Polymer combustion components

Ammonium perchlorate is used as a component of perchlorate high explosives. Lately it has been brought into prominence as a constituent of solid rocket fuels, the combustible components of which include such polymers as thiokol and methyl polymethacrylate (Vol. III). Hence a considerable interest has recently been taken in ammonium perchlorate. 

Flame retardants. These components are incorporated to inhibit or modify the polymer combustion when heated in an oxidative atmosphere. Typical flame retardants are C1-, Br- and P-containing organic compounds, as well as antimony oxide and hydrated alumina. 

A relationship was discovered between the portion of the antimony compound (per element) that is evaporated during polymer combustion and the change in 01 (oxygen Index) for a mixture containing Sb203- The amount of Sb used in the gas phase increases as the Cl component in polymer increases [115]. 

The chloride ion is one of the most frequently analysed by IC, e.g. following up combustion of polymers [854,855] similar analyses were reported for the bromide ion [854,855] and nitrite [855]. Analysis of polyester resins for halogens or phosphorous components may be carried out via conversion to halides and phosphates, respectively. 

The combustion performance of a rocket motor is dependent on various physicochemical processes that occur during propellant burning. Since the free volume of a rocket motor is limited for practical reasons, the residence time of the reactive materials that produce the high temperature and high pressure for propulsion is too short to allow completion of the reaction within the limited volume of the motor as a reactor. Though rocket motor performance is increased by the addition of energetic materials such as nitramine particles or azide polymers, sufficient reaction time for the main oxidizer and fuel components is required. 

This discussion has been concerned primarily with the chemistry of the polymer in filled crosslinked elastomer formulations. Since the purpose of these formulations is to produce a gas with high enthalpy, thermochemistry is important. The heat of combustion of the components and the effect of the nature and molecular weight of the gaseous products are included in several literature references. The increase in enthalpy that can be obtained by adding finely divided metals to the formulations makes the use of these materials desirable in many applications. Their presence has catalyzed many excellent studies on two-phase gas flow particularly during expansion in a nozzle. 

Insulating interlayers separates the inclusions from each other and from the matrix polymer in such system degradation catalyzed by nanoparticles starts within the interlayer. This layer should provide less combustible degradation products. A new method for the formation of PEP resin has been proposed recently [21]. A detailed analysis of PEP revealed the combined (gas and solid phase) mechanism of FR action in this material [41], This polymer was selected for forming an interlayer around clay nanoparticles. The monomer components were introduced during the compounding process and the interlayer was formed by in situ curing. 

Treatment of the monomer with an acidic catalyst leads initially to polymers of low molecular weight and ultimately to crosslinked, black, insoluble, heat-resistant resin (17). Despite their reportedly excellent properties, virtually no commercial use of such resins exists outside the Soviet Union. The structure and polymerization mechanism of these furfural-ketone polymers are described in a recent study (18). An excellent combustion-resistant resin has been reported (19) from the addition of dialkylphosphites to bis(2-furfurylidene) ketone (6). Furfural condensates with other aliphatic and aromatic ketones have been reported (20,21) to provide photo-crosslinkable resins and hypergol components. 

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