Effects of Gamma and Thermal Neutron Radiation of Nitrocellulose

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K. Heppell-Masys
H.W. Bonin
V.T. Bui
M. Bickerton
D. Murphy

Abstract

The effects of gamma and thermal neutron radiation on the nitrogen content of wet nitrocellulose using the SLOWPOKE-2 nuclear reactor were investigated. By irradiating the nitrocellulose, it was expected that its nitrogen content would be decreased following breakage of the chemical bonds between the NO2, groups and the main cellulose structure since these bonds possess a relatively low bond energy. If the technique of irradiation appears to be effective for the above purpose, it may be possible to neutron and convert the stocks of aged and unstable nitrocellulose explosives into commercially useful products.


Three stock solutions of commercial grade nitrocellulose were used: 12.11%N, 12.60%N and 13.11%N. These samples of about 1 g each contained in sealed polyethylene vials were irradiated for various times ranging from 2 to 24 hrs. In order to assess the extent of change in the nitrogen content, solutions of nitrocellulose samples in tetrahydro- were analysed using Gel Permeation Chromatography (GPC) and Fourier Transform Infrared Spectroscopy (FTIR). A decrease in molecular mass was observed from GPC results which indicated the possibility that breaking of nitro groups may have occurred together with some chain scission inside the cellulose backbone. New solutions of irradiated samples were scanned using FTIR Two specific absorption bands of the nitro groups: one at 1660 cm-1 (primary group) and the second at 1270 cm-1 (secondary) were focused for determining their respective fluctuations resulting from radiation doses. The results revealed a decrease in both absorption bands with the second band having larger decrease in concentration than the primary peak of nitro groups with radiation dose. The samples that originally had the highest percentage of nitrogen (13.11% N) decreased the most, and the samples that originally had the lowest nitrogen content (12.11 % N) decreased the least. The longer the samples were irradiated, the more the nitrogen content decreased. This relatively large effect on the nitrogen content of nitrocellulose may be attributed to the very low chemical bond energy of the -O-NO2 groups attached to the main structure of cellulose.

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