Exploring the Nonlinear Rheology of Composite Hydrogels: A New Paradigm for LAOS Analysis

TL;DR

This paper studies the complex nonlinear rheological behavior of composite biopolymer hydrogels, introducing an extended analysis framework that captures their transition from linear to nonlinear responses under large oscillatory strains.

Contribution

It extends the Sequence of Physical Processes (SPP) method to analyze and classify the nonlinear rheology of biopolymer composite gels using Cole-Cole plot analysis.

Findings

Nonlinear responses are not simply additive for composite gels.

Extended SPP provides a robust classification of nonlinear rheological behavior.

Time-resolved Cole-Cole plots reveal transition points between linear and nonlinear regimes.

Abstract

We investigate composite biopolymer networks composed of co-polymerized fibrin and gelatin networks and perform rheological measurements over a broad parameter space including strain amplitudes that go beyond the linear response regime. One goal of the work presented here is to provide a prototypical biocomposite material with highly separable polymerization times and controlled nonlinear rheological characteristics. We then extend the Sequence of Physical Processes (SPP)\cite{Rogers2017} into a statistical and geometrical framework that fingerprints the nonlinear rheological response of biopolymer composite gels. Our analysis is based on the changes in the shape of the time-dependent Cole-Cole plots that allow to reduce the time resolved analysis of the SPP method into the transition between linear and nonlinear behavior as the rheological parameters are varied. While the results clearly highlight how the mechanical responses of individual constituents are not simply additive, our extended SPP analysis provides a robust and intuitive classification scheme for comparing the nonlinear response of composite materials subjected to large oscillatory strain.