High performance fluoroelastomer composites filled with graphite and/or bismuth oxide for applications in gamma-ray shielding

Fluoroelastomer-based composites with nano-sized bismuth oxide (B) and/or graphite (G) as fillers were prepared and characterized using FKM type 1 fluoroelastomer as a matrix. The effects of these fillers used singly or in combination on the crosslinking process, mechanical, thermal, dynamic mechanical, electrical, optical, and high-energy radiation attenuation properties of FKM were investigated. The results showed that graphite significantly increased the moduli E50 (MPa) of FKM/G and FKM/GB composites by 1026% and 1459%, respectively, compared to FKM. On the other hand, bismuth(III) oxide did not affect the stiffness or elongation at break of FKM significantly. Graphite also imparted electrical conductivity to FKM (10(-6) Scm(-1)), which was reduced by bismuth oxide to 10(-12) Scm(-1). Furthermore, the linear attenuation coefficients (mu), half-value layer (HVL), and tenth-value layer (THV) of pure FKM and FKM composites were evaluated using a Cs-137 (662 keV) source, revealing that FKM/B and FKM/GB composites show 47.4% and 35.8% higher mu values, respectively, than FKM. Taking into consideration that the attenuation coefficient of FKM is 10 times higher than conventional elastomers such as natural rubber, these results indicate that thin flexible shielding against high electromagnetic radiation can be achieved to protect different sensitive equipment such as electronic devices used in nuclear power plants, gamma radiation facilities, telescopes, and artificial satellites.