High performance cellulose fibers regenerated from 1-butyl-3-methylimidazolium chloride solution: Effects of viscosity and molecular weight

In the present study, we focused on several factors affecting the utility of 1-butyl-3-methylimidazolium chloride (BMIMCl) for obtaining higher performance fibers. The dependence of the spinnability and tensile strength of the fibers on the zero-shear viscosity of the spinning solutions was investigated based on differences in the molecular weight of the cellulose, pulp concentration, and the pH of BMIMCl. We demonstrated an appropriate viscosity range of 2000–4000 Pa s⁻¹ (100 °C) for spinning dopes to obtain good spinnability and high tensile strength. The pH of the BMIMCl and the molecular weight of the cellulose clearly impacted tensile strength. The high molecular weight of cellulose contributed to high mechanical properties of the regenerated cellulose fibers. Optimizing the molecular weight and concentration of the cellulose based on the appropriate viscosity allowed us to prepare high performance cellulose fibers with a tensile strength of 1.15 GPa and a Young's modulus of 42.9 GPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48681.     

Cellulose fibers from cellulose/1‐ethyl‐3‐methylimidazolium acetate solution by wet spinning with increasing spinning speeds

Cellulose fibers from cellulose/1‐ethyl‐3‐methylimidazolium acetate solution were prepared by wet spinning with increasing extrusion speeds and draw ratios. The effects of spinning speeds on the structures and mechanical properties of these fibers were investigated by using scanning electron microscopy, wide angle X‐ray diffraction, birefringence, thermogravimetric analysis, tensile‐fineness tester, and wet friction. The results showed that the crystallinity, orientation, and mechanical properties of the fibers were improved with increasing draw ratio. The break draw ratios, degrees of crystallinity and orientation, tenacities, and wet friction time of the cellulose fibers decreased with increasing extruding speeds. The wet friction time decreased with increasing draw ratio and decreased faster under higher extrusion speed. Due to the high dope concentration and the increased draw ratio, the maximum tenacity of the regenerated cellulose fibers reached 2.73 cN/dtex. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40225.     

Tensile strength of handsheets from recovered fibers treated with N‐Methylol melamine and 1,3‐dimethylol‐4,5‐dihydroxyethyleneurea

The main objective of this study was to assess the effect of two amino resins, N‐methylol melamine (NMM) and 1,3‐dimethylol‐4,5‐dihydroxyethyleneurea (DMDHEU), on the intrafiber and interfiber strengths and water absorption of two types of waste paper categories, office paper (OP), and old corrugated containers (OCCs). The tensile strength of individual fibers measured at zero span was reduced by increases in the resin concentrations. The dry tensile strengths of the recovered handsheets measured at a finite span were enhanced with increases in the weight percentage gain of the resins. The increasing of the resin concentration also significantly improved the intrabonding of the OP and OCCs in moist measuring conditions. The water absorption of the handsheets considerably decreased at the higher concentration of the thermosetting resins, especially with NMM. The results are promising for the use of NMM‐ and DMDHEU‐treated recovered fibers as an alternative fiber resource for the production of laminated paper and also for the use of DMDHEU as a new N‐methylol compound for laminated paper. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41290.     

Wet spun fibers from solutions of cellulose in an ionic liquid with suspended carbon nanoparticles

Wet spun fibers from solutions of dissolving pulp in 1‐ethyl‐3‐methylimidazolium acetate (EmimAc) with up to 50 wt % (based on cellulose) suspended carbon black and graphene nanoplatelets particles were studied. Carbon fillers were dispersed by simple shearing in a Couette type mixer and the resulting spin dope was extruded into a hot water coagulation bath from a single hole spinneret. Microstructure, mechanical properties, and electrical conductivity were assessed as a function of filler loading and discussed in comparison to melt spun fibers with similar fillers. The coagulation process and subsequent drying of wet spun fibers was found to produce a significant microporosity, more so the higher the filler loading. The electrical percolation threshold was quite high in the wet spun fibers and relatively modest values of conductivity were obtained with regard to the high filler loadings. Carbon black was found to be superior to graphene nanoplatelets. This was related to flow‐induced orientation effects. The mechanical properties of the carbon‐filled fibers were found to be similar or lower compared to the pure cellulose fibers because of low interfacial interactions and formation of microporosity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41417.     

