Optimizing the porosity of flame-retardant nonwoven fabrics requires systematic control from three dimensions: fiber characteristics, web-forming process, and consolidation method. Fiber fineness and length are fundamental factors affecting porosity. Finer fibers form a denser network structure, reducing the average pore size; while longer fibers increase pore connectivity through entanglement. By adjusting the fiber crimp and cross-sectional shape (e.g., hollow or irregular cross-sections), the spatial arrangement of fibers during stacking can be altered, thereby precisely controlling the porosity distribution. Mixing fibers with different properties (e.g., coarse-fine blends or long-short fiber composites) can achieve a tiered pore distribution, meeting the requirements of specific applications for air permeability and filtration accuracy.

The flame-retardant mechanism of flame-retardant nonwoven fabrics for electrical applications is mainly based on the synergistic effect of chemical and physical flame retardancy. Chemical flame retardancy is achieved by adding flame retardants to polyester fibers. Common flame retardants include phosphorus-based, nitrogen-based, and halogen-based compounds.

The voltage withstand performance of insulating nonwoven fabrics mainly depends on the dielectric properties and structural design of the material itself. The purity of the fiber raw material is a fundamental factor; impurities or defects can become conductive channels, significantly reducing the material's voltage withstand capability. Polyester fibers, due to their stable molecular structure and high crystallinity, typically exhibit excellent dielectric strength; however, the presence of conductive components such as metal particles or carbon black in the fibers can have a negative impact. The uniformity of fiber diameter and length also directly affects the uniformity of the electric field distribution; uneven fiber arrangement may lead to localized electric field concentration, forming weak points for breakdown.

The performance changes of electrical nonwoven fabrics under high-temperature environments are mainly reflected in their mechanical properties, insulation properties, and dimensional stability. As temperature increases, the molecular chain mobility of polyester fibers increases, potentially leading to material softening or deformation. At high temperatures, the tensile strength and tear strength of nonwoven fabrics typically decrease, especially near the glass transition temperature of polyester, where this change is more pronounced. Therefore, in high-temperature applications, it is necessary to select polyester varieties with better heat resistance or add heat-resistant additives.

The moisture absorption properties of polyester nonwoven fabrics mainly depend on the hydrophobic properties of the fibers themselves and the microstructure design of the material. As a synthetic fiber, polyester fiber contains ester groups in its molecular structure, which gives it low moisture absorption. Under standard conditions, the moisture absorption rate of polyester fibers is typically low, allowing polyester nonwoven fabrics to maintain good dimensional stability and mechanical properties even in humid environments. However, this low moisture absorption also limits its performance in applications requiring rapid moisture absorption or permeability.