Abstract and subjects
Using gas-gun-driven plate impact techniques, we have measured the Hugoniot of the filled silicone elastomer DC745U cooled to -60 degrees C. DC745U consists of approximately 62 weight% poly-dimethyl-siloxane rubber and 38 wt% silicon dioxide filler. At similar to -50 degrees C, the poly-dimethyl-siloxane rubber in DC745U crystallizes with similar to 40% crystallinity. This is accompanied by a density change from 1.31 g/cm(3) at 23 degrees C to 1.45 g/cm(3) at -60 degrees C. Below the crystallization transition temperature, a measurable increase in the shock velocity was observed. This is coincident with a decrease in compressibility due to crystallization of the polydimethylsiloxane repeat units. The linear Us up Hugoniot also significantly changes from U-S = 1.62 + 1.74u(p) mm/mu s at 23 degrees C to U-S = 2.00 +/- 0.05 + (2.06 +/- 0.06)u(p) mm/mu s at -60 degrees C. Cooling to -60 degrees C and the associated crystalline phase transition therefore results in considerable stiffening. This is the first time, to our knowledge, that a polymer crystallization transition has been shown to affect shockwave properties in this way.