WO2015049285A1

WO2015049285A1 - Nitrocellulose-based propellant composition stabilized with a trialkoxy benzene stabilizer

Info

Publication number: WO2015049285A1
Application number: PCT/EP2014/071040
Authority: WO
Inventors: Alain Dejeaifve; Vincent BERTON; Rowan DOBSON
Original assignee: Pb Clermont Sa
Priority date: 2013-10-02
Filing date: 2014-10-01
Publication date: 2015-04-09
Also published as: GB201317421D0

Abstract

The present invention concerns a nitrocellulose-based propellant composition comprising: (a) a nitrate ester based propellant comprising nitrocellulose; and (b) a stabilizer consisting of a trialkoxy benzene of general formula (I), (II) or a mixture thereof, wherein R¹, R² and R³ are same or different and represents C_1-5 alkyl unsubstituted substituted with an alkoxy group.

Description

NITROCELLULOSE-BASED PROPELLANT COMPOSITION STABILIZED WITH A

TRIALKOXY BENZENE STABILIZER

Technical Field

[0001] The present invention relates to stabilized nitrocellulose-based propellant compositions. In particular it concerns nitrocellulose-based propellant stabilized with a stabilizer producing little to no carcinogenic and mutagenic by-products.

Background for the invention

[0002] Smokeless powders have been developed since the 1 9^th century to replace traditional gun powder or black powder, which generates substantial amounts of smoke when fired. The most widely used smokeless powders are nitrocellulose based. Nitrocellulose is obtained by using nitric acid to convert cellulose into cellulose nitrate and water according to a general reaction:

3HN0₃+ C₆Hio0₅→ C₆H₇(N02)305 + 3H₂0 Nitrocellulose-based smokeless powder is then obtained by treating the thus obtained nitrocellulose by extrusion or spherical granulation, with or without solvent, two techniques which are well known to the persons skilled in the art.

[0003] Various improvements have been developed since the first discovery of nitrocellulose, by addition of further components, such as nitroglycerin and/or nitroguanadine allowing an increase of the detonation velocity. Pure nitrocellulose propellant is referred to as single-base propellant, and double- and triple-base propellants refer to compositions comprising nitrocellulose and one or two additional energetic bases, respectively, typically blasting oils such as nitroglycerin, nitroguanidine, or secondary explosives. [0004] Nitrocellulose, as most nitrate esters, is prone to self-ignition as a result of thermal degradation due to the weakness of its O-N bond. When employed as an ingredient of propellants or other explosive compositions, the spontaneous ignition of nitrocellulose has caused serious accidents. It is obviously vital to inhibit or slow down this degradation for safety reasons but it is also important to retain the initial properties of the energetic composition. Degradation usually leads to gas emissions, heat generation and reduction of molecular mass affecting negatively the material structure and ballistic properties. [0005] The decomposition of the nitrocellulose usually starts with a bond scission or hydrolysis, generating alkoxy radicals and nitrogen oxide (NOx) species (cf. Figure 1 ). The radicals further react generating more radicals, speeding up the degradation process, and ultimately lead to chain scission accompanied by heat generation. In order to prolong the service life of the propellants, stabilizers are added to the energetic mixture in order to scavenge these radical species and slow down the degradation pattern.

[0006] All conventional stabilisers used to date for nitrocellulose-based propellants belong to (a) aromatic amines (e.g., diphenylamine, 4-nitro-N-methylamine) or (b) aromatic urea derivatives (e.g., akardite, centralite) and are or produce toxic and/or potentially carcinogenic species at some point during the propellant's lifetime. For example, the most widely used stabilizers to date are diphenyl amine, akardite, and centralite. These compounds, however, form carcinogenic derivatives such as N-nitrosodiphenylamine (cf. Figure 2(a)) or N-nitrosoethylphenylamine.

