Binder for propellants

Guenther, K.H. (1990) Thermoplastic copolyester elastomer binder for propellants. Eur. Patent EP 358,845 Chem. Abstr., (1990) 112, 237798k. 

Methods to dissolve the polymer binders used to hold energetic materials also are being developed. Polyurethane-based polymers are commonly used as binders for propellants and explosives. By undergoing hydrolysis at 230°C (445°F), the polyurethane groups in the binder split. The mixture is then treated by solvent extraction to recover both polyols and energetic materials from the binder. 

Elastomers Adhesives Sonar domes Hoses (water and fuel) Sealants (fuel and water tanks) Conductive sealants (electromagnetic shielding) Lubricants External tiles for submarine hulls Vibrational damping (engine and motor mounts) Electrical insulation Tires, belts, bushings, gaskets, seals Binders for propellants Foams Protective cover for hydraulic actuators... 

J. T. Gxsxe glmproved Specifications for Composite Propellant Binders for Army Weapon Systems,TR-T-19-16, A-aayMssAe Command, Huntsville, Ala.,July 1979. 

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 utihty in such diverse appHcations as adhesives, tooling compounds, and laminating systems. A moleculady distilled version is used as a binder for soHd 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. 

Energetic plasticizers and binders for explosive and propellant compositions... 

Hydroxy-terminated polybutadiene (HTPB) is considered to be the best binder for obtaining high combustion performance, superior elongation properties at low temperatures, and superior mechanical strength properties at high temperatures. This combination of properties is difficult to achieve in double-base propellants. HTPB is characterized by terminal -OH groups on a butadiene polymer. The other type of butadiene polymer used is carboxy-terminated polybutadiene (CTPB), which is cured with an imine or an epoxy resin. It should be noted that CTPB is somewhat sensitive to humidity, which has an adverse effect on its ageing charac-... 

K. Yamazaki H. Tokui, The Cross-Linking Reaction of Polybutadiene Binder for Composite Propellants , BullChemSocJapan 38 (12). 2774-78 (1965) (English) CA 64, 6391 (1966)... 

An extrusion press used in the manuf of fuel binder composite propellants for use in US aircraft jatos is shown in Fig 6... 

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. 

The problems associated with the multifunctional curing agents for CTPB and the resultant aging behavior of the cured polymers have led to a practical solution for curing binders and propellants—i.e., using mixed aziridines or a mixture of an aziridine and an epoxide. Such mixtures, when appropriately balanced, usually provide satisfactory mechanical behavior and high temperature stability. In dual curing systems such as MAPO and BITA or MAPO and a suitable multifunctional epoxide,... 

There are a number of inert binders such as polyester, epoxy, polysulfide, polyurethane which have been reported as binders for composite propellants and plastic bonded explosives (PBXs). At present, hydroxy-terminated polybutadiene (HTPB) is regarded as the state-of-the-art workhorse binder for such applications. However, the recent trend is to use energetic binders such as poly [3,3-bis(azidomethyl oxetane)] [poly(BAMO)], poly (3-azidomethyl-3-methyl oxetane) [poly(AMMO)], PNP, GAP diol and triol, nitrated HTPB(NHTPB), poly(NiMMO), poly(GlyN) and nitrated cyclodextrin polymers poly(CDN) for PBXs and composite propellants in order to get better performance. 

---