DH Special Arrangement
Bengaluru: Researchers at the Raman Research Institute (RRI) in Bengaluru, who are studying material science, have examined crack formation in clay. This research has applications in fields such as food testing, medicine, and paints and coating materials.
Materials like clay, blood and paint come under the category of colloids. Colloids are mixtures, where one substance is split into minute particles which are dispersed throughout a second substance.
Clay being a highly heat-resistant material is the first choice for extreme heat environment applications, like coatings of a spacecraft.
Prof Ranjini Bandyopadhyay, head of the RheoDLS lab and faculty at the Soft Condensed Matter group at RRI, and Vaibhav Parmar, a PhD student and first author of the paper, have proposed a relation between the time of emergence of the first crack, fracture energy (energy required to fracture a material) and the elasticity of the drying clay sample which can help predict the first
crack.
This relation was tested on the cracking of clay with different compositions and salinity and they found that the theoretical model and experimental data agreed well.
This model can be applied to other forms of drying colloidal layers, such as blood and paint. It has potential applications in diagnosing conditions like anaemia by observing drying droplets of blood, in painting restoration, and in enhancing the quality of paints used for coatings.
“We can apply this knowledge and suggest tweaking in the material composition at the time of manufacturing of industry-grade paints and coatings so that they can have better crack resistance and improve the product quality,” said Prof Bandyopadhyay, head of the RheoDLS lab and faculty at the Soft Condensed Matter group at RRI.
The research shows that by varying the concentration of the material, the salt or the pH levels, it is possible to tune the material’s elasticity and in turn, its cracking onset.
This could be used to delay cracks in coatings on a spacecraft or on a medicine capsule which are done in a controlled environment.
“In the Netherlands, physicists did a similar study on cracks to unravel the restoration history of paintings including the Vermeer’s Girl with a Pearl Earring. Researchers at IISc also determined the adulteration levels in milk by studying how it dries,” added Prof Bandyopadhyay.