A lightweight EVA ceramizable composite with high-temperature resistance and rapid sintering properties based on special amorphous hybrid hollow microspheres

Abstract

Ceramicizable cables are essential in environments such as nuclear power plants, electric power transmission systems, high-rise elevators, hospital operating rooms, and intensive care units to enhance fire safety and ensure power supply during fires. These composites behave like room-temperature polymers but can rapidly transform into ceramics with excellent mechanical properties at elevated temperatures. Achieving ceramification requires amounts of inorganic fillers, which can significantly compromise the material's mechanical and processing performance, while considerably increasing its density. In this study, we successfully fabricate lightweight composites with enhanced ceramifying performance. After vitrification at 800 °C, the sample's flexural strength reaches 21.4 MPa, significantly exceeding the values previously reported in the literature for similar materials. Furthermore, the material's density is only 807.5 kg/m³, which is merely 83.5 % of that of the EVA substrate without adding fillers. This reduction in density can significantly reduce production, transportation, and installation costs. Additionally, fire resistance test results show that after 90 minutes of butane torch ablation, the composite rapidly transforms into ceramic, effectively protecting the internal copper conductor from melting, and the bulb remains lit throughout. The effects of hollow microspheres and flux agents on the sintering process are examined, and the ceramization process and mechanism below 1000 °C are discussed in detail. This lightweight ceramizable composite is important not only for cable sheathing materials but also for developing the materials with a low density and high-temperature resistance.