Ductile "Ice": frozen hydrogels with high ductility and compressive yielding strength
Ice, the solid state of water, which mainly consists of a hexagonal crystal structure in bulk, is usually very brittle. Although ice appears less brittle under compression or shear at a relatively low strain rate, it is by no means a ductile material as metal and is seldom considered as an engineeri...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Published: |
Elsevier Ltd.
2019
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| Subjects: | |
| Online Access: | http://eprints.utm.my/id/eprint/89003/ http://dx.doi.org/10.1016/j.eml.2019.02.008 |
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| Summary: | Ice, the solid state of water, which mainly consists of a hexagonal crystal structure in bulk, is usually very brittle. Although ice appears less brittle under compression or shear at a relatively low strain rate, it is by no means a ductile material as metal and is seldom considered as an engineering material in applications other than igloos. We report herein the astonishing ductility and high compressive yielding strength of a polymeric hydrogel in a frozen state. Containing 88 wt. % of water, the hydrogel appears like ice when frozen, and embraces most other physical properties of ice. Meanwhile, the frozen hydrogel not only shows a high compressive modulus (∼1 GPa at -25 °C) and yielding strength (∼20 MPa at -25 °C), but is also ductile enough to sustain extremely large deformation such as bending, twisting, stretching, extensive shaping, and even machining in a large low temperature range. The ductility at a high strain rate also makes it a material with a significant impact resistivity. Moreover, the frozen gel also exhibits the repeatable ductility - the large plastic deformation is completely recoverable at an elevated temperature. These results will be important towards developing low-cost and environment-friendly engineering materials used in a low temperature range when ductility and reusability is required. |
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