Development of epoxy-based electrets
MetadataShow full item record
Epoxy-based electrets have been developed in this work. The use of a diepoxide resin in the form of 1,4-butanediol diglycidyl ether) as the epoxy resin, lithium perchlorate in the amount of 20 wt.%, a hardener (4,7,10-trioxatridecane-1,13-diamine) in the amount of 15 wt.% as a curing agent, and a poling electric field of 720 V/m, an electret that exhibits maximum voltage 3.4 V during poling (30 min) and stabilized voltage 0.67 V after depoling (7 h). An epoxy system that hardens slowly (such as one with a lower proportion of the hardener) is preferred for forming an electret, due to the longer time during poling for the ions to remain high in mobility. The rate of hardening rather than the rate of curing is the governing factor. The lithium salt hastens the curing, but it provides the necessary ions and stabilizes the electret voltage, particularly during the first 30 min of depoling. Decrease of the lithium salt proportion from 20 to 10 wt.% still provides an effective electret, although the performance of the electret is reduced. After the first 30 min of depoling, crosslinking becomes a significant mechanism for enhancing the stability of the electret voltage. The time constant for depoling is 0.8 h during the first 30 min of depoling and is 9 h after the first 30 min. An epoxy resin produced from Bisphenol F and epichlorohydrin is ineffective for providing epoxy-based electrets, due to the high viscosity and fast hardening.