Effect of Surfactants on the Structure, Thermal Conductivity, and Rheology of Composites Based on Paraffin and Petroleum Asphaltenes

Abstract

Various types of surfactants (Tween 20, Tween 80, Span 20, and Span 80) were used as a stabilizing additive in composites based on petroleum asphaltenes and paraffin -a material that has prospects for use as a phase-transition material in thermal accumulators. The influence of surfactants on the structure and morphology of composites, the rheology of their melts, thermal conductivity, and crystallization ability is shown. An increase in thermal conductivity of 9% has been demonstrated. This correlates with the formation of filler clusters in the presence of surfactants. The presence of surfactants in composites with paraffin has a slight effect on the crystal lattice parameters of paraffin in composites, while the introduction of Tween 20 at a concentration of 1% wt. leads to an increase in the degree of crystallinity of paraffin. In melts of paraffin-asphaltene composites, the network of filler contacts contributes to the presence of a pronounced yield strength. The introduction of a surfactant leads to a decrease in the strength of the contact network and an increase in the fluidity of systems, probably due to the presence of surfactant adsorption layers on the surface of the contacting particles.