The subject invention provides a composition and a process for forming a flexible polyurethane foam sealing device having improved compression set properties at increased temperatures. The sealing device is formed without the use of chemical blowing agents. The composition includes an isocyanate component for reaction with a resin component comprising an isocyanate-reactive component having a functionality of least four and a hydroxyl number of less than 40, a graft dispersion, and a physical blowing agent. The most preferred physical blowing agent is HFC-245 fa or 1,1,1,3,3-pentafluoropropane.