Surface modified-gadolinium/boron/polyethylene composite with high shielding performance for neutron and gamma-ray

Highlights: • A series of surface modified-gadolinium/boron/polyethylene composite was prepared. • The modification of fillers improved the interfacial compatibility and dispersion in HDPE. • The neutron and gamma shielding performance were significantly improved by modification. A series of surface modified-gadolinium/boron/polyethylene composites composed of surface modified fillers (M−microGd₂O₃ and M−nanoGd₂O₃) are prepared for shielding neutron and gamma radiation. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray energy spectrometer (EDS) reveal that the surface modification of fillers significantly improved the interfacial compatibility and dispersion in the polyethylene matrix. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and mechanical tensile tests show that the modification of nanoGd₂O₃ and microGd₂O₃ improve the thermal stability and mechanical property of the composites. The T_5% (initial decomposition temperature), T_p (endothermic peak temperatures) and Tensile strength of 10wt% M-nanoGd₂O₃/20wt% B₄C/70wt% HDPE reachs 463.5℃,137.2℃, and 19.6MPa, which is greatly improved compared with unmodified materials and neat HDPE. The neutron and gamma shielding mechanism of the composites is studied both by experimental measurements and Monte Carlo simulation. The results show that the improved interfacial compatibility and dispersion of fillers in the polyethylene matrix effectively enhances the neutron and gamma shielding rate. The shielding performance of the composite blended with M−nanoGd₂O₃ is significantly better than that of the composite blended with M−microGd₂O₃ and the unmodified materials with the relatively thin thickness. Finally, a superior composite containing 10 wt% M−nanoGd₂O₃/20 wt% B₄C/70 wt% HDPE reaches a neutron shielding rate of 90% at 9.1 cm under Cf-252 environment, and a gamma shielding rate of 70% at 13.7 cm under Cs-137 environment, which have the characteristics of lead free, low specific gravity and high shielding performance and is expected to be a promising radiation shielding materials used in neutron-gamma mixed fields.