Relationship between structural damage and performance failure of wood-based electrothermal composites with extreme aging treatment

Wood-based electrothermal composites (WBECs) are increasingly employed in household building materials. However, their practical effectiveness can be significantly impacted by cooling and heating cycles and high-temperature-and-humidity environments. Therefore, we investigated the effects of electrothermal and hygrothermal aging on colorimetric parameters, resistance variations, and electrothermal properties. The results indicated that the surface color of WBECs gradually shifted toward red and yellow with increasing electrothermal power density and the application of hygrothermal treatment. Similarly, the brightness and gloss value decreased, with the maximum gloss loss rate reaching 45.42%. The resistance of the WBECs increased during the aging process from 76.1 Ω in the control sample (in CS) to 147.27 Ω in the sample subjected to hygrothermal aging after electrothermal treatment at 2000 W/m² for 700 h (in EH2-3), corresponding to an increase rate of 93.52%. Owing to the aging of the internal carbon fiber conductive network and damage to the adhesive interface, the WBECs became more sensitive to temperature and hygroscopicity. Furthermore, the maximum surface temperature and electric-to-radiant power transfer efficiency of the WBECs considerably decreased from the control sample re-loading 1000 W/m² (CS-1) to EH2-3, while the temperature nonuniformity increased from 2.71 ℃ in CS-1 to 17.90 ℃ in EH2-3. High-temperature carbonization further demonstrated that the influence of hygrothermal aging on the structure and properties of the WBECs was greater than that of electrothermal aging. These results provide technical support for the stable and safe heating of WBECs in complex application environments.