Abstract
In the present work, the microstructure and rheological behavior of nanocrystalline cellulose (NCC) and cationically modified NCC (CNCC) were comparatively studied. The resultant CNCC generally showed improved dispersion and higher thermal stability in comparison to the un-modified NCC. The rheological behavior demonstrated that the viscosity of the NCC suspension substantially decreased with the increasing shear rate (0.01–100 s−1), showing the typical characteristics of a pseudoplastic fluid. In contrast, the CNCC suspensions displayed a typical three-region behavior, regardless of changes in pH, temperature, and concentration. Moreover, the CNCC suspensions exhibited higher shear stress and viscosity at a given shear rate (0.01–100 s−1) than the NCC suspension. Meanwhile, the dynamic viscoelasticity measurements revealed that the CNCC suspensions possessed a higher elastic (G′) and loss modulus (G″) than NCC suspensions over the whole frequency range (0.1–500 rad·s−1), providing evidence that the surface cationization of NCC makes it prone to behave as a gel-like structure.
Highlights
Nanocrystalline cellulose (NCC), an emerging renewable nanomaterial that is mainly derived from various plant fibers and cellulosic sources [1,2,3] and holds great promise for applications in many fields, e.g., plastics, chemicals, foods, pharmaceuticals, and cosmetics [4,5,6,7,8]
The cationically modified NCC (CNCC) suspension demonstrated three-region behavior, and G0 was independent of frequency and higher than G00 at all of the investigated frequencies from 0.1 to 100 s−1, regardless of how variations in pH, temperature, and concentration varied
CNCC was successfully prepared by grafting glycidyltrimethylammonium chloride (GTMAC) onto the surface of nanocrystalline cellulose (NCC)
Summary
Nanocrystalline cellulose (NCC), an emerging renewable nanomaterial that is mainly derived from various plant fibers and cellulosic sources [1,2,3] and holds great promise for applications in many fields, e.g., plastics, chemicals, foods, pharmaceuticals, and cosmetics [4,5,6,7,8]. Various surface modification processes may confer different microstructures and properties to the resulting NCC. Among those properties, the rheological behavior of NCC in aqueous media appears to be rather critical in governing its potential applications [16]. The rheological behavior of NCC suspensions as a function of the surface modification, cationic modification, was not reported in the previous works. In the present work, a comparative study was conducted with respect to the rheological behavior and microstructure of NCC and cationically modified NCC (CNCC). The effects of concentration, temperature, and pH on the rheological behavior of aqueous NCC and CNCC suspensions were investigated. We hope that understanding the microstructure of NCC and CNCC suspensions and its inter-relationship with the rheological properties will facilitate decision-making for process design and the optimization of NCC extraction and its subsequent handling
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