title: Effect of microstructure on anomalous strain-rate-dependent behaviour of bacterial cellulose hydrogel.
abstract: This study is focused on anomalous strain-rate-dependent behaviour of bacterial cellulose (BC) hydrogel that can be strain-rate insensitive, hardening, softening, or strain-rate insensitive in various ranges of strain rate. BC hydrogel consists of randomly distributed nanofibres and a large content of free water; thanks to its ideal biocompatibility, it is suitable for biomedical applications. Motivated by its potential applications in complex loading conditions of body environment, its time-dependent behaviour was studied by means of in-aqua uniaxial tension tests at constant temperature of 37 °C at various strain rates ranging from 0.000 1s(-1) to 0.3s(-1). Experimental results reflect anomalous strain-rate-dependent behaviour that was not documented before. Micro-morphological observations allowed identification of deformation mechanisms at low and high strain rates in relation to microstructural changes. Unlike strain-rate softening behaviours in other materials, reorientation of nanofibres and kinematics of free-water flow dominate the softening behaviour of BC hydrogel at high strain rates.
authors.affiliation: Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, UK.
authors.forename: Xing
authors.initials: X
authors.lastname: Gao
authors.affiliation: College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Lau
authors.affiliation: Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, UK.
authors.forename: Changqin
authors.initials: C
authors.lastname: Liu
authors.affiliation: College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Guang
authors.initials: G
authors.lastname: Yang
authors.affiliation: Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, UK.
authors.forename: Vadim V
authors.initials: VV
authors.lastname: Silberschmidt
mesh_terms: D001419:Bacteria / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry*; D006244:Hardness; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D008854:Microscopy, Electron; D057139:Nanofibers / Q000737:chemistry; D013718:Tensile Strength
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D002482:Cellulose
keywords: Bacterial cellulose hydrogel; Deformation mechanisms; In-aqua testing; Microstructural changes; Strain-rate softening