Effect of gamma dose rate in the crosslinking of PVC composites used for radiation protection in radiology

Flexible PVC composites loaded with various levels of tantalum carbide (TaC) were gamma irradiated at two different dose rates and their effect on crosslinking level, thermal stability and mechanical properties evaluated. The shielding properties of composites against X-Rays at radiodiagnosis energies were also evaluated. Gel percentage results indicate a relatively stable crosslinking level after irradiation, only some reduction was observed for highly loaded composite treated at a low dose rate, although thermal stability observed by TGA was maintained. TaC particles were properly dispersed within the PVC material, as seen by SEM and toughness increased when both E' and E" Moduli were enhanced after irradiation; even Tg, followed by Tan delta DMA curves, increased noticeably after treatment and for the higher TaC loaded composites, particularly when treated at low dose rate irradiation. Density measurements indicated lighter and manageable materials with respect to traditional shielding items. The shielding properties for composites, evaluated in a clinical X-Ray apparatus, in the 50-129 kV interval, show mass attenuation coefficients close to the ones reported for lead, even higher for 50% TaC loaded composite and a very competitive half-value layer (HVL) for all of them.