JNTU B.Tech III PROPERTIES OF NANOMATERIALS Previous Question Paper (May - 2018 - R15)

Thermal properties of nanomaterials are primarily governed by the confinement of phonons and the high surface-to-volume ratio. As the characteristic dimensions of a material approach the phonon mean free path, boundary scattering at the surface becomes the dominant mechanism limiting heat transport, leading to a significant reduction in thermal conductivity compared to bulk materials. Additionally, the increased surface energy and altered vibrational density of states in nanostructures result in size-dependent melting points and modified specific heat capacities.

Nanomaterials are increasingly utilized in the conservation and restoration of art and cultural heritage due to their unique chemical and physical properties. Their primary roles include:

1. Consolidation and Cleaning: Nanoparticles, such as calcium hydroxide nanoparticles dispersed in alcohols, are used to consolidate degraded wall paintings and stone monuments. They penetrate deep into the porous structures of the material, providing structural reinforcement without altering the aesthetic appearance or breathability of the surface.
2. Deacidification: Magnesium hydroxide or calcium hydroxide nanoparticles are applied to paper and canvas to neutralize acidic degradation products, effectively preventing the embrittlement and yellowing of historical documents and artworks.
3. Protective Coatings: Nanostructured coatings, often based on silica or titanium dioxide, provide self-cleaning and antimicrobial properties. These thin, transparent layers protect surfaces from environmental pollutants, moisture, and biological growth (such as fungi or bacteria) without obscuring the original artistic details.