Green Fabrication of Multi-functional Aerogel Composite from Fly Ash and Recycled Plastic Fibers for Heat and Sound Insulation

Abstract

Fly ash (FA), an abundant waste from thermal power plants in Vietnam, has been recycled 100 % into multi-functional aerogel composites for heat and sound insulation by the green fabrication developed in this study. The hollow structure of aerogel composites is created by sublimation of water in a mixture of FA and recycled polyethylene terephthalate (rPET) fibers bound by environmentally friendly adhesives including polyvinyl alcohol (PVA) and xanthan gum (XG). As result, the FA/rPET aerogel composites exhibit an exceedingly low density of 0.045 - 0.060 g/cm3 and high porosity of 94.81 - 97.02 %. The aerogel composites have a low thermal conductivity of 0.035 - 0.040 W/(m·K), a comparably high noise reduction coefficient (NRC) of 0.49, and a high working temperature of 220 °C. The prepared FA/rPET aerogel composites display the ability to slow down the burning in the presence of FA at 3.0 wt% with a burning rate of 1.0 mm/s and extinguish the flame only 30 s. The effect of FA content on the morphology, physical and mechanical properties as well as thermal conductivity, acoustic insulation, and slow-burning of the aerogel composites is also investigated comprehensively. The features of slow-burning aerogel composites from FA and rPET fibers such as lightweight, flexibility, thermal and sound insulation give them great potential in civil engineering towards a green approach and sustainable development.