Polyacrylonitrile Nanofiber Yarn Research Articles

MXene nanosheets woven in polyacrylonitrile nanofiber yarns aligned spider web as a highly efficient sorbent for in-tube solid phase microextraction of beta-blockers from biofluids

The use of electrospinning has received much attention in the production of nanofiber webs due to its advantages such as flexibility and simplicity. The direct electrospinning of nanofibers in an aligned or twisted form and the production of nanofiber yarns can turn nanofibers into woven fabrics, which leads to an increase in the diversity of nanofiber applications and improves their end-use possibilities. In this work, a victorious nanofiber yarn spinning system was used with the help of a rotating funnel. Yarn formation was studied using a composited polyacrylonitrile (PAN)/MXene polymer solution ejected from two oppositely charged nozzles. Finaly their application for packed-in-tube solid-phase microextraction of β-blocker drugs from biofluids was demonstrated. The separation and quantification of analytes were performed by HPLC-UV instrument. The 3D-yarn PAN/MXene sorbent exhibited high flexibility, porosity, sorbent loading, mechanical stability, and a long lifetime. The characterization of the final nanofiber was carried out utilizing Fourier-transform infrared spectroscopy, field emission scanning electron microscope, energy-dispersive X-ray mapping, transmission electron microscope and X-ray diffraction analysis. Various parameters that affect the extraction efficiency, such as extraction time, pH, ionic strength and flow rate of sample solution, and type, volume and flow rate of eluent, were investigated and optimized. Under optimized conditions, the limits of detection were obtained in the range of 1.5–3.0 μg L−1. This method demonstrated appropriate linearity for β-blockers in the range of 5.0–1000.0 μg L−1, with coefficients of determination greater than 0.990. The inter- and intra-assay precisions (RSDs, for n = 3) are in the range of 2.5–3.5%, and 4.5–5.2%, respectively. Finally, the validated method was put in an application for the analysis of atenolol, propranolol and betaxolol in human urine and saliva samples at different hours and acceptable relative recoveries were obtained in the range of 89.5% to 110.4%.

Investigation of continuous PAN nanofiber yarn produced with polymer additives

Nanofiber yarns were produced by electrospinning technique from polyacrylonitrile (PAN), thermoplastic polyurethane (TPU) added and polyvinylidene fluoride (PVDF) added PAN polymer solutions. The effects of the other polymers as additive to PAN nanofiber yarn are investigated. SEM, stress-strain characterizations were carried out. A sample plain fabric was woven from PAN nanofiber yarns to show that nanofiber yarns are feasible and can be integrated into conventional textile structures. Addition of the other polymers has increased the Young modulus by 40%, whereas TPU addition has increased the tenacity by 50% but TPU + PVDF addition has decreased the tenacity by half of only PAN. Breaking elongation was slightly decreased by the addition of TPU and PVDF polymers.

Flexible carbon nanofiber yarn electrodes for self-standing fiber supercapacitors

In this study, polyacrylonitrile (PAN) nanofiber yarns were obtained by twisting the nanofiber mat strips produced in the electrospinning device. On the drum collector, the nanofibers are produced in such a way that the diameter change can be controlled. Through stabilization and carbonization processes, PAN nanofiber yarns were converted to carbon nanofiber (CNF) yarns. The stabilization process stabilized the yarn structure, which was previously unstable, due to thermal treatments. The obtained CNF yarn had a diameter of approximately 360 μm and an average nanofiber diameter of 123 ± 20 nm. On a three-electrode system, the electrochemical performance of CNF yarn in 1 m H2SO4 electrolyte was determined using cyclic voltammetry and galvanostatic charge/discharge test methods. The specific capacitance of the CNF yarn electrode was determined to be 145 F/g at a current density of 0.2 A/g. Up to 500 charge/discharge cycles, the specific capacitance increased by approximately 20% and remained constant thereafter. Due to their superior properties such as high surface area, lightweight, and flexibility, CNF yarn electrodes can be used in a wide variety of electronic applications, including energy harvesting, energy storage (supercapacitors, batteries, etc.), and sensors.

Analysis of polyacrylonitrile nanofiber yarn formation in electrospinning by using a conical collector and two oppositely charged nozzles

Nanofiber production by electrospinning has become a common production method as it is an easy and flexible system producing nanofibrous webs. However, direct spinning of nanofibers into a yarn would lead to conversion of nanofibers into woven or knitted fabrics easily, therefore improving end-use possibilities of these fibers substantially. In this work a successful nanofiber yarn spinning system using polyacrylonitrile polymer is established and yarn formation by polymers ejected from two nozzles with opposite charges was analysed and potential of this system for bicomponent yarn production was shown. Fiber formation from each nozzle was also examined by high speed camera while distribution of the electric field strength and loads in the electrostatic state was analysed by electric field simulation . Finally, polyacrylonitrile nanofiber yarns produced at different collector and winding speeds were analysed in terms of fiber and yarn properties. Furthermore, the first fabric sample with nanofiber yarns woven manually was presented.

