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Multiple Cracks Propagate Simultaneously in Polymer Liquids in Tension.
Qian Huang1, Nicolas J Alvarez2, Aamir Shabbir1
1Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
Physical Review Letters
|September 3, 2016
Summary
Fracture initiation in viscoelastic fluids like polymer melts is unpredictable, but occurs reproducibly under specific stretch rates. This study reveals fracture depends on the material's dynamic state, not random flaws.
Area of Science:
- Rheology and fracture mechanics of complex fluids.
- Polymer physics and material science.
Background:
- Fracture in brittle solids is linked to material imperfections.
- The fracture initiation mechanism in viscoelastic fluids remains poorly understood.
- Understanding viscoelastic fluid fracture is crucial for material and process design.
Purpose of the Study:
- To investigate the mechanism of crack initiation and propagation in entangled polymer liquid filaments.
- To determine the relationship between material dynamics and fracture onset.
- To elucidate energy dissipation mechanisms during crack propagation.
Main Methods:
- Utilizing high-speed imaging to visualize crack propagation in polymer liquid filaments under tension.
- Analyzing crack initiation, propagation, and profiles.
- Quantifying critical stress and strain as functions of stretch rate.
Main Results:
- Multiple cracks were observed to propagate simultaneously.
- Critical stress and strain for fracture onset were reproducible functions of stretch rate.
- Crack initiation position was found to be random.
- Crack profiles provided insights into energy dissipation during propagation.
Conclusions:
- Fracture initiation in these viscoelastic fluids is governed by the material's dynamic state, not pre-existing flaws.
- The findings offer a new understanding of fracture mechanisms in complex fluids.
- This research has implications for designing materials and processes involving viscoelastic fluids.
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