Composites of EVA and hydrophobically modified PAMAM dendrimer: Effect of composition on crystallization and flow assurance of waxy systems

Wax crystallization of crude oil at low temperatures can cause several problems related to production and lo-gistics in the oil industry. Polymeric additives can be used to reduce the oil's viscosity and/or the pour point. However, the available additives do not act efficiently on all types of oil, so continuous study of new additives is essential. Composites are a promising alternative as pour point depressant additives. In this work, a dendrimer based on poly(amidoamine) (PAMAM, 2.5 generation) was synthesized, and chemically modified to insert hy-drocarbon chains containing 18 carbon atoms in its structure. Poly(ethylene-co-vinyl acetate) (EVA) containing 10 mol% vinyl acetate was used to produce dissimilar composites by the solution method at different EVA: dendrimer ratios, and their performance was evaluated in waxy model systems with different wax chain lengths, using different additive concentrations. The synthesized dendrimer acted as an efficient viscosity reducer but was unable to reduce the pour point of the systems. EVA was efficient only in the systems containing the shorter wax molecular length. On the other hand, EVA:dendrimer composites were able to reduce not only the viscosity, but also the pour point of both waxy systems containing the shorter and longer wax molecular length. This could be related to the different wax crystal morphology induced by the presence of the composite. The best result was achieved by the composite containing EVA:dendrimer ratio of 80:20 w:w, at 500 ppm concentration.