Effect of energetic materials on the thermal stability of polymers

Abstract

The effect of energetic additives such as ammonium perchlorate, ammonium persulfate, cyclotetramethylenetetranitramine, triaminoguanidine nitrate, plastisol nitrocellulose, and a nitrate lacquer at the 5% level had on the thermal stability of polyacetals, aliphatic and aromatic polyesters, and polyamides was investigated by isothermal and dynamic thermogravimetry in a nitrogen and air atmosphere. Activation energies were determined for some of the admixtures; the additives were found to lower the activation energy by 30 to 88%. The effect of a series of ammonium and potassium salts on the thermal degradation of polyacetals was determined. It was found that the more acid character the cation and anion moieties had, the more effective the substance was in decreasing the thermal stability of polyacetals. Thermal instability of an admixture of polymer and additive was observed as a shift of the thermogravimetry curve to a lower temperature or by an increase in the rate of volatilization. Dynamic thermogravimetry studies of polyacetal admixtures offered a novel method for distinguishing between the acid strengths of the additives.