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How tip geometry controls fracture in ductile polymer glasses and brittle elastomers
Asal Y Siavoshani1, Zehao Fan1, Shi-Qing Wang1
1School of Polymer Science and Polymer Engineering, University of Akron, Akron, Ohio 44325, USA. swang@uakron.edu.
Soft Matter
|June 16, 2026
Summary
This study reveals distinct fracture behaviors in polymers and rubbers. Ductile plastics show no initial tip plasticity, while elastomers exhibit crack tip blunting, impacting material design for packaging.
Area of Science:
- Materials Science
- Polymer Physics
- Fracture Mechanics
Background:
- Understanding polymer fracture is crucial for material design and performance.
- Previous studies often focused on specific polymer types, leaving gaps in broader comparative analysis.
- The fracture mechanics of ductile polymers, brittle polymers, and elastomers present unique challenges.
Purpose of the Study:
- To investigate and compare the fracture behavior of diverse polymeric materials including ductile plastics, brittle glassy polymers, and highly crosslinked rubbers.
- To elucidate the role of crack tip phenomena such as plasticity and blunting under various loading conditions.
- To establish relationships between remote loading, crack geometry, and crack tip stress/strain fields.
Main Methods:
- Spatially-temporally resolved polarized optical microscopy (str-POM) was employed to observe fracture processes.
- Experiments were conducted on various polymers and elastomers, including polyethylene terephthalate.
- Double-edge notch tension (DENT) tests were performed under plane stress conditions to analyze ligament behavior.
Main Results:
- Ductile plastics exhibited no crack tip plasticity below a threshold load.
- Ductile polymer glasses followed Inglis scaling (a^-1/2) before yielding.
- Elastomers showed significant crack tip blunting, leading to a stress saturation zone.
- In DENT tests, tensile force was independent of ligament length, and tip stress correlated linearly with far-field strain.
Conclusions:
- The study provides a comprehensive understanding of fracture mechanics across a spectrum of polymeric materials.
- Key differences in crack tip behavior (plasticity vs. blunting) were identified.
- Findings offer insights for designing robust packaging materials and predicting material failure.
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