# Cellulose

## List of Papers (Total 173)

#### Chromophores from hexeneuronic acids: chemical behavior under peroxide bleaching conditions

Hexeneuronic acids (HexA) are a major cause of discoloration (yellowing/brightness reversion) in pulps from xylan-containing wood, being generated from the xylan’s 4-O-methylglucuronic acid residues. The HexA-derived chromophores, whose identification and structure confirmation have been described in the previous part of this series (Rosenau et al. in Cellulose, 2017), were...

#### Chromophores from hexeneuronic acids: identification of HexA-derived chromophores

Hexeneuronic acids (HexA) have long been known as triggers for discoloration processes in glucuronoxylan-containing cellulosic pulps. They are formed under the conditions of pulping from 4-O-methylglucuronic acid residues, and are removed in an “A stage” along the bleaching sequences, which mainly comprises acidic washing treatments. The chemical structures of HexA-derived...

#### Barrier and mechanical properties of plasticized and cross-linked nanocellulose coatings for paper packaging applications

Barrier, mechanical and thermal properties of porous paper substrates dip-coated with nanocellulose (NC) were studied. Sorbitol plasticizer was used to improve the toughness, and citric acid cross-linker to improve the moisture stability of the coatings. In general, the addition of sorbitol increased the barrier properties, maximum strength and toughness as well as the thermal...

#### Swelling properties and generation of cellulose fines originating from bleached kraft pulp refined under different operating conditions

Cellulose fines are—in general—small particles removed from natural cellulose fibres during refining process which is typically carried out in papermaking industry. Fines have been recognized as a separate component of papermaking fibrous raw material since their properties differ considerably from those of cellulosic fibres. Fines are characterized by low dewatering ability...

#### Modification of cotton fabric with graphene and reduced graphene oxide using sol–gel method

Cotton fabrics were modified by xerogel coatings with dispersed particles of graphene (Gr) or reduced graphene oxide (RGO). To obtain a stable dispersion of Gr or RGO in organo-silicon sol, sodium lauryl sulfate as an anionic surfactant was used. The fabrics were padded with the organo-silicon sol containing dispersed Gr or RGO, forming a thin xerogel coating after drying. The...

#### Chemically modified cellulose micro- and nanofibrils as paper-strength additives

Chemically modified cellulose micro- and nanofibrils were successfully used as paper strength additives. Three different kinds of cellulose nanofibrils (CNFs) were studied: carboxymethylated CNFs, periodate-oxidised carboxymethylated CNFs and dopamine-grafted carboxymethylated CNFs, all prepared from bleached chemical fibres of dissolving grade, and one microfibrillated cellulose...

#### Alkali pretreatments and crosslinking of lyocell fabrics

Lyocell fabrics were pretreated with NaOH, KOH and LiOH and subsequently crosslinked with three urea–formaldehyde based crosslinkers DMDHEU, DMeDHEU and DMU. The mechanical properties varied with the alkali concentration in fabrics crosslinked after pretreatment with 2–8 mol/l NaOH and 4 mol/l LiOH. In fabrics crosslinked after pretreatment with 2–8 mol/l KOH and 1–3 mol/l LiOH...

#### On the dissolution of cellulose in tetrabutylammonium acetate/dimethyl sulfoxide: a frustrated solvent

We have found that the dissolution of cellulose in the binary mixed solvent tetrabutylammonium acetate/dimethyl sulfoxide follows a previously overlooked near-stoichiometric relationship such that one dissolved acetate ion is able to dissolve an amount of cellulose corresponding to about one glucose residue. The structure and dynamics of the resulting cellulose solutions were...

#### Switchable ionic liquids enable efficient nanofibrillation of wood pulp

Use of switchable ionic liquid (SIL) pulp offers an efficient and greener technology to produce nanofibers via ultrafine grinding. In this study, we demonstrate that SIL pulp opens up a mechanically efficient route to the nanofibrillation of wood pulp, thus providing both a low cost and chemically benign route to the production of cellulose nanofibers. The degree of fibrillation...

#### High-temperature decomposition of the cellulose molecule: a stochastic molecular dynamics study

The kinetics and products of cellulose pyrolysis can be studied using large-scale molecular dynamics simulations at high temperatures, where the reaction rates are high enough to make the simulation times practical. We carried out molecular dynamics simulations employing the ReaxFF reactive force field to study the initial step of the thermal decomposition process. We gathered...

#### A novel approach to determining the contribution of the fiber and fines fraction to the water retention value (WRV) of chemical and mechanical pulps

The swelling behavior of pulp fibers has a significant influence on process and product properties. The water uptake of fibers is controlled by a different mechanism. While fiber charge is a driving factor for swelling, the swelling is hindered by the solid structure of the fiber wall. In the case of the fines fraction of pulps, this structure is broken to some extent and the...

