U.S. patent application number 11/307626 was filed with the patent office on 2010-02-04 for methods for making and using high explosive fills for very small volume applications.
Invention is credited to Gartung Cheng, Brian E. Fuchs, Gerard Gillen, Neha Mehta, Daniel Stec, III.
Application Number | 20100024933 11/307626 |
Document ID | / |
Family ID | 41607116 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100024933 |
Kind Code |
A1 |
Stec, III; Daniel ; et
al. |
February 4, 2010 |
METHODS FOR MAKING AND USING HIGH EXPLOSIVE FILLS FOR VERY SMALL
VOLUME APPLICATIONS
Abstract
High explosives suitable for filling very small volume loading
holes in micro-electric initiators for micro-electro-mechanical
mechanisms, used as safe and arm devices, are prepared from
slurries of crystalline energetic materials including organic
liquid and applied using various methods. These methods include
swipe loading, pressure loading and syringe loading. The organic
liquid serves as a volatile mobile phase in the slurry so as to
partially dissolve the energetic material so that, upon evaporation
of the mobile phase, the energetic material precipitates and
adheres to the loading hole.
Inventors: |
Stec, III; Daniel; (Long
Valley, NJ) ; Cheng; Gartung; (Edison, NJ) ;
Fuchs; Brian E.; (Hackettstown, NJ) ; Gillen;
Gerard; (Milford, PA) ; Mehta; Neha;
(Sucasunna, NJ) |
Correspondence
Address: |
U.S. ARMY RDECOM-ARDEC;Attn: Lori Andrews
RDAR-GCL / BLDG 3
PICATINNY ARSENAL, DOVER
NJ
07806-5000
US
|
Family ID: |
41607116 |
Appl. No.: |
11/307626 |
Filed: |
February 15, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10248904 |
Feb 28, 2003 |
7052562 |
|
|
11307626 |
|
|
|
|
Current U.S.
Class: |
149/92 ;
149/109.6; 149/88; 264/3.1 |
Current CPC
Class: |
F42B 33/0242 20130101;
C06B 21/0025 20130101; F42B 33/0207 20130101; F42D 1/10 20130101;
F42B 33/0264 20130101; C06B 21/0033 20130101; F42B 33/0214
20130101 |
Class at
Publication: |
149/92 ; 264/3.1;
149/88; 149/109.6 |
International
Class: |
C06B 25/34 20060101
C06B025/34; C06B 21/00 20060101 C06B021/00; C06B 25/00 20060101
C06B025/00 |
Claims
1. A method for loading crystalline energetic material into a small
volume loading hole of a fixture of an explosive device, said
method comprising the steps of: preparing a slurry or paste
containing the crystalline energetic material; loading the slurry
or paste containing the crystalline energetic material to the
loading of the fixture of the explosive device wherein the
crystalline energetic material comprises high explosive material
and an organic liquid for the slurry or paste.
2. The method according to claim 1, wherein the step of loading the
slurry or paste comprises placing the slurry or paste on a blade
member and wiping the blade member over the fixture so as to force
the slurry or paste into the loading hole in the fixture.
3. A method according to claim 1, wherein said step of loading the
slurry or paste comprises placing the paste or slurry in a
contained space having an outlet orifice therein, and dispensing
the paste or slurry through the orifice into the hole in the
fixture.
4. A method according to claim 3, wherein the method employs a
pipette for dispensing the paste or slurry.
5. A method according to claim 3, wherein the method employs a
syringe for dispensing the paste and slurry and a plunger of the
syringe is used to force the paste or slurry through the
orifice.
6. A method according to claim 3, wherein the method employs a pump
for dispensing the paste or slurry.
7. A method according to claim 6, wherein said pump comprises a
positive displacement pump.
8. A method according to claim 6, wherein said pump comprises a
peristaltic pump.
9. A method according to claim 1, wherein the organic liquid serves
as a volatile mobile phase to the paste or slurry so as to
partially dissolve the energetic material such that, upon
evaporation of the at least one mobile phase, the dissolved
energetic material precipitates and adheres to a portion of the
fixture forming the loading hole.
10. A method according to claim 1, further comprising:
incorporating a polymeric binder into the slurry or paste so as to
provide adherence between crystals of the polycrystalline energetic
material and a portion of the fixture forming said loading
hole.
