Processing of Cellulose Using Ionic Liquids

Hermanutz, Frank; Vocht, Marc P.; Panzier, Nicole; Buchmeiser, Michael R.

doi:10.1002/mame.201800450

Cited by 89 publications

(71 citation statements)

References 91 publications

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“…The dissolution process of the pulp in the IL for the formation of the matrix precursor has been described earlier . Different concentrations of cellulose in the IL in the range of 3–8 wt% were used ( Table 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…However, CMCs based on these materials suffer from poor mechanical properties as a result of the defects in the carbonaceous and molecular structure of these biogenic materials, which both negatively influence mechanical properties. Recently, we reported on all‐cellulose composites (ACCs) based on high‐strength rayon fibers embedded in a cellulose pulp matrix . These ACCs offer good mechanical properties and have lower defects in the structure, show strong fiber‐matrix interaction and are thus promising starting materials for CMCs.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of C/C‐SiC Composites from All‐Cellulose Precursors

Schneck

Müller

Hermanutz

et al. 2019

Macro Materials & Eng

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All‐cellulose composites (ACCs) are manufactured from high‐performance cellulose fibers and a cellulose‐containing ionic liquid (IL) as matrix‐forming dope via wet‐winding processes, using different concentrations of cellulose in the IL. ACCs are carbonized at 1650 °C and then infiltrated with liquid silicon. Application of a carbonization aid (ammonium dihydrogenphosphate, ADHP) substantially improves the carbon yield after carbonization but also results in the depletion of the mechanical properties of the final carbon/carbon silicon carbide (C/C‐SiC) material. The microstructure of the porous carbon/carbon preforms strongly depends on both the concentration of cellulose in the IL and the concentration of ADHP. A C/C‐SiC composite manufactured from 6 wt% cellulose in the matrix‐forming dope, in the absence of ADHP, has a maximum flexural strength of 60 MPa. New C/C‐SiC composites with different shapes including Z‐profiles and tubes are successfully manufactured from pre‐shaped ACC precursors. These composites keep their shape during carbonization and the final siliconization process step.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preparation of C/C‐SiC Composites from All‐Cellulose Precursors

Schneck

Müller

Hermanutz

et al. 2019

Macro Materials & Eng

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“…Applying IL/cellulose solutions, there is a range of possibilities to process cellulose for applications other than continuous filaments or fibers. Such new developments were highlighted in a review by Hermanutz et al [ 146 ] Interesting technical applications such as all‐cellulose composites, spinning of polymer blends (e.g., cellulose plus chitin) and precursors for carbon fibers were described. [ 147 ] For carbon fiber precursors, it was shown that the use of different ILs makes it possible to co‐spin lignin (another abundant renewable wood‐based macromolecule) with cellulose.…”

Section: Regeneration Of Cellulose In Different Physical Formsmentioning

confidence: 99%

Cellulose Regeneration and Chemical Recycling: Closing the “Cellulose Gap” Using Environmentally Benign Solvents

Seoud

Kostag

Jedvert

et al. 2020

Macro Materials & Eng

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matched by synthetic fibers. Therefore, the demand on natural and fabricated cellulosic fibers is expected to continue and rise. The production of cotton, however, is not expected to meet this demand because of restrictions on farmland use and availability of irrigation water. [3] Anticipating the so-called "the cellulosic fiber gap," [1] the textile industry currently leads several initiatives for developing fibers that can complement cotton. [3] Consequently, there is incitement and opportunities for an increase in use of cellulose from other sources, in particular wood, and increased interest in physical (i.e., mechanical) and chemical recycling (CR) of biopolymers. [4] Production of fibers and other artifacts from cellulose extracted from wood involves chemical or physical dissolution of the biopolymer, followed by its regeneration in the desired physical form in an appropriate bath. The most important example of cellulose chemical dissolution (i.e., via covalent bond formation) is the viscose rayon fiber, produced by regeneration of cellulose from its xanthate in acid bath. The Lyocell fiber process involves, however, physical dissolution of cellulose in N-methylmorpholine-N-oxide (NMMO) hydrate, followed by regeneration in an aqueous bath. [5] Cellulose regeneration is not restricted to formation of fibers. The biopolymer and its derivatives, in particular esters, can be "shaped" into other physical forms including spheres of different diameters (down to the nanoscale), films produced by casting and spin coating, and nonwoven mats produced by electrospinning or solution blowing. This review covers some recent advances of the regeneration of cellulose from alkali solutions and ionic solvents, in particular those based on imidazole, quaternary ammonium electrolytes (QAEs), and salts of heterocyclic super-bases. We refer to these ionic solvents collectively as ionic liquids (ILs). Representative examples of the ILs employed for cellulose dissolution are shown in Figure 1. These solvents dissolve cellulose samples of a wide range of degrees of polymerization (DPs) and indices of crystallinity (Ics). For practical reasons, binary mixtures of ILs with molecular solvents (MSs) are used alongside pure ILs. This use is advantageous because of the concomitant decrease in solution viscosity; there are many examples where the binary solvent mixture dissolves more cellulose than the parent pure IL. [5] Strategies to mitigate the expected "cellulose gap" include increased use of wood cellulose, fabric reuse, and recycling. Ionic liquids (ILs) are employed for cellulose physical dissolution and shaping in different forms. This review focuses on the regeneration of dissolved cellulose as nanoparticles, membranes, nonwoven materials, and fibers. The solvents employed in these applications include ILs and alkali solutions without and with additives. Cellulose fibers obtained via the carbonate and carbamate processes are included. Chemical recycling (CR) of polycotton (cellulose plus poly(ethylene terephthalate)) is addressed...

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“…The tunability of anions and cations of ILs has shown great potential in the synthesis of materials, which can be used as a solvent and structure directing agent to improve the crystal form and morphology of inorganic materials in the synthesis of inorganic materials [ 52 , 53 , 54 ]. In addition, in the synthesis of organic materials, ILs can dissolve cellulose [ 55 ] and participate in organic synthesis [ 41 , 56 ] by taking advantage of its miscibility with organic matter and high solvation ability. As a green solvent and new type of reaction medium instead of traditional solvents, ILs are very easy to dissolve versatile precursors.…”

Section: Ils-contained Inorganicsmentioning

confidence: 99%

The Electric Field Responses of Inorganic Ionogels and Poly(ionic liquid)s

et al. 2020

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Ionic liquids (ILs) are a class of pure ions with melting points lower than 100 °C. They are getting more and more attention because of their high thermal stability, high ionic conductivity and dielectric properties. The unique dielectric properties aroused by the ion motion of ILs makes ILs-contained inorganics or organics responsive to electric field and have great application potential in smart electrorheological (ER) fluids which can be used as the electro-mechanical interface in engineering devices. In this review, we summarized the recent work of various kinds of ILs-contained inorganic ionogels and poly(ionic liquid)s (PILs) as ER materials including their synthesis methods, ER responses and dielectric analysis. The aim of this work is to highlight the advantage of ILs in the synthesis of dielectric materials and their effects in improving ER responses of the materials in a wide temperature range. It is expected to provide valuable suggestions for the development of ILs-contained inorganics and PILs as electric field responsive materials.

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Processing of Cellulose Using Ionic Liquids

Cited by 89 publications

References 91 publications

Preparation of C/C‐SiC Composites from All‐Cellulose Precursors

Preparation of C/C‐SiC Composites from All‐Cellulose Precursors

Cellulose Regeneration and Chemical Recycling: Closing the “Cellulose Gap” Using Environmentally Benign Solvents

The Electric Field Responses of Inorganic Ionogels and Poly(ionic liquid)s

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