Evaluating the Mechanical Response of Agarose-Xanthan Mixture Gels Using Tensile Testing, Numerical Simulation, and a Large Amplitude Oscillatory Shear (LAOS) Approach

Abstract

Large deformation stress response characteristics of hydrocolloid mixture gel systems were investigated based on texture and rheological measurements. Agarose and xanthan mixtures at different ratios (1:0, 0.75:0.25, and 0.5:0.5) were chosen as the model systems. A decrease in failure stress from 2.65 to 1.82 MPa and an increase in failure strain from 0.08 to 0.13 with higher xanthan ratios were obtained based on the ring tensile test, indicating that xanthan molecules could improve the flexibility of the agarose network. The gels showed severe water loss by compression, particularly for the pure agarose gel (6.74%). Compared to the compression test, the gels presented low water loss after the ring tensile test (<1.3%) indicating that the ring tensile test could calculate the correct stress–strain relationship. Digital image correlation (DIC) and numerical simulation revealed that agarose-xanthan gel systems possess a deformation behavior with homogeneous strain distribution before failure. Elastic and viscous Lissajous–Bowditch curves from the large amplitude oscillatory shear (LAOS) measurement at different strains and frequencies elucidated that the agarose-xanthan gel was dominated by the agarose structure with a similar magnitude of elasticity at a low frequency. The large deformation approach from this study has great potential for elucidating and understanding the structure of food and biopolymer gels.

Double Networks: Hybrid Hydrogels with Clustered Silica

“…This method enables analyzing the nonlinear viscoelastic behavior of a sample inside each cycle. It was used for studying viscoelastic soft materials, such as organogels, fibrin gels, and other hydrogels, − ,, amphiphilic polymer solutions, PDMS, and filled elastomers. , Note that the three-dimensional (3D) so-called Lissajous–Bowditch representation may be used to visualize the elastic and viscous stress contributions defined in eqs and in a single combined graph …”

“…Dynamic oscillatory shear tests have been commonly used to investigate a wide range of soft matter and complex fluids, with a recent renewal of interest in exploiting large amplitude oscillatory shear (LAOS) tests to investigate and quantify their complex nonlinear viscoelastic behavior. − Hybrid gels, which are composed of a dispersion of silica nanoparticles within a polymer matrix, present obvious similarities to filled elastomers. Subjected to large sinusoidal strains, filled elastomers were demonstrated to show a decrease in their storage modulus (Payne effect) along with nonlinear behavior (strain stiffening), meaning that their response is no longer purely sinusoidal. , …”

Food Hydrocolloids: Structure, Properties, and Applications

“…In food systems, the high affinity of hydrocolloids for water molecules significantly changes the rheological properties of food [3]. Rheological properties are defined as mechanical properties that cause food deformation and flow in the presence of stress.…”

Comparative Large Amplitude Oscillatory Shear (LAOS) Study of Ionically and Physically Crosslinked Hydrogels

“…Over the last decades, several combinations of either polysaccharides or proteins, or even polysaccharides with proteins (including inevitable gelatin), have been utilized to obtain the functionalized mechanical properties of hydrogels [ 1 , 2 , 9 , 10 , 11 , 12 , 13 , 14 ]. Moreover, the mechanical characterization of such hydrocolloid aqueous solutions, and the resulting gels, are studied beyond the LVE, including large-amplitude oscillatory shear (LAOS), among other methods [ 6 , 9 , 10 , 11 , 12 , 13 , 14 ]. When investigating binary gelatin-alginate systems for in situ gelation and ex situ individual gel layers, Goudoulas and Germann [ 9 ] reported comparable storage modulus G’ overshoots for the in situ gelation samples.…”