11. A method according to claim 10, wherein the amount of binder
ranges from between 0.01 and 10 wt. % of the energetic
material.
12. A method according to claim 11, wherein the binder is dissolved
in the slurry or paste.
13. A method according to claim 11, wherein the binder is
incorporated into the slurry or paste as a latex suspension.
14. A method according to claim 11, wherein the binder is
incorporated into the slurry or paste as an emulsion.
15. A method according to claim 1, wherein the organic liquid
comprises a mixture of ethanol and ethyl acetate serving as the
liquid component for the slurry.
16. A method according to claim 15, wherein the mixture of ethanol
and ethyl acetate is 90:10 to 60:40 volume/volume percent.
17. A method according to claim 1, further comprising incorporating
a polymeric binder into the slurry or paste to enhance the physical
strength of the slurry or paste.
18. A method according to claim 1, further comprising incorporating
a plasticizer binder into the slurry or paste to produce an
increase in adhesive strength and flexibility.
19. A method according to claim 1, wherein a binder system is added
to the slurry or paste which is selected from the group polyvinyl
alcohol, polyvinyl alcohol/polyvinyl A ester copolymers,
polyacrylates, casein, polyvinyl alcohol/polyvinyl pyrrolidone
copolymers, polyvinyl pyrrolidone, substituted polyvinyl
pyrrolidone, ethylenevinyl alcohol/acetate terpolymers,
polyurethanes, styrene-maleic anhydride copolymers, and
styrene-acrylic copolymers, epichlorohydrin-based polymers and
oxetane-based polymers.
20. A method according to claim 19, wherein said
epichlorohydrin-based polymers include the energetic polymers GAP
and polyGLYN.
21. A method according to claim 19, wherein the oxetane-based
polymers include polyBAMO, polyAMMO, BAMO-AMMO copolymers, and
polyNIMMO.
22. A method according to claim 1, wherein said high explosive
material is selected from the group consisting of CL-20, HMX, RDX,
TNAZ, PETN, HNS, and all crystalline polymorphs.
23. A slurry of a secondary high explosive material including an
organic liquid serving as a volatile mobile phase for delivering to
a loading hole in a fixture for an explosive device, said slurry
consisting of: the high explosive material which is selected from
the group consisting of CL-20, HMX, RDX, TNAZ, PETN, HNS, and
crystalline polymorphs; the organic liquid volatile mobile phase
which partially dissolves the high explosive material such that
upon evaporation of the mobile phase the dissolved high explosive
material precipitates wherein said organic liquid comprises a
mixture of ethanol and ethyl acetate in substantially 90:10 to
60:40 volume/volume percent; a polymeric binder dissolved into the
slurry, wherein the binder comprises between 0.01 and 0.5 wt. % of
the high explosives whereby, said 0.01 to 0.5 wt. % of polymeric
binder provides adherence between the precipitated high explosive
and said loading hole.
24-28. (canceled)
29. The slurry of claim 23, wherein said binder is incorporated
into the slurry as a latex suspension.
30. The slurry of claim 23, wherein said binder is incorporated
into the slurry as an emulsion.
31-32. (canceled)
33. The slurry of claim 23 further comprising a plasticizer to
produce an increase in strength and flexibility.
34. The slurry of claim 23, further comprising a binder system
selected from the group consisting of polyvinyl alcohol, polyvinyl
alcohol/polyvinyl A ester copolymers, polyacrylates, casein,
polyvinyl alcohol/polyvinyl pyrrolidone copolymers, polyvinyl
pyrrolidone, substituted polyvinyl pyrrolidone, ethylenevinyl
alcohol/acetate terpolymers, polyurethanes, styrene-maleic
anhydride copolymers, and styrene-acrylic copolymers,
epichlorohydrin-based polymers and oxetane-based polymers.
35. The slurry of claim 34, wherein said epichlorohydrin-based
polymers include the energetic polymers GAP and polyGLYN.
36. The slurry of claim 34, wherein the oxetane-based polymers
include polyBAMO, polyAMMO, BAMO-AMMO copolymers, and polyNIMMO.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of application
Ser. No. 10/248,904 filed Feb. 28, 2003 by Daniel Stec, III, et
al., the entire file wrapper contents of all of which application
is hereby incorporated by reference as though fully set forth.
