Morphologies and Mechanical and Thermal Properties of Epoxy Resins Modified by a Novel Polysiloxane Capped with Silane Coupling Agent, Epoxide, and Imino Groups

Abstract A novel polysiloxane capped with silane coupling agent, epoxide, and imino groups (AGPMS) was synthesized to modify the diglycidyl ether of bisphenol-A (DGEBA). The chemical structure of AGPMS was confirmed using Fourier transform infrared (FT-IR), 29Si NMR, and 13C NMR. The toughness of the epoxy resin, in terms of impact strength and fracture toughness, was improved by introducing AGPMS, while the tensile strength decreases a little at relatively low addition levels. The glass transition temperature from differential scanning calorimetry (DSC), the initial degradation temperature for 5% weight loss (Td 5%) and the residual weight percent at 800°C (R800) from thermogravimetric analysis (TGA), all increased. The morphologies of the fracture surfaces, examined by environmental scanning electron microscopy (ESEM), show that the miscibility of polysiloxane with epoxy resin increased after being capped with γ-aminopropyl triethoxysilane (APTES) and the size of the silicone phase increased with the increase of the AGPMS content. The silane coupling agent structure, and the epoxide and imino groups in AGPMS can react during the curing process, and chemically incorporate into the crosslinking network. AGPMS is thus expected to significantly improve the toughness of epoxy resin, and also increase the thermal stability. Keywords: epoxymechanical propertiesmorphologypolysiloxanethermal propertiestoughness