Preparation of a Novel Cellulose Insulation with Network Structure by Citric Acid Crosslinking

In this study, a novel cellulose insulation with low dielectric constant and loss is prepared by implementing citric acid (CA) crosslinking. In the modified cellulose insulation, the existence of network structure is confirmed by X-ray photoelectron, Fourier transform infrared spectra and dispersion experiments. Moreover, the effect of different CA concentrations on the dielectric properties and other crucial properties of cellulose insulation is investigated through molecular modeling and simulation and experiments. The results show that CA crosslinking reduces the polarizability of cellulose because the hydroxyl groups on cellulose chains are consumed. Moreover, the network structure effectively hinders the motion of the cellulose chains, which further reduces the orientation polarization. The dielectric constant and loss in cellulose insulation decrease by CA crosslinking. The dielectric constant of 0.4 mol/L CA-treated cellulose decreases from 4.89 to 4.12, and the dielectric loss decreases by 32.6% at 50 Hz as compared to the unmodified cellulose insulation. When the CA is completely crosslinked, the permittivity and dielectric loss decrease with the increase in the concentration of CA. Additionally, CA crosslinking modification does not deteriorate the properties of the cellulose insulation. Thus, CA crosslinking modification can be potentially used for preparing cellulose insulation with low dielectric constant and loss.