Fabrication of Flexible\nThermoplastic Polyurethane/Coal\nHydrogasification Semi-coke Composites with Low rGO Content for High-Performance\nMicrowave Absorption

Abstract

Semi-coke (SC), a residue of coal\nhydrogasification,\nis recycled\nand incorporated into thermoplastic polyurethane (TPU) to create composites\nfor microwave absorption (MA). Herein, we developed porous reduced\nSC (rSC)–reduced graphene oxide (rGO) hybrids (SGHs) via in\nsitu reduction of a preoxidized SC (oSC) and graphene oxide (GO) mixture.\nLow-content GO was introduced to considerably improve the dielectric\nproperties of SGHs while decreasing the production cost. Then, a solution\nblending technique was applied to develop microwave absorbers using\nTPU as the matrix. The obtained TPU/SGH5 composite with a feed ratio\nof 5:1 (oSC:GO) showed an optimum reflection loss of −48.81\ndB at a thickness of 2.5 mm and an effective absorption bandwidth\nof 4.30 GHz (7.74–12.04 GHz) in 2–18 GHz. However, the\nMA property of the obtained composites with the same amount of rSC\nor rGO alone was not comparable to that of the TPU/SGH5 composite.\nThe inherent magnetism, heteroatoms, and abundance of heterogeneous\nsurfaces of rSC and the considerable dielectric loss of rGO worked\ntogether to improve the MA performance of TPU/SGH composites. This\nstudy offers an easy and effective technical method for producing\nhigh-performance microwave absorbers with a low rGO content, illuminating\nthe path toward achieving sustainable development by converting waste\ninto wealth.