Wet Spinning Method Research Articles

Fibrous asymmetric supercapacitor based on wet spun MXene/PAN Fiber-derived multichannel porous MXene/CF negatrode and NiCo2S4 electrodeposited MXene/CF positrode

Fiber-shaped supercapacitors (FSSCs) are emerging potential power sources for next-generation flexible and wearable miniaturized electronic devices. However, the practical application of FSSCs is hindered by their low energy density due to limited design and constraints in fiber-shaped electrodes production. Herein, a rational design of wet spun MXene (Ti3C2Tx)/PAN fibers derived multichannel porous MXene/Carbon Fiber (W-MX/CF) is reported as a negative electrode (negatrode), and ultrathin NiCo2S4 electrodeposited W-MX/CF (NiCo2S4@W-MX/CF) as a positive electrode (positrode) for the fabrication of an asymmetric FSSC. It demonstrates high areal capacitance from both the negatrode (CA = 2160 mF cm−2) and positrode (CA = 1421 mF cm−2) fabricated from 80 wt% MXene loaded CF (W-MX/CF-4) with optimized multichannel porous features and faradaic NiCo2S4 nanosheets arrays grown on W-MX/CF-4. Solid-state fiber-shaped asymmetric supercapacitor was assembled using NiCo2S4-13@W-MX-4 and W-MX/CF-4 as positrode and negatrode, respectively, with PVA/KOH as solid electrolyte. The device exhibits a remarkable energy density of 40.70 mWh cm−3 at a power density of 301.51 mW cm−3, demonstrating an efficient FSSC. The present work shows a novel way to enhance the performance of FSSCs by exploiting synergistic effects between MXene and carbon fiber derived from PAN, prepared by a facile wet-spinning method employing a solvent/non-solvent exchange process.

A Biomimetic Textile with Self-Assembled Hierarchical Porous Fibers for Thermal Insulation.

Natural biomaterials with a porous structure inspired smart textiles for personal thermal management. Inspired by the hierarchically fibrous structure of hides, self-assembled hierarchical fibers with cross-scale porous networks are fabricated by the facile wet-spinning method. The biomimetic textile (abbreviated as "T") woven by such fibers exhibits a low thermal conductivity (0.07 W/mK) comparable to that of cowhide. It also shows a high mechanical strength of up to 10 MPa as well as good flexibility (fracture strain exceeds 300%) and hydrophobicity. The heat conduction mechanism of the hierarchical structure is analyzed via finite element simulation. When immersed with the phase-change material, the textile (named as "P") works like an adipose layer. Integration of the layers of T and P effectively slows down the heat conduction and decreases the surface temperature, resembling an animal insulation system. The study paves the way to mass production of high-performance biomimetic materials with hierarchical cellular microstructures for application in thermal insulation.

In Situ Loading of Polypyrrole onto Aramid Nanofiber and Carbon Nanotube Aerogel Fibers as Physiology and Motion Sensors.

Nanocomposite conductive fiber has been newly developed as a lightweight material with high flexibility and strong weavability, which can meet the requirements of flexible wearable devices. Herein, lightweight porous aramid nanofibers (ANF) and carbon nanotube (CNT) aerogel fibers coated with polypyrrole (PPy) layers are prepared by a wet spinning method for motion detection and information transmission. The ANF/CNT/PPy aerogel fiber with low density (56.3 mg/cm3), conductivity (6.43 S/m), and tensile strength (2.88 MPa) were used as motion sensors with high sensitivity (0.12) and long life (1000 cycles). At the same time, the differential conductivity of aerogel fibers is utilized to reduce the information transmission time (up to 46%). High- and low-temperature-resistant (-196 to 100 °C) aerogel fibers are also available as a quick heater and ionic solution detector. In summary, the prepared ANF/CNT/PPy aerogel fiber can be used as a multifunctional sensor for human-health detection and motion monitoring.

