Abstract: Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) were employed to determine the morphological structure parameters of the two types of ultra-fine glass fiber wool felts, the impact of temperature variations on the thermal conductivity of both wool felts was investigated using transient plane source (TPS) method. The findings reveal that the wool felt No. 1 has a smaller average fiber diameter (3.36 μm), higher porosity (95.51%), larger total pore volume and area (0.013 2 m³/kg and 1 270 m²/kg, respectively); in contrast, the wool felt No. 2 has a larger average fiber diameter (6.27 μm), with porosity, total pore volume, and total pore area of 93.61%, 0.008 3 m³/kg, and 669 m²/kg, respectively. At a test temperature of 273.15 K, the average thermal conductivities of wool felts No.1 and No.2 are 0.025 7 W/(m·K) and 0.030 7 W/(m·K), respectively. As the test temperature increases, molecular thermal motion accelerates, resulting in an increasing trend in the thermal conductivity of both wool felts. At 393.15 K, the average thermalconductivities of wool felts No.1 and No.2 increase to 0.037 0 W/(m·K) and 0.043 3 W/(m·K), respectively. Additionally, due to its smaller fiber diameter, higher porosity, larger total pore volume and area, the wool felt No.1 consistently exhibits lower thermal conductivity and better thermal insulation performance than wool felt No.2. This study provides theoretical and data support for the application of ultra-fine glass fiber wool felts in engineering thermal insulation.

Key words: ultra-fine glass fiber wool felts, scanning electron microscope, mercury intrusion porosimetry, transient plane source method, morphological structure, thermal conductivity