Effects of clay concentration on the morphology and rheological properties of xanthan gum‐based hydrogels reinforced with montmorillonite particles

ABSTRACT This work presents results of the morphology and rheological properties of xanthan gum (XG)‐based hydrogels reinforced by montmorillonite (MMT) particles. The results show that hydrogels exhibit self‐supporting characteristics when a critical MTT concentration of approximately 2.0% w/w is used. Wide‐angle, small‐angle X‐ray diffraction patterns and transmission electron microscopy reveal that for concentrations up to about 1.0% w/w the MTT particles are homogeneously distributed and exfoliated in the XG matrix. MTT particles aggregate at higher concentrations, contributing to the formation of junction points leading to hydrogels consolidation. Fourier transform infrared analysis indicates that the mechanism that enables the hydrogels formation might be attributed to hydrogen bonds crosslinking XG molecules with the surface of MTT particles. The storage modulus is higher as MTT concentration increases, but the loss modulus remains practically unchanged. Increasing temperature produces a drop in storage modulus, but the drop is minimized over a wider temperature range, as the MTT concentration is higher. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44517.