Facile preparation of high dielectric flexible films based on titanium dioxide and cellulose nanofibrils

A series of high dielectric composite films based on low-cost and eco-friendly titanium dioxide (TiO2) and cellulose nanofibril (CNF) was prepared under a facile condition. The relative dielectric constants (epsilon(r)) and dielectric loss (tan) were studied as the function of frequency and filler content. The epsilon(r) of CNF/TiO2 composite film was 19.51 (at 1kHz) with a relatively low dielectric loss. Compared with pure CNF films (epsilon(r)=6.92 at 1kHz), the epsilon(r) of the composite film was improved about three times with the dielectric loss increased slightly. The effects of TiO2 addition and hot-press treatment on microstructure, thermal stability, and dynamic mechanical properties of the composite films were also analyzed. It was found that the addition of TiO2 particles reduces the cellulose-cellulose bonding so generates more pores in the films, which has significant impacts on both dielectric and physical strength properties. [GRAPHICS] .