Abstract
Although radiation exposures in manned space missions are normally below the limits recommended to NASA by NCRP, in long-duration deep space exploratory missions astronauts may receive relatively high doses of ionizing radiation. Novel light polyethylene-based composites can be considered as effective radiation shields in space explorations. However, normally these composites cannot provide desired mechanical properties. Over the past several years our laboratories have focused on developing efficient methods for both physical and biological protection of the crew in long term space missions. In this study carbon nanotubes and either nano-sized or micro-sized boron carbide (B4C) fillers were incorporated into the continuous phase of low density polyethylene (LDPE). In the next phase, the mechanical characteristics of the composites as well as their neutron attenuation properties were studied. Findings of this study indicated enhanced mechanical properties accompanied by an enhanced shielding efficiency for neutrons at some specific weight fraction of the fillers.
Kurzfassung
Obwohl die Strahlenexposition bei bemannten Raumflügen normalerweise unter den von der NCRP der NASA empfohlenen Grenzwerten liegt, könnten Astronauten bei Langzeitweltraumflügen relative hohe Dosen ionisierender Strahlung erhalten. Neue, leichte Verbundwerkstoffe auf Polyethylen-Basis können als effektive Abschirmung in der Weltraumforschung betrachtet werden. Diese Verbundwerkstoffe haben jedoch oft nicht die nötigen mechanischen Eigenschaften. In den letzten Jahren haben sich unsere Laboratorien auf die Entwicklung von effizienten Methoden zum physikalischen und biologischen Schutz der Crew bei Langzeitweltraumflügen konzentriert. Im vorliegenden Beitrag wurden Kohlenstoffnanoröhren und Borkarbid (B4C)-Füllungen in Nano- bzw. Mikrogröße in die kontinuierliche Phase von Polyethylen niedriger Dichte (LDPE) einbezogen. In der nächsten Phase wurden die mechanischen Eigenschaften der Kompositen und ihre Neutronenschwächungseigenschaften untersucht. Die Ergebnisse dieser Studie zeigten verbesserte mechanische Eigenschaften mit verstärkter Abschirmwirkung für Neutronen bei einigen spezifischen Gewichtsanteilen der Füllungen.
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