Production of Polyvinyl Alcohol–Alginate–Nanocellulose Fibers

AbstractIn this study, nanocellulose is isolated from oil palm empty fruit bunches using ultrafine grinding and ultrasonication. Here, nanocellulose, a reinforcing agent, is mixed with polyvinyl alcohol and sodium alginate, which act as the matrices. Nanocellulose‐based fibers are produced via the wet spinning method using calcium chloride as a coagulant solvent. The effects of the nanocellulose content on the morphological, mechanical, and in vitro biocompatibility properties of the produced fibers are then examined, with the results demonstrating that the increase in nanocellulose content produces fibers with a rougher cross‐section and higher tensile strength with the addition of nanocellulose up to 3%. Meanwhile, the crystallinity of the fibers increases with the addition of nanocellulose content of up to 5%. The addition of 1% nanocellulose produce fibers with better in vitro biocompatibility, which is confirmed by the higher cell viability and lower inhibition.

Fabrication of electrically conductive poly(styrene-b-ethylene-ran-butylene-b-styrene)/multi-walled carbon nanotubes composite fiber and its application in ultra-stretchable strain sensor

Although flexible polymer composites based strain sensors have been widely studied, it is still a challenge to obtain flexible strain sensors with large working range, high sensitivity and reliable stability. In this research, a flexible strain sensor based on poly(styrene-b-ethylene-ran-butylene-b-styrene) (SEBS)/multi-walled carbon nanotubes (MWCNTs) composite fiber was prepared through the wet spinning method. In particular, the effects of MWCNTs content and aspect ratio (L/D) on the morphology, and mechanical, electrical and electromechanical properties of the composite fiber were studied. The results showed that with the increase of MWCNTs content, the tensile strength and elongation at break of the composite fiber decreased, while the electrical conductivity and the strain sensing range increased. For the same MWCNTs content, the composite fiber filled with MWCNTs of the lowest L/D ratio (1.25/15) showed the highest tensile strength and elongation at break; whereas the composite fiber filled with MWCNTs of the highest L/D ratio (20/15) showed the highest electrical conductivity, strain sensing range (0–506%) and sensitivity (gauge factor of 58.274 at 0%–275% strain, and of 197.944 at 275%–506% strain). The fabricated composite fiber could be formed into a knitted fabric and had the ability of detecting various human motions.

Wet spinning of fiber-shaped flexible Zn-ion batteries toward wearable energy storage

High-performance flexible one-dimensional (1D) electrochemical energy storage devices are crucial for the applications of wearable electronics. Although much progress on various 1D energy storage devices has been made, challenges involving fabrication cost, scalability, and efficiency remain. Herein, a high-performance flexible all-fiber zinc-ion battery (ZIB) is fabricated using a low-cost, scalable, and efficient continuous wet-spinning method. Viscous composite inks containing cellulose nanofibers/carbon nanotubes (CNFs/CNTs) binary composite network and either manganese dioxide nanowires (MnO2 NWs) or commercial Zn powders are utilized to spinning fiber cathodes and anodes, respectively. MnO2 NWs and Zn powders are uniformly dispersed in the interpenetrated CNFs/CNTs fibrous network, leading to homogenous composite inks with an ideal shear-thinning property. The obtained fiber electrodes demonstrate favorable uniformity and flexibility. Benefiting from the well-designed electrodes, the assembled flexible fiber-shaped ZIB delivers a high specific capacity of 281.5 mAh g−1 at 0.25 A g−1 and displays excellent cycling stability over 400 cycles. Moreover, the wet-spun fiber-shaped ZIBs achieve ultrahigh gravimetric and volumetric energy densities of 47.3 Wh kg−1 and 131.3 mWh cm−3, respectively, based on both cathode and anode and maintain favorable stability even after 4000 bending cycles. This work offers a new concept design of 1D flexible ZIBs that can be potentially incorporated into commercial textiles for wearable and portable electronics.

Rapid mold-free fabrication of long functional PDMS fibers

Polydimethylsiloxane (PDMS), an optically transparent and inert material, is widely used in biological and semiconductor applications owing to its excellent chemical stability and moldability. This study proposes a thermally induced wet spinning method for the fabrication of long PDMS fibers with a constant width. PDMS is a thermoset polymer that undergoes chemical crosslinking when heated, and the thermally induced wet spinning process allows for the formation of fibers without a mold. A rapid thermal curing step was used to instantly solidify the thermoset polymer, where immediate chemical crosslinking of fluid PDMS solution was achieved upon contact with an oil coagulation bath at 180–230 °C. A rapid stretching process was applied to pull out and control the width of the fiber, and the PDMS was stretched at a rate of 1.2–12.5 m/min during the crosslinking process. The fabricated pristine PDMS fibers were transparent and maintained a crosslinked network with excellent mechanical strength. In addition, the PDMS fibers were functionalized with silica nanoparticles, carbon nanotubes, and pores to adjust their transparency/opacity, conductivity, and heat insulation properties, respectively, for various applications. The proposed thermally induced wet spinning method shows promise for overcoming the limitations of existing molding methods, in which the PDMS fibers cannot be lengthened. Furthermore, the process is environmentally friendly and economical owing to the use of edible canola oil, which reduces the volume of harmful solvents and additives during fiber production.

