INFLUENCE OF SURFACE-ACTIVE SUBSTANCES ON RHEOLOGICAL AND DIELECTROMETRIC CHARACTERISTICS OF POLYPHENYLSILOXANE SOLUTIONS

Abstract

The influence of three varieties of surfactants on intermolecular interactions in the bulk phase of a film-forming polyphenylsiloxane was studied by viscosimetric and dielectrometric methods. A linear increase of specific viscosity with increase of polyphenylsiloxane concentration at constant temperature was observed. In solutions of all studied amine derivatives at concentrations above 0.5 g/dm3 , a significant deviation from the linear dependence of the specific viscosity with surfactant concentration was found. The results indicated the formation of associated structures. The viscosity incremental growth in the concentration range of 0.5-2 g/dm3 corresponded to the molecule-weight ratio of amino derivatives. Rheological properties of solutions of the studied amino derivatives was slightly effected by the temperature. The specific viscosity of solutions of low molecular weight amines increased at higher temperatures. The most pronounced change was noticed at concentration of surfactant of 0.5 g/dm3 . The effect was supposed to be due to solvation processes. In contrast, the specific viscosity of the solutions of high molecular weight amine derivatives decreased with increase of temperature up to T = 313 K. It was supposed that the temperature increase caused an increase in intermolecular interactions within the associates, which was accompanied by a decrease of their dimensions. The formed intermolecular structures folded into a tight ball creating less resistance for a flow and as a result the specific viscosity decreased. At increased surfactant concentrations (CSURF> 0.25 g/dm3 ), two types of association processes (mono and hetero-) were established depending on the individual characteristics of the organic amino derivatives (composition, structure, shape and hydrocarbon radical length). It has been proved that, the interaction between each other (monoassociation) was energetically more favorable for high-molecular amines with the simultaneous introduction of polyphenylsiloxane solutions macromolecules (mixed miccels) into their composition. In the solutions containing low-molecular amines, monoassociation processes were proved

Keywords

• surfactants
• polyphenylsiloxane
• viscosimetry
• dielectrometry
• rheology
• amino derivatives
• intermolecular interactions
• surface tension.