The electret effect in polypropylene fibers treated in a corona discharge

In this work, melt-spun polypropylene (PP) fibers were treated in an electr ic field of a corona discharge. The fibers were then characterized using th e thermally stimulated current (TSC) spectroscopy. It has been shown that t he electret state of corona-treated PP fibers is a result of the combinatio n of Maxwell-Wagner polarization and charge trapping. Activation energies a nd relaxation times for these processes have been determined, and character istics of trapping sites have been calculated. The electret state induced i n PP fibers by the corona discharge treatment holds for a long time (severa l months). Our analysis of the effect of processing temperature and electri c field intensity on the characteristics of the electret state in melt-spun PP fibers allows one to specify optimum technological regimes for industri al production of PP-based electret: filter materials. (C) 2000 John Wiley & Sons, Inc.