Ring-driven shear thickening in wormlike micelles?

The shear-thickening behaviour of wormlike micelles, at concentrations just below overlap, remains unexplained. In some cases, it has recently been co nfirmed that very slow relaxations must be present even in the quiescent st ate for example, the shear-thickening properties can depend on earlier ther mal cycling. We present a speculative scenario based on the presence, just below the ( apparent) overlap threshold, of large rings whose linking and d elinking kinetics control the shear-thickening process. Equilibration betwe en rings and open chains in turn controls the slow relaxations.