Multilayer polyethylene/ hexagonal boron nitride composites showing high neutron shielding efficiency and thermal conductivity

Polymer composites show huge potential as high efficiency neutron shielding and thermally conductive materials applying in aerospace, nuclear reactors, medical treatment fields, where neutron radiation is inevitable. Designing multilayer structure with concentrated filler in one layer is an effective strategy for achieving high neutron shielding efficiency at low filler loading. Herein, multilayer composite films with alternating high density polyethylene/hexagonal boron nitride (HDPE/hBN) layers and low density polyethylene (LDPE) layers were prepared by stacking hot-pressing. By selecting suitable hot-pressing temperature and pressure, multilayer composite films with highly oriented hBN sheets were successfully fabricated, and confirmed by the morphology and structure characterizations. As a result, the multilayered PE/hBN films show excellent neutron shielding performance through multiple repeated scattering, absorption, and dissipation between multilayers. At the filler content of 30 wt%, the ratio of transmitted neutrons to incident ones decreases to 4.16%, which is much lower than that with random PE/hBN composite (14.95%). Meanwhile, the concentrated and oriented hBN results in multilayer PE/hBN composite with a higher in-plane thermal conductivity than random one. Such the high thermal conductivity can contribute to the rapid dissipation of heat converted by neutron energy. Therefore, the superhigh neutron shielding efficiency and excellent thermally conductivity, as well as the simple and scale preparation process, mean our multilayer PE/hBN films with a huge application prospect.