Ed. Nikitin et al., ESTIMATION OF THE CRITICAL CONSTANTS OF LONG-CHAIN NORMAL-ALKANES, International journal of thermophysics, 17(2), 1996, pp. 455-469
Correlations between the critical constants of normal alkanes and the
number of carbon atoms in a molecule have been considered. In an appro
ximation of a self-consistent field for a polymeric fluid, an equation
of state of the van der Waals type has been written, and the dependen
ces of the critical constants of chain molecules on the number of mers
have been obtained. It has been found that for an infinitely long alk
yl chain, the limiting values of the critical temperature, the critica
l pressure, and the critical density are equal to, respectively, 1135
K, 0 MPa, and 0 kg . m(-3). A method of pulse heating of a wire probe
immersed in the substance under investigation has been used to measure
the dependence of the temperature of the attainable superheat T of l
ow-density polyethylene on the pressure p and the duration of heating
pulse t. Extrapolation has been used to obtain an estimation of the a
ttainable-superheat temperature of polyethylene T(p = 0, t* = 0) = 11
75 K, which can be treated as the ''critical'' temperature of polyethy
lene.