Phase Separation in Polymer Solutions from a Born-Green-Yvon Lattice Theory

TL;DR

This paper uses a lattice model based on the Born-Green-Yvon integral equation to predict phase separation and critical solution temperatures in polymer-alkane mixtures, showing good agreement with experimental data for longer alkanes.

Contribution

It introduces a BGY lattice model for polymer-alkane mixtures and demonstrates its effectiveness in predicting LCSTs based on pure component data.

Findings

The model accurately predicts LCSTs for higher alkanes.

It underestimates LCSTs for smaller alkanes.

Polymer chain length affects solubility in decane.

Abstract

Phase separation in mixtures of polymers and alkanes is investigated with the aid of a recently developed lattice model, based on the Born-Green-Yvon (BGY) integral equation approach to fluids. The system-dependent parameters of the BGY lattice model for binary mixtures are deduced from those of its pure components, which in turn are determined from a comparison with experimental data. The lower critical solution temperatures (LCST's) for polyethylene in various n-alkanes were predicted from the BGY lattice model and compared with experimental data. While the model underestimates the LCST's for the smaller alkanes it reproduces the experimental values very well for the higher alkanes (decane through tridecane). The effect of the chain length of the polymer on the solubility is investigated for the case of decane as a solvent.