Water redispersible cellulose nanofibrils adsorbed with carboxymethyl cellulose

Abstract

Cellulose nanofibrils (CNFs) are difficult to redisperse in water after they have been completely dried due to the irreversible agglomeration of cellulose during drying. Here, we have developed a simple process to prepare water-redispersible dried CNFs by the adsorption of small amounts of carboxymethyl cellulose (CMC) and oven drying. The adsorption of CMC onto CNFs in water suspensions at 22 and 121°C was studied, and the adsorbed amount of CMC was measured via conductimetric titration. The waterredispersibility of dried CNFs adsorbed with different amounts of CMC was characterized by sedimentation test. Above a critical threshold of CMC adsorption, i.e. 2.3 wt%, the oven dried CNF-CMC sample was fully redispersible in water. The morphology, rheological, and mechanical properties of water-redispersed CNF-CMC samples were investigated by field emission scanning electron microscopy, viscosity measurement, and tensile test, respectively. The waterredispersed CNFs preserved the original properties of never dried CNFs. This new method will facilitate the production, transportation and storage, and largescale industrial applications of CNFs.

Mechanical fabrication of high-strength and redispersible wood nanofibers from unbleached groundwood pulp

“…Moreover, in the commercialization of nanocelluloses, drying them is desired in many applications, but the redispersing of the nanofibers without hornification (Newman 2004) back to a solvent medium is still a challenge. Thus, the introduction of anionic charges through the use of additives (Lowys et al 2001), the chemical modification of the fibers via carboxymethylation (Eyholzer et al 2010;Butchosa and Zhou 2014), or the exploitation of nonwood plants with a high pectin content (Hiasa et al 2016;Hietala et al 2017) have been the most promising ways for recovering the properties of redispersed nanofibers. For nanofibers derived from wood, methods of drying and redispersing them in their native states in different media without the loss of any of their properties (Eyholzer et al 2010), and without the use of any additives or chemicals, would be advantageous for the fabrication of green bioproducts.…”

Core–shell cellulose nanofibers for biocomposites – Nanostructural effects in hydrated state

“…This reduces moisture sorption and swelling, and increases thermal stability. e) CNF 90 is biodegradable and, since dried CNF can be redispersed (Butchosa & Zhou, 2014), it has recycling 91 potential. f) Wood CNF are produced in industrial pilot plants in North America, Japan and Nordic 92 countries, and will potentially be available in large quantities at low cost.…”

Extraction and modification of cellulose nanofibers derived from biomass for environmental application

“…Wood based CNF are advantageous over other plant based CNFs due to its high cellulose purity, strong and ductile networks formed via CNF-CNF bonding of brils, 65 high intrinsic physical properties, 66 zero axial thermal expansion, 67 and high biodegradability. 68 CNFs have been isolated from both so and hard wood pulps. The structure of hardwoods is more complex and heterogeneous than sowoods.…”