Tungsten and Titanium dioxide filled VMQ polymer composites-a new lead free & flexible gamma ray-shielding materials

Flexible & lead-free gamma-ray-shielding composites were prepared using Vinyl Methyl Silicone (VMQ) matrix with Tungsten (W) and Titanium dioxide (TiO2) as fillers. The VMQ composites filled with 30 Phr (parts per hundred rubber) TiO2 and 0-70 Phr W were prepared by two-roll mill method. The dispersion of the filler particles in the composite matrix was analysed using Scanning Electron Microscope. Gamma ray shielding properties were studied in the energy range of 80 to 1170 keV using NaI(Tl) scintillation spectrometer. The mass attenuation coefficient (μm) of the prepared composites was found to increase with increasing concentration of W. Mass attenuation coefficients of 30 Phr W composites at gamma-ray energies of 356 and 1170 keV were found to be 0.1444 and 0.0644 cm2 g-1, while those of 50 Phr W composite were 0.1396 and 0.0707 cm2 g-1, respectively. The half value layer values of all the samples were found to decrease with increase in tungsten concentration. To appreciate the shielding ability of the prepared composites, comparison was made with the metal lead. The results show that addition of W into VMQ enhances the attenuation, whereas tensile strength and elongation at break reduces. The Shore A hardness of the W/TiO2/VMQ composites had a maximum value of 71 and the composites also prove to possess good thermal stability. Hence, the present study shows that the VMQ based W-TiO2 rubber composites serve to shield gamma radiations in medical applications and are considered as environmental friendly.