High‐strength regenerated cellulose fibers spun from 1‐butyl‐3‐methylimidazolium chloride solutions

High‐performance regenerated cellulose fibers were prepared from cellulose/1‐butyl‐3‐methylimidazolium chloride (BMIMCl) solutions via dry‐jet wet spinning. The spinnability of the solution was initially evaluated using the maximum winding speed of the solution spinning line under various ambient temperatures and relative humidities in the air gap. The subsequent spinning trials were conducted under various air gap conditions in a water coagulation bath. It was found that low temperature and low relative humidity in the air gap were important to obtain fibers with high tensile strength at a high draw ratio. From a 10 wt % cellulose/BMIMCl solution, regenerated fibers with tensile strength up to 886 MPa were prepared below 22 °C and relative humidity of 50%. High strengthening was also strongly linked with the fixation effect on fibers during washing and drying processes. Furthermore, an effective attempt to prepare higher performance fibers was conducted from a higher polymer concentration solution using a high molecular weight dissolving pulp. Eventually, fibers with a tensile strength of ～1 GPa and Young's modulus over 35 GPa were prepared. These tensile properties were ranked at the highest level for regenerated cellulose fibers prepared by an ionic liquid–based process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45551.     

Structure–property relationship of polyimide fibers containing ether groups

The copolyimide (co‐PI) fibers with outstanding mechanical properties were prepared by a two‐step wet‐spinning method, derived from the design of combining 4,4′‐oxydianiline (ODA) with the rigid 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA)/p‐phenylenediamine (p‐PDA) backbone. The mechanical properties of PI fibers were drastically improved with the optimum tensile strength of 2.53 GPa at a p‐PDA/ODA molar ratio of 5/5, which was approximately 3.7 times the tensile strength of BPDA/p‐PDA PI fibers. Two‐dimensional wide‐angle X‐ray diffraction indicated that the highly oriented structures were formed in the fibers. Two‐dimensional small‐angle X‐ray scattering revealed the existence of the needle‐shaped microvoids aligned parallel to the fiber axis, and the introduction of ODA led to the reduction in the size of the microvoids. As a result, the significantly improved mechanical properties of PI fibers were mainly attributed to the gradually formed homogeneous structures. The co‐PI fibers also exhibited excellent thermal stabilities of up to 563°C in nitrogen and 536°C in air for a 5% weight loss and glass transition temperatures above 279°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42474.     

High‐performance copoly(benzimidazole‐benzoxazole‐imide) fibers: Fabrication,structure, and properties

Novel high‐performance copolyimide (co‐PI) fibers containing benzimidazole and benzoxazole ring in the main chain were prepared by a two‐step spinning via the poly(amic acid)s. Effects of the incorporated benzimidazole and benzoxazole units on the micro‐structure and properties of co‐PI fibers were investigated. Fourier transform infrared (FTIR) results indicated that hydrogen bonding is formed in the co‐PI fibers. The co‐PI fibers exhibited discernible crystallization peaks at 14°～15° and 23°～26° (2θ), showing crystalline‐like structure. Moreover, the packing type of benzimidazole‐imide units determined the macromolecules packing of co‐PIs. It was amazedly found that the co‐PI fibers exhibited higher tensile strength and initial modulus than those of corresponding homo‐PI fibers, reaching tensile strength of 2.2–2.6 GPa, initial modulus of 99.1–113.2 GPa. The results of dynamic mechanical analysis (DMA) indicated co‐PI2 fiber had a positive T_g deviation due to the presence of strong intermolecular hydrogen bonding between benzimidazole‐imide and benzoxazole‐imide units, which maybe lead to the effective stress transfer between benzimidazole‐imide units and benzoxazole‐imide units. In addition, the obtained PI fibers exhibited excellent thermal properties with the 10% weight loss temperatures under N₂ in the range of 574–585°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42001.     

