Synthesis and characterization of novel epoxy‐urethane coating and its graphene nanocomposites

Epoxy polymers have good mechanical and thermal properties, high chemical resistance, and high adhesion properties; however, their brittleness limits their applications. Hydroxyl‐terminated polybutadiene (HTPB) was epoxidized and used to produce the initial epoxy‐urethane polymer as a polyol, including epoxy rings. The initial epoxy‐urethane polymer was added to epoxy resin to improve its thermal and mechanical properties. The epoxy‐urethane polymers nanocomposites were prepared using graphene nanoplatelets at 0.1, 0.5, and 1 wt% concentrations. The polymers were characterized afterward. The thermal properties were determined using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) analysis; and mechanical properties were determined through dynamic mechanical thermal analysis (DMTA) and tensile test. The morphology of the samples was studied using atomic force microscope (AFM) images. Thermal stability was enhanced in synthesized epoxy‐urethane by about 11°C compared to pristine epoxy resin. The obtained results from DMTA and DSC experiments demonstrated that the glass transition temperature (Tg) was increased in epoxy urethane polymers. The results indicated that the decrease of Young's modulus led to a good flexibility in obtained epoxy‐urethane as the coating material. Finally, and based on AFM images, the surface roughness was increased in the prepared samples. Preparation process of Epoxy‐urethane polymer.