Eutectic composition of two nitrazapentane derivatives

Abstract: A low freezing point eutectic solid propellant plasticizer composition component comprising a mixture of 1,5-dinitrato-3-nitrazapentane and 1,5-diazido-3-nitrazapentane having a eutectic freezing point below about -25°C.

Description: This invention relates to propellants and is particularly directed to solid propellant formulations employing a low freezing point eutectic solid propellant component comprising a mixture of 1,5-dinitrato-3-nitrazapentane (DINA) and 1,5-diazido-3-nitrazapentane (DANPE). Solid propellants are generally formulated to include solid oxidizers and fuels, together with suitable polymers and plasticizers to impart physical integrity. To enhance the propellant integrity, particularly in low temperature environments such as outer space or arctic conditions, the physical properties of the propellant system may be modified to influence the glass transition point. The use of nitrato plasticizers containing the energetic -ONO₂ group such as nitroglycerin have been utilized to impart additional energy to propellants. Unfortunately, many of the known nitrato compounds used as plasticizers limit the utilization of the range of propellant composition. EP-A-0 120 668 describes the azido nitramine 1,5-diazido-3-nitrazapentane and a method for making it. Further a propellant is described which contains 1,5-diazido-3-nitrazapentane as a plasticizer. US-A-4,379,903 discloses a multiple component catalyst system for curing of energetic urethane binders for solid fuel propellants which may comprise aluminum powder as a fuel. Accordingly there is provided by the present invention an energetic azido eutectic propellant composition component comprising a plasticizer mixture of 1,5-dinitrato-3-nitrazapentane (DINA) and 1,5-diazido-3-nitrazapentane (DANPE) having a eutectic freezing point below about -25°C. When combined in a propellant composition including oxidizers such as 1,3,5-trinitrazacyclohexane (RDX), 1,3,5,7-tetranitrazacyclooctane (HMX), and ammonium perchlorate (AP) a polymer such as glycidyl azide polymer (GAP) with a fuel such as aluminum, a solid propellant having enhanced performance characteristics at low temperatures results. Therefore it is an object of the present invention to provide an improved formulation for solid propellants. Yet another object of this invention is to provide plasticizer compositions for solid propellants which enhance the low temperature performance thereof. These and other objects and features of the present invention will be apparent from the following detailed description. According to the present invention a process for preparing a solid propellant composition including oxidizer, plasticizer, polymer and fuel, is characterized in that a low freezing point eutectic composition comprising a mixture of 1,5-dinitrato-3-nitrazapentane and 1,5-diazido-3-nitrazapentane having a freezing point below -25°C is used for plasticizing. In accordance with the present invention there is provided a solid propellant composition including an oxidizer blend of HMX and AP, a polymer such as glycidyl azide polymer (GAP), and a fuel such as aluminum, to which is blended a low freezing point eutectic solid propellant composition plasticizer component according to the present invention. It has been found that a solid propellant composition incorporating the low freezing point eutectic solid propellant plasticizer component of the present invention results in a propellant composition having equivalent specific impulse (Isp) to a nitroglycerin based system as shown in Table 1: Theoretical Solid Propellant Performance Composition (Wt. %) Isp (1000 ---> 14.7), sec. 10.0 GAP/10.0 NG/10.0Al/13.4 AP/56.6 HMX 271.2 10.0 GAP/10.0 Eutectic /10.0 Al/12.2 AP/57.8 HMX 271.1 The eutectic propellant component of the present invention is prepared by dissolving solid DINA (MP 52°C) into liquid DANPE (MP 8°C). More particularly, homogeneous liquid mixtures consisting of 50% DINA-50%-DANPE and 29% DINA-71% DANPE result in compositions having unusually low freezing points of about -25°C and about -55°C respectively. Another preferred solid propellant composition includes a eutectic plasticizer propellant component consisting of 37.5 percent (DINA) / 63.5 percent (DANPE). A freezing point diagram for eutectic propellant component mixtures is shown in Figure 1.

Claims: A process for preparing a solid propellant composition including oxidizer, plasticizer, polymer and fuel, characterized in that a low freezing point eutectic composition comprising a mixture of 1,5-dinitrato-3-nitrazapentane and 1,5-diazido-3-nitrazapentane having a freezing point below -25°C is used for plasticizing. The process according to Claim 1, wherein the low freezing point composition comprises a mixture of about 50 % 1,5-dinitrato-3-nitrazapentane and about 50 % 1,5-diazido-3-nitrazapentane. The process according to Claim 1, wherein the low freezing point eutectic composition comprises a mixture of about 37.5 % 1,5-dinitrato-3-nitrazapentane and about 63.5 % 1,5-diazido-3-nitrazapentane. A solid propellant composition obtainable in accordance with any of Claims 1 to 3. The solid propellant composition of Claim 4, wherein the oxidizer is a blend of HMX and AP, the polymer is GAP, and the fuel is aluminum. The solid propellant composition of Claim 5 comprising an oxidizer blend of 57.8 wt.-% HMX and 12.2 wt.-% AP, 10.0 wt.-% aluminum fuel, 10.0 wt.-% GAP polymer, and 10.0 wt.-% of a 50/50 blend of DANPE:DINA plasticizer. The solid propellant composition of Claim 6 wherein the plasticizer comprises a 10.0 weight percent of a 63.5 weight percent/37.5 weight percent blend of DANPE:DINA. The solid propellant composition of Claim 6 wherein the plasticizer comprises a 10.0 weight percent of a 71.0 weight percent / 29.0 weight percent blend of DANPE:DINA.

Inventors: FLANAGAN JOSEPH EDWARD, WOOLERY II DEAN OWEN, FLANAGAN, JOSEPH EDWARD, WOOLERY II, DEAN OWEN
Applicants: ROCKWELL INTERNATIONAL CORP, ROCKWELL INTERNATIONAL CORPORATION
Application year: 1988
Main classification: C06B25
IPC codes: C06D5, C06B45, C06B25