Rheology of 1‐butyl‐3‐methylimidazolium chloride cellulose solutions. III. Elongational rheology

The elongational rheology of solutions of cellulose in the ionic liquid solvent 1‐butyl‐3‐methylimidazolium chloride ([Bmim]Cl) was measured at 80, 90, and 100°C; 8, 10, and 12 wt% cellulose; Hencky strains 5, 6, 7; and strain rates from 1 to 100 s^?1. Master curves were generated by shifting the elongational viscosity curves with respect to temperature and Hencky strain. Also, general master curves were generated by simultaneously shifting with respect to both temperatures and Hencky strain. From the Arrhenius plots of the temperature shift factors, the activation energy for elongational flow was determined. The elongational rheology of these solutions was elongational strain rate thinning similar to that of their shear behavior and polymer melts and they were also strain hardening. Both effects and the viscosity increased with cellulose concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Rheology of 1‐butyl‐3‐methylimidazolium chloride cellulose solutions. I. Shear rheology

In this article, shear rheology of solutions of different concentrations obtained by dissolution of cellulose in the ionic liquid (IL) solvent 1‐butyl‐3‐methylimidazolium chloride ([Bmim]Cl) was studied by measuring the complex viscosity and dynamic moduli at different temperatures. The obtained viscosity curves were compared with those of lyocell solutions and melt blowing grade polypropylene melts of different melt flow rates (MFR). Master curves were generated for complex viscosity and dynamic moduli by using Carreau and Cross viscosity models to fit experimental data. From the Arrhenius plots of the shift factors with respect to temperature, the activation energies for shear flow were determined. These varied between 18.99 and 24.09 kCal/mol, and were compared with values for lyocell solutions and different polymeric melts, such as polyolefins, polystyrene, and polycarbonate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Carboxymethylcellulose (CMC) as a model compound of cellulose fibers and polyamideamine epichlorohydrin (PAE)–CMC interactions as a model of PAE–fibers interactions of PAE‐based wet strength papers

Carboxymethylcellulose (CMC) is a cellulose derivative obtained by the carboxymethylation of some hydroxyl groups in the cellulose macromolecules. In this article, we use CMC as a model compound of cellulose fibers to study polyamineamide epichlorohydrin (PAE)–fibers interactions during the preparation of PAE‐based wet strength papers. The main advantages of the use of CMC to replace cellulose fibers are its water‐soluble character and the homogeneous reaction medium during mixing with PAE resin. Based on ¹³C cross‐polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) and Fourier transformed infra‐red (FTIR) spectroscopy, we prove the formation of ester bonds in PAE–CMC films boosted by a thermal posttreatment at 105°C for 24 h. These ester bonds are derived from a thermally induced reaction between carboxyl groups in the CMC structure and azetidinium ions (AZR) in the PAE resin. PAE‐based handsheets were prepared from 100% Eucalyptus fibers. After preparation, some samples were thermally posttreated (TP) at 130°C for 10 min and stored under controlled conditions (25°C and 50% relative humidity or RH). For lowest PAE dosage, storage of the not thermally posttreated (NTP) PAE‐based handsheets does not allow them to reach the tensile strength values of TP PAE‐based handsheets (at 130°C for 10 min), but the difference in terms of breaking length remains low. For the highest PAE addition level, NTP and TP PAE‐based handsheets exhibit close values of the breaking length from 30 days of storage under controlled conditions (25°C and 50% RH). When a thermal posttreatment is applied, the wet strength development of PAE‐based papers is a combined effect of homo‐ and co‐cross‐linking mechanisms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42144.     

