Damage behavior of carbon fiber electrothermal adhesive films after long-term electrothermal and hygrothermal aging treatment

Abstract

Carbon fiber electrothermal adhesive films (CFEAFs) are the primary heating elements in wood-based electrothermal composites, and their durability is key to ensuring their long-term performance in high-temperature and high-humidity environments. In this work, the failure mechanism of CFEAFs was discussed by using long-term hygrothermal coupled treatments after electrothermal treatments at different power densities. The results showed that for CFEAFs which were only electrothermal treatment, increasing the power density produced more microscopic cracks on the surface, destroyed chemical bonds, and caused the thermal stability to decrease. The pyrolysis temperature decreased by 16.25 °C from 292.61 °C to 276.36 °C. Furthermore, under the coupled effects of electrothermal and hygrothermal treatments, the microscopic cracks on the CFEAFs became more obvious, and the surface roughness increased. The entry of water molecules further affected the chemical structure of the molecules inside CFEAFs, the maximum tensile strength of the whole material decreased by 65.6%, and the Tg decreased from 221.5 °C to 216.4 °C. These results provide a technical reference for using carbon fiber paper as the heating element of wood-based electrothermal composites to prevent electrical safety hazards during long-term cold-hot cycling.