Organic–Inorganic Hybrid Conductive Network to Enhance the Electrical Conductivity of Graphene-Hybridized Polymeric Fibers

With the rapid development of wearable electronic textiles, flexible and knittable polymer conductive fibers have received unprecedented attention from researchers. Practical applications of these devices are, however, impeded by their low electrical conductivity and suboptimal mechanical properties. In this study, we demonstrate an organic–inorganic hybrid strategy to build a conductive network in polymeric fibers (CPFs) at low GnP loading using an industrial wet-spinning method. Both the conductivity and spinnability of wet-spun graphene-hybridized poly(vinyl alcohol) (PVA/GnP) fibers are systematically investigated. A secondary additive, poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) is also incorporated for the fabrication of newly hybridized PVA/GnP/PEDOT:PSS (denoted as PVA/GnP/S) fibers. In addition, a hybrid synergistic effect that features a synergistic enhancement of their conductivity (33.6 S/m) has also been well demonstrated. Meanwhile, this type of hybrid fiber maintains its excellent mechanical performance (4.82 cN/dtex with a 16.2% strain) even after subsequent twisting and weaving into conductive fabrics. As an electron transport carrier, this fiber can widely be applied in wearable electronics.

Multifunctional sodium Alginate@ urushiol fiber with targeted Antibacterial, acid corrosion resistance and flame retardant properties for personal protection based on wet spinning

The protective clothing may face acid, high temperature, and bacterial attack in the process of use, affecting its protection efficiency, and multifunctional protective clothing that can meet a variety of needs appear more potential applications. However, multifunctional personal protection clothing has remained an unmet challenge. Here we report a new type of multifunctional clothing via a simple, environmentally friendly wet spinning method to load the urushiol with acid corrosion and antibacterial functions on sodium alginate fiber. This structure uniformly disperses a certain content of urushiol in sodium alginate solution, allowing alginate fibers to have flame retardant properties while having high acid resistance and excellent targeted antibacterial properties. Compared to alginate fibers, the fabricated fibers were treated with different concentrations of sulfuric acid, although the strength was reduced to a certain extent, the fibers retained their original shape and were not dissolved. The thermal analysis showed the fiber also has good flame retardant better than viscose fiber. In addition, the fabricated fiber has targeted antibacterial properties, with an efficiency of 99.99% against Staphylococcus aureus (S. aureus) and bacteriostatic effect on Escherichia coli (E. coli), and good biocompatibility under low concentration conditions. Our work may provide new insights for the development of “green” multifunctional protective clothing. It also provides a research possibility for absorbable surgical sutures.

SERS active fibers from wet-spinning of alginate with gold nanoparticles for pH sensing

Functional composite fibers were prepared by a wet-spinning method and used for pH sensing based on surface enhanced Raman scattering (SERS). Alginate solution with gold nanoparticles (AuNPs) was spun to fibers that acting as active substrate showed distinct SERS enhancement for low concentrations of dyes (1.0 × 10-9 M for rhodamine 6G and 1.0 × 10-8 M for crystal violet). After AuNPs were modified with 4-mercaptopyridine (4-MPY), the as-synthesized composite fibers (AuNPs@4-MPY/Ca-ALG fibers) displayed pH dependent SERS spectra due to the changes of chemical structures of 4-MPY under different pH conditions. The AuNPs@4-MPY/Ca-ALG fibers achieved fast response to the pH changes between 1.00 and 13.00. The flexible composite fibers were woven to a wearable “wrist band”, which has potential applications in health monitoring involving pH variation.

