Enzymatically Pretreated High-Solid-Content Nanocellulose for a High-Throughput Coating Process

Rajesh Koppolu (Corresponding Author), Gabriel Banvillet, Himal Ghimire, Julien Bras, Martti Toivakka

Research output: Contribution to journalArticleScientificpeer-review

Abstract

There is an ever-increasing interest toward utilizing nanocellulose as barrier coatings and films, and recent studies have underlined the efficiency of using innovative fibrillation processes such as twin-screw extrusion with an enzymatic pretreatment for producing nanocellulose suspensions with solid contents as high as 20 wt %, which can lead to faster coating speeds and reduced drying energy costs. The current work aims at understanding the factors that influence high-throughput processability of high-solid-content nanocellulose during roll-to-roll coating. The rheological properties of 12.5, 10, and 7.5 wt % suspensions were evaluated across a wide range of shear rates and geometries (rotational, pipe, and slot). The influence of dispersants [carboxymethyl cellulose (CMC) and sodium polyacrylate (NaPA)] on the rheology and coating quality was assessed. A Casson-power-cross model is proposed to explain the rheological behavior across a wide shear rate range and is used to predict useful parameters, viz., yield stress, transition shear rate, and power-law index at high shear rates. Finally, a 12.5 wt % nanocellulose suspension with CMC or NaPA dispersant was roll-to-roll-coated on paperboard using a slot-die applicator. CMC addition had a positive influence on the yield stress, thixotropy, and water release and, therefore, resulted in a better mineral oil and grease barrier of the coated samples compared to the rest.
Original languageUndefined
Pages (from-to)11302–11313
JournalACS Applied Nano Materials
Volume5
Issue number8
DOIs
Publication statusPublished - 26 Aug 2022
MoE publication typeA1 Journal article-refereed

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