Determination of Glass Transition Activation Energy for Homogeneous Solid Rocket Propellants

The paper presents results of experimental research of three types of homogeneous double-base solid rocket propellants with special attention given to the determination of glass transition temperature and calculating activation energy of the transition. The tested propellants belong to the group of highly energetic materials consisting mainly of nitrocellulose and nitroglycerine. The experiments were carried out with the use of NETZSCH DMA 242C analyzer with dual-cantilever testing mode, heating rate of 2K/min in the temperature range from -120 degrees C to 110 degrees C. Liquid nitrogen was used in order to achieve sub-zero temperature range in which the glass transition in solid rocket propellants occurs. The amplitude of applied dynamic force was set to 30 mu m. Basic characteristics of homogeneous double-base solid rocket propellants are presented. The aim of the research was to determine glass transition temperature of the propellants which is a key characteristics when considering safe operation of solid rocket propellants. The glass transition was determined from the peak of the loss modulus curve. In addition the activation energy of the glass transition process was calculated on the basis of the peak of the tan(delta) curve in multi frequency DMA testing mode.