Enhanced Mechanical Performance of Fluoroelastomer Composites with Boron–Gadolinium-Based Fillers for Cutting-Edge Applications

The notable interest in materials with high-performance multifunctional properties, coupled with the diverse availability of raw materials-despite geopolitical controversies-allows for the design of a wide variety of new materials. Flexible materials with inorganic fillers derived from rare earths are of particular interest, as elements such as gadolinium have multiple properties of high technological interest. In particular, gadolinium oxides and borates have not been explored as fillers in special rubbers, such as FKM fluoroelastomers, which correspond to copolymers based on hexafluoropropylene and difluorovinylidene. It is in this context that the present work consists of obtaining and characterizing FKM-based compounds containing gadolinium(III) oxide, gadolinium borate, or thermally treated gadolinium borate. The promising results allow us to identify unique qualities imparted by this type of filler in fluoroelastomers, especially regarding mechanical properties. In fact, the increase in tensile strength of the compounds reached up to 162%. Likewise, the elongation at break was almost doubled. DMA identified that the reinforcing effect of gadolinium compounds is limited; it is hypothesized that the electronic nature of gadolinium, with its available f orbitals, influences the structure of FKM and, consequently, its properties. Taken together, these results provide relevant information for the development of new materials that, due to their boron and gadolinium-based composition-both elements with high neutron capture cross sections-could be used in neutron shielding applications.