Recycling of Waste Glass Fiber Reinforced Plastics (GFRP) via Pyrolysis with Sodium Hydroxide using Microwave Heating

Abstract

Glass fiber reinforced plastics (GFRP) are composite materials with high strength and flame retardancy, and the disposal process is expensive to cause illegal dumping. Therefore, new recycling technology of waste GFRP is desired. In this study, recycling of waste GFRP via pyrolysis with sodium hydroxide (NaOH) under an inert atmosphere using microwave heating was attempted by carbonization of resin and conversion of glass fiber into soluble sodium silicate. The pyrolysis behavior of GFRP, the characteristics of the obtained residue, and the silica extraction into the solution were compared for microwave heating and conventional heating. In both heatings, the carbonization of the resin and the conversion of the glass fiber into soluble sodium silicate were confirmed by pyrolysis with NaOH, and the sample after the pyrolysis treatment can be pulverized into a powdery residue by washing the solution without mechanical crushing. In comparison with conventional heating, microwave heating could reduce the time for heat treatment (41.3% reduction), to reduce the energy consumption (75% reduction), suggesting that microwave heating can provide more efficient treatment.