Solid propellants, binders for

This low viscosity resin permits cure at low (70°C) temperatures and rapidly develops excellent elevated temperature properties. Used to increase heat resistance and cure speed of bisphenol A epoxy resins, it has utility in such diverse applications as adhesives, tooling compounds, and laminating systems. A moleculady distilled version is used as a binder for solid propellants (see Explosives and propellants) and for military flares (see Pyrotechnics). Its chief uses depend on properties of low viscosity and low temperature reactivity, particularly with carboxy-terminated mbbers. 

These materials are widely used as sealants, binders for solid propellants, caulking materials, and cements for insulating glass and fuel tanks. 

In 1962, Bowman showed that this polymer could be used as a binder for solid propellants [23]. Poly(glycolic acid) (PGA)was found easily thermally degraded [24] and its poor thermal and hydrolytic stabilities were problematic for any permanent appUcation. Choju et al. [25] mentioned that this PGA homopolymer is an unstabiUzed polymer and weight loss under heating begins at 240 °C [25]. 

Bowman, NJ (1959) inventor (Standard Oil Co.), assignee. Glycolic acid polymer as a binder for solid propellants. US Patent 800596 3047524, 1962 19570930. 

Curing Agents for Carboxyl-Terminated Polybutadiene Prepolymers. The types of curing agents used to prepare binders for CTPB propellants are the same as those for PBAN or PBAA. The bifunctionality of CTPB, however, requires that part of the curing agents be polyfunctional to provide for the formation of the tridimensional network. Almost without exception, the polyfunctional aziridines and epoxides used with CTPB undergo side reactions in the presence of ammonium perchlorate, which affects the binder network formation. Kinetic studies conducted with model compounds have established the nature and extent of the cure interference by these side reactions. The types and properties of some of the crosslinkers and chain extenders used to prepare solid propellants are summarized in Table IV. 

BAMO is perhaps the most prominent among the azido oxetanes class in terms of the number of polymers and copolymers reported so far. Due to its symmetrical azido groups, it assumes special significance as a hard block repeating unit in a thermoplastic elastomer. However, the homopolymer is solid and cannot be used directly for binder applications because of its crystal-tine nature. Also, poly(BAMO) shows relatively poor mechanical properties as a binder for solid rocket propellants [153]. Many copolymers of BAMO with non-energetic co-monomers tike tetrahydrofuran (THF) have been reported. The BAMO-THF copolymer is an excellent candidate for binder applications with its energetic BAMO content coupled with the THF block which affords... 

Hamilton, R.S., Lund, G.K., and Hajik, R.M. (1995) Manufacture of polyether compounds having both imine and hydroxyl functionality for solid propellant binder. US Patent 5,414,123 Chem. Abstr., (1995) 123 (4), 87609 k. 

Presently, research is on-going into trying to find alternatives to AP/A1 (see also Ch. 1.2.4). The problems with the AP/A1 mixtures which contain HTPB as a binder, are two-fold. On the one hand AP is toxic and should be substituted for this reason alone (see Ch. 1.2.4). On the other hand, such formulations are also problematic in slow cook-off tests (SCO test, see Ch. 6.2). It appears to be the case that here the AP slowly decomposes during the formation of acidic side-products. These acidic side-products then react with the HTPB binder, which can result in the formation of cracks und cavities in the composite, which consequently negatively affects the performance and sensitivity. Possible alternatives for AP are ADN, HNF and TAGNF. However, they cause other problems, such as, for example, the low thermal stability (ADN melts at 93 °C and already decomposes at 135 °C) and the binder compatibility is not always guaranteed either. Further research work is absolutely necessary in order to find better oxidizers for solid propellants. In this context, the following requirements must be fulfilled ... 

The major achievement of "Doc" Patrick was the controlled decomposition of Thiokol by sodium hydrosulftde and sodium sulfite. This low molecular weight Thiokol which was produced by Patrick and H.R. Fmrguson < uld be readily compounded on a ruMier mill and cured in a mold. The low molecular wei t liquid poisoner (LP-3) obtained by the decomposition tochnique became the binder for solid fuel rocket propellants in the 1940 s. 

Doc" Patrick retired and moved to Florida in 1948. However, he returned to Pennsylvania later and entered a new career as a builder and investor. In spite of his brilliant research and his being "the father of American synthetic rubber", "Doc" Patrick received little recognition during his active years with Thiokol, Corp. However, the use of Thiokol LP-3 as a binder for solid ftiel rocket propellants after World War II drew considerable attention to this modest scientist-inventor. 

Cationic polymerization of oxetanes has been more recently exploited to prepare a variety of functional polymer materials including functional polymer networks and energetic binders for solid rocket propellants. Polymerization of BCMO has been studied extensively in the past because of the industrial application of this process. After the production of Penton was discontinued the interest in polymers of BCMO ensued from the fact that they may serve as a precursor for various functional polyoxetanes. 

The LP polysulfides are used primarily as sealants and coatings for construction, transportation and chemical protection applications, and as a binder for solid rocket propellants. These uses will not be covered in this book, but there is a use for the LP series as reactive plasticizers for ST polysulfides to control viscosity but not seriously detract from final properties. 

As an energetic polymer, poly(glycidyl azide) (PGA) mance solid propellant binder [63,64]. For this purpose,... 

The key to the successful application of high performance, pourable nitrocellulose plastisols lies in a reasonably priced, high quality source of fine-particle, at least partially colloided, spheroidal nitrocellulose. Here we are speaking of particles much finer than the well-known ball powder, produced by the Olin Mathieson Chemical Co. for small arms for over 30 years (7). Actually, particles on the order of 5-50/x diameter appear to be required to assure a reasonable continuum of uniformly plasticized nitrocellulose binder in a propellant containing 45% or more of combined crystalline oxidizer and powdered metal fuel. Such a continuum of binder is necessary to assure acceptable mechanical properties and reproducible burning characteristics of the finished propellant. Preincorporation of a certain content of the water-insoluble solids within the nitrocellulose microspheres is an effective means of helping to assure this continuum of binder and alleviates the requirements for extremely small ball size. The use of a total of 45% or more of crystalline oxidizer and (generally) metal fuel is essential if the propellant is to be competitive with other modern propellants now in service. 

---