Structurized surface layers of normal alkanes

Influence of the tridecane and heptadecane molecule chain length on the structural characteristics of their epitropic liquid-crystal layers

“…As before [5], the difference between η eff and η b (η eff ≠ η b ) determined by the difference of the relative viscosity η rel = η eff ⁄ η b from unity is indicative of the structural inhomogeneity of the thin interlayer, and the non-Newtonian character of flow (η rel = f(γ) points to the change in the structure of the interlayer during the flow of the liquid (Fig. 2).…”

“…In the present work, using polarimetry and viscosimetry methods [3][4][5], we investigated the birefringence and viscosity of interlayers (between metallic substrates) of two n-alkanes, * tridecane (C 13 H 28 ), and heptadecane (C 17 H 36 ), with a molecule chain length of 15 and 20 A°, respectively [6].…”

“…The viscosity of the homologs under study was investigated in a Couette flow of their interlayer of thickness D (1.5, 4.5, 10.5, 15)⋅10 −6 m in a coaxial gap D of the viscosimeter rotation pair [5]. Using the measured moment of friction forces M at assigned discrete shear deformation rates γ, we calculated the viscosity of interlayer (for the interlayers containing the ELC layers, their effective viscosity η eff and apparent one were calculated).…”

“…In the range of shear rates γ (10 3 -10 4 s −1 ) we measured [5] the effective viscosity of micron liquid interlayers η eff , which was compared with their "bulk" viscosity η b measured by capillary viscosimeters. As before [5], the difference between η eff and η b (η eff ≠ η b ) determined by the difference of the relative viscosity η rel = η eff ⁄ η b from unity is indicative of the structural inhomogeneity of the thin interlayer, and the non-Newtonian character of flow (η rel = f(γ) points to the change in the structure of the interlayer during the flow of the liquid (Fig.…”

The structure of overlapped epitropic LC

“…In the process of such "orientational" melting [28] of the ELC layer, both its thickness and the proportion of "pile" q in it decrease, and the latent heat of this melting corresponds in order of magnitude to the phase transition of the ELC -isotropic liquid [17,19]. From the idea that on each of the substrates bounding the symmetrical heterogeneous interlayer there is a "pile" of an ELC layer of finite thickness 0s d , it follows the possible type of structure of such an interlayer at different ratios D and 0s d An increase in the intensity of the shear flow leads to a change in the configuration of associates and to a decrease in their concentration (they are partially "cut off") with a corresponding decrease both in the viscosity ( ( ) 0 µ γ < µ ) and in the thickness of the ELC layer (the layer is "cut off" [24]), so it is obvious that the function…”