Exploring wood micromechanical structure: Impact of microfibril angle and crystallinity on cell wall strength

Since wood has recently acquired increasing attention from structural engineers due to its green and low-carbon attribute, a growing interest in understanding the intricate relationships between the microstructure of wood and the mechanical properties of building components. This study was aimed at investigating the wood micromechanical structure of plantation Chinese fir (Cunninghamia lanceolata (Lamb.) Hook), focusing on assessing the impact of microfibril angle (MFA), chemical components and crystallinity on cell wall strength. Understanding these microstructural features is crucial, as they directly influence the overall strength of timber. Hence, significant factors contributing to the mechanical properties of the wood, i.e., the S2 layer's thickness and microfibril angle, along with the crystallinity and cellulose content, were comprehensively examined. A model was proposed to quantitatively forecast wood cell wall mechanical properties using information about MFA, chemical components, and crystallinity. This model can be used to predict the mechanical performances of wood components based on these key structural characteristics due to the close strength relationship between the micro- and macro-structures of wood. •Examining structure of Chinese fir:effects of MFA, crystallinity, and chemical components on cell wall strength.•Using microscopic and nanoindentation techniques to quantify microstructural and mechanical properties.•Developing a predictive model for cell wall strength based on MFA, crystallinity, and chemical composition.•Highlighting differences in cell wall properties between earlywood and latewood.