Dynamic mechanical and thermal analysis of crystallinity development in Kel-F 800 and TATB/Kel-F 800 plastic bonded explosives: Part I. Kel-F 800

Abstract Dynamic mechanical and differential scanning calorimeter measurements were made on Kel-F 800, a copolymer of chlorotrifluoroethylene and vinylidene fluoride, as a function of time. Samples annealed over a 30 day period at 50 ° C showed reduced relaxation strength in the glass transition which directly correlated with the development of between 10 and 15% crystallinity in this polymer. Kel-F 800 samples thermally cycled from −54 to 74 ° C without annealing for 12, 24, and 36 cycles developed only about half the crystallinity of the annealed samples. Kel-F 800 which was annealed 30 days and subsequently subjected to the above thermal cycling retained almost all of the crystallinity which developed during the annealing process. These results indicate that Kel-F 800 copolymer crystallizes at an extremely slow rate, but as long as the thermal excursion remains below the major melting peak most of the crystallinity remains.