Slow regions percolate near glass transition

TL;DR

This study uses a nano-second scale in situ probe to show that a bulk linear polymer undergoes a sharp phase transition near the glass transition, exhibiting percolation universality class behavior with matching critical exponents.

Contribution

It demonstrates that the glass transition in linear polymers can be characterized as a percolation phase transition with specific critical exponents.

Findings

Critical exponents b3 and b2 match 3D percolation values

Polymer undergoes a sharp phase transition near glass transition

Scaling behavior consistent with percolation universality class

Abstract

A nano-second scale in situ probe reveals that a bulk linear polymer undergoes a sharp phase transition as a function of the degree of conversion, as it nears the glass transition. The scaling behaviour is in the same universality class as percolation. The exponents \gamma and \beta are found to be 1.7 \pm .1 and 0.41\pm 0.01 in agreement with the best percolation results in three dimensions.