Microwave irradiation polymerization was studied in the presence of a carrier. The influence of different carriers, such as Al2O3, SiO2, and MgO on the microwave irradiation polymerization mechanism of acrylamide and 2-ethylhexyl acrylate was studied by adopting polymerization inhibitors such as an anionic inhibitor, cationic inhibitor, and radical inhibitor hydroquinone. When the system contains the carriers Al2O3, and SiO2, the polymerization mechanism occurs according to a radical mechanism, but when the system contains MgO, the polymerization mechanism occurs according to not only a radical mechanism but also an anionic polymerization mechanism with superficial grafting occurring. (C) 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1519-1524, 2004.