Enhanced X-ray Shielding Ability of Polymer-metal Composite by Multi-layer Structure

Abstract

In this study, as substitute shielding materials for lead, several polymer-metal composites were made and irradiated by X-ray of fixed absorbed dose and maximum photon energy, 1Gy and 150KeV each, to investigate the enhancement of shielding ability by multi-layer structure. With the mass attenuation coefficients of bismuth, tin, and tungsten, which have excellent shielding ability for diagnostic range of X-ray energy, contribution of density to shielding ability was discriminated from that of Z number(atomic number) effect Using tungsten powders in different particle size, the effect of particle dispersibility was confirmed. The more uniformly the particles are dispersed, the higher the shielding ability was, however, the effect of density become more important factor as tungsten composition increases. The effect of particle alignment was investigated with aligned flake-shaped Sendust particles in polymer matrix using roll mill machine. The composite of aligned Sendust particles exhibited 5% of maximum difference in dose ratio, however, the effect of alignment decreased with increasing filler content as the dispersibility. In the last experiment of laminating, layered sheet consisting upper part of tungsten plate and lower part of aligned Sendust shielding sheet showed better shielding ability than reversed one. As the high-energy photons lose their energy much passing through the tungsten sheet, the Sendust shielding sheet would attenuate the low-energy photons easily.