Dimensional stability of puffed wood-based metal composites and their mechanical failure modes after hygrothermal ageing treatment

Puffed wood-based metal composite (PWMC) is an innovative metallic wood material that has attracted attention for its decorative grain and good thermal conductivity, making it ideally suited for both construction projects and interior decoration. Nevertheless, its inherent wood shrinkage and swelling poses a challenge to its dimensional stability. Until now, the impact of the weak wood-metal interface on the mechanical failure modes of PWMC during hygrothermal ageing has remained unexplored. In this study, we delved into the changes in dimensions and mass of PWMC in dry and humid environments. Dynamic vapor sorption (DVS) characteristics and chemical structures revealed a decrease in moisture absorption. Furthermore, the modulus of rupture (MOR) and modulus of elasticity (MOE) were observed to be 9.58% and 60.32% higher than those of PW, respectively. The tensile strength of PWMC increased by a significant 86.3%. However, hygrothermal ageing decreased the mechanical properties of PWMC, which enlarged the interfacial gap between wood and metal parts. We compared the fracture morphology and discussed the mechanical failure modes before and after hygrothermal ageing.