Direct pretreatment of raw ramie fibers using an acidic deep eutectic solvent to produce cellulose nanofibrils in high purity

A deep eutectic solvent (DES) composed of sulfamic acid and glycerol allowed for the sustainable preparation of cellulose nanofibrils (CNF) with simultaneous sulfation. The reaction time and the levels of sulfamic acid demonstrated that fibers could be swelled and sulfated simultaneously by a sulfamic acid-glycerol-based DES and swelling also promoted sulfation with a high degree of substitution (0.12). The DES-pretreated fibers were further nanofibrillated by a grinder producing CNF with diameters from 10 nm to 25 nm. The crystallinity ranged from 53–62%, and CNF maintained the original crystal structure. DES pretreatment facilitated cellulose nano-fibrillation and reduced the energy consumption with a maximum reduction of 35%. The films prepared from polyvinyl alcohol (PVA) and CNF showed good UV resistance ability and mechanical properties. This facile and efficient method provided a more sustainable strategy for the swelling, functionalization and nano-fibrillation of cellulose, expanding its application to UV-blocking materials and related fields.

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Wet-Spun Composite Filaments from Lignocellulose Nanofibrils/Alginate and Their Physico-Mechanical Properties

Polymers ◽

10.3390/polym13172974 ◽

2021 ◽

Vol 13 (17) ◽

pp. 2974

Author(s):

Ji-Soo Park ◽

Song-Yi Han ◽

Rajkumar Bandi ◽

Eun-Ah Lee ◽

Azelia-Wulan Cindradewi ◽

...

Keyword(s):

Mechanical Properties ◽

Choline Chloride ◽

Cellulose Nanofibrils ◽

Deep Eutectic Solvent ◽

Average Diameter ◽

Al Content ◽

Pure Cellulose ◽

Orientation Index ◽

Lignocellulose Nanofibrils ◽

Cacl2 Solution

Lignocellulose nanofibrils (LCNFs) with different lignin contents were prepared using choline chloride (ChCl)/lactic acid (LA), deep eutectic solvent (DES) pretreatment, and subsequent mechanical defibrillation. The LCNFs had a diameter of 15.3–18.2 nm, which was similar to the diameter of commercial pure cellulose nanofibrils (PCNFs). The LCNFs and PCNFs were wet-spun in CaCl2 solution for filament fabrication. The addition of sodium alginate (AL) significantly improved the wet-spinnability of the LCNFs. As the AL content increased, the average diameter of the composite filaments increased, and the orientation index decreased. The increase in AL content improved the wet-spinnability of CNFs but deteriorated the tensile properties. The increase in the spinning rate resulted in an increase in the orientation index, which improved the tensile strength and elastic modulus.

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Preparation and Properties of Wet-Spun Microcomposite Filaments from Various CNFs and Alginate

Polymers ◽

10.3390/polym13111709 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1709

Author(s):

Ji-Soo Park ◽

Chan-Woo Park ◽

Song-Yi Han ◽

Eun-Ah Lee ◽

Azelia Wulan Cindradewi ◽

...

Keyword(s):

Tensile Strength ◽

Elastic Modulus ◽

Tensile Properties ◽

Cellulose Nanofibrils ◽

Deep Eutectic Solvent ◽

Microfluidic Channel ◽

Cellulose Nanofibril ◽

Pure Cellulose ◽

Alginate Fibers ◽

Cacl2 Solution

We aimed to improve the mechanical properties of alginate fibers by reinforcing with various cellulose nanofibrils (CNFs). Pure cellulose nanofibril (PCNF), lignocellulose nanofibril (LCNF) obtained via deep eutectic solvent (DES) pretreatment, and TEMPO-oxidized lignocellulose nanofibril (TOLCNF) were employed. Sodium alginate (AL) was mixed with PCNF, LCNF, and TOLCNF with a CNF content of 5–30%. To fabricate microcomposite filaments, the suspensions were wet-spun in calcium chloride (CaCl2) solution through a microfluidic channel. Average diameters of the microcomposite filaments were in the range of 40.2–73.7 μm, which increased with increasing CNF content and spinning rate. The tensile strength and elastic modulus improved as the CNF content increased to 10%, but the addition of 30% CNF deteriorated the tensile properties. The tensile strength and elastic modulus were in the order of LCNF/AL > PCNF/AL > TOLCNF/AL > AL. An increase in the spinning rate improved the tensile properties.

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