Effects of Cellulose Structure of Sugarcane Stem on Mechanical Properties of Cell Wall

Cellulose is skeletal material of sclerenchymatous cell wall. The relationship between the structure of cellulose and the mechanical properties of the cell wall was studied in the research. Samples of cells were from different position at the cross section (rind, near rind, and core) of different position along sugarcane stem (top, middle, and base) during 1st, 2nd and 3rd growth stages (respectively in June, September, and December). The size of cellulose crystals, its microfibril angle and distribution in S2, and the indentation modulus of S2 were measured by X-ray diffraction, laser confocal Raman microspectroscopy, and nanoindentation tests respectively. The results showed that the microfibril angle increased during 1st to 3rd stage and from rind to core. The size of cellulose crystal decreased from rind to core. Both of them changed little from base to top. By the Raman spectral curve, the spectral intensity of rind in the 3rd growth stage was the highest. During 1st to 3rd stage, the distribution intensity of cellulose crystals at the rind and core firstly decreased and then increased, and it changed conversely at the near rind. The crystal size and microfibril angle strongly correlated, while the cellulose distribution weakly correlated, with the modulus.