Analysis of crazing mechanism of glassy polymers

doi:10.19491/j.issn.1001-9278.2025.09.003

Abstract

Abstract:

This study investigated the crazing mechanism in glassy polyethylene using coarse⁃grained molecular dynamics simulations with the LAMMPS package. A bead⁃spring model was employed to examine the microstructural evolution and stress⁃strain behavior under tensile deformation at varying strain rates. The analysis included quantification of entanglement density along the original chain paths and characterization of entanglement network evolution through energy landscape mapping. Results indicated significant strain rate dependence in the crazing initiation process. The craze growth mechanism was demonstrated to be fundamentally governed by chain disentanglement. Furthermore， temperature⁃dependent simulations revealed a self⁃healing capability of crazes at elevated temperatures. These findings provide molecular⁃level insights into the deformation mechanisms of glassy polymers under mechanical stress.

Key words: polymer, craze, entanglement, molecular simulation, self?heal, coarse?grained model

CLC Number:

TQ320.1

YAN Wanhua, ZHAI Ming, RUAN Shilun, SHEN Changyu. Analysis of crazing mechanism of glassy polymers[J]. China Plastics, 2025, 39(9): 12-17.

Figures/Tables 13

Fig.1. Coarse⁃grained bead spring model of polyethylene

Fig.2. Bond distribution and angle distribution of coarse⁃grained beads

Fig.3. The glass transition temperature of coarse⁃grained model

Fig.4. schematic of original path calculation

Fig.5. Microstructural deformation plots at ν=1×10-5fs-1

Fig.6. Microstructural deformation plots at ν=1×10-4fs-1

Fig.7. The deformation of SiO2⁃modified polyethylene model at a strain rate of ν=1×10-5fs-1

Fig.8. Stress⁃strain response relationship of the model during crazing at different strain rates

Fig.9. energy dissipation during the crazing

Fig10. Entanglement number during the crazing

Fig.11. System configuration before and after warming of the model at ν=1×10-5fs-1

Fig.12. System configuration before and after warming of the model at ν=1×10-4fs-1

Fig.13. Variation of the number of entanglements with temperature during temperature rising

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