Tree-like crack patterns in clay dried in a uniform DC electric field
| Autor: | Sujata Tarafdar, Sudeshna Sircar, Tapati Dutta, Tajkera Khatun, Ankita Ghosh |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
chemistry.chemical_classification
Materials science Aqueous solution Polymers and Plastics Metals and Alloys Charge density 020101 civil engineering Field strength 02 engineering and technology 021001 nanoscience & nanotechnology 0201 civil engineering Surfaces Coatings and Films Electronic Optical and Magnetic Materials Biomaterials chemistry Electric field Electrode External field Counterion Composite material 0210 nano-technology Anisotropy |
| Zdroj: | Materials Research Express. 6:026305 |
| ISSN: | 2053-1591 |
| Popis: | We report desiccation crack formation on a layer of aqueous Laponite® RD gel, exposed to a uniform static electric field varying from 357 to 928 V m−1. The cracks formed exhibit an interesting tree-like pattern. A large number of cracks (~70) appear initially at the positive end of the sample. Several neighbouring cracks merge with each other, while proceeding towards the negative end leading to a smaller number of cracks. This process is repeated a few times before the hierarchical pattern thus formed reaches the negative end of the sample. The number of cracks is finally reduced to ~10. The initial number of cracks increases with increasing field strength. The disc-like Laponite® RD clay particles behave as negatively charged in an aqueous medium, because of the diffusion of positive counterions into the solvent, which form a double layer. The external field causes gradual build up of density of positive counterions towards the negative electrode. The bare Laponite® discs which are negatively charged repel each other to create the cracks at the positive end. We develop a simple model to calculate the charge distribution of counterions along the sample. We offer an explanation for the structure of the anisotropic tree-like crack patterns observed on the basis of this model. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|