Radiation impact on robot-relevant polymers for high gamma environments

Polymers offer a number of properties of interest in robotics design, from the well established such as low weight, electrical and thermal insulation , to the more novel, where their visco-elasticity is of great benefit in designing vine robots and flexible sensors. The more dangerous the environment, for example in cases where high radiation is present, the greater the need for robotic solutions to keep people out of harm’s way. However, polymers do have drawbacks in their use in high gamma environments, where the radiation can alter the polymer material’s properties. This work evaluates how material properties change for PEEK (Polyetheretherketone), PAI (Polyamide-imide), PI (Polyimide), Silicone , and TPU (Thermoplastic Polyurethane), irradiated to a total integrated dose of up to 5 MGy gamma. The polymers were characterised using Raman Spectroscopy , X-ray diffraction, Nano-indentation, and their response to tensile testing . Results show that PEEK, PAI and PI mechanical characteristics remain relatively unchanged up to a dose of 5 MGy, whereas Silicone and TPU lose their useful characteristics at levels of around 10 kGy. It was found that the selected sample size and limited number of samples complicated testing and prevented the generation of statistically significant results. A very clear colour change was detected in blue TPU which opens up possibilities of using this particular polymer/colour combination as a “litmus paper” for radiation, providing visual information of accumulated gamma dose. • Radiation is a known hazard for fusion reactor maintenance. Robotics solutions operating inside or in close proximity to fusion reactors need to be designed to withstand the radiation in order to maintain the complex machine and all its services. • Polymers offer many advantages in robot design due to their low weight, insulating properties, and visco-elasticity. • This work evaluates how material properties change for PEEK, PAI, PI, Silicone, TPU, irradiated to Total Irradiated Dose up to 5 MGy gamma. • The polymers were characterised using Raman Spectroscopy , X-ray diffraction, Nano-indentation, and Tensile testing. • Results show that PEEK, PAI and PI mechanical characteristics remain relatively unchanged up to a dose of 5 MGy. • Silicone and TPU lose their useful characteristics at levels of around 10 kGy.