Comparison of Viscosity and Molecular Arrangement in Twenty-Two Liquid Octyl Alcohols

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Abstract
A comparison is made between the x-ray diffraction halos of 22 octyl alcohols and their corresponding viscosities and an unmistakable correlation found. The assumptions are that the halos indicate periodicities, that the periodicities may be interpreted as structural in the "cybotactic" groups, and that the relative diffraction intensity of the halos computed by assuming crystal structure may be used to estimate roughly the perfection of the liquid groups. It thus is shown that there is a correlation between the coefficient of viscosity and the perfection of grouping in the direction of the length of the chain molecules. This corresponds with the reasonable view that the viscosity within the liquid groups is caused by longitudinal slippage. Moreover, since the groups at any instant occupy a large fraction of the volume of the liquid, this viscosity is an important part of that measured. This interpretation accounts for the negative temperature coefficient of the viscosity, since the size of the groups decrease with temperature. The experiments and conclusions are in accord with Andrade's theory of momentary "crystallization" and with Ornstein's theory of the formation of liquid crystal groups, yet it is to be noted that these theories deal with different aspects and not the entire phenomenon.