Flexible, stimuli-responsive and self-cleaning phase change fiber for thermal energy storage and smart textiles

Smart textiles have emerged as potential part for wearable devices and protective systems. Integrating phase change materials (PCMs) into stimuli-responsive fibers offers exciting opportunities for smart clothing to realize instant energy conversion/storage and temperature regulation. However, the production of flexible and efficient smart energy storage fiber is still challenging. Here, flexible electro-/photo-driven energy storage polymer fiber with outstanding hydrophobicity and self-cleaning property is fabricated. The smart fiber is prepared by integrating conductive silver nanoflowers and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) as well as hydrophobic fluorocarbon resin with a facile and novel wet-spun phase change fiber to gain high flexibility, excellent electrical conductivity , high enthalpy, tunable phase change temperature , extra shape stability and outstanding hydrophobicity. The highest elongation of the smart fiber is more than 500% and the enthalpies of the fibers varies from 98.6 to 124.5 J g −1 according to the adjustable content of phase change materials. The coordination of Ag nanoflowers and PEDOT:PSS enable the fiber outstanding electrical conductivity of 190 S/m 2 . The high electrical conductivity, excellent photo capture and good heat dissipation enable the fiber high electro-/photo-heat conversion efficiency (70.1% and 89.0%, respectively). The smart energy storage fiber with integrative properties could be woven into fabrics, providing a new option for smart textiles in wearable and protective systems. • A facile and novel wet spinning method was used to prepare phase change fibers. • Ag nanoflowers and PEDOT:PSS coating enabled the fiber high electrical conductivity. • The fiber exhibited photo-/electro-responses with high energy conversion and storage. • The smart energy storage fiber performed effective energy conversion underwater.

Facile fabrication of flexible alginate/polyaniline/graphene hydrogel fibers for strain sensor

Continuous production of conductive hydrogel fibers has received extensive interests due to their wide application in strain sensors. In this paper, we report on the fabrication of continuous alginate/polyaniline/graphene hydrogel fibers by the in situ polymerization and wet spinning methods. The obtained hydrogel fiber with good flexibility, high water absorbability (11.37 g/g), proper resistivity (220 Ω·m ) and stable resistance changes at both low strain (10%) and high strain (20% and 50%) could be used as a working strain sensor for a wearable human movements monitor. The conductive alginate/polyaniline/graphene hydrogel fiber shows highly sensitive, flexible, and recoverable (90% retention after five cycles) properties when monitoring palm, elbow, and knee movements. This kind of hydrogel with high elasticity and high sensitivity provides a possibility for the preparation of electromechanical sensors.

A Comprehensive Study on the Rheological Properties of Collagen/PVA Spinning Solutions from Acetic Acid Solvent

Collagen and polyvinylalcohol (PVA) are extremely important in the applications of biomaterials including with electrospinning and wet-spinning methods. However, the rheological behavior of collagen and PVA blended solutions before spinning is still scarce. In this work, collagen was firstly extracted from pigskin building on the maximum maintenance of the natural structure and blended with PVA. The following detailed investigation on the viscosity and the rheology of blended solutions were carried out by rotate rheometer. The obtained results suggested that collagen/PVA solutions performed as Non-Newtonian fluids. Significantly, all the samples showed the shear thinning pseudoplastic behaviors with the steady shear rate. With increasing the collagen content or decreasing the operating temperature, the viscosity of blended solutions both increased at the same shear rate of 16.8 s−1, accompanied by the fall of the Non-Newtonian index (n) for the collagen/PVA samples. Furthermore, both low temperature and high concentration increased the structure of the spinning solution, which indicated that the temperature should be controlled in a higher range to improve the spinnability of the solution, but without collagen decomposition in the whole process. The increase of PVA content could reduce the degree of system structure, that was to say that the addition of PVA improved the spinnability of the system. As an application, the solution of collagen/PVA was wet spinned with the ethanol absolute as coagulant and collagen/PVA composite fibers were successfully prepared, which have compensated for the disadvantage of mono-component collagen materials. Of course, this experimental results is not limited to the above application, which really extends the potential use of collagen/PVA blended solutions towards the design of the collagenbased biomaterials.

