ignites at 175 °C
175 °C ignites
PVN stands for polyvinyl nitrate, which means that this explosive is a continually linked chain of vinyl nitrate over and over again. The material appears to be a white powder if the polymer has fewer links in the molecule and as tough white strands if there are many links in the molecule. PVN was first prepared in Germany in 1929 by G. Frank and H. Kruger by nitrating polyvinyl alcohol. This laboratory procedure comes from, I believe, two French scientists named Chédin and Tribot who experimented on method of PVN preparation after WWII. The densities of PVN can vary depending on the density of the starting polyvinyl alcohol and range from a low 0.3 g/mL to 1.5 g/mL and corresponding detonation velocities of 2030 m/s to 6560 m/s. Obviously it is better to have a higher density product. This product has found a niche in military applications mainly in propellents, but not so much in industrial applications.
|acetic anhydride||250-mL beaker|
|ethyl alcohol||graduated cylinder|
|nitric acid||stirrer/stirring rod|
|sodium bicarbonate||vacuum desiccator|
Over a period of 1 hour, very slowly add 5 g of finely pulverized polyvinyl alcohol (containing 10% moisture) to 100 mL of 99-100 nitric acid in a 250-mL beaker. The beaker should be in a salt-ice bath to provide cooling during the addition. Maintain constant stirring and a temperature of -8 °C throughout the addition, and for an additional 2 hours after the addition. The resulting slurry is slowly drowned in an equal volume of ice water while vigorously stirring. Filter this to collect the white powder that should have formed, wash the powder with water until neutral to litmus, then put it in clean water for 12 hours. Repeat the washing and standing process using 95% ethyl alcohol, and again repeat the process with 12% sodium bicarbonate solution. Finally, the powder is washed with water until neutral to litmus, dried in the open air, then in a vacuum desiccator. The yield is about 96%. You will need a graduated cylinder for measuring liquids, a stirring rod or magnetic stirrer for mixing, and a thermometer to monitor the temperature.
It may be possible to increase the nitration yield by adding the polyvinyl alcohol to acetic anhydride first and using more nitric acid, the procedure is followed as above.
Here are the formulas for WC846 and M9 propellants:
|82% PVN||57.75% PVN|
|10.2% nitroglycerin||40.0% nitroglycerin|
|0.7% dinitrotoluene||1.50% potassium nitrate|
|6.1% dibutylphthalate||0.75% ethyl centralite|
|1.0% diphenylamine||0.50% ethyl alcohol|
Lab Skills|Lab Equipment|Safety|Rogue Science|Links|What’s New|Contact Me|Disclaimer