymer chains orient themselves in the direction of the applied load and form crystalline regions. If the sample is retracted, the original amorphous rubber network is restored. Due to crystallization, properties of rubber change considerably. Reinforcing effect of the crystallites stiffens the rubber and increases the crack growth resistance in it. Hence, it is of great importance to understand the mechanism leading to strain-induced crystallization and to be able to model it. However, limited theoretical work has been done on investigation of the kinetics of strain-induced crystallization. A key characteristic observed in the stress-stretch diagram of strain-crystallizing rubber is the hysteresis. This hysteresis is entirely attributed to strain-induced crystallization. In this work, we propose a micro-mechanically motivated material model for strain-induced crystallization in rubbers. To this end, we construct a model for a single crystallizing polymer chain based on non-Gaussian chain statistics. The modified chain model is then incorporated into the affine full network model. The proposed model is numerically implemented and its performance is compared with experimental data.
