Investigation of New Isotactic Polypropylene and Syndiotactic Polystyrene Materials for High Pulsed Power Capacitors; Final rept. 1 Jan 2005-28 Feb 2008

摘要

Under this ONR program, we have been studying two new polymers, including long chain branched polypropylene (LCBPP) and PVDF copolymers, toward the Navy capacitor goal with energy density >30 J/cc and low energy loss. The approach in LCBPPs is to increase breakdown strength by preparing high quality thin films via the combination of LCB structure and bi-axially stretching. The experimental results show some high quality LCBPP thin films, exhibiting a very high breakdown electric field >1000 MV/m, energy density approximately 13 J/cm3 (about 10 times higher than that of the current state-of-the-art PP capacitor), and nearly no energy loss. On the other hand, in the PVDF copolymers containing polar crystals, the research has been focusing on the polarization- depolarization profile. Some VDF/TrFE/CTFE terpolymers with relaxed dielectric properties provide both AC and DC powered capacitors with a relatively balanced property. shows a charging energy density >20 J/cm3 at E=500 MV/m, but with a significantly high energy loss >30% during the discharging cycle.