#### Thickness difference induced pore structure variations in cellulosic separators for lithium-ion batteries

The pore structure of the separator is crucial to the performance of a lithium-battery as it affects the cell resistance. Herein, a straightforward approach to vary the pore structure of Cladophora cellulose (CC) separators is presented. It is demonstrated that the pore size and porosity of the CC separator can be increased merely by decreasing the thickness of the CC separator...

#### Rheological properties of nanocellulose suspensions: effects of fibril/particle dimensions and surface characteristics

The rheological properties of aqueous suspensions based on three different nanocelluloses were compared. One system was obtained via acid hydrolysis (thus yielding crystalline nanocellulose, CNC) and the other two from mechanical shearing, but from different origins and subjected to different pretreatments. Of the latter two, one was considered to be a rather typical cellulose...

#### Chemisorption of air CO2 on cellulose: an overlooked feature of the cellulose/NaOH(aq) dissolution system

A natural abundance of the air CO2 in NaOH(aq) at low temperature was investigated in terms of cellulose-CO2 interactions upon cellulose dissolution in this system. An organic superbase, namely 1,8-diazabicyclo[5.4.0]undec-7-ene, DBU, known for its ability to incorporate CO2 in carbohydrates, was employed in order to shed light on this previously overlooked feature of NaOH(aq) at...

#### A cautionary note on thermal runaway reactions in mixtures of 1-alkyl-3-methylimidazolium ionic liquids and N-methylmorpholine-N-oxide

N-Methylmorpholine-N-oxide (NMMO) cannot be completely separated by extraction from mixtures with common 1,3-dialkylimidazolium ionic liquids (ILs) due to strong ionic interactions between the two components. At elevated temperatures, above approx. 90 °C, especially under dry conditions and in the presence of acid, alkylating or acylating agents, remaining NMMO in ILs tends to...

#### Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

The first drying of wood cell walls from the native state has sometimes been described as producing irreversible structural changes which reduce the accessibility to water, a phenomenon often referred to as hornification. This study demonstrates that while changes do seem to take place, these are more complex than what has hitherto been described. The accessibility of wood cell...

#### On the dissolution state of cellulose in cold alkali solutions

We have characterized the dissolved state of microcrystalline cellulose (MCC) in cold alkali [2.0 M NaOH(aq)] solutions using a combination of small angle X-ray (SAXS) and static light scattering (SLS), $$^1$$H NMR, NMR self-diffusion, and rheology experiments. NMR and SAXS data demonstrate that the cellulose is fully molecularly dissolved. SLS, however, shows the presence of...

#### Electrically conductive coatings consisting of Ag-decorated cellulose nanocrystals

For the preparation of electrically conductive composites, various combinations of cellulose and conducting materials such as polymers, metals, metal oxides and carbon have been reported. The conductivity of these cellulose composites reported to date ranges from 10−6 to 103 S cm−1. Cellulose nanocrystals (CNCs) are excellent building blocks for the production of high added value...

#### Multi-layer nanopaper based composites

Native cellulose nanofibrils (CNF) were prepared from bleached birch pulp without any chemical or enzymatic pretreatment. These CNF were modified by adsorption of a small amount of water-soluble polysaccharides and used to prepare nanopapers, which were processed into composites by lamination with an epoxy resin and subsequently cured. The results were compared to the properties...

#### Steady-shear and viscoelastic properties of cellulose nanofibril–nanoclay dispersions

We have investigated the steady-shear and viscoelastic properties of composite dispersions of cellulose nanofibrils (CNFs) with medium or high charge density and two different nanoclays, viz. rod-like sepiolite or plate-like bentonite. Aqueous dispersions of CNFs with medium charge density displayed significantly lower steady-state viscosity and storage modulus but higher...

#### Synthesis of silver nanoparticles in NMMO and their in situ doping into cellulose fibers

We present a method for synthesis of silver nanoparticles in N-methylmorpholine N-oxide (NMMO) and the associated mechanism, as well as their use for in situ volume modification of cellulose fibers. The synthesized particles had diameter of about 4 nm, and their colloid solution was stable for 1 year. The nanoparticles were stabilized using polyethylenimine, which apart from...

#### Effect of the size of the charged group on the properties of alkoxylated NFCs

The impact of the size of the charged group on the properties of alkoxylated NFC was studied by two chloroalkyl acid reagents. It was found that the employment of the larger 2-chloropropionic acid reagent leads to improved properties, e.g. higher fraction of nano-sized materials, and significantly better redispersion as compared to when the smaller monochloroacetic acid was...

#### Drying of a cellulose II gel: effect of physical modification and redispersibility in water

The agglomeration of cellulosic materials upon drying, often called hornification, causes a reduction of water retention, among other undesired effects. It is one of the main issues in industrial cellulose processing, especially with regard to nanocelluloses. As a consequence, high transportation and storage costs arise since nanocelluloses need to remain in aqueous suspensions...