All‐wood biocomposites by partial dissolution of wood flour in 1‐butyl‐3‐methylimidazolium chloride

After cedar‐derived wood flour (WF) and bark flour (BF) were mixed with 1‐butyl‐3‐methylimidazolium chloride (BMIC) at 100°C, the obtained compounds with BMIC content 40 wt % were compression‐molded at 210°C to give WF/BMIC and BF/BMIC composites, respectively. The BMIC contained in the composites was twice extracted with ethanol at 60°C to afford WF/BMIC‐E and BF/BMIC‐E biocomposites, which were subsequently annealed at 200°C for 24 h to produce WF/BMIC‐A and BF/BMIC‐A biocomposites. The Fourier transform infrared spectroscopic analysis revealed that WF has a higher content of cellulose and a lower content of lignin than BF does, and that the BMIC content diminished by the extraction process. The scanning electron microscopy analysis showed that woody particles joined together by the compression molding of WF/BMIC and BF/BMIC compounds, and that the extraction of BMIC roughened the surface and the annealing again smoothed the surface due to the fusion of the residual BMIC and woody particles. The XRD measurements indicated that the annealing enhanced the crystallinity of cellulose component. The tensile properties and 5% weight loss temperature of the biocomposites were considerably improved by the extraction of BMIC and further by the annealing. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Rheology of 1‐butyl‐3‐methylimidazolium chloride cellulose solutions. II. Solution character and preparation

The focus of this article of a three part series is the effects of preparation and composition on the shear rheology of cellulose in the ionic liquid 1‐butyl‐3‐methylimidazolium chloride ([Bmim]Cl). Included are the effects of three different degrees of polymerization, (i.e., average molecular weight), manual versus high shear mixing, a range of cellulose concentrations, and the effects of controlled amounts of lignin and a hemicellulose. The rheology implies that a gel phase develops at higher degrees of polymerization, higher concentration, and at lower temperatures. The first article focused primarily on shear rheology of cellulose in [Bmim]Cl with a high shear preparation technique, one degree of polymerization, a narrow range of cellulose concentrations, and temperature. The third article focuses on elongational rheology of cellulose in [Bmim]Cl. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Swelling behaviors of natural cellulose in ionic liquid aqueous solutions

In the study, a series of methylimidazolium ionic liquids were prepared, including five acidic and seven neutral ionic liquids; and the effects of these ionic liquids on swelling behavior of bagasse cellulose were investigated. The focus of this work is to investigate the relationship between the properties of ionic liquids and the swelling capacity. The swelling absorbency for cellulose in the acidic ionic liquid aqueous solutions was less than in distilled water. It was found that the partial hydrolysis on cellulose surface occurred along with swelling simultaneously. In neutral ionic liquid aqueous solutions, the nonlinearity of swelling ability with the alkyl chain length was discovered. It could be attributed to the dual role of hydrophobic interactions and steric effects provided by cations. Furthermore, small polarizable anions also contribute to the swelling of cellulose to some extent. The properties of treated cellulose were also investigated and compared with the native fibers by scanning electron microscopy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40199.     

Synthesis and application of cotton‐based chelate fibers grafted with poly(1‐vinyl‐1,2,4‐triazole) side chains

Cotton‐based chelate fibers grafted with poly(1‐vinyl‐1,2,4‐triazole) (PVTAZ) side chains were synthesized facilely by ozone‐induced graft polymerization of 1‐vinyl‐1,2,4‐triazole (VTAZ) monomer onto cotton fibers. The synthesis conditions were optimized to improve the yield and mechanical strength of the products. The obtained cotton‐g‐PVTAZ fibers were characterized and evaluated for batch adsorption of heavy metal ions from aqueous solutions. The maximum adsorption capacity of Ag(I), Pb(II), and Cu(II) on the fibers at pH 6.8 was 522, 330, and 184 mg/g, respectively. At 30% graft yield, the Young's modulus of cotton fiber increased about 26.5%, and its adsorption capacities of Ag(I), Pb(II), and Cu(II) increased about 2.6, 1.9, and 1.4 times, respectively. After washed with 0.1 mol/L HNO₃ solutions, the adsorbed metal ions were eluted, and the regenerated cotton‐g‐PVTAZ fibers could be used repeatedly for water treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41617.     

