Films of nitrocellulose (NC), glycidyl azide polymer (GAP), and nitroglycerine (NG) have been evaluated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, dynamic mechanical analysis (DMA), and tensile testing. The SEM micrographs demonstrate that, even at low GAP concentration, a portion of GAP will coalesce into spherical domains due to a saturation effect. This is related to the inability of higher molecular weight GAP to effectively situate itself between NC polymer chains. The addition of a small fraction of lower molecular weight NG completely changes this behavior. DMA confirms that two transitions are present and can be attributed to a plasticizer rich phase (β), a polymer rich phase (α) and that NC plasticized with GAP is in accordance with the Gordon‐Taylor equation. Tensile results show that the addition of a small fraction of NG to a NC/GAP based‐formulation increases elongation at break to values similar to that of the NC/NG base formulation. The combination of these two plasticizers, GAP and NG, allows for the plasticization of NC at significantly lower environmental and human toxicity levels.
The performance of the extruded cord geometry of nitrocellulose (NC) propellants plasticized by glycidyl azide polymer (GAP) and nitroglycerine (NG) has been evaluated using both closed and erosion vented vessel techniques in order to obtain the linear burning rate and the relative erosivity of these propellants. The closed vessel experiments performed at −46, 21 and 63 °C demonstrate that the measured maximum pressure is in accordance with the calculation obtained using the CHEETAH V2 thermochemical code. From the closed vessel analysis, the linear burning rates show that it is on average 89±3 % that of the 21 °C propellant when fired at −46 °C. and 112±4 % when fired at 63 °C. The addition of either GAP or NG increases the linear burning rate when compared to the neat NC formulation. Relative erosion data obtained in the erosion vented vessel are in agreement with the Arisawa‐Kimura models and it is found that the ratio of CO/CO2 concentration in combustion gases is a better erosivity indicator than N2/CO ratio.
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