A comparison of partially acetylated nanocellulose,nanocrystalline cellulose,and nanoclay as fillers for high‐performance polylactide nanocomposites

Partially acetylated cellulose nanofibers (CNF) were chemically extracted from sisal fibers and the performance of those CNF as nanofillers for polylactide (PLA) for food packaging applications was evaluated. Three PLA nanocomposites; PLA/CNF (cellulose nanofibers), PLA/CNC (nanocrystalline cellulose), and PLA/C30B (Cloisite^TM 30B, an organically modified montmorillonite clay) were prepared and their properties were evaluated. It was found that CNF reinforced composites showed a larger decrease on oxygen transmission rate (OTR) than the clay‐based composites; (PLA/CNF 1% nanocomposite showed a 63% of reduction at 23°C and 50% RH while PLA/C30B 1% showed a 26% decrease) and similar behavior on terms of water vapor barrier properties with 46 and 43%, respectively of decrease on water vapor transmission rate at 23°C and 50% RH (relative humidity). In terms of mechanical and thermomechanical properties, CNF‐based nanocomposites showed better performance than clay‐based composites without affecting significantly the optical transparency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43257.     

Performance and structure changes of the aromatic co‐polysulfonamide fibers during thermal‐oxidative aging process

The changes in performance during thermal‐oxidative aging process of the aromatic co‐polysulfonamide (co‐PSA) fibers over a broad temperature range from 250 °C to 320 °C have been investigated. In addition, the mechanism of thermal‐oxidative aging process has been studied by using structural information obtained from the fibers at varying length scales. The results showed that a significant reduction in tensile strength was observed compared with that of initial modulus during aging process. Macroscopically, thermal‐oxidative aging mainly causes color changes of fibers and thermally induced macro defects begin to appear only at 320 °C for 100 h. On a micro level, the crystal structure of fibers remained stable and did not show significant changes expect that aging at 320 °C. In addition, thermo‐degradation as well as crosslinking has been observed primarily in amorphous region. With the increase of temperature and time duration, the crosslinking became more dominant and crosslinking density increases. Correspondingly, the fibril length decreases due to degradation and then increases due to the formation of crosslinked structures within the fibers. The results suggest that molecular degradation is the main cause of strength loss and the formation of crosslinking structure within the fibers contributes to the retention of modulus and improvement of creep resistance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44078.     

Processing,structure, and properties of multiwalled carbon nanotube–poly(phenylene sulfide) composite fibers

To improve the processability and properties of the poly(phenylene sulfide) (PPS) fibers at room temperature and high temperatures, a series of composite fibers based on PPS and multiwalled carbon nanotubes were prepared by melt spinning. We researched the processability with a high‐pressure capillary rheometer, and the properties of the composite fibers were investigated in detail by scanning electron microscopy, differential scanning calorimetry, fiber sonic velocity measurement, and single‐fiber strength testing. The results show that the carbon nanotubes (CNTs) had good interfacial adhesion with PPS and dispersed homogeneously in the PPS matrix. When the shear rate was higher than 500 s^?1, the oriented CNTs induced the orientation of PPS molecular chains; this resulted in a decline in the apparent viscosity and an increase in the orientation degree of the molecular chains. Meanwhile, the CNTs acted as nucleating agents to effectively improve the crystallization of PPS. The strength of the fibers at room temperature were improved by 28.8% after the addition of 0.2% CNTs, and the initial modulus was also significantly enhanced. The strength retention at 160 °C was promoted from 60.58 to 88.32% with the addition of 1.0% CNTs. The shrinking percentage decreased to almost zero from higher than 15%; this suggested that the CNTs could efficiently improve the dimensional stability at high temperatures. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44609.     

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.     