FEDERAL RESEARCH STATEMENT
[0002] [The inventions described herein may be manufactured, used
and licensed by or for the U.S. Government for U.S. Government
purposes.]
BACKGROUND OF INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to methods for preparing and
using energetic fills containing crystalline high explosive
materials.
[0005] 2. Related Art
[0006] The basic standard methods for loading energetic or
explosive materials into munitions are press-loading, and cast
loading (whether using melt-cast or cast-cure techniques). With the
relatively recent emergence of the production of smart weapon
systems that are lighter and smaller and have greater lethality and
survivability, the need exists for smaller, reliable Safe and Arm
(S&A) devices for activating the explosive train of the
explosive device. The challenges in producing Micro-Energetic
Initiators (MEI) for Micro Electro-mechanical Mechanisms (MEMs) as
safe and arm devices, involve the need to introduce the energetic
materials into extremely small volumes and to have the energetic
materials function properly after such introduction. MEIs for safe
and arm devices will necessarily be smaller in size and weight than
traditional fuzing devices, and will permit a larger loading of the
energetic fill of the end item, thereby resulting in increased
lethality. The standard loading methods mentioned above cannot be
used to load the very small (microliter) volumes contained in these
devices.
[0007] Considering the latter point in more detail, as indicated
previously, the standard methods for loading an energetic fill into
a munition are press-loading and cast-loading. With respect to the
former, delivering the material to the fixture, followed by
consolidation thereof by pressing, presents difficulties because of
the very small required volume of the solids. Further, because of
the delicateness of the materials of construction of the critical
fixture, press loading of the energetic fill into the fixture is
not a viable option. One potential approach would be to prepare a
pellet of the energetic material externally of the fixture, and
then load the pellet into the fixture. To complete the process, in
order to maintain the pellet in place, some kind of adhesive would
have to be applied to the pellet, e.g., on the side thereof, or to
the wall of the fixture. It will be appreciated that such a process
would be cumbersome and relatively costly.
[0008] As was also mentioned previously, casting of an energetic
fill into a fixture can be done either by melt casting and cast
curing. Melt casting basically entails heating a substance to a
temperature above its melting point, adding any needed ancillary
materials to the melt, pouring the mixture into the volume to be
filled, and allowing the fill to solidify in place. Among other
problems with this approach, because of the very small delivery
volumes involved in producing MEIs for safe and arm devices, heat
loss to the ambient environment would be a problem and, in this
regard, could cause the energetic material to solidify before being
emplaced.
[0009] Cast curing basically entails mixing the substance to be
cast in a liquid polymer mixed with a cross-linking reagent. The
resultant cast mixture has a finite "pot life" after which the
viscosity of the mixture increases because of the chemical
crosslinking process. This change in rheological properties may
cause difficulty in the delivery into the fixture of energetic
material prepared in this way.
[0010] There are, of course, a number of state-of-the-art delivery
devices for the delivery of small volumes of materials including
ink jet printing. The latter is a mature technology that can be
used to accurately deliver small volumes of material. However, the
present technology is unsuitable for delivering energetic materials
for two reasons. First, most inks used for ink jet printing are
dye-based, i.e., the colorant dye is dissolved in the fluid medium,
and although there are pigment-based ink jet inks available wherein
the colorant is an undissolved crystalline material, the
undissolved solids are of a sub-micron particle size. Important
secondary high explosives such as CL-20 (epsilon HNIW) are not
presently available in a sub-micron particle size. Further, in an
ink jet printer, the ink is typically delivered from the print head
by a piezoelectric discharge that ejects droplets of ink at
elevated pressure and temperature onto the printing substrate; the
combination of an electric discharge and high temperature/pressure
may be a safety hazard when attempting to deliver energetic
materials using ink jet printing.
SUMMARY OF INVENTION
[0011] As indicated above, the present invention is concerned with
loading crystalline high explosive materials into small volume
munitions and is especially concerned with MEMs/MEI "micro" region
explosive initiation trains. As will appear, the methods of the
invention serve to overcome the problems discussed above in
connection with loading crystalline high explosive materials into
small volumes.
