Evaluation of HFC 245ca and HFC 236ea as Foam Blowing Agents

Hydrochlorofluorocarbons (HCFCs) have been widely adopted as an interim blowing agent in urethane insulations. Due to their scheduled phase-out, research efforts are being devoted to the identification and development of alternatives with zero ozone depletion potential. Physical blowing agents identified have included hydrocarbons, fluorocarbons, hydrofluoroethers, and more predominantly, hydrofluorocarbons (HFCs). The majority of the HFC evaluations have focused on the more readily available, low boiling candidates such as HFC 134a. Higher boiling HFC candidates that could be handled at ambient conditions and use current processing equipment would be more desirable.

This paper will describe results from a research program of two such candidate HFCs performed as a cooperative effort between the Environmental Protection Agency, Oak Ridge National Laboratory and Martin Marietta Manned Space Systems. The purpose of this effort was to perform a limited evaluation of the developmental HFCs 245ca and 236ea as blowing agents in urethane based insulations. These two materials were selected from screening tests of 37 C₂, C₃ and C₄ isomers based on physical properties, atmospheric lifetime, flammability, estimated toxicity, difficulty of synthesis, suitability for dual use as a refrigerant and other factors. Solubility of the two materials in typical foam components was tested, pour foaming trials were performed and preliminary data were gathered regarding foam insulation performance.