Thermal Stability and X-ray Attenuation Studies on α -Bi₂O₃, β -Bi₂O₃ and Bi Based Nanocomposites for Radiopaque Fabrics.

Nanocomposites containing α-Bi2O3, β-Bi2O3 and Bi nanoparticles as nanofillers in vulcanized silicone resin as a matrix are prepared and their diagnostic X-ray attenuation property is studied. The nanocomposites are prepared using a simple solution casting technique, with nanofiller concentration varying from 2-50 wt%. Thermogravimetric analysis and differential scanning calorimetry are performed to study the thermal stability of the nanocomposites. The attenuation property is studied by exposing the nanocomposites containing α-Bi2O3, β-Bi2O3 and Bi nanoparticles to X-rays of energy 30-60 keV. Nanocomposites containing β-Bi2O3 nanoparticles are found to exhibit the highest attenuation than nanocomposites of α-Bi2O3 and Bi nanoparticles of similar concentration. Nanocomposites containing 50 wt% of β-Bi2O3 nanoparticles exhibit an X-ray attenuation of 93, 86, 71, 45 and 10% at an X-ray photon energy of 40, 45, 50, 55 and 59 keV, respectively. Further increase in photon energy is found to saturate the flat panel detector owing to the lower thickness of the nanocomposites. Analysis of high resolution X-ray radiographs of the nanocomposites confirms the uniform distribution of nanofillers in the matrix. Thermal analysis confirms the structural integrity and thermal stability of the nanocomposites. Heat flow curves also confirm the interaction of nanofillers with the matrix, corroborated by a change in the peak position and its endothermic/exothermic nature, corresponding to the phase transition of the nanofillers. It is also interpreted from thermal analysis of nanocomposites that the nanofillers interact with the matrix either by intercalating in the bridging polymer chain of silicone resin network structure or by occupying the interchain space. Thermal analysis of X-ray exposed nanocomposites shows no significant change in heat flow rates, thus, confirming the stability of the nanocomposites. Our study shows that nanocomposites containing β-Bi2O3 nanofiller are potential candidates for radiopaque fabrics which can find application in diagnostic X-ray shielding in mammography, dental scan, etc.