Transparent,flexible, and high‐strength regenerated cellulose/saponite nanocomposite films with high gas barrier properties

Regenerated cellulose‐saponite nanocomposite films were prepared from LiOH/urea solutions, and exhibited high optical transparency and flexibility. The saponite platelets formed intercalated nanolayered structures in the composites. The longitudinal directions of both the cellulose II crystallites and the saponite platelets were preferentially oriented parallel to the film surface in the composites. The good nanodispersibility and high orientation of the saponite platelets in the composite films resulted in high mechanical strength, high Young's modulus, and good thermal dimensional stabilities, and gas barrier properties in the composites, compared with a reference cellulose film. Moreover, the tensile strength and Young's modulus of the composite film reached 241 MPa and 7.7 GPa, respectively, when a simple drawing process was applied to the wet composite film; this is probably owing to the improvement in the orientation of the cellulose II crystallites and saponite platelets in the composites. The composite films also showed high toughness and ductility. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3168–3174, 2013     

Regenerated cellulose membrane prepared with ionic liquid 1‐butyl‐3‐methylimidazolium chloride as solvent using wheat straw

BACKGROUND: Currently, cellulose membranes are prepared by cellulose acetate hydrolysis or chemical derivatization dissolution and regeneration using cotton pulp or wood pulp. In this study, the concept ‘lignocelluloses biorefinery’ was used, and good quality long fiber was fractionated from wheat straw using clean technologies. The objective of this study is to develop wheat straw cellulose to prepare regenerated cellulose membrane with ionic liquid 1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl) as solvent. RESULTS: Wheat straw cellulose (WSC) fractionated from wheat straw contained 93.6% α‐cellulose and the degree of polymerization (DP) was 580. WSC was dissolved directly without derivatization in [BMIM]Cl. With increase in dissolving temperature, the DP of the regenerated cellulose dropped, which resulted in a decrease in the intensity of regenerated cellulose membrane. After regeneration in [BMIM]Cl, the WSC transformed from cellulose I to cellulose II, and the crystallinity of the regenerated cellulose was lower than the original cellulose. The regenerated WSC membrane had good mechanical performance and permeability, the tensile strength and breaking elongation were 170 MPa and 6.4%, respectively, the pure water flux was 238.9 L m^?2 h^?1 at 0.3 MPa pressure, and the rejection of BSA was stabilized at about 97%. CONCLUSION: Wheat straw cellulose fractionated from wheat straw satisfied the requirement to prepare regenerated cellulose membrane using ionic liquid [BMIM]Cl as solvent. Copyright © 2012 Society of Chemical Industry     

Dual antibacterial functional regenerated cellulose fibers

N‐[3‐(dimethylamino)propyl]methacrylamide monomer was used to impart dual antibacterial functionality to regenerated cellulose fibers. In this regard, the monomer was grafted onto the surfaces by a “grafting from” technique, then the tertiary amine groups were quaternized and the acyclic amide groups were halogenated. Antibacterial activities of the mono‐ and dual‐functional coatings were comparatively evaluated. All the treatments were found to be effective against Staphylococcus aureus and Escherichia coli with about six logs bacterial reduction. It was found that dual‐functional coatings provided rapid inactivation as opposed to the monofunctional coatings. FTIR, TGA, and SEM analysis, wash fastness, light stabilities, and the mechanical properties of the coated fabrics were also comparably reported. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44872.     

