Recovering of components from plastic bonded propellants
|Waste management 17 (1998), Nr.2/3, S.175-185|
|Fraunhofer ICT ()|
In order to recover the components of so-called "plastic-bonded propellants" (e.g., cryst. energetic materials bonded in a chem. three-dimensional crosslinked polyurethane matrix), the polyurethane matrix is broken solvolytically with water and alk. water (0.05 N-0.5 N NaOH) at 130-170.degree.. Using a model rocket propellant, consisting of a polyether polyol mixt. (Lupranol 1000/2021) cured with Desmodur T80 and filled with 60 wt.% ammonium perchlorate (AP), 84-90% of the polyether polyol component was recovered, and 98% of the AP content subsequently detd. in the aq. hydrolyzate. The polyether polyols were nearly unchanged at 170.degree. for 2 h, as shown by the molar mass distributions (detd. by gel permeation chromatog.). The solid gun propellant KHP (86 wt.% RDX-14 wt.% GAP-Desmodur N100 binder) was solvolyzed at 130, 150, and 170.degree. with pure water and with 0.05 N NaOH for 10, 30, and 60 min. RDX was recovered in high yields and high purity. Under similar hydrolyticconditio ns, GAP did not behave in the same way as the Lupranol polyether polyols. The molar mass distribution of GPA was broadened and its azide content reduced, as detd. via IR absorption of the asym. N3 stretching vibration, and by differential scanning calorimetry, in both cases in relation to the azide content of the unreacted GAP. Neither the GAP-N100 binder or GAP were recoverable. Under these conditions, the N3 group decompd., yielding a nitrene functionality which formed solvolytically not scissionable C-N bonds by intermol. insertion reactions. The main gaseous reaction products in the solvolysis of KHP were N2, and N2O, with a little CO2, O2, and CO, and small amts. of NH3 and HCHO. The following ionic decompn. products were obsd.: NO2-, NO3-, HCOO- and NH4+.