Graphene and Hexagonal Boron Nitride in Molybdenum Disulfide/Epoxy Composites for Significant X-ray Shielding Enhancement

Abstract

Lead (Pb) is commonly used as a X-ray shielding material but has many limitations because of its heaviness and toxicity; thus, it is imperative to be replaced with lightweight and Pb-free shielding materials. To address this problem, molybdenum disulfide (MoS2)/epoxy (MoS2-EP) composites were considered as a possible solution. However, the low compatibility between MoS2 and an epoxy (EP) matrix and an unideal particle dispersion he lack of their distribution have hindered their designed X-ray shielding performance. To overcome this problem, this paper presented how the combination of graphene (GN) and hexagonal boron nitride (hBN) additives can significantly enhance the X-ray shielding performance of MoS2-EP composites. The results showed that when GN or hBN were introduced into the EP-MoS2 composite, X-ray transmission was reduced to 9.8% at 30 kVp and 40.3% at 80 kVp for EP-MoS2-GN and 7.1% at 30 kVp and 34.3% at 80 kVp for EP-MoS2-hBN. These results were explained due to the high aspect ratio of GN, which improved the MoS2 distribution within the EP matrix in the case of hBN, and the electrostatic forces at the interface of hBN and EP leading to better dispersion and interaction with the EP matrix compared to GN. Moreover, by employing an equal amount of the GN−hBN mixture, the synergistic effect of the EP-MoS2-GN-hBN composite film was observed with a significant X-ray shielding enhancement of 52.1% at 30 kVp and 33.2% at 80 kVp compared to that of the EP-MoS2 composite with the same thickness (2 mm) and density. These results were attributed to the molecular bonding of GN or hBN, which improved the compatibility between MoS2 and the EP matrix, providing other benefits of reduced surface roughness (0.46 μm) and improved composite hardness (65.7 HD). This work highlights a new strategy using combined GN and/or hBN for other high atomic number (Z) compounds−polymer composites and the development of advanced non-Pb X-ray shielding applications.