TY - JOUR
T1 - Enzymatically Pretreated High-Solid-Content Nanocellulose for a High-Throughput Coating Process
AU - Koppolu, Rajesh
AU - Banvillet, Gabriel
AU - Ghimire, Himal
AU - Bras, Julien
AU - Toivakka, Martti
N1 - Funding Information:
R.K. received funding from Åbo Akademi University Graduate School in Chemical Engineering, Magnus Ehrnrooth Foundation, Finnish Forest Products Engineers Association, and Walter Ahlström Foundation. G.B. performed the experiments at LGP2 (Université Grenoble Alpes), which is part of the LabEx Tec 21 (Investissements d’Avenir; Grant ANR-11-LABX-0030) and of PolyNat Carnot Institute (Investissements d’Avenir; Grant ANR-16-CARN-0025–01). The authors gratefully thank the Association Nationale Recherche Technologie and Arjowiggins France SAS for financial and material support.
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/8/26
Y1 - 2022/8/26
N2 - 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.
AB - 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.
KW - barrier coatings
KW - enzymatic pretreatment
KW - nanocellulose
KW - rheology
KW - roll-to-roll coating
UR - http://www.scopus.com/inward/record.url?scp=85136025076&partnerID=8YFLogxK
U2 - 10.1021/acsanm.2c02423
DO - 10.1021/acsanm.2c02423
M3 - Article
SN - 2574-0970
VL - 5
SP - 11302
EP - 11313
JO - ACS Applied Nano Materials
JF - ACS Applied Nano Materials
IS - 8
ER -