[0012] Before considering the invention in more detail, a further
loading method of particular interest here is one used exclusively
for primary explosives. As will be understood by those familiar
with this field, a distinction is drawn between primary explosives
(e.g., lead styphnate and the like) which are high power highly
sensitive explosives that may detonate in response to a small
"insult" and secondary explosives which are of lower power and
require a strong shock to detonate, a shock which is typically
provided by a primary explosive. Primary explosives in small
quantities have been ground up wet and added to a slurry which is,
e.g., deposited on a bridgewire. With secondary explosives, the
typical applications are large volume applications such as
munitions wherein the secondary explosive is the main energetic
fill, and wherein maximum power or performance is desired. An
important figure of merit in determining performance is the %
Theoretical Maximum Density (TMD). The aim is that this percentage
should be as high as possible because cracks, porosity and the like
reduce the power/performance of the secondary explosive and also,
undesirably, increase the sensitivity of the explosive. As a
result, secondary explosive formulations are normally cast or
pressed into final or near-final shape as described above because
if such formulations were to be loaded as a slurry into a large
volume munition, the drying time (for evaporation of the slurry
medium) would be excessively long and the volatile medium would
have to diffuse through dried material potentially causing defects
in the fill such as porosity, voids, cracks, entrapped slurry
medium and the like. These defects would result in safety and
performance problems and thus, slurry loading has not been used for
secondary explosives.
[0013] The present invention is based, in part, on the inventive
appreciation that, despite the serious potential problems with
slurry loading of secondary explosives, such an approach can be
used to great advantage in small volume applications. The
surprising finding has been that in such an approach, even though
the resulting fill has a lower % TMD than if pressed or cast and
thus has an attendant increase in the number of defects, the
evaporation takes place in a straightforward manner, the resultant
solid fill has the physical strength and integrity essential for
proper functioning of the loaded item, and, quite unexpectedly, the
resultant increase in defects does not have a deleterious effect on
the energetic performance in the MEM scale. In the latter regard,
despite the density decrease, the energetic performance of the fill
has been found to be much better than would normally be
expected.
[0014] In accordance with a first aspect of the invention, there is
provided a method for loading crystalline energetic materials into
small volume loading hole of a fixture of an explosive device, said
method comprising the steps of:
[0015] preparing a slurry or paste containing the crystalline
energetic material; and
[0016] loading the slurry or paste containing the crystalline
energetic material into the loading hole of the fixture of the
explosive device.
[0017] In one preferred embodiment, the step of loading the slurry
or paste comprises placing the slurry or paste on a blade member
and wiping the blade member over the fixture so as to force the
slurry or paste into the loading hole in the fixture.
[0018] In another preferred embodiment, the step of loading the
slurry or paste comprises placing the paste or slurry in a
contained space having an outlet orifice therein, and dispensing
the paste or slurry through the orifice into the hole in the
fixture.
[0019] In one preferred implementation of this embodiment, the
method employs a pipette for dispensing the paste or slurry. In
another preferred implementation, the method employs a syringe for
dispensing the paste and slurry and a plunger of the syringe is
used to force the paste or slurry, through the orifice. In yet
another implementation, the method employs a pump for dispensing
the paste or slurry. Advantageously, the pump comprises a positive
displacement pump. In another advantageous approach, the pump
comprises a peristaltic pump.
[0020] Preferably, the method further comprises incorporating at
least one volatile mobile phase to the paste or slurry so as to
partially dissolve the energetic material such that, upon
evaporation of the at least one mobile phrase, the dissolved
energetic material precipitates and thus adheres to a portion of
the fixture forming the loading hole.
[0021] In another preferred implementation, the method further
comprises incorporating a polymeric binder into the slurry or paste
so as to provide adherence between crystals of the polycrystalline
energetic material and a portion of the fixture forming said
loading hole. The amount of binder preferably ranges between 0.01
and 10 wt. % of the energetic material. Advantageously, the binder
is dissolved in the slurry or paste. In another advantageous
approach, the binder is incorporated into the slurry or paste as a
latex suspension. In yet another advantageous approach, the binder
is incorporated into the slurry or paste as an emulsion.
[0022] In another advantageous implementation, the crystalline
energetic material comprises CL-20 and a mixture of ethanol and
ethyl acetate is used as a liquid for the slurry. Preferably, the
mixture is in the range of 90:10 to 60:40 volume/volume
percent.
