Composition-Dependent Performance of Hydrophobic Glass Wool Fiber Aerogels for Oil Absorption and Thermal Insulation

Glass wool provides a lightweight fibrous framework with inherent thermal-insulation capability, yet its direct use in hydrophobic monolithic aerogels has received comparatively limited systematic investigation. Here, glass wool fiber (GWF)/poly(vinyl alcohol) (PVA) aerogels were fabricated by freeze-drying followed by vapor-phase methyltrimethoxysilane (MTMS) modification. A composition matrix of 1.0–3.0 wt.% GWF and 0.10–1.00 wt.% PVA was evaluated to determine composition-dependent changes in density, calculated porosity, wettability, compressive response, thermal conductivity, crude-oil absorption, uptake kinetics, and cyclic reusability. The aerogels exhibited densities of 0.014–0.046 g/cm3, calculated porosities of 97.68–99.39%, water contact angles of 131.0–141.3°, thermal conductivities of 32.1–38.5 mW/m·K, and compressive stress at 50% strain up to 146.20 kPa. Crude-oil absorption, defined here as predominantly physical uptake and retention within the porous fibrous network, ranged from 18.86 ± 1.50 to 55.12 ± 1.57 g/g. At 0.25 wt.% PVA, samples containing 1.0–3.0 wt.% GWF reached 81–91% of equilibrium uptake within 10 s. The pseudo-second-order model provided the better empirical fit without implying chemisorption. Overall, composition influenced the balance among oil uptake, mechanical resistance, cyclic reuse, and thermal insulation.