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 measurements at 90 °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 °C. This paper presents two different approaches for the preparation of superior polycarbonate electrets. Both physical aging and incorporation of additives yield an increased charge storage capability in comparison to the non‐treated polycarbonate films. However, polycarbonate electrets of excellent quality can be achieved by a combination of both approaches, which add their beneficial effects to each other.