Studies of the Breakdown Mechanism of Polymers. VII. The Thermal Decomposition of a Polyhydrazide and of Polyoxadiazoles

摘要

Poly-1,3-phenylene hydrazide, when heated to 250C in vacuum, partially undergoes cleavage of the N-N bond to yield isophthalonitrile, water, carbon monoxide, and carbon dioxide. The major part converts to the corresponding polyoxadiazole. Poly-1,3- and -1,4-phenylene -2,5,(1,3,4-oxadiazole) decompose essentially in the 450 to 500C region to yield isophthalonitrile (also p-aminobenzonitrile in the case of the 1,4-polymer), nitrogen, carbon dioxide, hydrogen cyanide, carbon monoxide, water, ammonia, methane, and hydrogen. The 1,4-polymer decomposes at a slightly higher temperature than the 1,3-polymer and forms less gaseous products and more condensate. The oxadiazole ring degrades before the benzene ring. Initial competing reactions seem to be the removal of nitrogen and further degradation of the remaining ether linkage, and the elimination of oxygen with subsequent cleavage of the residual -C=N-N=C linkage. (Author)