Solvent treatment of wet-spinning PEDOT:PSS fiber towards wearable thermoelectric energy harvesting

Wearable energy supply nowadays gains great interest due to a sharp increase in demand for highly flexible, stretchable and embedded electronics, where fiber-based thermoelectric (TE) energy harvesting is a competitive counterpart compared with other energy supply systems. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) fiber has been prepared with wet-spinning method. However, the conductivity of the pristine PEDOT:PSS fiber is poor. Herein, PEDOT:PSS fibers were treated with different solvents to remove the insulative PSS chains and improve the conductivity of the fibers. In particular, the fiber sequential treated with EG and H2SO4 (EG-H2SO4) displayed an improved conductivity of 676.59 S cm−1. Therefore, the optimized PEDOT:PSS fibers achieved a power factor of 9.42 μWm−1 K−2 with a slightly reduced Seebeck coefficient. Finally, a simple fiber TE device was assembled based on the optimized PEDOT:PSS fiber with an output voltage of 1.7 mV. This work can supply an effective technique for preparing and regulating chemical composition for wearable energy harvesting.

Simultaneous degumming and deacidification of crude palm oil using mixed matrix PVDF membrane

The research work aimed to investigate the compatibility of polyvinylidene difluoride (PVDF) membrane embedded with various inorganic adsorbents for producing a mixed matrix membrane (MMM) and to examine the capability of mixed matrix PVDF membrane (PVDF-MMM) for simultaneous degumming and deacidification of crude palm oil (CPO). Four different adsorbent were tested which includes calcium silicate (CaS), magnesium silicate (MagS), ZSM-zeolite (ZSM) and activated carbon (AC). The in-house made PVDF-MMM was fabricated according to the dry-jet wet spinning method. The performances of these PVDF-MMMs were assessed with respect to the removals of phosphorus, FFA and colour. Based on finding showed that the combination of 18PVDF embedded with 3 wt% MagS showed the most compatible polymer-inorganic hybrid MMM to perform pre-treatment of CPO. Increasing the MagS concentration from 3 to 8 wt% in the polymer matrix recorded the highest removals of FFA at 16.51 %, phospholipid at 93.31 % and colour at 18.8 %, respectively. Nevertheless, high amount of MagS added to the polymer matrix affected the spinnability and reproducibility performance of MMM. Future work, surface modifications of inorganic adsorbent can be evaluated to facilitate good dispersion of filler in polymer matrix during membrane fabrication to maintain good membrane reproducibility.

Assessing the potential of integrally skinned asymmetric hollow fiber membranes for addressing membrane fouling in pressure retarded osmosis process

Thin-film composite (TFC) membranes are generally preferred over integrally skinned asymmetric (ISA) membranes in pressure retarded osmosis (PRO) process due to their much higher water permeability, but they cannot operate in the active layer facing feed solution (AL-FS) orientation because of potential delamination of the rejection layer under the high applied pressure. However, operating under AL-FS orientation is preferred as a strategy for better fouling control. Hence, in this study, three ISA hollow fiber membranes were fabricated using a dry-jet wet-spinning method, followed by chemical cross-linking to obtain membranes for PRO application. The best-performing membrane was subjected to fouling test in two orientations. Our results demonstrate that the AL-FS orientation is better for a sustainable long-term PRO operation, given the stable performance throughout the two-day testing. Also, the current use of power density per membrane area as a performance benchmark may not be practical for large-scale PRO operation, and the volumetric power density per module is more relevant. In terms of volumetric power density for a hypothetical 5-in. module, our best-performing membrane is predicted to generate a 3.6 to 10 times better power density than commercial modules, rendering our ISA hollow fiber membranes promising for scaling-up to bigger modules.

Wearable and Robust Polyimide Hydrogel Fiber Textiles for Strain Sensors.

Conductive ionic hydrogel fibers and textiles with excellent mechanical properties and chemical stability are requested for flexible and wearable electronic devices, strain sensors, and even artificial skin. However, most of the reported hydrogel fibers are not suitable in complex environments, especially in alkaline solutions and organic solvents due to their poor chemical stability. Herein, we report ionic polyimide hydrogel fibers derived from an organosoluble polyimide salt that can be continuously and rapidly prepared via a facile wet spinning method. Thanks to their ion-rich property and robust skeletal structure, the obtained ionic polyimide hydrogel fibers showed an excellent conductivity of ∼21 mS/cm and outstanding mechanical properties with a tensile strength of 2.5 MPa and breaking elongation of 215%. Furthermore, the as-prepared fibers could be easily woven to form integral textiles, endowing them with good wearable properties. Accordingly, facile strain sensors assembled by polyimide hydrogel fibers show a linear response with high sensitivity and good cycling stability, which have great potential for applications in wearable and flexible strain sensors under diverse complex environments.

