A novel mica‐based composite with hybrid aramid fibers for electrical insulating applications: largely improved mechanical properties and moisture resistance

Abstract

The fabrication of mica‐based composites with good mechanical properties is very important especially for electrical insulation applications. In this study, a new aramid fibrid along with chopped fibers was introduced into a mica system, and the composites were prepared using a papermaking machine. It was found that the mechanical properties of both fibrid–mica composite (F‐M paper) and fiber/fibrid–mica composite (A‐M paper) were largely improved in comparison with the reference sample (M paper) with an increase in the content of fibrid or hybrid floc/fibrid. This enhancement can be attributed to two mechanisms: (1) enhanced interfacial adhesion derived from the addition of fibrids with good flexibility and wrapping properties and (2) significant reinforcing due to the frameworks originating from the addition of chopped flocs with high modulus and rigid‐rod morphology. Interestingly, a synergetic effect of enhanced interfacial adhesion and reinforcing could also be observed when both flocs and fibrids were introduced, which further improved the mechanical properties. Furthermore, the addition of aramid fibrid greatly enhanced the moisture resistance, which expands the potential for mica‐based composites. Thus, we successfully fabricated a mica‐based composite for electrical insulation with good mechanical properties, high end‐use temperature and excellent moisture resistance by adding hybrid aramid fibers. © 2017 Society of Chemical Industry

A Bioinspired Ultratough Multifunctional Mica-Based Nanopaper with 3D Aramid Nanofiber Framework as an Electrical Insulating Material

“…Laminated mica tape, a stacking product of mica paper, polymer adhesive, and glass fiber cloth, possesses improved mechanical strength, but the presence of polymer adhesive leads to low heat resistance . Composite mica paper with only incorporation of short aramid microfiber (AMF) reinforcement has high heat resistance, but its mechanical property and dielectric strength are still inadequate because of poor uniformity on a microscopic level and low stress transfer efficiency between microscale components . Also, such composite mica paper is thick (typically 80–360 μm) and not suitable for miniaturized high-power electrical equipment.…”

“…6 Composite mica paper with only incorporation of short aramid microfiber (AMF) reinforcement has high heat resistance, but its mechanical property and dielectric strength are still inadequate because of poor uniformity on a microscopic level and low stress transfer efficiency between microscale components. 7 Also, such composite mica paper is thick (typically 80−360 μm) and not suitable for miniaturized high-power electrical equipment. Therefore, the development of mica-based composite materials with integration of small volume, excellent mechanical properties, high dielectric strength, and good heat resistance has been a huge challenge for a long time.…”

Enhanced Mechanic Strength and Thermal Conductivities of Mica Composites with Mimicking Shell Nacre Structure

“…The second approach is to reduce the mica tape thickness through lowering the addition of adhesive or finding alternative reinforced material. Recent works have reported some new inorganic-polymer composite insulating materials with improved mechanical performances, which is inspired by the structure of natural conch nacre [10][11][12]. This provides an inspiration for designing high-strength mica composites without reinforced materials [13][14][15].…”

Force-Induced Self-Assembly of Supramolecular Modified Mica Nanosheets for Ductile and Heat-Resistant Mica Papers

“…14 The preparation method requires that the raw materials be mixed and stirred in advance and then densely bonded to increase the strength through processes such as vacuum filtration and hot pressing. 15 This results in a complicated process, which greatly limits the application of this composite material. 16,17 Similar to other layered materials, mica can also be completely cleaved and peeled into single-layered materials.…”