Plasma modification of man‐made cellulose fibers (Lyocell) for improved fiber/matrix adhesion in poly(lactic acid) composites

The present study investigates the influence of different plasma treatments on the tensile characteristics of lyocell fibers and the interfacial interactions of lyocell fibers in a poly(lactic acid) matrix. For the investigations, the fibers were coated by an amine‐functional, nanoporous layer (a‐C:H:N) using a gaseous mixture of NH₃:C₂H₄ of 1:1 and 5:3, respectively, an oxygen‐functional layer (a‐C:H:O) with CO₂:C₂H₄ and CO₂ posttreatment, or an oxygen‐functional layer (a‐C:H:O) comprising hydroxyl groups with H₂O:C₂H₄ and H₂O posttreatment. As reference, uncoated fibers and fibers coated with a crosslinked, amorphous hydrocarbon layer (a‐C:H) without functional group incorporation were investigated. While the different treatments maintained the tensile strength of the lyocell fibers, which were all in the range between 295 and 338 N/mm², the interfacial shear strength, measured by the pull‐out test, was clearly influenced. The best improvement of the fiber/matrix adhesion was obtained by a plasma treatment with a mixture of water vapor and ethylene resulting in an interfacial shear strength of 17.8 N/mm² in comparison to the untreated lyocell fiber with 10.3 N/mm². Amine‐functional plasma polymers (a‐C:H:N) were also found to be suitable for adhesion‐promoting interlayers on lyocell fibers in poly(lactic acid). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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.     

Preparation and characterization of epoxidized soybean oil‐based paper composite as potential water‐resistant materials

Epoxidized soybean oil‐based paper composites (ESOPCs) were prepared by fabricating poly epoxidized soybean oil (PESO) with paper. With boron trifluride diethyl etherate as catalyst, epoxidized soybean oil was in situ polymerized on the surface of the paper and within the interspaces of the paper cellulose fibers. Fourier transform infrared analysis confirmed the polymerization of epoxidized soybean oil. Scanning electron microscopic analysis showed that ESOPCs had nanostructured wrinkle morphology on the surfaces and the PESO combined tightly with the paper cellulose fibers. The tensile strength of ESOPCs was 17.3–24.8 MPa, which was higher than that of most vegetable oil‐based neat polymers. Thermogravimetric analysis indicated that ESOPCs were thermally stable up to 360°C in a nitrogen atmosphere. Water vapor permeability (WVP) tests revealed that the WVP of ESOPCs was 3.52–4.45 × 10^?12 g/m/s/Pa, significantly lower than many of other biobased polymeric materials, which would promote the application of vegetable‐based polymers as potential water‐resistant materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41575.     

Synthesis and properties of carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide) as a novel cellulose‐based superabsorbent

A new cellulose‐based superabsorbent polymer, carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide), was prepared by the free‐radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N′‐methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose‐graft‐poly(acrylic acid‐co‐acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 50°C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1382–1388, 2007     

Improvement in mechanical properties of poly(p‐phenylene sulfide) fibers by high‐tension multiannealing method

High‐tension multiannealing (HTMA) was applied to improve the tensile properties of poly(p‐phenylene sulfide) fibers, which was furthermore applied to the fibers produced and improved with the zone‐drawing and zone‐annealing treatments. The HTMA treatment was repeatedly applied to the fibers under the conditions of a 250°C temperature and an applied tension of between 201.0 and 188.0 MPa. As a result, at the 13th treatment the degree of crystallinity increased to 40%. On the other hand, the orientation factor of crystallites increased dramatically to 0.982 during the zone‐drawing treatment, but increased only slightly during the subsequent treatments of zone annealing and HTMA. The finally obtained fiber had a tensile modulus of 10.4 GPa and a tensile strength of 0.73 GPa. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1569–1576, 2000     

Electrospinning of ultrafine cellulose fibers and fabrication of poly(butylene succinate) biocomposites reinforced by them