Lightweight, Robust, Conductive Composite Fibers Based on MXene@Aramid Nanofibers as Sensors for Smart Fabrics.

Developing one-dimensional fiber-based sensors to meet the requirement of spinnability, portability, flexibility, and easeful conformability in smart wearable devices has attracted increasing interest. Here, we report highly conductive MXene@aramid nanofibers (ANFs) with a distinct skin-core structure by the wet spinning method. MXene, an emerging 2D conductive material, is applied to build internal conductive paths. ANF frameworks function as protective and skeleton structures to reduce the fiber oxidation probability and achieve superior strength. The obtained MXene@ANF fiber with superior conductivity (2515 S m-1) and tensile strength (130 MPa) works as a promising sensor for smart fabrics to detect different human movements with abundant detection motions, fast response time (100 ms), and long service life (up to 1000 cycles). Benefiting from its high flexibility, it can be sewn into textile and gloves as a smart wearable device. Besides superior thermal stability, it shows promising electrothermal properties with wide heating temperature (25-123 °C) and fast heating temperature (10 s). Therefore, the MXene@ANF fiber with the skin-core structure shows great potential as a promising sensor to be applied in electric heating and smart wearable fabrics.

Loading dependency of 2D MoS2 nanosheets in the capacitance of 3D hybrid microfibre-based energy storage devices

This study reports a wet spinning method to spin composite micro-fibres of 2D liquid crystalline graphene oxide (GO) and exfoliated MoS2 nanosheets with very high MoS2 loading. The MoS2 dispersion was found to be isotropic irrespective of solvent type or solute concentration in the dispersion and thus found to be non-spinnable via wet spinning process. The liquid crystallinity of GO induces birefringence in the composite dispersion and enables the spinning of the composite dispersion containing high loading of MoS2 with great flexibility. We were able to spin composite microfibers with 69 wt% MoS2 loading for the first time. The resulting fibres were annealed at high temperature to produce flexible conductive rGO#MoS2 fibres. Scanning electron microscopy (SEM) and Raman analysis strongly suggest homogeneous distribution of MoS2 throughout the fibres. Mechanical properties of the fibres were studied and maximum tensile strength (76.5 MPa) and Young's modulus (13.3 GPa) obtained with 10 wt% MoS2 loading. All solid-state flexible symmetric supercapacitor from these composite fibres was fabricated and the electrochemical performance was studied. The electrochemical study shows high areal capacitance of the produced composite fibres (as high as 282.6 mF cm−2) with good cycling stability (82.5% capacitance retention after 5000 cycles) that indicates high potential of these composite fibres as energy storage system for smart textile of the future.

Melt spinning of poly(acrylonitrile)-co-styrene copolymer

The search for alternative processes and high performance materials precursors for carbon fibers, has been continuously the aim for use in the aerospace, automotive, energy and sports goods market. The reduction in the precursor production cost is then essential to allow the installation of an industrial plant to produce a general purpose carbon fiber. Polyacrylonitrile has been the main precursor for carbon fiber production. It has been produced by the wet and dry spinning process since it has been discovered in the beginning of the forties. Nowadays, the extrusion process of PAN fibers shows potential of cost reduction in relation to the wet spinning method. This innovative technology enables spinning by melting PAN polymer by using glycerin as the primary plasticizer, avoiding the use of highly toxic solvents. In the present work, PAN copolymer was copolymerized by conventional aqueous suspension. Its characterization was performed by FT-IR, GPC and DSC analysis. The fibers obtained by extrusion process were characterized by SEM, DSC/TGA analysis and kinetics of the thermal stabilization process was studied by Kissinger method. The results showed that styrene monomer was suitable for polymerization with PAN leading to a molecular weight Mn= 46,000 g/mol and Mw = 138,000 g/mol. The PAN-co-Styrene copolymer was suitable for obtaining extruded PAN fibers continuously with morphological and thermal properties having properties similar to commercial PAN fibers.