Propellants surface coatings

Moderated. In propellants, implies the presence of a surface coating to the grain which slows down the initial rate of burning. 

Apart from the inherent burning characteristics of a propellant the burning rate can also be varied by the use of surface coatings (moderants) on the granules of propellant. 

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. 

MAJOR USES Used in the production of latex surface coating resins, dyes, photographs, gelatins, agricultural chemicals, rocket propellant fuels and medicines petroleum refining rubber industry paper industry. 

OTHER COMMENTS used as a chemical intermediate in latex surface coating resins, in textile, dye and paper industries used as an oil additive for viscosity control, high pressure performance, and oxidation resistance use in rubber and pharmaceutical industries used in floc-culants in petroleum refining and in rocket propellant fuels. 

Chem. Descrip. Glycerol triester of fatty acids Uses Surface coating for expanded polystyrene beads containing a propellant... 

The combustion properties of the propellant can also be altered by using various surface coatings and additives such as stabilizers, oxidizers, plasticizers or gelatinizers, and deterrents or retardants. 

Adhesion between the propellant and the case in solid rocket fuel propellants was studied. The adhesion mechanisms between an inert propellant (a highly filled PU, based on hydroxy-terminated polybutadiene prepolymer, diisocyanate and inert loadings) and a liner of the same nature of prepolymer, diisocyanate, chain extenders and carbon black were investigated. The interfacial properties were found to be influenced by the properties of the prepolymer used. The adhesion of the assembly was only slightly affected by the state of cure of the liner before propellant coating. In peel tests, cohesive failure occurred in the propellant near the interface, IR spectrometry of the propellant surface after separation showed the formation of an interphase in the propellant, dependant on the prepolymer. 3 refs. 

Figure 13, A schematic diagram of the motility assay. Myosin molecules (HMM or S-1 are also used) stick to glass coverslips coated with nitrocellulose. Actin, in solution, is then added to the glass coverslip and it binds to the myosin molecules. When ATP is added, actin can move over the surface, propelled by the myosin molecules.

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