Time-dependent rheological behaviour of bacterial cellulose hydrogel

Kuśmierczyk

Journal of the Mechanical Behavior of Biomedical Materials

et al. 2016

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Biological hydrogels, e.g. bacterial cellulose (BC) hydrogel, attracted increasing interest in recent decades since they show a good potential for biomedical engineering as replacements of real tissues thanks mainly to their good biocompatibility and fibrous structure. To select potential candidates for such applications, a comprehensive understanding of their performance under application-relevant conditions is needed. Most hydrogels demonstrate time-dependent behaviour due to the contribution of their liquid phase and reorientation of fibres in a process of their deformation. To quantify such time-dependent behaviour is crucial due to their exposure to complicated loading conditions in body environment. Some hydrogel-based biomaterials with a multi-layered fibrous structure demonstrate a promise as artificial skin and blood vessels. The results show a good potential to use a fraction-exponential model to describe such behaviour of multi-layered hydrogels, especially at stages of stress decay at low forces and of stress equilibrium at high forces.

Section: Fraction-exponential Operatorsmentioning

confidence: 99%

Section: Fraction-exponential Operatorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Through-thickness stress relaxation in bacterial cellulose hydrogel

Kuśmierczyk

Journal of the Mechanical Behavior of Biomedical Materials

et al. 2016

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“…The BC hydrogel is practically a viscoelastic material thanks to its high liquid content [41,42]. Motion of water during a process of deformation is involved in the network's response, affecting the measurements of its stiffness [43].…”

Section: Measurement Of Effective Elastic Modulusmentioning

confidence: 99%

Assessing stiffness of nanofibres in bacterial cellulose hydrogels: Numerical-experimental framework

Sozumert

Materials Science and Engineering: C

et al. 2017

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This work presents a numerical-experimental framework for assessment of stiffness of nanofibres in a fibrous hy-drogel -bacterial cellulose (BC) hydrogel -based on a combination of in-aqua mechanical testing, microstructur-al analysis and finite-element (FE) modelling. Fibrous hydrogels attracted growing interest as potential replacements to some tissues. To assess their applicability, a comprehensive understanding of their mechanical response under relevant conditions is desirable; a lack of such knowledge is mainly due to changes at microscale caused by deformation that are hard to evaluate in-situ because of the dimensions of nanofibres and aqueous en-vironment. So, discontinuous FE simulations could provide a feasible solution; thus, properties of nanofibres could be characterised with a good accuracy. An alternative -direct tests with commercial testing systems -is cumbersome at best. Hence, in this work, a numerical-experimental framework with advantages of convenience and relative easiness in implementation is suggested to determine the stiffness of BC nanofibres. The obtained magnitudes of 53.7-64.9 GPa were assessed by calibrating modelling results with the original experimental data.

“…In a study of Nimeskern et al [8], stress-relaxation indentation was performed to characterize viscoelastic properties of the BC with various cellulose contents for evaluation of potential use for ear-cartilage replacement. In-plane creep tests at various stress levels were carried out to determined viscoelastic properties of a BC hydrogel in terms of a fractional-exponential formulism [18].…”

Section: Introductionmentioning

confidence: 99%

Effect of microstructure on anomalous strain-rate-dependent behaviour of bacterial cellulose hydrogel

Materials Science and Engineering: C

Lau

et al. 2016

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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 inaqua 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.