Polymerization and decomposition of terephthaloyl chloride and p-phenylenediamine at 500 °C

Abstract

In order to synthesize the high temperature solid lubricating film by gas-phase polymerization at 500 °C with two kinds of gasified monomers for use in airplane and rocket engines, the polymerizing activity of terephthaloyl chloride (TPC) and p-phenylenediamine (PPD) at 500 °C and their polymerized product poly-p-phenyleneterephthamide (PPTA) as well as its decomposed solid residues were researched. It was proved by FT-IR and 1HNMR on the solid residues after the 10 min experiment of the both monomers in muffle furnace at 500 °C and PPTA synthesized by conventional method that at 500 °C the polymerization tendency of these monomers should trump their decomposition tendency. The solid residues after the 10 min experiment mainly consisted of polymerized products which would decline as the experimental period increases, while the content of decomposed and carbonized products would raise. FT-IR and elemental analysis revealed a similar structure of the solid residues after the both monomers or PPTA calcined for 60 min at 500 °C, which further demonstrated the polymerized products would degrade, decompose and carbonize after the prophase polymerization. Finally, effects of experimental temperature and monomers molar ratio on amounts and structures of the solid residues were discussed to propose preliminary mechanisms of polymerization and decomposition.