In this study, electrospinning conditions for ultrafine cellulose fibers was systematically studied and poly(butylene succinate) biocomposites reinforced by the ultrafine cellulose fibers (cellulose/PBS biocomposite) were fabricated. The ultrafine cellulose fibers were electrospun from cellulose (DP = 700) solutions in N‐methylmorpholine‐N‐oxide hydrate (85/15 w/w) at 100°C. The optimal electrospinning concentration of the cellulose solutions was determined to be 7 wt % and the average diameter of the resulting cellulose fibers was 560 nm. The cellulose I structure of the native cellulose was converted to the cellulose II structure after electrospinning. The ultrafine cellulose fibers showed a reinforcing effect in the cellulose/PBS biocomposite, suggesting that they have potential applications as reinforcement fibers for biocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Biodegradable composites of poly(butylene succinate‐co‐butylene adipate) reinforced by poly(lactic acid) fibers

Biodegradable composites of poly(butylene succinate‐co‐butylene adipate) (PBSA) reinforced by poly(lactic acid) (PLA) fibers were developed by hot compression and characterized by Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analyzer, and tensile testing. The results show that PBSA and PLA are immiscible, but their interface can be improved by processing conditions. In particular, their interface and the resulting mechanical properties strongly depend on processing temperature. When the temperature is below 120 °C, the bound between PBSA and PLA fiber is weak, which results in lower tensile modulus and strength. When the processing temperature is higher (greater than 160 °C), the relaxation of polymer chain destroyed the molecular orientation microstructure of the PLA fiber, which results in weakening mechanical properties of the fiber then weakening reinforcement function. Both tensile modulus and strength of the composites increased significantly, in particular for the materials reinforced by long fiber. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43530.     

Structure–property relationships in thermally aged cellulose fibers and paper

The research presented in this paper investigates the effect of thermally accelerated aging on the submicrostructure of cellulose and attempts to relate such changes to the well‐documented loss of mechanical strength in aged paper. Filter paper and ramie fibers samples were aged in vacuo at 160°C. Small angle X‐ray scattering (SAXS) was used to study void structure within the fibers and hydration used as a structural probe. On hydration, the void radius of gyration and area decrease, while the void aspect ratio and overall void fraction increase. After aging, the wet structure more closely resembles the dry, suggesting that water cannot expand the structure to the same extent. It is postulated that increases in local ordering on aging create a structure more resistant to disruption by water. The use of additional techniques, namely Fourier transform IR spectroscopy, wide angle X‐ray scattering, scanning electron microscopy (SEM), environmental SEM, and measurement of water retention value, provided additional indirect support for the postulated model. There is no direct evidence for significant crystallinity changes in aged material, suggesting that if structural rearrangements occur, they will be local in nature. There is also no evidence for the formation of covalent crosslinks or new chemical species on aging. Water retention values and wet SAXS results concur, highlighting the importance of water in the cellulose structure and the reduced capacity for water sorption in aged samples. SEM observations show that the failure mechanism in paper changes with age from fibers pull out (i.e., interfiber bond failure) to fiber failure, and wide and zero span tensile tests indicate a weakening of the fibers. These results are consistent with previous reports, and we attribute them primarily to chain scission, although the increased intrafiber bonding may have an influence on the values obtained. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1465–1477, 1999     

The effects on mechanical properties and crystallization of poly (l‐lactic acid) reinforced by cellulosic fibers with different scales

Bacterial cellulose (BC), microcrystalline cellulose (MCC), and bamboo cellulosic fibers (BCFs) were used to reinforce poly(l ‐lactic acid) (PLLA) based bio‐composites. The mechanical properties and crystallization of the composites were studied through mechanical testing, differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and polarizing microscope. The incorporation of all three kinds of cellulose increased the stiffness of the composites compared to pure PLLA. The reinforcing effect of the MCC in the composites is most significant. The Young's modulus and impact toughness of the MCC/PLLA composites were increased by 44.4% and 58.8%, respectively. The tensile strength of the MCC/PLLA composites was increased to 71 MPa from 61 MPa of PLLA. However, the tensile strength of the composites reinforced with BCF or BC was lower than PLLA. The three kinds of cellulosic fibers improved the crystallization of PLLA. The BC with smallest size provided the composites with smallest grain and highest crystallinity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41077.     