Numerical investigation of spinneret geometric effect on spinning dynamics of dry‐jet wet‐spinning of cellulose/[BMIM]Cl solution

In this study, the effect of spinneret geometry, including the entrance angle α of the entrance channel, the length L_s, and the diameter D₀ of the exit channel, on the spinning dynamics of dry‐jet wet‐spinning of cellulose/1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl) solution was simulated by using finite element method. Based on the mathematical model of dry‐jet wet‐spinning established in our previous work (Xia et al., Cellulose 2015, 22, 1963) the radial and axial profiles of velocity, pressure, and shear rate in the spinneret and the profiles of diameter, temperature, and tensile stress in the air‐gap region were obtained. From the simulated profiles, the effect of spinneret geometric parameters on the flow behavior and the pressure drop of polymer solution in the spinneret and the die‐swell ratio near the spinneret was discussed. The entrance angle α of the entrance channel mainly influences the flow behavior of polymer solution in the spinneret and the die‐swell effect near the spinneret. As the decrease of the entrance angle α of the entrance channel, the vortices in the spinneret could be removed and the die‐swell ratio decreases. The increase of the length L_s of the exit channel results in the increase of pressure drop in the spinneret and the decrease of the die‐swell ratio. It is also found that the increase of the diameter D₀ of the exit channel reduces the flow velocity of polymer solution and decreases the pressure drop in the spinneret at a constant mass flow rate. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43962.     

Study on the poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)‐based nanocomposites reinforced by surface modified nanocrystalline cellulose

As a kind of reinforcing agent, the application of nanocrystalline cellulose (NCC) is widely limited in hydrophobic polymers owing to its rich hydroxyl surface. In this study, NCC was modified with lauric acid/p‐toluensulfonyl chloride mixture, then the modified nanocrystalline cellulose (mNCC) was incorporated into biopolyester poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P(3,4)HB) by solution casting to prepare P(3,4)HB/mNCC nanocomposites. The prepared mNCC and P(3,4)HB/mNCC nanocomposites were characterized by Fourier transform‐infrared, X‐ray diffraction, contact angle test, transmission electron microscopy, scanning electron microscopy, differential scanning calorimetric, polarized optical microscope, dynamic mechanical analysis, and thermogravimetric analysis. The results show that the crystallinity and mechanical properties of P(3,4)HB are greatly improved due to the fact that NCC can be modified successfully and the mNCC can distribute uniformly in nanoscale in the matrix with good compatibility along the interface. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2015–2022, 2013     

Effect of the dissolution time on the structure and properties of lyocell‐fabric‐based all‐cellulose composite laminates

In this study, all‐cellulose composite laminates were prepared from lyocell fabric with ionic liquid (1‐butyl‐3‐methyl imidazolium chloride), a conventional hand layup method, and compression molding. Eight layers of lyocell fabric, which were impregnated with ionic liquid, were stacked symmetrically and hot‐pressed under compression molding for various times; this resulted in the partial dissolution of the surface of the lyocell fibers. The dissolved cellulose held the laminas together and resulted in a consolidated laminate. Finally, the prepared laminate was impregnated in water to remove the ionic liquid and to regenerate a matrix phase in situ; this was followed by hot‐press drying. Optical microscopy and scanning electron microscopy studies were used to analyze composite structures. With increasing dissolution time, the void content in the composites decreased, and the interlaminar adhesion improved. For LC‐2h and LC‐3h, the highest tensile strength and modulus values obtained were 48.2 MPa and 1.78 GPa, respectively. For LC‐4h, the highest flexural strength and modulus values obtained were 53.96 MPa and 1.2 GPa, respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43398.     

