Preparation of cellulose insulating paper of low dielectric constant by OAPS grafting

This study aims to decrease the dielectric constant of cellulose insulating paper by octa(aminophenyl)silsesquioxane (OAPS) grafting. OAPS was grafted onto the primary hydroxyl group of cellulose molecules via amino groups and epichlorohydrin. The dielectric constant and dielectric loss of insulating paper before and after modification were investigated. Relative to the unmodified paper, the dielectric constant of 15 wt% OAPS-grafted paper decreased from 5.27 to 4.28, and the dielectric loss decreased by 37.5% at 50 Hz. The movement and orientation polarization of the cellulose chains could be restricted due to the porous macromolecular structure and nano quantum interface effect produced by OAPS, thereby resulting in the reduction of cellulose polarizability. Moreover, the OAPS grafting modification does not degrade the other properties of cellulose insulation, i.e., its thermal stability, mechanical performance, fire-resistant properties, and electrical strength. OAPS grafting has promising potential application for preparing low dielectric constant insulating paper.