The polymerization of the bisaliphatic epoxy resin, 3,4-epoxycyclohexylmethyl, 3,4-epoxycyclohexylcarboxylate initiated by diaryliodonium or triarylsulfonium salts under both microwave energy and conventional thermal heating, was investigated. DSC and FTIR methods to determine the extent of polymerization were established. Some polymerization phenomena such as polymerization selectivity, polymerization temperature shift, and polymerization temperature shift by microwave power setting in microwave fields compared to thermal fields were investigated. to explain the phenomena, a theory that a new partition function existed in microwave fields was proposed with statistical thermodynamics. © 2004 Wiley Periodicals, Inc.