[0007] Hindered amines, such as triphenylamine, reduce the formation of N-NO groups, but fail to stabilize nitrocellulose satisfactorily. Conventional hindered phenols used in the plastics industry have been tested and at short term stabilize nitrocellulose with little to no N-NO formation. The phenols are able to trap the alkoxy radicals generated during the degradation of nitrocellulose and thus form new, relatively stable alkoxy radicals, by delocalisation of an electron at the foot of electron-rich, hindered groups as illustrated in Figure 2(b). The long term stability is, however, not always guaranteed, probably due to rapid phenol depletion and relative stability of the newly formed alkoxy radicals.

[0008] CB2092563 and US4299636 discloses a class of alkoxy substituted aromatic stabilisers including 1 ,3,5-trimethoxybenzene. The latter, however does not fulfil STANAC requirements for a 80 wt. nitrocellulose / 20 wt. nitroglycerin double base propellant composition (cf. Figure 6)

[0009] There thus remains in the field of solid propellants a need for stabilizers allowing long term stabilization of nitrocellulose-based propellants, fulfilling at least STANAC 4582 (Ed. l ) and which do not produce carcinogenic and/or mutagenic by-products. The present invention proposes a family of stabilizers fulfilling both above requirements. These and other advantages of the present invention are presented in continuation.

Summary of the invention

[0010] The present invention is defined in the appended independent claims. Preferred embodiments are defined in the dependent claims. In particular, the present invention concerns a nitrocellulose-based propellant composition comprising:

(a) a nitrate ester based propellant comprising nitrocellulose; and

(b) a stabilizer consisting of trialkoxy benzene of general formula (I), (II) or a mixture thereof,

(I) (ID

Wherein R¹ , R² and R³ are same or different and represents G-s alkyl unsubstituted or substituted with an alkoxy group.

[001 1] Unless otherwise specified, the expression "substituted" and derivatives thereof is to be construed as any -H in a molecule may be substituted by any of an alkyl, alkene, or an aromatic ring. The alkyl or alkene is preferably CI -C9, more preferably C2-C4. A propellant composition is considered as being a "nitrocellulose-based propellant composition" if it comprises at least 40 wt.% nitrocellulose, based on the total weight of the composition. An "alkoxy group" refers to any alkyl group, R, singular bonded to oxygen as -R-0-. [0012] The nitrate ester based propellant may be a single base propellant consisting of nitrocellulose alone or, alternatively, may be a double or higher base propellant comprising nitrocellulose in combination with at least one blasting oil and/or at least one energetic additive. As known by a person skilled in the art, a blasting oil is herein defined as an energetic compound obtained by nitration of a polyol such as glycerol, glycol, diethylene glycol, triethylene glycol, metriol... The obtained nitrate is most of the time heavy, oily and presents explosive properties. Nitroglycerin is probably the most common blasting oil employed in the industry. The term "NOx" is used herein in its generally recognized sense, as a generic term for mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide). In a preferred embodiment the blasting oil comprises at least a nitrated polyol, said nitrated polyol is obtained by nitration of polyol selected from a group consisting of glycerol, glycol, diethylene glycol, triethylene glycol and metriol, preferably glycerol.

[001 3] An energetic additive according to the present invention ; like blasting oils, are used to enhance the blasting power of nitrocellulose. Energetic additives can be an energetic plasticizer or an explosive. Examples of energetic plasticizers comprise nitramines such as butyl-NENA or dinitrodiazaalkane (DNDA). Examples of explosives suitable for use as energetic additives include RDX, HMX, FOX7, FOX1 2, CL20.

[0014] The preferred stabilizers of the present invention are capable of reacting with radical alkoxy groups formed by degradation of the nitrate ester to form a first by-product capable of reacting with NOx formed by degradation of the nitrate ester to form a second by-product comprising no NNO groups. It is even more preferred if the second by-product is itself also capable of reacting with radical alkoxy groups or with NOx formed by degradation of the nitrate ester forming third by-products. Optimally, the third and subsequent by-products are also capable of reacting with such radical alkoxy groups or with NOx, thus substantially prolonging the efficacy of the stabilizer.

