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1

Influence of the Prepolymer Structure of Glycidyl Azide Polymer (GAP) on Binder Properties – Some Theoretical Considerations

Gettwert Volker Juergen, Keicher Thomas

Central European Journal of Energetic Materials

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2024

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Vol. 21, no. 1

53--67

EN

Glycidyl azide polymer (GAP) is a promising energetic binder for solid propellants, but it suffers from poor mechanical properties compared to hydroxyl-terminated polybutadiene (HTPB). This paper reviews the main factors affecting the mechanical properties of GAP-based binders, such as molecular weight and functionality, and discusses some possible strategies on how it could be improved. The equation of Carother is used for the theoretical consideration of the functionality of the GAP prepolymer.

2

Zwiększenie energetyczności α, ω- dihydroksypolibutadienu (HTPB) wykorzystywanego w stałych heterogenicznych paliwach rakietowych

Prasuła Piotr, Sztejter Beata, Kasprzak Piotr, Chmielarek Michał

Problemy Techniki Uzbrojenia

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2022

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R. 51, z. 161

37--59

PL

Stałe heterogeniczne paliwa rakietowe (SHPR) cieszące się dużą popularnością oraz szerokim zastosowaniem w przemyśle zbrojeniowym (silniki napędowe pocisków kierowanych oraz przeciwlotnicze rakiety dalekiego, bliskiego i średniego zasięgu) posiadają inertne lepiszcza, które znacząco wpływają na końcowe parametry użytkowe ładunków napędowych. W pracy przeprowadzono modyfikację popularnego lepiszcza HTPB polegającą na wprowadzeniu grup azydkowych do łańcucha polimeru podczas trzech różnych syntez. Otrzymano związki o różnej zawartości grup eksplozoforowych, które zostały poddane ocenie kompatybilności z podstawowymi składnikami SHPR: chloranem(VII) amonu i adypinianem dioktylu. Następnie przeprowadzono wstępne badania aplikacyjne otrzymanej pochodnej HTPB, wykazując potencjał otrzymanego energetycznego polimeru oraz możliwości jego zastosowania jako lepiszcza w stałych heterogenicznych paliwach rakietowych.

EN

Solid heterogeneous rocket propellants (SHRP), which are very popular and widely used in the armaments industry (guided missile propulsion engines and long-range, short-range and medium-range anti-aircraft rockets) have inert binders that significantly affect the final performance parameters of propulsion charges. In this study, the popular HTPB binder was modified by introducing azide groups into the polymer chain during three different syntheses. Compounds with different content of explosive groups were obtained and tested for compatibility with the essential SHRP components: ammonium chlorate(VII) and dioctyl adipate. Then, preliminary application tests of the obtained HTPB derivative were carried out, showing the potential of the obtained energetic polymer and the possibility of its use as a binder in solid heterogeneous rocket fuels.

3

Effects of Azide-Hydroxyl-Terminated Polybutadiene on the Properties of Solid Heterogeneous Rocket Propellants

Chmielarek Michał, Sztejter Beata, Kasprzak Piotr, Prasuła Piotr

Central European Journal of Energetic Materials

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2022

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Vol. 19, no. 4

392--407

EN

Solid heterogeneous rocket propellants (SHRPs) are increasingly used, mainly in the armaments industry. SHRPs are usually based on an inert binder - hydroxy-terminated polybutadiene (HTPB). The use of an inert polymer reduces the performance of the propellants, therefore this paper presents the preparation of propellants with different contents of the previously synthesized azide-HTPB and the results of research on their properties, such as density, calorific value, mechanical and thermal parameters and burning rate. An improvement in the tested parameters was noted in comparision to the properties of propellants without azide-HTPB. An increase in the calorific value of the propellants with the addition of azide-HTPB was noted, with a simultaneous reduction in the amount of oxidant in the SHRP composition. Azide-HTPB as a rocket propellant component has a significant impact on the mechanical properties of the propellant and also increases the propellant’s burning rate and the maximum pressure in the motor chamber.