[0023] Advantageously, the method further comprises incorporating a
polymeric binder into the slurry or paste to modify the viscosity
of the mobile medium and improve the physical strength of the
slurry or paste.
[0024] In another advantageous implementation, the method further
comprises incorporating a plasticizer, either energetic or
non-energetic, into the slurry or paste to produce an increase in
adhesive strength and flexibility.
[0025] Preferably, a binder system is added to the slurry or paste
which is selected from the group of polyvinyl alcohol/polyvinyl
ester copolymers, polyacrylates, polymethacrylates, poly(vinyl
pyrrolidone/vinyl alcohol) copolymers, ethylene-vinyl
alcohol/acetate terpolymers, polyurethanes, styrene-maleic
anhydride copolymers, styrene-acrylic copolymers,
epichlorohydrin-based polymers, oxetane-based polymers, substituted
celluloses such as ethyl cellulose and nitrated cellulose
derivatives, including the energetic polymers GAP and polyGLYN and
oxetane-based polymers such as polyBAMO, polyAMMO, BAMO-AMMO
copolymers, and polyNIMMO
[0026] The high explosive material is preferably selected from the
group consisting of CL-20, HMX, RDX, TNAZ, PETN, HNS, and the
like.
[0027] In accordance with a further aspect of the invention there
is provided a slurry of a secondary high explosive material in a
volatile mobile phase for delivery to a loading hole in a fixture
for an explosive device.
[0028] Further features and advantages of the present invention
will be set forth in, or apparent from, the detailed description of
preferred embodiments thereof which follows.
BRIEF DESCRIPTION OF DRAWINGS
[0029] FIG. 1 is a schematic side elevational view, partially in
section, of an energetic fill slurry delivery system in accordance
with a first embodiment of the invention;
[0030] FIG. 2 is a schematic perspective view of an energetic fill
slurry delivery system in accordance with a further embodiment of
the invention;
[0031] FIG. 3 is a schematic side elevational view, partially in
section, of an energetic fill slurry delivery system in accordance
with another embodiment of the invention; and
[0032] FIG. 4 is a schematic side elevational view of an energetic
fill slurry delivery system in accordance with yet another
embodiment of the invention.
DETAILED DESCRIPTION
[0033] As indicated above, the present invention is particularly
concerned with MEMs-based safety and arming devices. It will be
understood that a MEMs (mechanical) S&A is not a "sensor"
device per se but rather a device wherein the components thereof
intrinsically combine both "sense" and "actuate" functions in a
single unpowered chip. Although the invention is obviously not
limited to use with a particular device, an example of such a
device is disclosed in U.S. Pat. No. 6,167,809, which is hereby
incorporated by reference. Devices of this kind can include a
transfer charge as well as conventional primary explosives upstream
of the transfer charge, with all other explosives, including the
transfer charge, being secondary explosives. As discussed above,
loading of secondary explosives into the very small volumes
associated with the fixtures of MEMs S&A devices presents
special problems.
[0034] As is believed to be evident from the foregoing, in order to
provide a MEMs safe and arm device that performs reliably, despite
the small volume thereof, it is essential that the explosive fill
used have a high energetic output and a small critical diameter.
One explosive fill that meets both requirements is CL-20 (epsilon
HNIW), although as discussed below, a number of other fills, such
as HMX, RDX, TNAZ, PETN, HNS and others, including all crystalline
polymorphs, are also excellent candidates. These other energetic
fills are well known in the art and, for example, TNAZ is
1,3,3-trinitroazetidine.
[0035] As indicated above, in accordance with an important feature
of the invention, the energetic fill material is prepared as a
slurry, and a number of different liquids can be used as the mobile
phase, which can be aqueous or organic in nature. In one preferred
embodiment, organic liquids are used as the mobile phase and, more
preferably, the organic liquid used is selected from the group
consisting of ethanol, isopropanol, texanol. and the like, and a
mixture of one alcohol and an ester or ketone, such as ethyl
acetate, two alcohols, although other mutually soluble organic
liquids can be used. In this regard, CL-20 has low solubility in
the alcohols and high solubility in ethyl acetate and the
solubility of the energetic fill material can be controlled by
adding alcohol to the slurry liquid. Again, it will be appreciated
by those skilled in this art that a variety of different liquids
can be used and the solubility of the explosive fill can be
tailored using different liquids in order to meet the needs of the
actual system into which the energetic fill material is to be
loaded.
