Figure 28.

(a) Response of a monolayer with coexisting phases to uniform compression: when ω ≪ k_p, domains grow much faster than the rate of compression, and the LE phase offers no elastic resistance. By contrast, when ω ≫ k_p, the rate of compression exceeds the rate of molecules changing phases, and the LE phase offers a net resistance to compression. (b) Measurements of Arriaga et al. (2010) showing elastic and viscous moduli from oscillatory measurements in LE and in coexistence. The solid lines are fit to a Maxwell viscoelastic fluid with characteristic relaxation time $\tau =k_p^{-1}\approx 140\text{s}$, and the dashed lines are slopes from equilibrium (ω → 0) isotherms. (c) Effective elastic and viscous modulus following (5.16).