AbstractIn this study, the structure, gas permeability, and mechanical properties of new elastomers based on liquid polybutadiene and epoxy resin were investigated by dynamic mechanical thermal analysis, thermogravimetric analysis, stress–strain analysis, and water‐resistance and gas permeability tests. The results reveal that there was complete phase separation between the epoxy resin and polybutadiene. With increasing epoxy resin content, the glass‐transition temperature of the soft segment varied little. These elastomers had tensile strengths of 6–10 MPa and ultimate elongations of 500–100% according to the different epoxy resin contents. Thermogravimetric analysis revealed that these elastomers had better thermal stability, with a 5% weight loss at a temperature of around 350°C. The gas permeabilities of these elastomers were measured to be 13.2–15.3 barrers for oxygen, 4.8–5.3 barrers for nitrogen, and 28–35 barrers for carbon dioxide at 23°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010