Potential flame retardancy of high-density polyethylene (HDPE) composite for possible use as a radiation shield

Abstract

Radiation shielding materials should have high thermal stability and environmental resistance. In this study, attempts were made to develop a polymeric material using high-density Polyethylene (HDPE) via imparting flame retardant characteristics as well as neutron shielding by the addition of ammonium dihydrogen phosphate (NH4H2PO4)/silicon dioxide (SiO2) mixtures of different compositions with fixed portions of lead oxide Pb2O3. Flame retardant properties as well as the thermal stability of the developed composite materials evaluated by studying the burning behavior test, the Limiting Oxygen Index (LOI), and thermogravimetric analysis (TGA) as a function of (NH4H2PO4/SiO2) percentage. Results show that the flame retardant performance and thermal stability of the composite materials were improved as a result of the inclusion of (NH4H2PO4/SiO2) and such improvement increases by increasing the additive portion. The obtained results also indicated that exposure to a 30 kGy irradiation dose has no significant effect on the mechanical properties of the developed material. Neutron shielding parameters have been measured for all studied samples using a collimated beam of fast neutrons 241Am–Be with energy 4.5 Mev. The result shows that the removal cross-section of fast neutron (Σʀ) increased from 0.109 (cm−1) for pure HDPE to 0.233 (cm−1) for the sample containing 40 phr of (NH4H2PO4/SiO2). And more efficient in neutron shielding conditions of all studied ratios. The results also indicate that shielding efficiency increases with thickness. Measurements concluded that additives enhance both flame retardant and shielding properties of HDPE composite.