RESUMO
Polymeric dielectrics exhibit remarkable dielectric characteristics and wide applicability, rendering them extensively employed within the domain of electrical insulation. Nevertheless, the electrical strength has always been a bottleneck, preventing its further utilization. Nanocomposite materials can effectively improve insulation strength, but uniform doping of nanofillers in engineering applications is a challenge. Consequently, a nanocomposite interfacial coating was meticulously designed to interpose between the electrode and the polymer, which can significantly improve DC breakdown performance. Subsequently, the effects of filler concentration and coating duration on DC breakdown performance, high field conductivity, and trap distribution characteristics were analyzed. The results indicate that the composite coating introduces deep traps between the electrode-polymer interface, which enhances the carrier confinement, resulting in reduced conductivity and enhanced DC breakdown strength. The incorporation of a composite coating at the interface between the electrode and polymer presents novel avenues for enhancing the dielectric insulation of polymers.
RESUMO
Two new triterpenoid saponins, named ilexsaponins B(4) (1) and C (2), have been isolated from the roots of Ilex pubescens. Their structures have been established as ilexgenin B 3-O-alpha-L-arabinopyranosyl-(2-->1)-beta-D-glucopyranosyl-(2-->1)-beta-D-xylopyranoside (1) and 3-O-beta-D-xylopyranosyl spathodic acid 28-beta-D-glucopyranosyl ester (2) by means of spectral and chemical methods.