An object of this invention is to provide a composition of beryllium hydride and carboxy-terminated polybutadiene which is stable. Another object of this invention is to provide a method for inhibiting the reactivity of beryllium hydride toward carboxy-terminated polybutadiene. It was found that a small amount of lecithin inhibits the reaction of beryllium hydride with the acid groups in carboxy terminated polybutadiene

Thompson, W. W.

English

NASA Technical Reports Server

United States Patent 1191 
Thompson 
1111 
1451 Sep. 5, 1978 
INHIBITED SOLID PROPELLANT 
COMPOSITION CONTAINING BERYLLIUM 
HYDRIDE 
Inventors: T. 0. Paine, Administrator of the 
National Aeronautics and Space 
Administration, with respect to an 
invention of Wallace W. Thompson, 
Los Angeles, Calif. 
Appl. NO.: 849,274 
Filed: Aug. 5,1969 
Int. Cn.2 .............................................. CMB 45/10 
US. Cl. ................................ 149/19.9; 149/19.92; 
149/20 
Field of Search ................ 149/19, 20, 19.9, 19.92 
1561 References Cited 
U.S. PATENT DOCUMENTS 
3,035,948 5/1962 Fox ........................................ 149/19 
3,087,844 4/1963 Hudson et al. ......................... 149/19 
3,094,444 6/1963 Hedrick et al. ........................ 149/19 
3,215,573 11/1965 Winkler ............................. 149/19 X 
3,305,523 2/1967 Burnside ............................ 149/19 X 
3,476,622 11/1969 Harada et al. ......................... 149/19 
Primary Examiner-Edward A. Miller 
Attorney, Agent, or Firm-John H. Warden; G. T. 
McCoy; Monte F. Mott 
A small amount of lecithin inhibits the reaction of beryl- 
lium hydride with the acid groups in carboxy termi- 
nated polybutadiene. 
1571 ABSTRACX 
5 Claim, No Drawings 
https://ntrs.nasa.gov/search.jsp?R=19790006057 2020-03-20T17:53:54+00:00Z
4,111.729 
IPJHIPBITED SOLID PROPELLANT 
COMPOSITION C0m-G BERnLIUM 
HYDRIDE 
ORIGIN OF THE INVENTION 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provisions of Section 305 of the National 
Aeronautics and Space act of 1958, Public law 83-568 
(72 Stat. 435; 42 USC 2457). 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is in the field of propellants. More 
particularly, the invention relates to solid propellant 
compositions utilizing beryllium hydride as a fuel. 
2. Description of the Prior Art 
For some time it has been known that beryllium can 
be utilized as a metal fuel additive in solid propellant 
formulations. In more recent years, beryllium hydride 
has been utilized rather than beryllium because it pro- 
vides the highest theoretical impulse of any known fuel 
when associated with a wide variety of oxidizers. 
One of the more recent and prevalent forms of beryl- 
lium hydride utilized in composite solid propellants is 
BEANE which is produced by the pyrolysis of beryl- 
lium alkyls. BEANE has the general formula: 
wherein: 
n varies from 10 to about 250 depending on the de- 
gree of pyrolysis of the beryllium alkyl, and 
X and Y can be individually selected from H or R 
where R is a lower alkyl group of one to four car- 
bon atoms. 
BEANE has an intrinsic low density of approxi- 
mately 0.65 gram/cc. As a result, the material has a 
large specific volume and surface and thus it is very 
difficult to obtain high solids loading in solid propellant 
formulations. One method that has been recently dis- 
2 
minated polybutadiene which otherwise is an excellent 
binder candidate. 
OBJECTS AND SUMMARY OF THE 
INVENTION 5 
An object of this invention is to provide a composi- 
tion of beryllium hydride and carboxy-terminated poly- 
butadiene which is stable. 
Another object of this invention is to provide a 
10 method for inhibiting the reactivity of beryllium hy- 
dride toward carboxy-terminated polybutadiene. 
The above and other objects of this invention are 
accomplished by incorporating a small amount of leci- 
thin in propellant formulations containing beryllium 
DESCRIPTION O F  THE PREFERRED 
EMBODIMENTS 
15 hydride and carboxy-terminated polybutadiene. 
Lecithin, a well known surface active wetting agent, 
20 has been previously utilized in polyurethane propellants 
in that capacity and aids in the reduction of viscosity of 
the propellant so that it can be more easily mixed or 
blended. In attempting to formulate propellant compo- 
sitions of BEANE with carboxy-terminated polybutadi- 
25 ene as a binder, it was found desirable to reduce the 
viscosity of the mixture so that it could be more readily 
formulated into a propellant during the mixing process. 
As a result, initial effort was directed toward selecting 
known surface active agents which would aid in this 
30 processability. Because of the previous use of lecithin in 
the polyurethane propellants, as indicated, the material 
became one of the candidates investigated. 
In utilizing lecithin with BEANE and carboxy-ter- 
minated polybutadiene, surprisingly it was found that 
35 there was very little reduction in viscosity of the mix- 
ture. In other words, lecithin did not serve as a success- 
ful wetting or surface active agent in this composition. 
Concurrent with the problem of processability men- 
tioned above, it was noted in attempting to formulate 
4.0 propellant compositions of BEANE and carboxy-ter- 
minated polybutadiene that the beryllium hydride ap- 
peared to react with the acid groups in the CTPB to 
give free hydrogen and beryllium salts of the polymer. 
Obviously, this results in a degradation of both the 
45 binder and the beryllium hydride components. Further, 
a significant increase in viscosity of the mixture can 
result due to the reaction and the porosity of the mix- 
ture is affected due to the gas bubbling therethrough. In 
view of this, serious doubts arise concerning the feasibil- 
into CTPB binder mate- 
rial, One particular disclosed method of uti.izing 
BEANE successfully is to previously coat the beryllium 
