Size segregation percolation

Mixing due to diffusion occurs when particles roll over a sloping powder surface. The random movement of particles on the free surface results in a redistribution of the particles. As was discussed in section 1.2.2.I, the movement of particles on a free surface can also give rise to segregation due to the percolation of fine particles if particles of different size are present in the mixture. Only when the particles within the mixture have identical properties can diffusional mixing be a truly randomizing process. 

The mechanism of segregation as observed in rotary kilns indicates that percolation is the primary cause of driving smaller size particles to the core of the bed. To model the phenomenon, several... 

Up to now, the sign, magnitude, and cause of Tg anomalies on the nanometer size scale are still under discussion [52]. Many model approaches have been developed for treating the above-mentioned effects, including comparison of film thickness h or confined nanovolume value with the scale of cooperative motion act or molecular coil size (molecular end-to-end distance Ree)- The free volume theory the percolation model the manifestation of intrinsie size effect and a supposition about segregation of chain ends to the free surface, etc., were applied (see reviews [40,52,53]). 

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