[0036] In one important embodiment, the energetic material, e.g.,
CL-20, is placed in a conductive container, the slurry liquid is
added in a dropwise manner, i.e., drop by drop, with a stirring or
mixing implement until a paste is obtained. The stirring or mixing
implement is preferably made of a metal, conductive plastic, PTFE
or the like.
[0037] Once the paste of energetic material is produced, a number
of different methods can be used to load the paste into the small
volume opening of the safe and arm fixture.
[0038] In accordance with a loading method in accordance with one
important implementation of the invention, the energetic material
in the form of a paste is loaded using a swipe loading technique
wherein the paste is taken up on a spatula or other wiping element
and is swiped or wiped over the hole or opening to be filled.
Referring to FIG. 1, a spatula or other blade or wiping element is
denoted 10 and a paste including an energetic material is indicated
at 12. By wiping element 10 over a hole 14 in a fixture 16, the
hole 14 can be filled with the paste 12, as shown.
[0039] It will be appreciated that wiping element can also be part
of an automatic wiping apparatus. As shown schematically in FIG. 2,
a pivotable blade 20, which is affixed to a rotatable shaft 22
driven by a motor 24, can be used to wipe the energetic fill paste
26 across a loading hole 28 in a fixture 29. It will also be
appreciated that the energetic material, denoted 20, can be in a
looser slurry form, rather than a paste, and still be forced or
dispensed into the volume to be filled.
[0040] A specific non-limiting example of this implementation is
also discussed below in Example 1.
[0041] A loading method in accordance with a further embodiment of
the invention involves pressure loading of the energetic material,
wherein, broadly speaking, a slurry or paste of energetic material
is placed into a container and forced through an orifice in the
container into a loading hole in a fixture. This method is
illustrated schematically in FIG. 3 which shows a container 30 that
is filled with a slurry or paste 32 of energetic material, and that
includes a plunger 33. Container 30 also includes an outlet orifice
or opening 36. Depressing of plunger 33 causes the energetic
material 32 to be expressed out of orifice 34 into a loading hole
36 in a fixture indicated schematically at 38. It will be
appreciated that a number of different pressure-loading devices can
be used including, for example, pipettes, syringes, and various
pumps, including peristalic and positive-displacement pumps. The
latter approach is illustrated schematically in FIG. 4 which shows
a pump 40 for receiving energetic material 42 in a paste or slurry
form and for pumping the energetic material 52 through a delivery
tube 44 into loading hole 46 in a fixture 48.
[0042] In an important implementation using CL-20, the slurry
liquid is a mixture of ethanol and ethyl acetate and, preferably,
the mixture is 90:10 to 60:40 volume/volume percent.
[0043] The physical integrity of the loaded energetic fill material
can be substantially improved by dissolving a polymer in the mobile
phase prior to slurrying of the energetic fill material. In an
important implementation, wherein the energetic fill material was
CL-20, the polymer coated the CL-20 as well as the metal/plastic
surfaces of the loaded fixture when the mobile liquid phase
evaporated. A binder loading as low as 0.01-0.5 weight percent with
respect to explosive fill, was found to improve the physical
integrity of the loaded CL-20 without degrading or interfering with
its energetic performance.
[0044] A wide range of polymers can be used for the purposes just
described and both non-energetic and energetic polymers can be
used. Suitable binder systems include polyvinyl alcohol/polyvinyl
ester copolymers, polyacrylates, polymethacrylates, poly(vinyl
pyrrolidone/vinyl alcohol) copolymers, ethylene-vinyl
alcohol/acetate terpolymers, polyurethanes, styrene-maleic
anhydride copolymers, styrene-acrylic copolymers,
epichlorohydrin-based polymers, oxetane-based polymers, substituted
celluloses such as ethyl cellulose and nitrated cellulose
derivatives. Energetic polymer systems that can be used include
GAP, polyGLYN and oxetane-based polymers such as polyBAMO. AMMO,
BAMO-AMMO copolymers, and polyNIMMO. The latter are well known
energetic polymers and, for example, BAMO is
3,3-bis-azidomethyl-oxetane while AMMO is
3-azidomethyl-3-methyloxetane, and the oxetane thermoplastic
elastomer energetic binder is available from Thiokol
Corporation.
