On study of X-ray absorption and properties of dispersion of W, MoS₂ and B₄C particles in high density polyethylene

Abstract

<span>Shielding radiation from both x-rays and gamma-rays is important for personnel in medical fields e.g. interventional radiology, nuclear power stations, and other inspection facilities where radiation is involved. Lead is known for its effective shielding property against these high energy radiations, however heaviness and toxicity are its main drawback. In this study effectiveness of non-lead polymeric composite materials, which include high-atomic-number / or known barrier elements to absorb photons from the radiations was evaluated. High density polyethylene as matrix and powders of spherical W and lamellar MoS₂ and B₄C as particulate fillers with different loadings were melt mixed in an internal mixer, followed by compression molding in to sheet form. The goodness of dispersion was manifested via SEM and EDX images. Radiation attenuation capability of these compounds was examined with direct diagnostic x-ray exposure and compared with that of Pb. Dynamic rheology measurements were carried out to evaluate viscoelastic properties of the molten composite materials, necessary in shaping process operations. The mechanical and thermal properties were further investigated from the product performance point of view. Results demonstrated that the flexible composite sheet made with 45% (wt) tungsten provided comparable x-ray absorption to non-flexible lead sheet but much lighter in weight. Significant difference was observed between flow characteristics and yield strength of composite materials of highly loaded spherical metallic particles and lamellar particles of metallic compounds. The melt viscoelastic behavior of former was similar to that of neat matrix melt.</span>