Polymethacrylimide foam (referred to as PMI) is a new type of polymer structural foam with the best comprehensive performance. It is light, high strength, high/low temperature resistant. The PMI structural foam is a closed-cell, rigid rigid foam obtained by foaming a copolymer of methacrylic acid (MAA) and methacrylonitrile (MAN).
The MAA-MAN copolymer sheet was obtained by free radical bulk polymerization of MAA and MAN, and the PMI foam sheet was prepared by gasification of the pre-embedded foaming agent in the copolymer at a foaming temperature of 180-230 °C. At the same time of high temperature foaming, the adjacent cyano group (-CN) and carboxyl group (-COOH) in the MAA-MAN copolymer undergo a nucleophilic addition reaction to form a cyclic imide structure, and the structure has strong polarity and The high stiffness gives the PMI foam a good overall performance.