Brownian simulations for fracture of star polymer phantom networks

TL;DR

This study uses Brownian dynamics simulations to explore how thermal agitation influences the fracture behavior of star polymer networks, revealing rate-dependent master curves related to cycle rank.

Contribution

It extends previous energy-minimized network studies by incorporating thermal motion effects through Brownian simulations, highlighting the impact of strain rate on fracture characteristics.

Findings

Master curves for strain and stress at break depend on cycle rank.

Lower strain rates lead to behavior similar to energy-minimized networks.

Fracture process is influenced by Brownian motion, elongation, and bond degradation.

Abstract

Based on a recent simulation study [Masubuchi et al., Macromolecules, 56, 9359 (2023)], the cycle rank plays a significant role in determining the fracture characteristics of network polymers. However, the study only considered energy-minimized networks without the effects of thermal agitation. We conducted Brownian dynamics simulations at various stretch rates to address this gap. The results showed that even with Brownian motion, the strain and stress at the break obtained for different node functionalities and conversion ratios exhibited master curves if plotted against cycle rank. These master curves were dependent on the strain rate, with the curves tending to approach those observed in energy-minimized simulations as the strain rate decreased, even though the fracture process was affected by the competition against Brownian motion, elongation, and bond degradation.