An investigation of the neutron radiation shielding potential of PEI/H3BO3 composite for space missions.

Abstract

The study of space and its exploration play an important role in the evolution of technologies and the development of human civilization. One of the biggest problems facing the interplanetary spaceflight missions is cosmic neutron radiation. To support these missions, the thesis aims to investigate the neutron shielding potential of new composite (PEI/H3BO3) inspired by theoretical studies. Three PEI composites with different H3BO3 content (10 wt%, 20 wt% and 30 wt%) were produced using the solvent casting method with N,N-Dimethylformamide (DMF) as the dissolved solvent. In this thesis, the goal was to study and compare the neutron shielding efficiency through the method of pulse-height analysis (PHA) between the three contents of PEI composite. The applied neutron source was an Am-Be source that generates fast non-monoenergetic neutron energy (MeV). In the end, the solvent technique was not successful, as the relative thickness and the theoretical areal density for the composites were not achieved. This led to a non-relative comparison of neutron shielding potential between each content of PEI/H3BO3 composite. As the result of the solvent experiment, there were some particles found within the composite supernatant, which were assumed to be H3BO3. The UV-Vis spectrophotometer was used to determine the quantity of H3BO3 within the solution supernatant that could not react with the precipitated composite. However, the provided data were inaccurate since there were more unidentified impurities than expected. In the PHA, it was recorded that the 30 wt% sample has the highest total neutron count while 20 wt% sample has the lowest, as had been expected after the material production due to the thickness and some trapped solvent. Due to the limited time frame of COVID-19 outbreak, the experiment could not have been repeated many times, causing the lack of confirmation on the result of the neutron count. Although the experiment was not fully accomplished, PEI/H3BO3 composite still showed its shielding effectiveness against fast neutron energy in the PHA test. With proper experimental work, the potential of using this combined material for neutron shielding in a space environment may be worthwhile for future space missions.