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Preparation of Eutectic KNO3-NaNO3-mannitol Propellant
Summary: my usual method of eutectic KNO3-NaNO3-mannitol 35-30-35 propellant preparation is described.
KNO3:and NaNO3 reagent grade "pure for analysis". Moisture content 0.1-0.2%. They were not milled, crystals' size is about 0.5 mm.
Mannitol: pharmaceutical grade. Moisture content <0.1%.Crystals' size is about 0.5-1 mm.
50 g batch of thoroughly mixed unmilled KNO3-NaNO3-mannitol propellant mixture was placed in glass beaker and heated with temperature controlled heat plate. Temperature was measured with thermometer at the bottom of the beaker.
0 min, temperature 22C. The thickness of propellant layer is 4.5 cm
20 min, 150C, mannitol starts to melt. After this point magnetic stirrer was turned on.
25 min, 160C
30 min, 167C
35 min, 173C
40 min, 175C. It is clearly seen on the video, that liquid is intensively stirred, so its temperature is uniform. But significant part of nitrates is not solved yet at 175C.
45 min, 185C. complete dissolution of nitrates is achieved