PMI foam can be expanded by bulk polymerization to obta […]
PMI foam can be expanded by bulk polymerization to obtain expandable methacrylic acid / acrylonitrile copolymer board; foamed at 190 ° C for 1 h to obtain PMI foam. Fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance (1H-NMR), dynamic mechanical thermal analysis (DMTA), and differential scanning calorimetry (DSC) were used to analyze the effect of heat treatment on the copolymer structure and study The molecular structure change during the foaming process.
It is shown that during the foaming process of the copolymer, a six-membered imide ring and an acid anhydride ring are formed in the molecule; ammonia gas generated by the decomposition of the blowing agent also participates in the reaction, and further changes the acid anhydride ring into an imide ring; Crosslinked structure; the chemical shift δ of the NH bond hydrogen in the imide ring is 10.50. The obtained PMI foam has a high closed-cell structure, the cell structure is complete, and the cell size is relatively uniform.