Epoxy resins containing sulfhydryl hyperbranched polysiloxane with desirable mechanical properties and lower curing temperature

Abstract

High-performance epoxy materials often necessitate curing at high-temperature, which can lead to defects, brittleness, deformation and processing difficulties. In this paper, the modifier sulfhydryl hyperbranched polysiloxane (HSiSH) was fabricated by the “one-pot” method. And investigated the effect of HSiSH on the curing temperature, mechanical and thermal properties of epoxy resin. The epoxy with the addition of 2.0 wt% HSiSH showcased superior comprehensive properties, including flexural strength of 159.37 MPa, impact strength of 24.77 kJ/m², and tensile shear strength of 14.02 MPa, as well as the thermal properties are improved. Moreover, the presence of 2 wt% HSiSH can facilitate the curing process reducing the apparent activation energy by 12.25%. The highly branched topology, chain entanglement, "rigid-flexible" -Si-O-C- segment and active groups improve the strength and toughness of the material. Simultaneously, the numerous reactive groups within HSiSH actively participate in the curing reaction, thereby enhancing the adhesion between the resin and the substrate surface which increasing the bonding performance of the adhesive. This study lays a solid theoretical foundation for developing high-performance epoxy resins cured at lower and moderate temperatures.