Effect of microstructure on anomalous strain-rate-dependent behaviour of bacterial cellulose hydrogel
journal contributionposted on 2016-03-07, 15:37 authored by Xing Gao, Zhijun Shi, Andrew Ka-Chun Lau, Changqing Liu, Guang Yang, Vadim SilberschmidtVadim Silberschmidt
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 0.0001 s- 1 to 0.3 s- 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.
The authors would like to acknowledge the 7th European Community Framework Programme for financial support through a Marie Curie International Research Staff Exchange Scheme (IRSES) Project entitled “Micro-Multi-Material Manufacture to Enable Multifunctional Miniaturised Devices (M6)” (Grant No. PIRSES-GA-2010-269113). Additional support from China-European Union technology cooperation programme (Grant No. 1110) is also acknowledged.
- Mechanical, Electrical and Manufacturing Engineering