DWNT/Hydrogenated Fullerene Reinforced Polyethylene for Radiation Shielding Applications

Phase I has demonstrated the feasibility of the overall objective to develop strong and lightweight polyethylene composites with double-walled nanotubes for radiation shielding applications. Multi-gram quantities of pure DWNTs, hydrogen-containing functional derivatives of DWNTs, highly hydrogenated fullerenes have been synthesized and incorporated in polyethylene matrix to form composite materials of exceptional mechanical strength, thermal stability and enhanced proton radiation shielding efficiency. The tensile strength of the low-density polyethylene composites with DWNTs was evaluated to be in excess of 200 MPa, and the Young's modulus exceeds 3500 MPa, while the composite toughness is retained at a very high level of ca. 10 J/cm3. These values compare favorably to the strongest polymer films, including those of aramide polymers. The thermal oxidation degradation point of polyethylene is up-shifted by more than 100 oC at 1 wt. % loading of the DWNT filler. A prominent increase in proton radiation shielding efficiency, reaching 35 % in terms of water equivalence thickness was obtained for composites containing DWNTs and fullerene hydrides. Virtually no degradation in properties was observed upon proton irradiation. In Phase II, the central technological achievement of Phase I effort, the effective lamination of the unique as-produced DWNT films with polyethylene will be further developed for manufacturing practical composite articles for aerospace applications, including advanced components for EVA suits. The DWNTs, fullerene hydrides and appropriate thermoplastic polymers will be explored for composite components.