## Abstract

A Lennard-Jones statistical associating fluid theory, the soft-SAFT equation of state, is used to study the dependence of the critical properties on chain length for pure polymers. The critical constants of chains up to 10^{6} monomer units are predicted. The main advantage of these calculations, versus others found in the literature, is the fact that the equation is able to accurately predict experimental data available only for short chain lengths and, at the same time, it is able to predict the criticai properties in the infinite chain length scaling regime, without any further assumptions. The equation gives quantitative agreement with experimental and Monte Cario simulation data for normat alkanes. For very long chains, the equation predicts mean-field scaling behaviour, as expected. Moreover, taking advantage of the linearity of the molecular volumes and dispersive energies with the chain molecular weight, a value of 1/5 is found for the critical compressibility factor of an infinitely long n-alkane chain. It is demonstrated that this is not contradictory to Wertheim's theory.

Original language | British English |
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Pages (from-to) | 2519-2529 |

Number of pages | 11 |

Journal | Molecular Physics |

Volume | 100 |

Issue number | 15 |

DOIs | |

State | Published - 10 Aug 2002 |