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.


Erten, Emre; Kaynak, Cevdet; Atalar, Taner; Department of Metallurgical and Materials Engineering (2022-8)
Hydroxyl-Terminated-Polybutadiene Polyurethane (HTPB-PU) elastomer materials are mainly used in the “liner” layer of solid propellant rocket motor cases. The required levels of mechanical and thermal properties are obtained by reinforcing this elastomer matrix with approximately 10 wt% micron-sized carbon black (mCB) particles. Therefore, the main purpose of this study was to investigate effects of mCB alone and then when used together with 3 wt% nano-sized carbon black (nCB), micron-sized zirconia (mZrO2),...
Numerical simulation of charring ablation coupled with computational fluid dynamics
Alanyalıoğlu, Çetin Ozan.; Özyörük, Yusuf; Department of Aerospace Engineering (2019)
Usage of charring ablators as nozzle liners is a common practice in the field of solid rocket motor industry. Among them, silica-phenolic is a commonly employed material due to its excellent insulation capability. During the design of a solid propellant rocket motor employing silica-phenolic as a nozzle liner, it is desired to have an accurate thermal analysis along with throat recession rate estimation, as the interior ballistics of a solid rocket motor is tightly coupled with throat diameter. This work pr...
Mechanical properties of HTPB-IPDI-based elastomers
Haska, SB; Bayramli, E; Pekel, F; Özkar, Saim (1997-06-20)
A polyurethane elastomer having mechanical and adhesive properties suitable for liner applications in solid rocket propellants was developed using HTPB as the prepolymer and IPDI as the curing agent. The effects of the NCO/OH ratio (R value) and the triol/diol ratio on the mechanical properties of the polyurethane matrix were investigated. The reaction of HTPB and IPDI is followed by monitoring the changes in the IR absorption bands of the NCO stretching at 2255 cm(-1) and the CO stretching at 1730 cm(-1). ...
Improvement of rheological, mechanical and interface properties of solid rocket motor liner
Aslan, Onurcan; Özkan, Necati; Yılmaz, Gürkan Atınç; Department of Polymer Science and Technology (2021-2-11)
This study aims to improvethe mechanical, rheological, and interface propertiesofthe currently used liner formulation (referred to as the standard liner) based on carbon black filled polyurethanestructure.Two types of carbon black powders (Thermax N-991 and Printex-U) were used as fillers inHydroxyl-Terminated Polybutadiene(HTPB) -Isophorone Diisocyanate(IPDI)based polyurethane liner. Three different dispersing agents (alkylammonium salt of a high molecular-weight copolymer, high...
Numerical investigation on the effect of transversal fluid field deformation on heat transfer in a rod bundle with mixing vanes
Tas-Koehler, Sibel; Lecrivain, Gregory; Krepper, Eckhard; Unger, Sebastian; Hampel, Uwe (Elsevier BV, 2020-05-01)
Spacer grids of fuel rod assemblies are equipped with vanes, which promote flow mixing and turbulence within and across the sub-channels, thereby enhancing the heat transfer. First, a literature study about the various effect of the spacer grid has on the sub-channel thermo-hydrodynamics is provided. It follows, that the multiple effects on the vane angle are insufficiently understood. The effect of the vane angle on design parameters, namely the evolution of the Nusselt number, the pressure drop, the cross...
Citation Formats
S. Benli, “Thermal and mechanical properties of rocket motor liners,” Middle East Technical University, 1997.