High And Low Temperature Alternating And Electron Irradiation Effects On Ecoflex 00-30 Silicone Rubber For Flexible Robotic Tentacles

As a cross-linked polymer whose backbone is composed of silicon atoms and oxygen atoms,liquid silicone rubber is widely used in space environment because of its good resistance to high and low temperature and irradiation environment.The material used as deformed portion of the flexible robotic tentacles should be an elastomer which can maintain good mechanical and thermal properties in the complex space environment with multi-factor coupling.Many scholars have studied the properties and structure of silicone rubber at different temperatures and being irradiated by various particles.However,studies on the changes in properties and structure of liquid silicone rubber in high-low temperature alternating environment,irradiation environment and what’s more coupling environment arestill blank.Therefore,A study was performed on the degradation effects of electrons irradiation and thermal cycles,as well as the combined effect of both on Ecoflex 00-30 silicone rubber（LSR）which is widely used in flexible robotic tentacles by analyzing the change of structural and properties and revealing the evolution of mechanical properties and thermal stability.The changes of internal structure were analyzed from surface morphology,bonding strength,orientation degree and crosslink density,which provided theoretical basis and data support for the application and life prediction of liquid silicone rubber in complex space environment.It was found that Ecoflex 00-30 silicone rubber has good thermal stability and cold resistance.The temperature alternating promoted the formation of wrinkles and resulted in the deterioration of the crystallinity and disordering of the crystal structure.Moreover,the temperature alternating led to a significant decrease in elongation and increase of hardness and Young’s modulus.However,the tensile strength,chemical bond content and crosslinking degree of silicone rubber are not significantly affected by temperature alternating.The elongation at break can reach 928.6%after 120 cycles of temperature alternating within-40¹50^oC.In this temperature range,-40²5^oC and 40¹50^oC were selected to coMPare the changes of performance after temperature alternating.The results show that high temperature makes it easier to form pores on the surface.After the temperature alternating from-40^oC to 150^oC,the glass transition temperature increased from-109.5^oC to-60.4^oC,the glass transition temperature changed to-95.4^oC and 94.8^oC respectively after 120 cycles of temperature alternating within 40²5^oC and 40¹50^oC.Electron irradiation contributed to a higher roughness of surface and a lower order of molecular structure.After irradiation,the crosslink density increased and the tensile strength and elongation at break decreased,the hardness and elastic modulus increase,and the thermal stability decreases.CoMPared with the original silicone rubber,a high-flux irradiation of 1×10¹⁶ e/cm² led to large-scale pit damage on surface thus cause brittle fracture of the material,and the tensile strength and elongation at break decreased by72.83%and 90.48%,respectively,and the Shore hardness and Young’s modulus increased by 94.43%and 1775.83%.Moreover,the crosslinking density increased from 2.59×10^-4to 9.69×10^-4mol/cm³.The properties of Ecoflex 00-30 silicone rubber are largely affected by electron irradiation during the combination treatment of electron irradiation and temperature alternating.The increase of irradiation fluence resulted in worse damage and a increase roughness of surface,and the increase in the number of cycles will promote the formation of wrinkles.A low-flux irradiation led to the combination effect of both electron irradiation and temperature alternating.After combination treatment,the cross-linking density of the silicone rubber increased significantly,and the order of molecular arrangement decreased,and the chemical bond content did not change significantly.A fluence of 5×10¹⁴e/cm²can enhance the damage of temperature alternating to the mechanical properties of silicone rubbe.With the increase of irradiation fluence,combination treatment reduce the aggravation of damage to mechanical properties,coMPared to individual electron irradiation.The change in structure and mechanical properties after combination treatment is not a simple superposition of the two effects,but the effect on thermal stability is the offset of the two effects.