[001 5] It is preferred that the blasting oil comprises at least a nitrated polyol, said nitrated polyol is obtained by nitration of polyol selected from a group consisting of glycerol, glycol, diethylene glycol, triethylene glycol and metriol, preferably glycerol. In a preferred embodiment, R¹ and R³ in formulae (I) or (II) represent CH3. It is further preferred that R² represents one of:

•

• a polymeric alkoxylated chain, preferably endcapped with a benzene of formula (I) of the type,

CH3O

OCH,

H wherein n is comprised between 1 and 50, preferably between 1 0 and 25 , yielding a stabilizer of formula (la), (lb), or (Ic), respectively:

(lb)

[0016] The trialkoxy benzene stabilizer may be present in the composition in an amount comprised between 0.1 and 5.0 wt. , preferably between 0.2 and 2.0 wt. , more preferably between 0.5 and 1 .5 wt.%, with respect to the total weight of the composition. The nitrate ester based propellant may comprise nitrocellulose only, thus defining a single base propellant or, alternatively, it may comprise a blasting oil, such as nitroglycerin, to define a double base propellant. A double base propellant according to the present invention preferably comprises not more than 60 wt.% nitroglycerin, and preferably comprises between 5 and 45 wt.%, more preferably between 7 and 22 wt.% nitroglycerin, with respect of the total weight of nitrate ester based propellant.

[001 7] The propellant compositions of the present invention should fulfil the stability requirements defined in STANAC 4582 (Ed. l ), namely generating less than 350 μ\Λ/ / g of heat flow for at least 3.43 days at a temperature of 90°C. Many propellant compositions of the present invention can achieve much better that this and may remain stable for over 30 days at 90°C.

[0018] Beside a nitrate ester based propellant and a stabilizer, the propellant compositions of the present invention may comprise additives. In particular, they may comprise one or more of the following additives:

(a) a potassium salt, such as potassium nitrate (KNO3) or sulphate (K2SO4), preferably in an amount comprised between 0.01 and 1 .5 wt. %;

(b) combustion moderators such as phthalates, CI and citrate derivatives,

preferably in an amount comprised between 1 .0 and 1 0.0 wt. %;

(c) an anti-static agent such as graphite, preferably in an amount comprised between 0.01 and 0.5 wt. %; (d) calcium carbonate, preferably in an amount comprised between 0.01 and 0.7 wt. ,

(e) anti-coppering agent such as bismuth or tin oxides, 0.01 to 1 .5 wt.%.

Wherein the wt.% are expressed in terms of the total weight of the propellant composition. [0019] The present invention also concerns the use of a trialkoxy benzene stabilizer of formula (I), (II) or a mixture thereof as defined above, for stabilizing a nitrocellulose-based propellant composition. The stabilizer is preferably trimethoxy benzene of formula (I).

Brief description of the Figures

[0020] For a fuller understanding of the nature of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings in which:

Figure 1 : shows a reaction of spontaneous decomposition of nitrocellulose with formation of free radicals and NOx.

Figure 2: shows assumed stabilization mechanisms of (a) akardite (Akll) and diphenylamine (DPA) (prior art), (b) a substituted trimethoxyphenol (prior art), and (c) trialkoxy benzene according to the present invention.

Figure 3 :. shows the normalized heat flow expressed in μ\Λ/ / g generated by a single base nitrocellulose propellant stabilized with various amounts of trimethoxy benzene of formula (I).

Figure 4:. shows the normalized heat flow expressed in μ\Λ/ / g generated by various nitrocellulose / nitroglycerin double base propellant compositions stabilized with trimethoxy benzene of formula (I)

Figure 5 : compares the normalized heat flow curves generated by a 90 wt.% nitrocellulose / 1 0 wt.% nitroglycerin double base propellant composition stabilized with trimethoxy benzene of formula (la) and with DPA according to prior art. Figure 6: compares the normalized heat flow curves generated by a 80 wt. nitrocellulose / 20 wt. nitroglycerin double base propellant composition stabilized with trimethoxy benzene of formula (la) and with 1 ,3,5-trimethoxy benzene according to prior art.

