PAPERmaking! Vol7 Nr2 2021

Cellulose (2021) 28:5775–5791 https://doi.org/10.1007/s10570-021-03817-7 (0123456789().,-volV) ( 0123458697().,-volV)

ORIGINAL RESEARCH

Accessibility of fiber surface sites for polymeric additives determines dry and wet tensile strength of paper sheets

J.-L. Scha¨fer . S. Scho¨lch . O. Prucker . T. Brandstetter . J. Ru¨he . A. Ritter v. Stockert . T. Meckel . M. Biesalski

Received: 4 November 2020 / Accepted: 5 March 2021 / Published online: 18 April 2021  The Author(s) 2021

Abstract This contribution focuses on understand- ing of paper wet-strength properties, by taking a closer look at the spatial distribution of wet-strengthening polymers inside the cellulosic fiber network deposited under different treatment conditions using confocal laser scanning microscopy as in situ imaging tool. We compare the behavior of paper samples treated with a photochemically cross-linkable copolymer using an impregnation process employing three different sol- vents, namely water, 2-propanol (IPA) and 1-butanol

(BuOH), respectively. As these solvents swell paper fibers to quite different extents, the deposition of the polymer, on, in or in-between the cellulosic fibers varies quite strongly, as is shown by in-depth analysis using confocal laser scanning microscopy. The differ- ence in accessibility of distinct surface sites exclu- sively on or also in and between the fibers controls the macroscopic tensile strength under both dry and wet conditions.

Keywords

Cellulose  Paper  Wet strength  Spatial

distribution  Swelling  Photo-crosslinking

J.-L. Scha¨fer, S. Scho¨lch contributed equally.

Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/ s10570-021-03817-7. J.-L. Scha¨fer  A. R. v. Stockert  T. Meckel  M. Biesalski ( & ) Department of Chemistry, Macromolecular Chemistry & Paper Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany e-mail: markus.biesalski@tu-darmstadt.de S. Scho¨lch  O. Prucker  T. Brandstetter  J. Ru¨he ( & ) Department of Microsystems Engineering (IMTEK), Laboratory for Chemistry & Physics of Interfaces, Albert- Ludwigs-Universita¨t Freiburg, Georges-Ko¨hler-Allee 103, 79110 Freiburg, Germany e-mail: ruehe@imtek.uni-freiburg.de

S. Scho¨lch  O. Prucker  T. Brandstetter  J. Ru¨he Freiburg Institute for Interactive Materials and Bioinspired Technologies (FIT), Albert-Ludwigs- Universita¨t Freiburg, Georges-Ko¨hler-Allee 105, 79110 Freiburg, Germany

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