Mesoscale Simulation of Polymer Pyrolysis by Coarse-Grained Molecular Dynamics: A Parametric Study.

Area of Science:

• Materials Science
• Computational Chemistry
• Polymer Science

Background:

• Polymer pyrolysis is vital for thermal protection systems but involves complex multi-scale phenomena.
• Existing simulations often focus on atomistic or continuum levels, leaving a gap in mesoscale understanding.

Purpose of the Study:

• To develop and apply a novel mesoscale simulation approach for polymer pyrolysis.
• To bridge the gap between atomistic and continuum modeling of polymer thermal degradation.
• To investigate polymer behavior under extreme hyperthermal conditions with and without oxygen.

Main Methods:

• Coarse-grained molecular dynamics (CG MD) simulations were employed to model polyethylene (PE) pyrolysis.
• Bond-breaking criteria based on bond energy or length were used to simulate thermal degradation.
• Cook-off simulations and ReaxFF comparisons optimized the bond dissociation protocol.
• Large-scale simulations (hundreds of nanometers) investigated aerobic hyperthermal pyrolysis.

Main Results:

• The mesoscale simulation effectively modeled the configurational changes of PE during thermal degradation.
• The study observed intricate pyrolysis phenomena from the material surface to its interior.
• Intrinsic thermal durability of PE under extreme conditions, with and without oxygen, was simulated.

Conclusions:

• The proposed mesoscale simulation approach provides a viable method for studying polymer pyrolysis.
• This work enhances the prediction of thermal degradation properties for continuum-scale simulations.
• The findings contribute to a larger-scale understanding of polymer pyrolysis for thermal protection applications.