Effects of Sm2O3 and Gd2O3 in poly (vinyl alcohol) hydrogels for potential use as self-healing thermal neutron shielding materials

Abstract

This work investigated the mechanical, self-healing, and thermal neutron shielding properties of poly (vinyl alcohol) (PVA) hydrogels with the addition of varying samarium oxide (Sm2O3) or gadolinium oxide (Gd2O3) contents from 0 to 10.5 wt% in 3.5 wt% increments, prepared using a freezing/thawing method. The results showed that the addition of Sm2O3 and Gd2O3 fillers could greatly enhance the thermal neutron shielding properties of the PVA hydrogels, in which Gd2O3/PVA hydrogels had slightly higher neutron shielding efficiencies than Sm2O3/PVA hydrogels at the same filler content and thickness. Additionally, both the Sm2O3/PVA and Gd2O3/PVA hydrogels showed autonomously self-healing capabilities at damaged/fractured surfaces, with the healing time and filler content affecting the recoverable strength of the self-healed specimens. In terms of mechanical properties, increasing the Sm2O3 or Gd2O3 contents resulted in the increases of tensile modulus and tensile strength but the decrease in elongation at break of the hydrogels, in which Gd2O3/PVA hydrogels showed higher overall tensile properties than Sm2O3/PVA hydrogels at the same filler contents. In summary, the overall properties suggested that Sm2O3/PVA and Gd2O3/PVA hydrogels presented potentials to be utilized as self-healing thermal neutron shielding materials, in which the materials could be applied as a replacement of paraffin in transport casks or as a patient's shielding biomaterial used during medical diagnosis and radiotherapy.