Wyniki wyszukiwania - BazTech

1

Novel Composite Solid Propellant with High Resistance to Thermo-oxidative Degradation Reactions, Extended Shelf Life, and Superior Combustion Characteristics

Elbasuney Sherif, Elsaka Eslam, Elbeih Ahmed, Mostafa Hosam E.

Central European Journal of Energetic Materials

|

2021

|

Vol. 18, no. 1

143--158

EN

Hydroxy-terminated polybutadiene (HTPB) pre-polymer is the main constituent that is responsible for conferring high mechanical properties on composite solid propellants. However, HTPB pre-polymer suffers from oxidative degradation reactions that diminish its mechanical properties and shelf life. Composite solid propellant formulations based on an advanced stabilizing agent (anti-oxidant), Flexzone 6-H, with different curing ratios, 0.7 and 1.1, were developed via mixing and casting under vacuum. The developed formulations were subjected to artificial ageing using Vant Hoff,s formula by isothermal heating at 80 °C for up to 35 days. The change in strain with ageing was evaluated using a uni-axial tensile test. The propellant formulation based on a curing ratio of 0.7 demonstrated a high ageing resistance coefficient and an extended service life of up to 15 years, compared with 5 years for higher curing ratio. A propellant grain is considered to be ‘aged out’ at 30% reduction in its maximum strain value. The propellant formulation based on the 0.7 curing ratio exhibited superior thermal stability as it offered a minimum decrease in heat released after ageing using DSC. Additionally, the 0.7 curing ratio formulations exhibited a minimum change in burning rate and pressure exponent with ageing time. It can be concluded that the propellant with 0.7 curing ratio can maintain its mechanical, thermal, and ballistic properties with ageing.

2

Odpowiedzi wybranego złożonego paliwa rakietowego na obciążenia osiowe przy zróżnicowanych warunkach eksploatacyjnych

Zalewski R., Wolszakiewicz T.

Przemysł Chemiczny

|

2016

|

T. 95, nr 12

2452--2455

PL

Przeprowadzono badania wytrzymałościowe stałego paliwa rakietowego, wyznaczając krzywe siła-wydłużenie i naprężenie-odkształcenie. Zaprezentowano przykładowe wyniki badań doświadczalnych. Skupiono się na przeprowadzeniu prób jednoosiowych ze zróżnicowanymi prędkościami odkształcenia. Na podstawie uzyskanych doświadczalnie krzywych naprężenie-odkształcenie analizowano podstawowe parametry wytrzymałościowe badanego paliwa. Stwierdzono, że odpowiedzi mechaniczne paliwa różniły się w zasadniczy sposób zarówno co do charakteru rejestrowanych krzywych doświadczalnych, jak i wartości zarejestrowanych parametrów mechanicznych, w zależności od parametrów prowadzonych prób doświadczalnych.

EN

A solid propellant consisting of NH₄ClO₄, acrylonitrile-butadiene rubber, Al powder and dioctyl adipate was studied for uniaxial tension strength to determine the force-elongation and stress-strain curves. The propellant behaved as a typical viscoplastic material.

3

Investigation of Selected Ingredients of Composite Propellants Using DTA, SEM and Calorimetric Techniques

Szala M., Maranda A., Florczak B.

Central European Journal of Energetic Materials

|

2015

|

Vol. 12, no. 2

323--330

EN

The results of instrumental analysis of some ingredients of composite propellants are presented. Scanning electron microscopy, water calorimetry, elemental analysis and differential thermal analysis were used for characterization of ammonium chlorate(VII), aluminum-magnesium alloy and polybutadienes. The results showed that the oxidizer is in the form of spheroidal particles with a diameter 100-200 μm. Morphological analysis of the aluminum-magnesium alloy showed that the powder contains several fractions differing in size and shape. The predominant fractions are polygons with edges joined at acute angles. The grain size of the main fraction does not exceed 100-150 μm. The commercial polymers tested have similar elemental compositions and heats of combustion in oxygen. The standard enthalpies of formation calculated for the tested polymers have positive values and are in good agreement with literature data for non-cured HTPB.