Ptychographic X-ray Computed Tomography Study of the Paper Pulp Fiber to Fiber Bond
David Prochinig
11:15 - 12:15 Wednesday 01 April 2020 Link to the video
The strength of paper depends strongly on both, the strength of the individual cellulose fibers and the bonded area between cellulose fibers [1]. For the latter, a distinction between the intersection area and the actual bonded area has to be made. The intersection area is the optically overlapping area between two bonded fibers. The actual bonded area is the region in which the two fibers are in molecular contact. Admittedly, the whole Fiber to Fiber (FtF) bond can not be resolved to the molecular regime, thus the term relative contact area (RCA) is used. The RCA describes the subsection of the intersection area which is measured to be in contact, regarding the achieved experimental resolution [2].
A novel technique called Ptychographic X-ray Computed Tomography (PXCT) has shown to provide 3D electron density maps with nanometer resolution [3] and was used to image FtF-bonds in ambient and cryogenic conditions. In the ambient condition experiment, the sample suffered immense radiation damage, whereas in the cryogenic condition experiment, the sample morphology did not change significantly, allowing for a resolution between 50 and 100 nm.
Combining the results of ambient and cryogenic condition experiments, statements about the maximum bearable radiation dose and the ideal parameters and setup for PXCT experiments with cellulose samples can be made. Additionally, the RCA between two bonded fibers can be calculated and quantitative opening thickness maps similar to those in the work of Sormunen et. al. [4] can be generated.
[1] Page, D.H. A theory for the tensile strength of paper, Tappi J. 52 (4), 674 (1969).
[2] Sormunen, T. Measuring the contact area in cellulose fibre bonds using X-ray nanotomography. MSc Thesis. University of Jyväskylä. Department of Physics 2018.
[3] Holler, M., Diaz, A., Guizar-Sicairos, M. et al. X-ray ptychographic computed tomography at 16 nm isotropic 3D resolution. Sci Rep 4, 3857 (2015); DOI: 10.1038/srep03857
[4] Sala, S., Batey, D.J., Prakash, A., Ahmed, S., Rau, C., Thibault, P. Ptychographic X-ray computed tomography at a high-brilliance X-ray source. Opt. Express 27, 533-542 (2019); DOI: 10.1364/OE.27.000533
[4] Sormunen, T., Ketola, A., Miettinen, A. et al. X-Ray Nanotomography of Individual Pulp Fibre Bonds Reveals the Effect of Wall Thickness on Contact Area. Sci Rep 9, 4258 (2019); DOI: 10.1038/s41598-018-37380-2
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Institute of Solid State Physics
