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Aggregate Morphology and Aqueous Dispersibility of Spray-Dried Powders of Cellulose Nanocrystals
journal contribution
posted on 2019-10-17, 14:48 authored by Yussef Esparza, Tri-Dung Ngo, Carole Fraschini, Yaman BolukSpray drying is the most cost-efficient
technology to produce bulk
quantities of dry cellulose nanocrystals (CNCs) from acid hydrolyzed
CNC suspensions. Spray drying results in the aggregation of CNC particles
in granular material which is difficult to redisperse in water to
individual particles. In this research, we investigated cospray drying
of CNC suspensions with nonionic surfactant (10-mol ethoxylated octylphenol)
at different concentrations and the role of this nonionic surfactant
on the redispersion of spray-dried granular CNC particles. Dispersions
of spray-dried CNC powder samples in water were investigated under
static, mechanically stirred, and ultrasound-assisted mixing conditions.
The granular morphology of spray-dried CNCs was affected by the concentration
of nonionic surfactant. Overall, the formations of hollow and blistered
particles in the presence of 5 and 10 mM OPE-100 were attributed to
interactions between nonionic surfactant and CNCs which cause a reduction
in the repulsion of nanoparticles during the shrinking of spray drying
droplets. Higher light transmission properties, improved dispersion
stability, and narrower particle size distribution of spray-dried
CNC suspensions were achieved with the incorporation of nonionic surfactant
at 5 and 10 mM prior to spray drying. These results are explained
by the presence of hollow particles and by the increased interparticle
interaction distance of CNCs due to weak and reversible adsorption
of nonionic surfactant. Therefore, the addition of a nonionic surfactant
is an attractive approach to control granular particle morphology
and aqueous redispersion of CNC granular powder. Such results are
of particular significance in the commercialization and process optimization
for the manufacture of CNCs.