Temperature-time response of a polymer bonded explosive in compression (EDC37)

The compressive strength of the energetic composition EDC37 has been measured at a temperature of 293 ± 2 K over a range of strain rates from 10-8 to 103 s-1, and at a strain rate of 10-3 s-1 over a range of temperatures from 208 to 333 K. The results show that failure stress is a monotonic function of applied strain rate or temperature, which is dominated by the relaxation properties of the polymeric binder; this is confirmed by dynamic mechanical thermal analysis performed on both EDC37 and its binder. Similarities between the compressive strain rate/temperature data sets can be understood by temperature-time superposition; data collected at a strain rate of 10-3 s-1 over a temperature range 208 to 333 K were mapped onto a plot of strain rate dependent strength at 293 K, using an empirically determined sensitivity of -13.1 ± 0.3 K per decade of strain rate. Sample size was noted to have a modest effect on the stress-strain behaviour; small length to diameter ratios gave results consistent with an increased degree of confinement. Samples taken to large strains exhibited strain localization in the form of shear bands