Role of stress relaxation in stress-induced polymer crystallization

Stress relaxation is a common process that reduces the deformation of polymer coils against the strain-induced crystallization during the processing of polymeric materials for fibers, thinfilms and molding plastics. By introducing Maxwell model of stress relaxation into each polymer in dynamic Monte Carlo simulations, we compared stress-induced to strain-induced polymer crystallization under parallel conditions of various strain rates and temperatures. The results demonstrated the scenario of competitions among the factors of stress relaxation, strain rates and temperatures in the crystallization process. We found that, owing to fast stretching, the limited extent of stress relaxation plays the dominantly kinetic role rather than the expected thermodynamic role in the retardation of crystallization, similar to the factor of high strain rate. In addition, we observed the enhanced stress relaxation during the post-growth process of polymer crystallization, which influences the finally achieved crystallinity and crystal morphology. Our results facilitate a better understanding of polymer crystallization during the fast stretching processing.

Automated summary

Our study focused on the competition among stress relaxation, strain rates, and temperatures in the polymer crystallization process under different conditions. We found that stress relaxation, limited by fast stretching, plays a dominant kinetic role in slowing down crystallization, similar to the effect of high strain rate. Enhanced stress relaxation during post-growth polymer crystallization influences the final crystallinity and crystal morphology achieved.