Advanced fabrication and multi-properties of rubber aerogels from car tire waste

For the first time, recycled car tire fibers (RCTF) shredded from car tire waste are developed successfully into a novel material, a rubber aerogel, using polyvinyl alcohol (PVA) and glutaraldehyde (GA) as crosslinkers through a cost-effective freeze-drying method. Its structure and main physical properties are investigated comprehensively for high-value applications, such as heat and sound insulation of buildings and oil spill spilling clean up. The rubber aerogel has ultra-low density (rho(a) = 0.035 - 0.145 g/cm(3)) and high porosity (Phi(avg) = 84.31-96.20 %). With a simple but effective coating method with methoxytrimethylsilane (MTMS), both the interior and exterior of the whole rubber aerogel surface can be well coated, and the coated aerogel exhibits a super-hydrophobicity with a water contact angle of up to 134.4 degrees. The rubber aerogel exhibits excellent heat insulation properties (K-avg = 0.035 - 0.047 W/m.K), very good thermal stability up to 500 degrees C, and significantly-enhanced rigidity up to a Young modulus of E-avg = 458.12 kPa, much larger than that of commercial Styrofoam. The rubber aerogel shows very good durability as it springs back to its original shape after compression tests. The rubber aerogel has a noise reduction coefficient (NRC) of 0.41 and performs approximately 10% better than commercial sound foam absorber at 2000-3000 Hz. The maximum oil absorbtion capacity of the rubber aerogel in this work is 19.3 g/g, very competitive to commercial sorbents. The fabrication method can also be scaled up for several other industrial applications, not limited to sound, heat and sorbent applications.