Influence of solvent solubility parameter on the performance of EVA copolymers as pour point modifiers of waxy model-systems

High molar mass paraffins in the crude oil solidify with the reduction of temperature during offshore production, which can reduce production or even block outflow lines. Polymers can be used to inhibit the wax deposition. However, the efficiency of the additives depends on the type of oil and, because it is a complex mixture, this relationship still needs further investigation. The aim of this work is to evaluate the influence of different types of compounds present in petroleum on the action of poly(ethylene-vinyl acetate) as pour point reducers using model systems of paraffins in solvents. The study was carried out based on results of pour point, wax appearance temperature and polymer-solvent interaction. The results showed that only the asphaltenes (C5I and C7I) changed the pour point to lower values. The other compounds, such as naphthalene, naphthenic acid and adamantene, at the concentration used of 1 wt/v%, did not alter the melting point of the model systems or interfere with the additive action. On the other hand, by analyzing the influence of the solvent composition, it was observed that (i) the wax solubility in the medium affected the WAT but did not affect the pour point (the higher the solubility of the paraffin in the medium, the lower the WAT is); and (ii) the solubility of the additive in the solvent medium did not affect the WAT but significantly affected the pour point (the higher the polymer-solvent interaction, the lower the pour point of the model-system containing the additive).