11:15 AM - MT04.04.05
Neutron Characterization of Boron-Containing PDMS Composites for Space and Nuclear Applications
Joseph Dumont1,Samantha Talley1,Eamonn Murphy1,Zachary Brounstein1,Alexander Long1,Tom Robison2,Kwan-Soo Lee1,Andrea Labouriau1
Los Alamos National Laboratory1,National Security Campus2
Polydimethylsiloxane (PDMS) or silicone, is widely used in both industrial applications and academic research area due to its low cost, easy manufacturability, backbone flexibility, low surface energy, and chemical and thermal stability. PDMS elastomers are typically prepared by a hydrosilyation reaction between the hydride groups and the vinyl groups in PDMS. Alternatively, it has been used to synthesize foams vulcanized at room temperature for cushioning applications by reacting a hydride-functional PDMS with a hydroxyl-terminated PDMS at room temperature.1-3
There is an increased demand in aerospace, nuclear reactors, and other neutron-producing sources for neutron shielding materials to mitigate ionizing radiation damage.4-5 The attenuation from neutrons radiation in space and nuclear applications can be performed using isotopically-enriched boron (10B) because of its large neutron cross-section. 10B has previously been successfully incorporated in a PDMS and other polymer matrixes for these types of applications.3, 6 However, compliant PDMS composites with high concentrations of 10B (≥ 70 wt%) have not been proposed.
The Energy-Resolved Neutron Imaging (ERNI) Flight Path at the Los Alamos Neutron Science Center (LANSCE) allows to probe boron-containing materials and obtain an energy resolved transmission spectra on a pixel-by-pixel bases. This allows 3D reconstructions via Computed Tomography (CT) of the samples and verifies the filler distribution.
In this work, we study the neutron attenuation and boron distribution of highly-filled boron-containing PDMS composites (50-70% by weight) using the capabilities at LANSCE and CT. Additionally, the chemical, thermal and mechanical properties will be studied using a wide range of experimental techniques are used including Fourier transform infrared spectroscopy, mass spectroscopy, differential scanning calorimetry, thermogravimetric analysis, nuclear magnetic resonance spectroscopy, and mechanical testing. The resistance of the composite materials to solvents will be investigated through solvent swelling experiments and exposure to high humidity. The presented work lays the foundation for highly-filled composite polymer foams to be considered for space and nuclear applications.
(1) Labouriau, A.; Robison, T.; Geller, D.; Cady, C.; Pacheco, A.; Stull, J.; Dumont, J. H. Coupled aging effects in nanofiber-reinforced siloxane foams. Polymer Degradation and Stability 2018.
(2) Labouriau, A.; Cox, J. D.; Schoonover, J. R.; Patterson, B. M.; Havrilla, G. J.; Stephens, T.; Taylor, D. Mössbauer, NMR and ATR-FTIR spectroscopic investigation of degradation in RTV siloxane foams. Polymer degradation and stability 2007, 92 (3), 414-424.
(3) Labouriau, A.; Robison, T.; Shonrock, C.; Simmonds, S.; Cox, B.; Pacheco, A.; Cady, C. Boron filled siloxane polymers for radiation shielding. Radiation Physics and Chemistry 2018, 144, 288-294.
(4) Thibeault, S. A.; Kang, J. H.; Sauti, G.; Park, C.; Fay, C. C.; King, G. C. Nanomaterials for radiation shielding. Mrs Bulletin 2015, 40 (10), 836-841.
(5) Schaeffer, N. M. Reactor shielding for nuclear engineers; Radiation Research Associates, Inc., Fort Worth, Tex.(USA): 1973.
(6) Harrison, C.; Weaver, S.; Bertelsen, C.; Burgett, E.; Hertel, N.; Grulke, E. Polyethylene/boron nitride composites for space radiation shielding. Journal of applied polymer science 2008, 109 (4), 2529-2538.