Development of a new multifunctional polymer-based nanocomposite for neutron shielding applications

In this study, a multifunctional nanocomposite has been developed for neutron shielding applications. Epoxy was utilized as the base polymer due to its hydrogen-rich structure, serving as a neutron moderator and benefiting from the lightweight nature of the resulting nanocomposite. Additionally, layered silicate nanoparticles were incorporated at different weight percentages of 2, 4, 6, and 8 wt% into the polymeric matrix to enhance its mechanical and thermal strengths. Given the thermal insulation properties of the epoxy resin, graphite was added at a ratio of 5 to 20 wt% to improve the thermal diffusivity, considerably. Furthermore, the neutron shielding properties were developed by incorporating boron carbide through mechanical mixing, ultrasonication, and degassing techniques. The optimization of the layered silicate content was conducted based on the results of X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and tensile tests. The XRD results indicated that the polymer-layered silicate (PLS) nanocomposite with 2 wt% layered silicate exhibits an exfoliated structure. Additionally, SEM analysis and TGA and tensile tests demonstrated that this nanocomposite not only possessed a homogeneous distribution of particles, but also achieved considerable improvements in thermal stability and mechanical properties, increasing the thermal degradation temperature by 98.3 °C, the tensile strength by 25%, and the elastic modulus by 49.5%. Xenon Flash Thermal Diffusivity analysis revealed that increasing the graphite content improved the thermal diffusivity coefficient, so that the nanocomposites containing 5 wt% graphite showed the optimal heat transfer properties while maintaining minimal loss in the mechanical and thermal characteristics. Finally, neutron attenuation tests on boron containing samples indicated that the nanocomposite with 10 wt% boron carbide and a thickness of 6.6 mm stops 98.1% of thermal neutrons while exhibiting thermal diffusivity 21.64 times higher than the base material.