hydride particles with a melt of an oxidizer or oxidizer 
which could contain from l5 to 25 weight percent 55 coated with hydrazine nitrate or a mixture of hydrazine 
BEANE and from 15 to 20 weight percent binder, the nitrate and either ammonium i t ra te  or ammoium per- 
remaining being the oxidizer. However, even with the chlorate. The coated B E A ~  particles are then mixed 
new approach of mating the BEANE with the oxidizer, into the propellant binder to formulate the final prod- 
another major problem remained unsolved. uct. However, even the BEANE that had been coated 
One of the most prevalent and Popular candidates for 60 with the oxidizer was found to be reactive with car- 
a binder to be utilized in composite solid propellants boxy-terminated polybutadiene in the Same manner 
covered for improving the solid loading capability of 5o ity of incorporating 
the BEANE is to coat the beryllium hydride particles 
with a fused solid oxidizer composition. The oxidizer 
coated BEANE particles can then be subsequently in- 
coporated into a propellant fornulation combination. Thus, BEANE has been successfully 
incorporating BEANE or beryllium hydride is carbow- previously described above. 
terminated polybutadiene, CTPB. The beryllium hy- Since lecithin was a well known surface active agent 
dride, even when coated with an oxidizer, reacts with which had been previously utilized in polyurethane 
the acid group of the carboxy-terminated polybutadi- 65 propellant formulations to aid processability, an attempt 
ene, releasing free hydrogen and precipitating beryllium was made to utilize it with propellant formulations de- 
salts in the polymer. This has severely limited and af- scribed herein. However, the lecithin did not signifi- 
fected the use of beryllium hydride with carboxy-ter- cantly affect the viscosity of propellant mixtures con- 
4,111,729 
3 4 
EXAMPLE I1 
Eighty grams of the same hydrazine nitrate-BEANE 
mixture were formulated with the same carboxy termi- 
Unexpectedly, however, the lecithin, though it did 5 nated polybutadiene and Plasticizers as shown in Exam- 
ple I, with the addition of 0.5 grams lecithin. The prod- 
uct retained its ability to flow under pressure and exhib- 
ited no gassing as no porosity was observed. The vis- 
cous, tacky material retained its consistency even after 
taining BEANE and carboxy-terminated polybutadi- 
ene. In other words, the lecithin did not perform the 
function that it had previously performed when incor- 
porated in polyurethane propellants. 
not improve the processability of the propellants de- 
scribed herein, did prove to Serve a very important 
function, the 
reaction of the beryllium hydride with the acid groups 
of the carboxy-terminated polybutadiene. This thus 
permitted production of homogenous mixture of pro- 
pellant without significant degradation. The amount of 
lecithin required to inhibit the reaction is less than 0.5 
Thus, it can be seen that the lecithin did not serve to 
perform its previously known function, but rather acted 
in a totally unexpected manner which had no relation to 
it being a wetting or surface active agent. It is believed 
that the invention will be further understood from the 20 
following specific examples: 
the lecithin was found to 
10 several months of storage. 
What is claimed is: 
A solid composition of matter comprising: 
t e d a t e d  polybutadiene, 
beryllium hydride, 
weight percent of the total propellant 15 and an amount of lecithin sufficient to inhibit any 
reaction between said beryllium hydride and said 
carboxy terminated polybutadiene during storage 
of the composition prior to ignition thereof. 
2. A solid propellant composition comprising: 
from 15 to 20 weight percent carboxy terminated 
from 15 to 25 weight percent of beryllium hydride, 
an amount of lecithin sufficient to inhibit reaction 
between said beryllium hydride and said carboxy 
terminated polybutadiene during storage of the 
propellant prior to ignition thereof, 
polybutadiene as a binder, 
EXAMPLE I 
Sixty grams of hydrazine nitrate was melted and 
mixed with 40 grams of BEANE in an all Teflon rod 25 
mill while cooling below the melting point of the hydra- 
.& nitrate. n e  resulting granular mixture 
screened to provide (> mp), medium 3. The propellant of claim 2 wherein said lecithin 
( s w p ) ,  and fine (<5oP), fractions and then recorn- 
bined to form a trimodal blend consisting of 40 weight 30 lant 
percent coarse, 40 weight percent medium, and 20 4. The propellant of claim 3 wherein said oxidizer is 
selected from the group consisting of hydrazine nitrate, 
and the remainder being a suitable oxidizer. 
less than 0.50 weight Percent of said Propel- 
weight percent fine* 
were mixed with l2 grams Of a carbOxY terminated 
grams Of the a mixture of hydrazine nitrate and ammonium nitrate, 
and a mixture of hydrazine nitrate and ammonium per- 
5. In a method of formulating propellant by mixing 
polybutadiene, 4 grams of dioctyl azelate, and 4 grams 35 &lorate. 
of a purified mineral oil* The mixture was 
Placed under vacuum to remove most of the occluded 
gases and finally extruded through 0.1 inch slits under 
vacuum to complete mixing and insure no occluded 
gases. The product was a smooth, Slowly flowing, vis- 40 
cous, tacky mixture which, on standing for one to seven 
days, increased in volume, became porous, crumbly, 
together with losing its tack and ability to flow even 
under pressure. 
beryllium hydride with carboxy terminated polybutadi- 
ene, the improvement which comprises: 
mixing with said propellant an amount of lecithin 
sufficient to inhibit reaction between said carboxy 
terminated polybutadiene and said beryllium hy- 
dride during storage of the propellant prior to igni- 
tion thereof. * * * * *  
45 
50 
55 
60 
65 


Inhibited solid propellant composition containing beryllium hydride

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