Tailored Additives to Improve the Electret Performance of Polycarbonates

An electret is a dielectric material exhibiting a quasi-permanent electric charge. The aim of this work is to give access to PC electret materials with a distinctly improved electret performance. In this context, the charge storage capabilities of corona charged films of several PC grades were investigated by isothermal potential decay to measurements at 90 degrees C. The most promising PC grade was further improved by a new class of bisimide additives. The best additive at the most efficient concentration in combination with a physical aging step yielded excellent PC electrets maintaining almost their complete applied charge even at 90 degrees C.