Fabrication and optimization of multifunctional nanoporous aerogels using recycled textile fibers from car tire wastes for oil-spill cleaning, heat-insulating and sound absorbing applications

A nanoporous rubber aerogel (NRA) is fabricated successfully using recycled textile fibers (RTFs) from car tire wastes, polyvinyl alcohol (PVA) via freeze-drying. The NRA exhibits a low density (down to 0.025 g/cm3), a high porosity (up to 98%), a robust mechanical property with the compressive resistance at 10% deformation above 20 kPa, a high oil-absorption capacity (up to 18 g/g), low thermal conductivity (down to 35 mW/m-K), and a high noise reduction coefficient (NRC value of up to 0.55). In our study, the production time is reduced significantly from 48 h to 17 h compared to previous works. More importantly, the central composite design and response surface methodology are applied to investigate the effect of the RTFs and PVA contents on the volume shrinkage, density, porosity, compressive resistance, oil absorption capacity, and thermal conductivity. As a result, it is found that the contents of RTFs and PVA should be in the range of high-level (4.0-5.0 wt%) and lowlevel (1.0-1.5 wt%), respectively. In addition, the effect of thicknesses and compositions on the sound absorption property of the NRA is further discussed using the analysis of variance (ANOVA). A higher noise reduction coefficient (NRC) is attained at a large thickness for compositions 1 (5.0 wt% RTFs, 1 wt% PVA). The sound absorption coefficient of the NRA in the high frequencies (1000-6000 Hz) is relatively high, and for the low- and medium frequencies (125-1000 Hz) relatively low. As a result, the NRA can be a potential candidate for oil-spill cleaning, heat-insulating and sound absorbing applications.