Controlled Dispersion and Setting of Cellulose Nanofibril - Carboxymethyl Cellulose Pastes

Abstract

This work investigated the redispersion and setting behavior of highly loaded (~18 wt.% solids in water) pastes of cellulose nano brils (CNFs) with carboxymethyl cellulose (CMC). A single-screw extruder was used to continuously process CNF+CMC pastes into cord. The adsorption of CMC onto the CNF brils was assessed through zeta potential and titration which revealed a surface charge change of ~61 % from -36.8 mV and 0.094 mmol/g COOH for pure CNF to -58.1 mV and 0.166 mmol/g COOH for CNF+CMC with a CMC degree of substitution of 0.9. Dried CNF with adsorbed CMC was found to be fully redispersible in water and re-extruded back into a cord without any di culties. On the other hand, chemical treatment with hydrochloric acid, a carbodiimide crosslinker, or two wet strength enhancers (polyamide epichlorohydrin and polyamine epichlorohydrin) completely suppressed the dispersibility previously observed for dried-untreated CNF+CMC. Turbidity was used to quantify the level of redispersion or setting achieved by the untreated and chemically treated CNF+CMC in both water and a strong alkaline solution (0.1 M NaOH). Depending on the chemical treatment used, FTIR analysis revealed the presence of ester, N-acyl urea, and anhydride absorption bands which were attributed to newly formed linkages between CNF brils, possibly explaining the suppressed redispersion behavior. Water uptake of the differently treated and dried CNF+CMC materials agreed with both turbidity and FTIR results.

Turning Recycled Cardboard Container-Derived Lignin-Containing Cellulose Nanofibrils into a Robust Gas Barrier UV-Shielding Film

“…Sharma & Deng (2016) also reported that this crosslinking not only improved the wet strength but also improved the dry strength of cellulose nanofibril films through a dual mechanism of crosslinking and hornification that occurred during the curing process at a high temperature . A recent report also described a similar crosslinking mechanism between the CMC and PAE chains, which is more indicative of our system under study …”

“…39 A recent report also described a similar crosslinking mechanism between the CMC and PAE chains, which is more indicative of our system under study. 40 To confirm if a similar ester linkage occurred in our films, we performed FTIR analysis as illustrated in Figure 2b,c. However, due to the presence of lignin and other additive materials in OCC-LCNFs, the FTIR spectra of pristine LCNF films showed a wide range of functional groups, including the majority of the functional groups expected to be present after crosslinking.…”

Methacrylated Cellulose Nanocrystals as Fillers for the Development of Photo-Cross-Linkable Cytocompatible Biosourced Formulations Targeting 3D Printing

“…Indeed, several types of interactions could be involved in these formulations. First, van der Waals interactions and hydrogen bonding between mCMC and CNC or mCNC could occur, even in the presence of negative charges brought by carboxylate groups on the mCMC backbone. ,, The lower surface sulfate content of mCNCs could probably facilitate the surface absorption of mCMC onto the nanorods. Due to the presence of methacrylate groups on both mCMC and mCNC, hydrophobic interactions between these two compounds could also occur, increasing the possibility of mCMC adsorption on mCNCs.…”

Liquid Foam Stabilized by a CO2-Responsive Surfactant and Similarly Charged Cellulose Nanofibers for Reversibly Plugging in Porous Media

“…The ζ-potential increased from +2.2 mV for the CNF to +48.8 mV for the CCNF, indicating that the mutual repulsion of the electric double layer between CCNF molecules was far greater than van der Waals’ attraction according to the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory. Therefore, the formed energy barrier prevented the molecules from being close and the Debye length was enhanced as well . As colloid molecules became scattered, the stability of the dispersion was promoted remarkably.…”

“…Therefore, the formed energy barrier prevented the molecules from being close and the Debye length was enhanced as well. 36 As colloid molecules became scattered, the stability of the dispersion was promoted remarkably. Furthermore, CCNF could reach 300 nm−1 μm in length and 1−5 nm in diameter, detected by AMF as shown in Figure S2, showing an incomparable advantage in the application of stabilizing foam.…”