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The reliability of the method described in the preceding paper (B. Song and J. Springer, J. Colloid Interface Sci. 183, in press, 1996) for the determination of surface and interfacial tension (IFT) of liquid-fluid systems from the profile of a pendant drop has been studied experimentally. Influences on the resultant IFT values from factors such as the location of the drop profile and illumination conditions are considered. The reproducibility and accuracy of the measurement method were examined by measuring the time dependence of polyethylene glycol (PEG600)/air and water/air systems and by determining the temperature dependence of the polyethylene glycol (PEG6000)/N2 and LD (low-density) polyethylene/N2 systems. The effect of drop vibrations on the accuracy of the method is discussed.

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Dielectric spectroscopy is employed to study the dependence of the molecular dynamics of liquid-crystalline polyacrylates on the mesophase structure. The temperature dependence ofthe rate ofthe 3-relaxation which was assigned to rotational fluctuations ofthe mesogenic unit around its long axis can be described by an Arrhenius equation. Both the preexponential factor and the activation energy increase with the order of the mesophase which is discussed in the frame ofthe cooperativity ofthe n-relaxation. It is shown that the activation parameters of this process correlate to lateral distance of mesogenic groups. The a-relaxation is related to the dynamic glass transition. Its dependence on the mesophase structure is interpreted in terms of microphase separation. The rate of the ô-relaxation caused by rotational fluctuations ofthe mesogenic unit around its short axis is reduced by that of the a-process. The temperature dependence ofthis ratio is related to that ofa molecular order parameter.

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