Detailed description of the invention

[0021] As illustrated in Figure 1 , degradation of nitrocellulose forms free oxide radicals (R-O ) and NOx. These degradation products are capable of reacting further with nitrocellulose, which can rapidly lead to an explosion of the nitrate ester based propellant due to excess heat generation. The most commonly used stabilizers are certainly akardite (Akll) and diphenyl amine (DPA) as illustrated in Figure 2(a). Akardite (Akll) when exposed to NOx, forms carcinogenic N-NO compounds as illustrated in reaction (A) of Figure 2(a). Simultaneously or sequentially, it dissociates upon exposure to heat to form diphenyl amine (DPA) following reaction (B) of Figure 2(a). Whether used directly as stabilizer, or present in the composition following heat dissociation (B) of akardite, diphenyl amine (DPA) stabilizes a propellant composition by the following mechanism. A free radical alkoxy group generated by the propellant abstracts the hydrogen of the amine group of DPA to form a stable compound (ROH) (cf. reaction ® of Figure 2(a)). The radical formed on the amine can react with a NOx to form stable N-nitrosodiphenylamine (cf. reaction @ of Figure 2(a)). The NNO group of N-nitrosodiphenylamine is, however, carcinogenic and should be avoided for safety reasons. Triphenylamine has been tested in the past in order to prevent formation of NNO groups, but with little success in stabilization properties. Hindered phenols as illustrated in Figure 2(b) effectively react with free oxide radicals (R-O ) but forming stable components which are unlikely to further react with NOx (cf. reaction ® of Figure 2(b)). The efficacy of such stabilizers is limited to short periods of time only because of rapid phenols depletion. [0022] A trialkoxy benzene stabilizer as used in the present invention has one of the following general formulae (I) or (II):

Wherein R¹ , R² and R³ are same or different and represent alkyl unsubstituted or substituted with an alkoxy group.

R¹ and R³ in formulae (I) or (II) preferably represent CH₃. More preferably, R² represents one of:

•

a polymeric alkoxylated chain, preferably endcapped with a benzene of formula (I) of the type,

CH3O

OCH,

H wherein n is comprised between 1 and 50, preferably between 1 0 and 25 , yielding a stabilizer of formula (la), (lb), or (lc), respectively:

[0023] with n comprised between 1 and 50, preferably between 1 0 and 25. A stabilizer of formula (la) is particularly preferred.

[0024] Not wishing to be bound by any theory, it is believed that a stabilizer as defined in the present invention reacts as illustrated in Figure 2(c). It is believed that the donating groups, i.e., the alkoxy groups in general and, methoxy gourps in particular, are able to sufficiently activate the aromatic ring at o and p positions. It is strongly suspected that several intermediate or side reactions not represented in Figure 2(c) occur simultaneously with the reactions shown therein, but it is believed that Figure 2(c) illustrates the main stabilization mechanism observed with stabilizers according to the present invention. The long term stabilization obtained with stabilizers according to the present invention is attributed to a sequential reaction cascade, wherein the trialkoxy benzene stabilizer of the present invention is capable of reacting with radical alkoxy groups or NOx formed by degradation of the nitrate ester to form a first by-product capable of reacting with another radical alkoxy group or NOx formed by degradation of the nitrate ester to form a second by-product comprising no NNO groups. In a preferred embodiment, the second by-product is capable of reaction with radical alkoxy groups or with NOx formed by degradation of the nitrate ester, forming a third component by-product which is stable. [0025] The propellant composition may be a simple base propellant, wherein the nitrate ester propellant consists of nitrocellulose only. Figure 3 illustrates the stability of a simple base propellant composition stabilized with various amounts of a stabilizer (la) according to the present invention. [0026] Alternatively, the propellant composition may be a double base propellant, wherein nitrocellulose is combined with a blasting oil and/or at least one energetic additive. The most common blasting oil is nitroglycerin. Figure 4 illustrates the stability of a various double base propellant compositions wherein nitrocellulose is combined with 1 0, 20, and 40 wt.% nitroglycerin, a commonly used blasting oil, and stabilized with 0.8 wt.% of a stabilizer of formula (la). Blasting oils preferably comprise at least a nitrated polyol, said nitrated polyol being obtained by nitration of polyol selected from a group consisting of glycerol, glycol, diethylene glycol, triethylene glycol and metriol, preferably glycerol. Nitroglycerin is a preferred blasting oil. Energetic additives, on the other hand, can be an energetic plasticizer selected from the group of nitramines such as butyl-NENA, dinitrodiazaalkane (DNDA), or an explosive such as RDX, HMX, FOX7, FOX1 2, CL20. A double base propellant composition according to the present invention preferably comprises a nitrate ester based propellant comprising not more than 60 wt.% blasting oil (such as nitroglycerin) or energetic additive with respect to the total weight of nitrate ester based propellant. More preferably, it comprises between 5 and 45 wt.%, most preferably between 7 and 22 wt.% blasting oil or energy additive, with respect of the total weight of nitrate ester based propellant.