4

Synthesis and Curing of Allyl Urethane NIMMO-THF Copolyether with Three Functional Groups as a Potential Energetic Binder

Wang Xiaochuan, Li Ping, Lu Xianming, Mo Hongchang, Xu Minghui, Liu Ning, Shu Yuanjie

Central European Journal of Energetic Materials

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2020

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Vol. 17, no. 1

141--163

EN

A tri-functional NIMMO-THF copolyether (T-NT) was synthesized by polymerization of 3-nitratomethyl-3-methyloxetane (NIMMO) and tetrahydrofuran (THF) in the presence of trimethylolpropane and catalyzed by BF3·OEt2. The allyl urethane NIMMO-THF copolyether with three functional groups (AUT-NT) was synthesized from tri-functional NIMMO-THF copolyether and allyl isocyanate. The polymer was characterized by FT-IR, 1H NMR, and 13C NMR. Furthermore, an elastomer that was prepared from allyl urethane NIMMO-THF copolyether with three functional groups and trimethylisophthalodinitrile oxide (TINO) had satisfactory mechanical properties and good thermal stability. The elastomer is expected to be used in composite solid propellants and polymer-bonded explosives (PBX).

5

Synthesis of High-Energy Polymer : Glycidyl Azide Polymer (GAP)

Kasztankiewicz A., Kogut A., Jankiewicz M., Maksimowski P.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2018

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Vol. 9, Nr 2 (32)

59--72

EN

Glycidyl Azide Polymer (glycidyl polyazide) (GAP) is one of the best known energetic binders, applicable as a component increasing a calorific value of rocket propellants. In this article, a synthesis of GAP is described allowing to obtain a polymer of different molecular masses. The change of a molecular mass can influence on properties of the obtained compounds. The synthesis was carried out according to an active monomer mechanism. The obtained products were characterized using such methods as FTIR, GPC, MALDI-ToF, TG, and NMR.

PL

Poliazydek glicydylu (GAP) jest jednym z najbardziej znanych lepiszczy energetycznych, znajdujących zastosowanie jako składnik zwiększający kaloryczność paliw rakietowych. W artykule opisano syntezę GAP-u pozwalającą na uzyskanie polimeru o różnych masach cząsteczkowych. Zmiana masy cząsteczkowej może wpływać na właściwości otrzymanych związków. Syntezę prowadzono według mechanizmu aktywnego monomeru. Otrzymane produkty scharakteryzowano z wykorzystaniem takich technik, jak: FTIR, GPC, MALDI-ToF, TG i NMR.

6

Synthesis, Characterization and Compatibility Studies of Poly(DFAMO/NIMMO) with Propellant and PBX Ingredients

Li H., Yang Y., Pan J., Wang W., Pan R., Zhu W.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

85--99

EN

Oxetane-based polymers substituted with difluoroamino groups can be used as energetic binders in propellants and polymer-bonded explosives (PBXs). As a novel candidate, poly(3-difluoroaminomethyl-3-methyloxetane/3-nitratomethyl-3-methyloxetane) (PDN) was synthesized and its structure was established. Thermogravimetry (TG) and differential scanning calorimetry (DSC) were employed to investigate its thermal decomposition behaviour. The compatibility between PDN and some common ingredients of propellants and PBXs was evaluated by the DSC method. PDN with good thermal stability was synthesized via a cationic solution polymerization process. Additionally, it has improved compatibility with cyclotetramethylenetetranitramine (HMX), carbon black (C.B.) and lead carbonate (PbCO3) compared with homopoly(3-difluoroaminomethyl-3-methyloxetane) (PDFAMO). PDN could be used as a promising difluoroamino energetic binder in the future.

