Enhanced mechanical, thermal and dielectric properties of polyimide nanocomposites containing SiCp (SiCw) nanofillers for high energy-storage applications

In order to systematically investigate the dependence of the properties of nanocomposites on the shape of nanofillers, including spherical and fibrous, and the contents and its special arrangement, polyimide (PI) as matrix, nano-silicon carbide particles (SiC p ) and whisker (SiC w ) as fillers were applied to prepare PI nanocomposite films by in-situ polymerization. FTIR and XRD tests verified the successful polymerization of SiC/PI nanocomposites. FESEM observations showed that both SiC p and SiC w nanofillers were uniformly dispersed in the PI matrix during in-situ polymerization and contributed to the improvements of properties. Compared with pure PI film, addition of SiC nanofillers enhanced obviously the heat resistance and the thermal stabilities of PI nanocomposites, as verified by TGA. Tensile tests indicated that the mechanical properties of PI nanocomposites enhanced with increasing SiC nanofillers. Moreover, SiC w was more prominent than SiC p in the reinforcement of PI nanocomposites. Due to the influences of dielectric properties by the changes of the spatial arrangement and the local distribution of electric field of the nanofillers in PI matrix, the dielectric constant of 3wt.%SiC p /PI and 3wt.%SiC w /PI nanocomposites reached 4.3 and 5.6, respectively. Compared with pure PI film, the dielectric constants of SiC p /PI and SiC w /PI nanocomposites were enhanced by 26% and 64%, respectively. In comparison, PI nanocomposites containing SiC w possessed higher effective permittivity than those containing SiC p under the same nanofillers concentration. This work is expected to show great significance to understand the microscopic mechanism of PI dielectric nanocomposites for high energy-storage applications.