Preparation and properties of silicone modified epoxy structural adhesive film

Epoxy-based adhesives are one of the most important types of adhesives in the industrial field due to their excellent bond strength, low shrinkage, and favorable processability. However, epoxy-based adhesives tend to have disadvantages such as inadequate toughness and strength, which limits their use in structural bonding applications. In this paper, a novel silicone modified epoxy structural adhesive film was prepared through a condensation reaction between the terminal hydroxyl groups of polydimethylsiloxanes and the hydroxyl groups of epoxy resin. The silicone modified epoxy films have excellent lap shear and peel strength. Moreover, nanosilica was added to further improve the performance of adhesive films. The rheological, mechanical and thermal properties of the films were measured, FT-IR and SEM were used to further analyze the toughening mechanism. The results indicated that the low content of nanosilica can play an excellent modification effect on the adhesive films. The rigid-flexible integrated structure formed by nanosilica and silicone in the adhesive film system improves the mechanical properties, and reduced maximum thermal decomposition rate of the adhesive films.