Insulation of Rocket Motors

The PU system based on HTPB-MDI-TMP and filled with carbon black and antimony trioxide was also evaluated for inhibition of CMDB propellants. Due to superior mechanical properties, thermal properties and low NG migration, this PU system holds a potential for inhibition of CMDB propellants [357]. 

Such polymeric materials or rubbers are known as insulating materials or insulators and the process of their application is known as insulation. The motor insulation not only provides protection to motor but also functions as an inhibitor. The case-bonded motors have a little less inert mass and as a result, give slightly better performance. However, they are more stressed and more difficult and expensive to manufacture. Many tactical missiles and almost all larger rockets or missiles for defense and space applications use case-bonded motors. 

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Neoprene and nitrile rubbers (gum stocks) filled with silica are generally used for insulation of rocket motors and the general process consists of (i) sand blasting of rocket motor followed by cleaning with petrol or organic solvent and drying,... 

Another rubber which appears to be of interest for insulation of rocket motors is hydrogenated hydroxy-terminated polybutadiene (HHTPB). As this rubber is derived from HTPB, it is more compatible and would also have strong bond with the HTPB-based propellants. Further, as the quantum of unsaturahon is considerably reduced in HHTPB, the life of rocket motors insulated with HHTPB will also be more. In a nutshell, the use of HHTPB results in an increased stability to... 

Miscellaneous applications of poly(phosphazenes) include ter-butoxycarbonyl protected materials for chemically amplified resists in microlithographythin film electroluminescent devices,optical wave guides, aryloxy derivatives as components of fire-, heat- and impact-resistant materials and components of a low-density, thermoplastic elastomeric, ablative insulation for rocket motors. ... 

Replacement of Asbestos in Flexible Insulators for Rocket Motors, Technical Report MMT 3811051 FR3 (May 1985). 

Propellants cast into rockets are commonly case-bonded to the motors to achieve maximum volumetric loading density. The interior of the motor is thoroughly cleaned, coated using an insulating material, and then lined with a composition to which the propellant binder adheres under the environmental stresses of the system. The insulation material is generally a mbber-type composition, filled with siUca, titanium dioxide, or potassium titanate. SiUca-filled nitrate mbber and vulcanizable ethylene—propylene mbber have been used. The liner generally consists of the same base polymer as is used in the propellant. It is usually appHed in a thin layer, and may be partially or fully cured before the propellant is poured into the rocket. 

Phenolic resins are adaptable to many applieations. The list is very long, however, the major uses are wood binders, glass insulation binders, molding compounds, laminates, foundry binders, coatings, friction linings, abrasives, and oil well propants [59-66]. They have found their way into a number of new, high technology uses such as rocket motor wear parts, military armor, sports equipment. 

FIGURE 12.18 Stress-strain curves of rubber-fiber composites developed for solid rocket motor insulator A, ethylene-propylene-diene monomer (EPDM) rubber-carbon fiber composites B, EPDM mbber-melamine fiber composites C, EPDM mbber-aramid fiber composites and D, EPDM rubber-aramid pulp composites. 1 and 2 stands for unaged and aged composites respectively. Carbon fiber- and melamine fiber-reinforced composites contain resorcinol, hexamine, and silica in the concentrations 10, 6 and 15, respectively and aramid fiber- and aramid pulp-based composites contain resorcinol, hexamine, and silica in the concentrations 5, 3 and 15, respectively. (From Rajeev, R.S., Bhowmick, A.K., De, S.K., and John, B., Internal communication. Rubber Technology Center, Indian Institute of Technology, Kharagpur, India, 2002.)... 

The temperature and composition of propellant combustion products are of interest to those concerned with materials of construction and insulation for the combustion chamber and nozzle of the rocket motor. These values are readily computed from basic thermodynamic data for the specific propellant composition and operating pressure of interest with the aid of today s large-scale digital computers. By way of illustration, however, the products of combustion computed this way for the three typical plastisol propellants given in Table I are shown in Table III for a combustion pressure of 1000 p.s.i.a. Approximate propellant composition is also shown for convenient reference. 

Rao, S.S., and Ninan, K.N. (2000) Development of EPDM rubber based low density insulator for solid propellant rocket motors. Proc. 3rd Inti High Energy Materials Conf. and Exhibit, Dec. 6-8, 2000, Thiruvananthapuram, pp. 265-268. 

Guillot, D.G (2008) Method of insulating case of solid propellant rocket motor. U S Patent No. 7,410,607. 

Metcalf, G.S. and White, W.E. 2003. Method of constructing insulated metal dome structure for a rocket motor. U.S. Patent 6,544,936. 

A solid propellant rocket motor is quite simple in concept, although in practice a complete motor is more complex. As shown in Fig. 37.15, the rocket propellant is contained within a case, which may be metal or a reinforced high-performance composite. Frequently, the case is internally shielded by a bonded layer of insulation. The insulation is coated with a liner that bonds the propellant to the insulation. The integrity of the propellant-to-liner bond is of utmost importance failure at this interface during a motor firing can result in a sudden increase in the area of propellant surface exposed to combustion, with potentially catastrophic results. 

Siltemp [Ametek], TM for a substantially pure fibrous silica for use in rocket and missile construction and for high-temperature insulation of motor components and similar applications. 

Continued commercial interest in poly(phosphazenes) is demonstrated by extensive patent activity and related applications oriented publications (some of which have been noted above). Fire retardency is an ongoing theme in cyclo-and linear phosphazene applications (see section 3). Aryloxy phosphazenes, including a commercial product, Eypel A, have been utilized for components for fire resistance in foam cushioning, rocket motor insulation and electrical wire coating . Alkoxy phosphazene polymers and copolymers impart antistatic properties to silver halide based... 

DEVELOPMENT OF COST-OPTIMIZED INSULATION SYSTEM FOR USE IN LARGE SOLID ROCKET MOTORS. VOL 1. TASK 1. 

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