Viscosity and Free Surface Energy as Parameters Describing the Adhesion of the Epoxy Resin to the Substrate

Abstract

The polymers engineering is a dynamically developing branch of technology. The main research directions are the search for new polymers and methods for modifying existing ones. Among the extensive group of polymers, construction, coating, and adhesive polymers are the most commonly used in the construction industry. The last family includes the epoxy resins that are used to combine two or more materials with different properties. Under the influence of the hardening agent (catalyst or temperature), the polymers are cross-linking to obtain a solid form. During the gluing process, the most important aspect is the resin preparation procedure and the state of the surface to which it will be applied. The adhesion of the resin to the substrate, the effectiveness and durability of the resulting mixture depend on three factors: resin's composition, viscosity, and adhesive parameters of hardened resin. The paper contains the research results aimed at modification of the epoxy resin using inorganic fillers: microsilica and carbon nanotubes. An epoxy resin is commonly used for e.g., reinforcing structural elements. Ultrasounds were used as a disintegrating agent of the liquid resin structure, allowing mixing it with the filler. The effect of sonication and fillers on the viscosity of the resin at 22 °C was determined. Next, the free surface energy was evaluated, which is the factor determining the final adhesion. Based on the results obtained, the phenomena occurring at the interface between the liquid phase of the resin and the solid phase of the fillers were explained.