[0027] Figure 6 compares the normalized heat flow curves generated by a 80 wt.% nitrocellulose / 20 wt.% nitroglycerin double base propellant composition stabilized with trimethoxy benzene of formula (la) and with 1 ,3, 5-trimethoxy benzene as disclosed in CB2092563 and US4299636. It can be seen that the composition stabilized with l ,3,5- trimethoxy benzene (dashed line) does not fulfil the requirements of STANAC, with a normalized heat flow rising above 350 μ\Λ/ / g in the course of the second day of testing, reaching values of about 400 μ\Λ/ / g. By contrast, the normalized heat flow of a similar composition stabilized with 1 ,2,3-trimethoxybenzene according to formula (la) of the present invention (solid line) remains below 1 50 μ\Λ/ / g during 3.43 days of STANAC test and long beyond.

[0028] A propellant composition according to the present invention comprises a trialkoxy benzene stabilizer of formula (I), (II) or a mixture thereof, preferably in an amount comprised between 0.1 and 5.0 wt. , more preferably between 0.2 and 2.0 wt. , most preferably between 0.5 and 1 .5 wt. , with respect to the total weight of the composition. Figure 3 illustrates the stability of a single base propellant composition stabilized with various amounts of a stabilizer according to formula (la) comprised between 0.25 and 2.00 wt.% and Figure 4 illustrates the stability of various double base propellant compositions stabilized with 0.8 wt.% of a stabilizer according to formula (la). Although it is generally considered that a propellant composition cannot be satisfactorily stabilized with less than 1 wt.% stabilizer, it can be seen in Figures 3&4 that excellent stability results are already obtained with as little as 0.8 wt.% and less of a stabilizer of formula (la). [0029] Beside a nitrate ester based propellant and a stabilizer, a propellant composition according to the present invention may comprise additives. In particular, it may comprise one or more of the following additives:

(a) a potassium salt, such as potassium nitrate (KNO3) or sulphate (K2SO4),

preferably in an amount comprised between 0.01 and 1 .5 wt. %;

(b) combustion moderators such as phthalates, centralite and citrate derivatives, preferably in an amount comprised between 1 .0 and 1 0.0 wt. %;

(c) an anti-static agent such as graphite, preferably in an amount comprised

between 0.01 and 0.5 wt. %;

(d) calcium carbonate, preferably in an amount comprised between 0.01 and 0.7 wt. %,

(e) anti-coppering agent such as bismuth or tin oxides, 0.01 to 1 .5 wt.%.

Wherein the wt.% are expressed in terms of the total weight of the propellant composition. [0030] Table 1 lists an example of propellant composition according to the present invention.

