To investigate the thickness evolution of nanocellulose in water, in situ SAXS (small angle X-ray scattering) was used to characterize bamboo fibers. The thickness of nanocellulose was calculated by ln I(q)−q² curve and the results indicated that the thickness of nanocellulose decreased (from 13.38 ± 2.358 nm to 8.77 ± 0.98 nm) in the first 6 h, then stabilized at 8 nm in the range of 9–19 h after soaking in water. Additionally, the internal pores of bamboo changed, with the macropores decreasing and tiny pores increasing, respectively. In particular, the thickness of the crystals in nanocellulose decreased which might be attributed to the expansion and more disordered amorphous zone in lignin and hemicellulose under the influence of water. As the mechanical properties of bamboo increased apparently with the increased water content, this study can promote a better understanding of the water effects on the mechanical behaviors and toughening mechanisms within natural cellulose fibers.

为了研究纳米纤维素在水中的厚度演变，使用原位SAXS（小角度X射线散射）表征竹纤维。纳米纤维素的厚度通过ln I（q） − q ^2计算曲线和结果表明，纳米纤维素的厚度在开始的6 h内减小（从13.38±2.358 nm减小到8.77±0.98 nm），然后在水中浸泡9–19 h后稳定在8 nm。此外，竹子的内部孔发生了变化，大孔减少，细孔增加。特别地，纳米纤维素中晶体的厚度减小，这可能归因于在水的影响下木质素和半纤维素的膨胀和更无序的无定形区。随着竹子的机械性能随着水含量的增加而明显增加，这项研究可以促进人们更好地了解水对天然纤维素纤维内机械性能和增韧机理的影响。