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Journal of Nanomaterials
Volume 2013, Article ID 594734, 6 pages
Research Article

Water-Triggered Dimensional Swelling of Cellulose Nanofibril Films: Instant Observation Using Optical Microscope

1School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
2Forest Products Laboratory, USDA Forest Service, Madison, WI 53726-2398, USA

Received 2 January 2013; Accepted 30 January 2013

Academic Editor: Yongfeng Luo

Copyright © 2013 Yan Qing et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


To understand the swelling behavior of cellulose nanofibril (CNF) films, the dimensional variation of untreated and phenol formaldehyde modified CNF (CNF/PF) films soaked in distilled water was examined in situ with microscopic image recording combined with pixel calculation. Results showed that a dramatic thickness increase exhibited in both CNF and CNF/PF films, despite being at different swelling levels. Compared to thickness swelling, however, the width expansion for these films is negligible. Such significant difference in dimensional swelling for CNF and PF modified films is mainly caused by nanofibril deposition and their mesostructure. However, addition of PF modifier has a positive effect on the constraint of water absorption and thickness swelling, which is strongly dependent on PF loadings.