Table 1 : typical propellant compositions according to the present Invention

EXPERIMENTAL TESTS

[0031] STANAC 4582 (Ed. 1 ) of March 9, 2007 entitled "Explosives, nitrocellulose-based propel lants, stability test procedure and requirements using heat flow calorimetry", defines an accelerated stability test procedure for single-, double-, and triple base propellants using heat flow calorimetry (HFC). The test is based on the measurement of the heat generated by a propellant composition at a high temperature. Fulfilment of the STANAC 4582 (Ed. l ) test qualifies a propellant composition for a 1 0 year stability at 25°C.

[0032] A sample of propellant composition is enclosed in a hermetically sealed vial and positioned in a heat flow calorimeter having a measuring range corresponding to 1 0 to 500 μνν/g. The sample is heated and maintained at a constant temperature of 90°C for the whole duration of the test and the heat flow is measured and recorded. A heat flow not exceeding 350 μ\Λ/ / g for a period of 3.43 days at 90°C is considered to be equivalent to at least 1 0 years of safe storage at 25°C. The graphs of Figures 3 to 5 are plots of such measurements. The full scale of the ordinate (normalized heat flow) corresponds to a value of 350 }\N / g not to be exceeded according to STANAC 4582 (Ed. l ), and the vertical straight line indicates 3.43 days. The initial heat flow peak comprised within the shaded area of the graphs of Figures 3 to 5 is ignored as it is not representative of any specific reaction or phase transformation of the propellant composition, provided it does not exceed an exotherm of 5 J.

[0033] Figure 3 shows the results of the stability tests carried out on a single-base nitrocellulose-based propellant stabilized with various amounts of a stabilizer according to formula (la) comprised between 0.25 and 2.00 wt.%. It can be seen that even with as little as 0.25 wt.% stabilizer the heat flow never exceeds 1 50 μ\Λ/ / g for 3.43 days, when STANAC 4582 (Ed. l ) requires to maintain the heat flow below 350 μ\Λ/ / g (full scale of the ordinate). The time scale of the graph of Figure 3 extends to 5 days, and it can be seen that even after 5 days, the exotherm curve remains very stable at values comprised between about 1 00 and 1 40 μJ / g for all the stabilizer contents tested.

[0034] Figure 4 shows the results of the stability tests carried out on double-base nitrocellulose-based propellants containing various amounts of nitroglycerin (1 0, 20, and 40 wt.%) stabilized with 0.8 wt.% of a stabilizer of formula (la). It can be seen that the values reached by the exotherm increases with the amount of nitroglycerin present in the propellant composition. In all cases, however, including a double-base propellant composition comprising 40 wt.% nitroglycerin the exotherm nevers exceeds about ^ 60 ^^N / g during a period of at least four days, well below the maximum level of 350 μ\Λ/ / g (= full scale of the ordinate) defined by STANAC 4582 at a temperature of 90°C.

[0035] Figure 5 compares the stability of a double-base propellant composition (90 wt.% nitrocellulose and 1 0 wt.% nitroglycerin) stabilized with, on the one hand, 0.8 wt.% of a stabilizer of formula (la) according to the present invention (solid line) and, on the other hand, with 0.7 wt.% of diphenyl amine (DPA) of the prior art (dashed line). It can be seen that both stabilizers (Stabilizer (la) and DPA) fulfil the requirements of STANAC 4582 (Ed. l ), The stabilizer (la) according to the present invention is, however, advantageous over DPA because,

(a) After a little more than two days at 90°C, the exothermic curve associated with the trimethoxy benzene stabilizer of formula (la) levels out at a value of about Ι ΟΟ μνν / g, whilst the curve associated with DPA reaches a level of about 1 50 μ\Λ/ / g, i.e. , 50% higher than the former.

(b) Contrary to DPA, stabilizers according to the present invention do not generate any N-NO carcinogenic by-product upon their stabilization activity.

(c) DPA curve (dashed line) shows after two days a sharp peak stabilizing in a plateau at higher heat flow values (about ^'\ 50 }\N / g). By contrast, no discontinuity in the heat flow can be identified with stabilizer (la) over 3.5 days, and even over 5 days.

