Alkanes and Related Systems

X-Ray scattering studies of octadecane, CH3(CH2)i6CH3, and other even chain length alkanes in their triclinic phase formed by the supercooling of melt, have shown that a transient metastable rotator phase exists. Such metastable and transient phases are likely to have analogues in polymeric systems.  

Investigations of mixtures of alkanes for C19H40-C20H42 indicate that the temperature range of the rotator phase widens due to chain mixing.Eicosane has also been studied and X-ray scattering measurements indicate the existence of a rotator phase.Studies of the ultrasonic attenuation and DSC measure- 

Raman scattering studies indicated the concentration of gauche-trans defects increased continuously with increasing temperature and these defects can be associated with the ends of the chain. 

The diffusion coefficients in a number of w-alkanes have been investi-gated, which show the influence of the rotator phase assisting the motion of the polymer chains. Rotator phases have been reported in chains with as 

Plot of the acoustic velocity in the chain direction (a) and the DSC trace (b) for the melting of eicosane. The dotted line in (a) indicates the linear extrapolation of the velocity from low temperature. 

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