Impact of fibre reinforcement on cryogenic performance of novel epoxy composites for cryogenic applications

Due to the dynamic development of technology and science, there is an increasing demand for materials combining high mechanical resistance to extreme temperature conditions and suitable thermal properties. Especially the knowledge of heat transfers by conduction and thermal radiation is crucial for the successful design of devices operating at cryogenic temperatures, such as Dewars, cryostats, or space probes. This study aimed to assess important thermal and mechanical properties at cryogenic temperatures for three composite materials made of identical epoxy resin reinforced by carbon, basalt or glass fibres. Apart from loading/unloading cyclic tensile tests conducted at room temperature and in cryogenic environments at 77 K, thermal conductivity and total hemispherical emissivity were obtained in wide temperature ranges from 5 K up to 300 K. The results highlighted the importance of the fibre material and have potential to help with optimal material selection. We found that the initial stiffness of the laminates increased at low temperatures, and the glass composite exhibited the best mechanical properties. On the other hand, the carbon composite showed the lowest but steeply increasing thermal conductivity with increasing temperature. This, together with the lowest emissivity, makes the carbon composite a more favourable option for the lowest temperatures.