7

Optimization of Curing Agents for Linear Difunctional Glycidyl Azide Polymer (GAP), with and without Isocyanate, for Binder Applications

Agawane N. T., Soman R. R., Wagh R. M., Athar J., Talawar M.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

206--222

EN

Glycidyl Azide Polymer (GAP) is one of the most potential energetic binders for rocket propellants and gas generator compositions. In the present paper GAP of molecular weight (Mn) ~2000 was cured with a mixture of di- and tri-isocyanates without a cross linker. The curing profile and time of curing was recorded using a rheometer. The minimum curing time was observed for samples cured with Desmodour N-100 alone, whereas the maximum curing time was observed for samples cured with a mixture of Desmodour N-100 and Isophorone Diisocyanate (IPDI) (1:1 w/w). It was observed that all of the samples cured well and were void or bubble free. The mechanical properties data showed that the tensile strength (TS) of GAP cured with Desmodour N-100 alone was 1.19 kgf/cm2, which is a minimum, while the maximum TS (3.66 kgf/cm2) was achieved with a mixture of N-100 and 4,4’methylenebis(phenylisocynate) (MDI). The percent elongation for a sample cured with Desmodour N-100 was 160, and was reduced to 64.27 when a mixture of MDI and N-100 was used. In order to study the curing of GAP without an isocyanate, GAP diol was cured with hexanediol di-acrylate. GAP was also cured with an alkyne-based curing agent i.e. bis-propargyl succinate (BPS), which showed improved curing. Comparative thermal studies of GAP cured with isocyanate and acrylate was carried out. Differential Scanning Calorimetry (DSC) and Simultaneous Thermal Analysis (STA) curves for all of the cured samples were recorded in order to study and compare the thermal decomposition behaviour of the cured GAP. Isocyanate cured GAP exhibited a single stage decomposition, with larger heat output. Acrylate cured GAP exhibited a two stage decomposition. Finally, a mixture of IPDI and Desmodour N-100 was selected for curing of GAP. Accordingly, curing was carried out and was tested in a small ballistic evaluation motor (BEM) to observe the combustion behaviour and burn rate. From the pressure-time profile it was found that this composition gave smooth burning with a pressure of ~3 kg/sec2 for 7 seconds of burn.

8

The Elimination of NO2 from Mixtures of the Nitramines HMX, RDX and CL20 with the Energetic Binder Glycidyl Azide Polymer (GAP) - A Computational Study I

Bohn M. A., Hammerl A., Harris K., Klapötke T. M.

Central European Journal of Energetic Materials

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2005

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Vol. 2, nr 2

29-44

EN

The energetic plasticizer glycidyl azide polymer (GAP) is used for new types of rocket propellants which are formulated with the objective of achieving higher burning rates. The reaction profiles for several possible initial steps in the decomposition of mixtures of the nitramines octahydro-1,3,5,7-tetranitro-1,3,5,7- tetrazacyclooctane (HMX), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and hexanitrohexaazaisowurtzitane (CL20) with a monomer of GAP-diol have been examined computationally. Comparison of the activation energies for the decomposition of the mixtures with those for the decomposition of the isolated nitramines shows that the presence of GAP-diol decreases the activation energy for the elimination of NO2 by at least to 8 kJ mol-1 for CL20, wheras the NO2 elimination from HMX is only favored by 1 kJ mol-1 and NO2 elimination from RDX is inhibited in the presence of GAP-diol by 2 kJ mol-1.

9

Further Decomposition Pathways of Mixtures of the Nitramines HMX, RDX and CL20 with the Energetic Binder Glycidyl Azide Polymer (GAP) - A Computational Study II

Bohn M. A., Hammerl A., Harris K., Klapötke T. M.

Central European Journal of Energetic Materials

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2005

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Vol. 2, nr 3

3-19

EN

The energetic plasticizer glycidyl azide polymer (GAP) is used for new types of rocket propellants which are formulated with the objective of achieving higher burning rates. While the homolytic fission of an N-NO2 bond, which we discussed previously, is energetically favored as the initial decomposition step, experiments show that the decomposition of mixtures of the nitramines octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and hexanitrohexaazaisowurtzitane (CL20) with a monomer of GAP-diol is more complex. Therefore we investigated further possible decomposition pathways. Comparison of the calculated activation energies for the decomposition of the mixtures with those for the decomposition of the isolated nitramines shows that the presence of GAP-dioldecreases the activation energies of certain decomposition steps by up to 20 kJ mol-1. GAP-diol facilitates the decomposition of CL20 and RDX to a larger extent than the decomposition of HMX. However, the investigated decomposition pathways of GAP-diolwere inhibited by the presence of the nitramines.