Fig. 2

A schematic of the wood cell structure (a) and the microfibrils and matrix in an S2 cell wall (b). P, S1, S2, and S3 indicate the primary wall and secondary walls 1, 2, and 3, respectively; in addition L, 1, 2, and ω indicate the longitudinal direction of the wood, the longitudinal direction of the microfibrils, the cross-section direction of the microfibrils, and the microfibril angle