[0045] A plasticizer can be used along with the binder to improve
the adhesive strength and flexibility of the dried energetic
material.
Example 1
[0046] A small amount of a CL-20 slurry, prepared as described
above, was taken up on a PTFE spatula and wiped over a loading hole
in a fixture of an explosive device (as in FIG. 1). The mobile
phase was allowed to dry. A loading hole in a second fixture was
loaded with lead azide. Upon drying of the slurry mobile phase, an
electrical resistance bridgewire was placed in direct contact with
the lead azide and connected to the terminals of a battery. The
CL-20 energetic material was successfully functioned.
Example 2
[0047] A fixture was provided comprising a plate (made of PMMA or
aluminum) having a hole drilled through the plate and a trough
inscribed on the plate surface so as to be in communication with
the hole. CL-20 was incorporated in a slurry with ethanol, and
loaded into the hole in the plate with a small volume of the slurry
placed in the trough. In addition, lead styphnate was placed in the
trough in direct contact with the CL-20 and so as to partially fill
the trough. Lead azide was then placed in the trough to fill the
remaining trough volume. An electrical resistance bridgewire was
placed in direct contact with the lead azide and the bridgewire was
connected to the terminals of a battery. The device was
successfully functioned and, in this regard, the primary
explosives, lead styphnate and lead azide, set off the CL-20 fill
material, which carried out a 90.degree. corner turn and made a
dent in a lead witness plate disposed in the end of the explosive
train. In a closely related example, the device also functioned
without the inclusion of lead styphnate in the explosive train.
Example 3
[0048] A fixture plate made of PMMA or aluminum having a hole
drilled through the plate thickness was provided and the hole was
loaded as in Example 1. The device was successfully functioned
using a low voltage electric bridgewire, with lead azide being used
as the primary initiating explosive.
Example 4
[0049] A slurry of CL-20 prepared as in Example 1 was thinned with
a few drops of EtOH and taken up in a disposable Pasteur pipette.
The tip of the pipette was placed over the loading hole of a
fixture plate (as described above) and the bulb of the pipette was
squeezed so that a small amount of the thinned slurry was injected
into the hole in the fixture.
Example 5
[0050] A slurry of CL-20 as described above was thinned with a few
drops of EtOH and taken up in a disposable Pasteur pipette. The tip
of the pipette was placed in the barrel of a plastic 1-ml syringe.
A disposable 18-gauge stainless steel needle, cut down in length to
0.5 inches, was attached to the barrel of the syringe. The
aforementioned slurry was loaded into the syringe and the syringe
plunger was placed in the barrel. The tip of the needle was
positioned over the loading hole in the fixture, the plunger
depressed and the required amount of slurry containing the
energetic material was injected into the hole in the fixture.
Example 6
[0051] An aluminum plate having a through hole therein was
prepared. The hole was loaded with a CL-20 slurry as in Examples 1,
4 and 5. Lead azide was placed over the CL-20 slurry and the
resultant device was successfully functioned using a low voltage
electric bridgewire connected to a battery. Further, a plate
prepared as above, and loaded as above, was placed over a second
plate or another plate as described above, also loaded with CL-20.
The upper plate of the resultant device was functioned and the
detonation was successfully transferred from the upper initiating
plate to the item placed under the upper plate, resulting in a dent
in a lead witness plate.
Example 7
[0052] A 70:30 weight/weight texanol
(2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, Eastman
Chemical)/ethanol mixture was prepared. To 4.5 grams of the
solution was added 0.5 grams ethyl cellulose (ETHOCEL, Dow
Chemical.) The mixture was stirred until the solids had dissolved.
Dry CL-20 (9.5 g) was added portionwise with mixing to the
solution. A thick, smooth paste was obtained. The formulation was
loaded into a disposable syringe and dispensed onto a piece of
aluminum. The formulation flowed smoothly and adhered to the metal.
The piece of aluminum was elevated to a temperature of 55.degree.
C. to facilitate drying of the formulations.
[0053] Although the invention has been described above in relation
to preferred embodiments thereof, it will be understood by those
skilled in the art that variations and modifications can be
effected in these preferred embodiments without departing from the
scope and spirit of the invention.
* * * * *