Influence of process parameters on the structure formation of man‐made cellulosic fibers from ionic liquid solution

The influence of dry‐jet wet spinning parameters on the production of man‐made cellulosic fibers from 13 wt % cellulose/1,5‐diazabicyclo[4.3.0]non‐5‐ene acetate solutions was investigated. The spinneret nozzle diameter, extrusion velocity, draw ratio, and coagulation bath temperature were the studied parameters. The production of highly oriented fibers was favored by selecting higher extrusion velocity and lower spinneret diameter. A spinneret size of 100 µm and a draw ratio of 6 were sufficient to highly orient the cellulose macromolecules and achieve tenacities above 40 cN/tex (600 MPa). Total orientation assessed via birefringence measurement, tenacity, and Young's modulus values reached a plateau at a draw of 6 and no further development in properties was observed. A temperature of the aqueous coagulation bath of 15 °C slightly promoted greater orientation of the fibers by hampering structural changes of the cellulose macromolecules in the nascent solid fibers. Furthermore, the determination of the elongational viscosity of the liquid thread via the measurement of radial force tensor was tested and showed promising results. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43718.     

Comparison of direct solvents for regenerated cellulosic fibers via the lyocell process and by means of ionic liquids

Because new technology using ionic liquids (ILs) for cellulose processing enables the spinning of cellulose with various techniques, the resulting fiber property profiles differ significantly, depending on the process parameters. ILs are thermally stable, nontoxic, environmentally friendly solvents and dissolve cellulose directly; this leads to a high flexibility in the complete process chain for man‐made cellulosics. A comparison of the manufacture of cellulosic fibers according to the Lyocell process and by means of ILs is presented. The rheological behavior of the spinning dopes, the structures, and the physical textile properties of the prepared fibers were determined. The fibers spun from solutions of cellulose in N‐methyl morpholin‐N‐oxide monohydrate, 1‐ethyl‐3‐methyl imidazolium acetate, and 1‐ethyl‐3‐methyl imidazolium diethyl phosphate were compared. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Novel hydrogels of PVP–CMC and their swelling effect on viscoelastic properties

Polyvinylpyrrolidone (PVP) and carboxymethyl cellulose (CMC) mixed hydrogels were prepared by heat treatment. The physical characteristics of the hydrogels were studied by Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling study of the hydrogels in water shows remarkable water absorption property. The swelling effect on the rheological behavior of PVP‐, PVP–CMC‐, and CMC‐based hydrogels was investigated to judge its application on uneven surface of body. The rheological properties (storage modulus, loss modulus, and complex viscosity) of samples before drying and swelled (15, 30, and 60 min) were measured against angular frequency and composition. The hydrogel containing PVP/CMC ratio of 20 : 80 appeared to be the best hydrogel from rheological and water absorbent points of view. These properties and low cost of the materials utilized in this work suggest that this hydrogel is a viable alternative product for dressing materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Characterization of polyamideamine‐epichlorohydrin (PAE) resin: Roles of azetidinium groups and molecular mass of PAE in wet strength development of paper prepared with PAE

Polyamideamine‐epichlorohydrin (PAE) resin is a crosslinked heteropolymer having cationic charges, and has been widely used as a wet strength agent of paper in the papermaking process. In this study, more accurate molecular mass values of PAE were determined by size exclusion chromatography attached with a multi angle laser light scattering detector (SEC‐MALS). The obtained weight average molecular mass (M_w) values of commercial and laboratory‐made PAE samples were 1,140,000 and 494,000, respectively, and these values were much higher than those reported so far. SEC‐MALS analysis also revealed that PAE molecules had highly crosslinked structures and extremely wide molecular mass distributions. Molecular mass values and content of 3‐hydroxy‐azetidinium (AZR) groups in PAE and PAE intermediates during the course of PAE synthesis were also determined by the SEC‐MALS and ¹H NMR methods, and the relationships between these values and the wet strength development of handsheets prepared with these PAE samples were studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2249–2255, 2005