[0036] The propellant com positions of the present invention mark the begi nning of the use of a new generation of stabilizers which can be referred to as "green stabilizers," which com bine efficient, long term stability of nitrocellulose-based propellants without formation of any detectable amounts of carcinogenic or mutagenic by-products.

Claims

1 . Nitrocellulose-based propellant composition comprising:

(a) a nitrate ester based propellant comprising nitrocellulose; and

(b) a stabilizer consisting of a trialkoxy benzene of general formula (I), (II) or a

2. Propellant composition according to claim 1 , wherein a nitrate ester based propellant consisting of nitrocellulose alone (single base) or in combination at least with a blasting oil (double or higher base).

3. Propellant composition according to claim 1 or 2, wherein the stabilizer trialkoxy benzene is a substance capable of reacting with radical alkoxy groups formed by degradation of the nitrate ester or with NOx to form a first by-product capable of reacting with NOx or a second radical alkoxyformed by degradation of the nitrate ester to form a second by-product comprising no NNO groups.

4. Propellant composition according to claim 3, wherein the second by-product is capable of reaction with radical alkoxy groups or with NOx formed by degradation of the nitrate ester, preferably forming a third and subsequent by-products which is stable.

5. Propellant composition according to any one of preceding claims, wherein the blasting oil comprises at least a nitrated polyol, said nitrated polyol is obtained by nitration of polyol selected from a group consisting of glycerol, glycol, diethylene glycol, triethylene glycol and metriol, preferably glycerol.

6. Propellant composition according to any of the preceding claims, wherein both R¹ and R³ represent CH₃.

7. Propellant composition according to claim 6, wherein the trialkoxy benzene consists of general formula (I).

8. Propellant composition according to claims 6 and 7, wherein R² represents one of:

H

H H

9. Propellant composition according to any one of preceding claims, wherein the trialkoxy benzene stabilizer is present in the composition in an amount comprised between 0.1 and 5.0 wt. %, preferably between 0.2 and 2.0 wt. , more preferably between 0.5 and

I .0 wt. ,with respect to the total weight of the composition.

1 0. Propellant composition according to any one of preceding claims, wherein the nitrate ester based propellant comprises not more than 60 wt. % nitroglycerin, and preferably comprises between 5 and 45 wt. %, more preferably between 7 and 22 wt. % nitroglycerin, with respect of the total weight of nitrate ester based propellant.

I I . Propellant composition according to any one of preceding claims, having a stability measured according to STANAC 4582 (Ed. 1 ) at a temperature of 90 °C without heat generation above 350 μνν/g of at least 3.43 days, preferably of at least 5 days.

1 2. Propellant composition according to any one of the preceding claims further comprising one or more of the following additives:

(a) a potassium salt, such as potassium sulphate (K2SO4), preferably in an amount comprised between 0.001 and 1 .5 wt. ;

(b) combustion moderators such as dibutylphthalates, CI and ethyl citrate derivatives, preferably in an amount comprised between 1 .0 and 1 0.0 wt. ; (c) an anti-static agent such as graphite, preferably in an amount comprised between 0.01 and 0.5 wt. ;

(d) calcium carbonate, preferably in an amount comprised between 0.001 and 0.7 wt. ,

(e) anti-coppering agent such as Bismuth or Tin oxides, 0.01 to 1 .5 wt.%.

Wherein the wt. % are expressed in terms of the total weight of the propellant composition. 1 3. Use of a trialkoxy benzene consisting of general formula (I), (II) or a mixture thereof

(I) (ID for stabilizing a nitrate ester based propellant comprising nitrocellulose, wherein R¹ , R² and R³ are same or different and represents G-s alkyl unsubstituted or substituted with an alkoxy group.

1 4. Use according to claim 1 3, wherein the component consists of general formula (I), and R¹ and R³ represent CH₃.

1 5. Use according to claim 1 4, wherein the component is of formula (la), (lb) or (lc):,

(la)

Ch O Ch O

(lc)

0CH₃ 0CH₃ with n comprised between 1 and 50, preferably between 10 and 25.