NanoComposites in Tennis Balls

Nano composites consists of nano sized particles embedded in some type of matrix -are group of promising new materials being infused in some of our modern technologies. 

One type of nano composites is currently being used in high performance tennis balls. These balls retain their original pressure and bounce twice as long as conventional ones. Air permeation through walls is inhibited by a factor of two due to presence of a flexible and very thin (10 to 50 microns) nanocomposite barrier coating that covers the inner core.

This nanocomposite coating consists of matrix of butyl rubber, within which is embedded thin platelets of vermiculite, a natural clay mineral. The vermiculite platelets exists as single molecule thin sheets- on the order of nano meter thick-that have a very high aspect ratio. 

Furthermore vermiculite platelets are exfoliated that is they remain separated from each other. Also within the butyl rubber, the vermiculite platelets are aligned such that all their lateral axes lie in the same plane; and throughout this barrier coating there are multiple layers of these platelets. 

The presence of vermiculite platelets accounts for the ability of the nanocomposite coating to more effectively retain air pressure within the tennis balls. These platelets act as multi layer barrier to the diffusion of air molecules and slow down the diffusion rate. 

Technique commercially exploited  by Wilson Sporting Goods Company in their Double Core tennis balls.