Department of Physics, University of Jyväskylä, Jyväskylä, 40014, Finland.
VTT Technical Research Centre of Finland, Oulu, 90571, Finland.
Sci Rep. 2019 Mar 12;9(1):4258. doi: 10.1038/s41598-018-37380-2.
Fibre bonds play an essential role in various properties of paper. Much research has focused on their strength, but the determination of the actual contact area also provides a challenge. Many of the research methods rely on optical tools, which are restricted by the wavelength of light that is utilised. Novel X-ray computed tomography devices utilise X-rays in studying the inner structure of materials, and surpass the optical methods in terms of resolution, allowing detection of even smaller details and variations in distance between the fibres in the bond intersection area. X-ray nanotomography was used to image 26 individual cellulose fibre bonds made of springwood and summerwood fibres of refined bleached softwood kraft pulp. Various dimensional properties of the bonds were measured, most importantly the relative contact area (apparent contact area/intersection area), whose values showed wide variation from 6.4 to 85% with an average of 57.7%. Although the summerwood bonds had a somewhat smaller intersection and contact area than springwood bonds, there were no significant differences in the relative contact area between the bond types. This suggests that the effect of relative and absolute contact area on the strength differences between bond types seems to be minor.
纤维键在纸张的各种性能中起着至关重要的作用。许多研究都集中在纤维键的强度上，但确定实际接触面积也带来了挑战。许多研究方法依赖于光学工具，而这些工具受到所使用的光波长的限制。新型的 X 射线计算机断层扫描设备利用 X 射线研究材料的内部结构，在分辨率方面超越了光学方法，可以检测到更小的细节和纤维在键交叉区域之间的距离变化。X 射线纳米断层扫描被用于对 26 个由精制漂白软木牛皮纸的春材和夏材纤维制成的单个纤维素纤维键进行成像。测量了各种键的尺寸特性，最重要的是相对接触面积（表观接触面积/交叉面积），其值从 6.4%到 85%不等，平均值为 57.7%。尽管夏材纤维键的交叉和接触面积比春材纤维键略小，但两种纤维键的相对接触面积没有显著差异。这表明相对和绝对接触面积对不同纤维键类型之间强度差异的影响似乎较小。
