Synergetic optimisation of mechanical and electrical properties of aramid composite insulation paper by modulation of fibrid morphology

The fibrids in aramid insulation paper exhibit good adhesion ability. However, the effects of fibrids morphology on the mechanical and electrical properties of aramid insulation paper remains poorly understood. Aramid fibrids with different morphological structures were prepared by modifying the preparation process, and then they were used to fabricate aramid composite insulation paper under the same condition. The results showed that increasing the shear rate and aramid solution concentration affected the magnitude of the shear force and double diffusion process, thus affecting the average length, specific surface area, and crystallinity of the fibrids. When the rotor frequency is 25–30 Hz and the solution concentration is 15%, the fibrid has a large specific surface area while ensuring high crystallinity, which is beneficial to the improvement of breakdown strength. When the average length of fibrids is 0.8–1.4 mm, the fine content is 1.3%–2.3%, specific surface area is 57.5–62 m2 g−1, and crystallinity is 18.5%–27%, the aramid composite insulation paper has the optimal mechanical and electrical properties. Combined with the micromorphology test results, the influence mechanism of fibrids properties on the mechanical properties, dielectric properties, and AC and DC breakdown strength of aramid composite insulation paper was obtained. The result is of great theoretical significance and practical value for the preparation and application of high‐performance aramid composite insulation paper. 1. Different morphological fibrids were prepared by modifying the preparation process. 2. The relationship between fibrids structure and the properties of aramid composite insulation paper was analysed. 3. An optimal morphological structure of the fibrid is proposed.