Abstract

The production capacity of cellulose nanomaterials (CNM) is limited in part due to lacking standardized, rapid and reliable characterization methods for quality control. In this study, we demonstrate the potential of using rheology as a tool to address this challenge by developing detailed test protocols and a rheological model combining power law and the Cross model: \(\eta = a\dot{\gamma }^{ - b} + \eta_{\infty } + \frac{{\eta_{0} - \eta_{\infty } }}{{1 + \left( {\lambda \dot{\gamma }} \right)^{m} }}\), where \(\dot{\gamma }\) is the shear rate and \(\eta\) is the viscosity. The test protocols, including sample preparation and viscosity measurement procedures, ensure obtaining robust and accurate data. The model, which combines the power law and the Cross model, describes the flow curves over the full range of shear rates across concentrations for both cellulose nanocrystals and TEMPO-oxidized cellulose nanofibrils. The model parameterizes the viscosity data for quick comparisons of different flow curves using all data rather than selectively using viscosity values at specific shear rates. Key model parameters correlate well with the suspension concentrations. We show that this model can be used to estimate the concentration of an uncharacterized CNM sample, and to estimate the salt concentration in a sample. Both applications are relevant to quality control.

Graphic abstract

摘要

纤维素纳米材料（CNM）的生产能力有限，部分原因是缺乏用于质量控制的标准化，快速和可靠的表征方法。在这项研究中，我们通过开发详细的测试协议以及结合幂律和Cross模型的流变模型，证明了使用流变学作为解决这一挑战的工具的潜力：\（\ eta = a \ dot {\ gamma} ^ {- b} + \ eta _ {\ infty} + \ frac {{\ eta_ {0}-\ eta _ {\ infty}}} {{1 + \ left（{\ lambda \ dot {\ gamma}} \ right）^ { m}}} \），其中\（\ dot {\ gamma} \）是剪切速率，\（\ eta \）是粘度。测试方案，包括样品制备和粘度测量程序，可确保获得可靠，准确的数据。该模型结合了幂律和Cross模型，描述了纤维素纳米晶体和TEMPO氧化纤维素纳米原纤维在整个浓度范围内的剪切速率整个范围内的流量曲线。该模型将粘度数据参数化，以便使用所有数据快速比较不同的流量曲线，而不是选择性地使用特定剪切速率下的粘度值。关键模型参数与悬浮液浓度密切相关。我们表明该模型可用于估计未表征的CNM样品的浓度，并估计样品中的盐浓度。两种应用都与质量控制有关。

图形摘要