Quantitative insights into rheology of self-crosslinking dialdehyde carboxymethyl cellulose/collagen solution: A comprehensive experimental and modelling investigation

Abstract

Rheological behaviors (fluid type, thixotropy, viscoelasticity and deformation resistance) of self-crosslinking dialdehyde carboxymethyl cellulose (DCMC)/collagen solutions were comprehensively investigated and quantitatively modelled. The formation of self-crosslinking bonds gave rise to the enhancement of entanglements among collagen molecules and aggregates, resulting in the improvement of collagen solution's mechanical properties. The collagen solution was typical pseudoplastic fluid with shear-thinning behavior, and DCMC did not alter its flow behavior; therefore, the flow curves for all samples could be well simulated by Ostwald-de Waele and Carreau models. However, the viscosity and pseudoplasticity increased, and the effect of DCMC became more pronounced at higher DCMC/collagen ratios. Similar upward variation was observable for thixotropy, detected by the increased area of hysteresis loops from 20.947 to 219.978 Watts/m3. Additionally, the negative values of apparent yield stress and flow index below 1 from Herschel–Bulkley model confirmed that the DCMC/collagen solutions remained pseudoplasticity without yield stress. The viscoelasticity was examined based on dynamic frequency sweep and creep–recovery measurement and then simulated using Leonov model, Burger model and a semi-empirical model, respectively. The increases in elastic moduli and proportion of recoverable compliance reflected the self-crosslinking DCMC/collagen solutions had stronger elasticity and exhibited more resistance to deformation than the native collagen solution. Nevertheless, the more complicated structures of the DCMC/collagen solutions required more time to recover after removing external force. These data can be directly applied to the utilization of DCMC/collagen solutions, whilst also provide a basis for the prediction of printability or spinnability of collagen-based materials.