Comparison of the performance of copper oxide and yttrium oxide nanoparticle based hydroxylethyl cellulose electrolytes for supercapacitors

Biodegradable solid polymer electrolyte (SPE) systems composed of hydroxylethyl cellulose blended with copper(II) oxide (CuO) and yttrium(III) oxide (Y₂O₃) nanoparticles as fillers, magnesium trifluoromethane sulfonate salt, and 1‐ethyl‐3‐methylimidazolium trifluoromethane sulfonate ionic liquid were prepared, and the effects of the incorporation of CuO and Y₂O₃ nanoparticles on the performance of the SPEs for electric double‐layer capacitors (EDLCs) were compared. The X‐ray diffraction results reveal that the crystallinity of the SPE complex decreased upon inclusion of the Y₂O₃ nanoparticles compared to CuO nanoparticles; this led to a higher ionic conductivity of the Y₂O₃‐based SPE [(3.08 ± 0.01) × 10^?4 S/cm] as compared to CuO [(2.03 ± 0.01) × 10^?4 S/cm]. The EDLC performances demonstrated that the cell based on CuO nanoparticles had superior performance in terms of the specific capacitance, energy, and power density compared to the Y₂O₃‐nanoparticle‐based cell. However, Y₂O₃‐nanoparticle‐based cell displayed a high cyclic retention (91.32%) compared to the CuO‐nanoparticle‐based cell (80.46%) after 3000 charge–discharge cycles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44636.     

Microwave assisted glycolysis of poly(ethylene terephthalate) catalyzed by 1‐butyl‐3‐methylimidazolium bromide ionic liquid

The combination of ionic liquid (IL) associated with microwave energy may have some potential application in the chemical recycling of poly (ethylene terephthalate). In this processes, glycolysis of waste poly (ethylene terephthalate) recovered from bottled water containers were thermally depolymerized with solvent ethylene glycol (EG) in the presence of 1‐butyl‐3‐methyl imidazolium bromide ([bmim]Br) as catalyst (IL) under microwave condition. It was found that the glycolysis products consist of bis (2‐hydroxyethyl) terephthalate (BHET) monomer that separated from the catalyst IL in pure crystalline form. The conversion of PET reach up to 100% and the yield of BHET reached 64% (wt %). The optimum performance was achieved by the use of 1‐butyl‐3‐methyl imidazolium bromide as a catalyst, microwave irradiations temperature (170–175°C) and reaction time 1.75–2 h. The main glycolysis products were analyzed by ¹H NMR, ¹³C NMR, LC‐MS, FTIR, DSC, and TGA. When compared to conventional heating methods, microwave irradiation during glycolysis of PET resulted in short reaction time and more control over the temperature. This has allowed substantial saving in energy and processing cost. In addition, a more efficient, environmental‐friendly, and economically feasible chemical recycling of waste PET was achieved in a significantly reduced reaction time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41666.     

A comparative study on the effects of material blending method on the physico‐mechanical properties of WPCs made from MDF dust

The present study was carried out to investigate the effect of material ‐ blending method and filler content on the physical and mechanical properties of medium density fiberboard (MDF) dust/PP composites. In the sample tests preparation, 40, 50, and 60 wt % of MDF dust were used as lignocellulosic material. Test samples were made to measure the influence of material ‐ blending method and MDF dust content on water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), modulus of rupture (MOR), tensile strength, tensile modulus, and withdrawal strengths of fasteners. The mechanical properties of the test panels significantly decreased with increasing MDF dust contents due to the reduction of interface bond between the fiber and polymer matrix. The WA and TS values also increased by increasing the amount of MDF dust. So with the increase in the MDF dust content, there are more water residence (high hydroxyl groups (? OH) of cellulose and hemicelluloses) sites, thus more water is absorbed, so it can reduce mechanical strength. Furthermore, the results indicated that the physical and mechanical properties of samples made with melt ‐ blend method were more acceptable than those of dry ‐ blend method. Field emission scanning electron microscopy micrographs also showed that the polymer and the filler phase mixed better in the melt ‐ blend method. On the basis of the findings of this research, it appears evident that certain amount of MDF dust material with suitable material ‐ blending method can be used in manufacturing of wood–plastic composites for providing good physical and mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40513.