Thermal and mechanical properties of rocket motor liners

Benli, Salih
Rocket motor liners are usually chosen from filled elastomers. The primary function of the liner layer is to bind the propellant grain to the motor case. A rocket motor liner also serves as a thermal insulator and burning inhibitor during the operation of the rocket motor. The primary objective of this study was to make thermal and mechanical characterization of polyurethane based rocket motor liners, and develop new liner compositions with optimum thermal, mechanical and processing properties. In the first part of the study, the effect of NCO/OH and üiol/diol ratios on thermal and mechanical properties of liners were investigated. Consequently, the optimum NCO/OH and triol/diol ratios were determined as 1.1 and 0.1 respectively. In the second part which was related to fillers unfilled polyurethane and liners filled with ISAF and MT type carbon blacks and silica were prepared. Afterwards, the effects of these fillers on thermal degradation, erosion rates, thermal conductivity and tensile properties of liners were investigated. As a result, ISAF type C. black was selected as the base filler and its content was kept constant in the rest of the filler study that followed. In the second part of the filler study, liner compositions with ISAF type of carbon black, silica, aluminum oxide, zirconium oxide, carbon fiber and MT type of carbon blacks were prepared and the effects of these fillers on thermal and mechanical properties of the liners were investigated. From these investigations, it was realized that the fillers did not considerably affect the thermal degradation of liners. On the other hand, the erosion resistance and tensile properties of the liners were considerably improved by the fillers. Finally, the liner composition with aluminum oxide as an extra filler, at a filler content of 12 weight percent, was selected as the optimum liner composition by also considering the fluidity of the liner mixture.


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Citation Formats
S. Benli, “Thermal and mechanical properties of rocket motor liners,” Middle East Technical University, 1997.