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Modification of the burning layer of nitrocellulose powders with liquid nitroesters

Cieślak Katarzyna, Gołofit Tomasz, Tomaszewski Waldemar, Chmielarek Michał, Maksimowski Paweł, Pawłowski Wojciech

Materiały Wysokoenergetyczne

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2021

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T. 13

48--58

EN

The article describes the use of liquid nitroesters (nitroglycerine, dinitrodiethyleneglycol and dinitrotriethyleneglycol) as modifiers of the burning layer of nitrocellulose powders. The properties of the modified powder were determined and compared with those of the base powder. The modification process did not change the powder’s geometry. The increase in heat of combustion is obtained by using a larger amount of nitroglycerine (from 6 to 8 phr) or by using dinitrotriethyleneglycol without an inert polymer. By using the appropriate composition and type of modifiers, a similar intensity of gas formation was obtained for different nitroesters. A faster loss of the stabilizer was observed for the powders with nitroglycerine. All modified powders will be stable for 10 years of storage at 25 °C.

PL

W artykule opisano zastosowanie ciekłych nitroestrów (nitrogliceryny, dinitrodietylenoglikolu i dinitrotrietylenoglikolu) jako modyfikatorów warstwy palnej prochów nitrocelulozowych. Określono właściwości prochów modyfikowanych i porównano je z prochem bazowym. Stwierdzono, że proces modyfikacji nie wpływa na zmianę geometrii prochów. Wzrost kaloryczności uzyskuje się przy zastosowaniu większej ilości nitrogliceryny (od 6 do 8 phr) lub zastosowaniu dinitrotrietylenoglikolu bez inertnego polimeru. Stosując odpowiedni skład i rodzaj modyfikatorów uzyskano zbliżoną intensywność powstawania gazów dla różnych nitroestrów. Dla prochów z nitrogliceryną zaobserwowano szybszy ubytek stabilizatora. Wszystkie modyfikowane prochy będą stabilne przez 10 lat składowania w temperaturze 25 °C.

2

Studies on the Effect of Nitrate Esters on the Properties of Advanced Energetic Propellants

Kumar Amit, Chavan Prakash V, Sadavarte Vaibhav S, Bhowmik Debdas, Mada S.S.N.M. Santosh, Pande Shrikant M.

Central European Journal of Energetic Materials

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2020

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Vol. 17, no. 3

384--407

EN

Propulsion designers all over the world are exploring the possibility of achieving higher performance by enhancing the energy of solid propellants. This can be achieved by replacing non-energetic ingredients with energetic ones or by replacing low density ingredients, particularly binders, with higher density ones, without affecting the processibility and ageing characteristics. The same has been attempted by using nitroglycerine (NG) and butanetriol trinitrate (BTTN) as plasticizers in propellant compositions. In the present study, NG and BTTN have been used in different plasticizer to polymer ratios (Pl/Po) and various parameters of each composition have been theoretically predicted. Three propellant compositions plasticized with NG, BTTN and a 1:1 combination of NG and BTTN, have been processed and analyzed for targeted properties. From the theoretical data, it was observed that there is a negligible increase in density impulse beyond a Pl/Po ratio of 2, apart from the higher density and calorimetric values of the NG-plasticized propellant; these plasticizers have a significant effect on the ballistic and mechanical properties. Another observation was that the elongation of BTTN and NG/BTTN (1:1) plasticized propellants is significantly higher at a low crosshead rate than NG-plasticized propellant, implying that the two former propellants have higher strain capabilities at low temperatures and can be used for missiles having long term low temperature storage requirements. Thermal decomposition studies have been carried out by DSC, and for each composition 5 distinct peaks were observed.

3

Synthesis of Novel Plasticizers Based on Poly(ε-caprolactone) and a Consideration of Their Influence on Nitroglycerine Migration in Double Base Solid Propellants

Abrishami F., Zarei A., Karegar M.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

150--161

EN

The presence of nitroglycerine (NG) in double base propellants and its subsequent migration from the propellant towards the inhibitor has always been an important issue. This problem may be considerably reduced by exploiting the concept of the introduction of electron donor sites to the propellant formulation. Plasticizers based on ε-caprolactone (ε-CL) were synthesized and characterized, and their activities for absorbing nitroglycerine were investigated. According to the results, the order of NG absorption is: PCL-(OH)2 < PCL-(OH)3< PCL-(OH)4< H-PCL. The observed differences in the properties of the plasticizers is discussed in terms of structural considerations. The data also showed that the hyperbranched poly(ε-caprolactone) (H-PCL) has the greatest effect in decreasing NG migration. Furthermore, the activity of these plasticizers in decreasing NG migration was also investigated by IR analysis.

4

Applicability of Non-isothermal DSC and Ozawa Method for Studying Kinetics of Double Base Propellant Decomposition

Matečić Mušanić S., Fiamengo Houra I., Sućeska M.

Central European Journal of Energetic Materials

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2010

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Vol. 7, nr 3

233-251

EN

In order to determine Arrhenius kinetic constants various experimental techniques and testing conditions have been used. Also, various kinetic approaches and data treatment procedures have been applied, resulting sometimes in considerable disagreement in the values of the kinetic parameters reported in literature. Kinetics of decomposition of DB propellants from non-isothermal DSC experiments using unhermetically closed sample pans, and effect of nitroglycerine (NG) evaporation on the kinetic results and kinetics of NG evaporation has been studied by isothermal thermogravimetry. It has been shown by experiments and numerical simulation that at slower heating rates and smaller sample mass NG may completely evaporate before DSC peak maximum, resulting in a higher values of the activation energy (173 kJ/mol). At faster heating rates and larger sample masses certain amount of NG still exists in the propellant at the peak maximum temperature, resulting in lower values of the activation energy (142 kJ/mol). The discontinuity point on the Ozawa plot is connected with the presence of NG in the propellant at DSC peak maximum temperature. This implies that the activation energy obtained using small samples and slow heating rates (173 kJ/mol) corresponds to the activation energy of decomposition of nitrocellulose from DB propellant.