Microstructural evolution and mechanical investigation of hot stretched graphene oxide reinforced polyacrylonitrile nanofiber yarns

To reveal the enhancement effect of graphene oxide (GO) in polymer nanofiber yarns, polyacrylonitrile (PAN)/GO nanofibers with different GO content (0.1‐0.5 wt%) were electrospun. The alignment of PAN chains and GO in nanofibers was enhanced by hot stretching of the yarn in dry conditions. The microstructure of the composite nanofiber yarns was investigated through X‐ray diffraction, polarized Fourier transform infrared spectroscopy and transmission electron microscopy. The results demonstrated that the hot stretching above Tg of PAN precursor lead to the increased orientation‐induced crystallization and alignment of PAN chain and GO. The yarn with 0.1 wt% GO and stretched by 4 times its length obtained the highest strength and modules (310.88 ± 24.68 MPa and 7.24 ± 0.55 GPa), which were 600% and 500% higher than those of the as‐electrospun pure PAN yarn. The most promising tensile properties found in hot stretched yarns with low GO content was because the strong interaction occurred between PAN molecules and oxygen‐containing functional groups. Indirect evidence of GO aggregation was also presented, which adversely affected the mechanical properties at higher GO content. Composite nanofiber yarns were sewable and weavable, and could be used as a new generation of composite reinforcement after pyrolysis.

A Stretchable, Highly Sensitive, and Multimodal Mechanical Fabric Sensor Based on Electrospun Conductive Nanofiber Yarn for Wearable Electronics

AbstractThe development of highly sensitive, stretchable, and wearable electronic skin with multimodal mechanical‐sensing performance is of great research value for applications in health monitoring, and wearable electronic devices. In this work, a fabric‐like sensor with high flexibility and weavability that could detect the mechanical forces induced by pressure, strain, and flexion is designed. The fabric‐like sensor is woven by composite yarns (GCNF@ECYs) formed by winding graphene oxide‐doped polyacrylonitrile nanofiber yarns with in situ polymerized conductive polypyrrole on elastic yarns. The hierarchical structure of the fabric ranged from the macroscopic yarn to the submicron‐scale fibers to the nanometer‐scale particles as well as the wrapped structure constructed by winding conductive nanofiber yarn on elastic yarn. This offers more conductive pathways, larger deformation space, and multimodal mechanical‐sensing capabilities. The GCNF@ECY sensor unit has high sensitivity (the gauge factor was ≈68), wide pressure‐sensing range, excellent cycling stability, and good repeatability (over 10 000 cycles). The sensor can detect human respiration, facial expressions, pulse monitoring, and a full range of human motion. Moreover, the fabric sensor can be easily woven into textiles to produce electronic textiles with great potential in wearable human health monitoring electronics devices.

A highly sensitive strain sensor based on a carbonized polyacrylonitrile nanofiber woven fabric

In this study, a flexible highly sensitive strain sensor was fabricated using thermoplastic polyurethane (TPU) and carbonized woven fabric based on polyacrylonitrile nanofiber yarn (PNY). The carbonized PNY fabric was prepared according to the following steps: filaments fabricated by electro spinning were twisted into a yarn; the yarn was treated by a sizing agent and weaved as a weft yarn; subsequently, the woven fabric was washed, pressed, and dried; finally, the carbonized PNY woven fabric was obtained through stabilization and carbonization. The effects of the thickness of the TPU film and the structure of the fabric on the sensing properties are discussed. The flexible strain sensor exhibits excellent sensitivity in the high-sensing strain range (average gauge factor = 77.3 within 12% strain) and high durability and stability (more than 1000 stretching cycles at 5% strain). Moreover, the strain sensor exhibits an excellent linear relationship between the strain and relative resistance change and accurately detects a full range of human activities (both vigorous and subtle). Such flexible highly sensitive strain sensors can be easily incorporated onto the surfaces of textiles and within electronics for use in various applications, toward applications such as smart textiles and health monitoring.

Structures and mechanical properties of plied and twisted polyacrylonitrile nanofiber yarns fabricated by a multi-needle electrospinning device

Polyacrylonitrile (PAN) nanofiber filaments were manufactured continuously for several hours by a homemade multi-needle electrospinning device. The yarns were continuously obtained by plying and twisting nanofiber filaments using a self-made twisting device. The structures and mechanical properties of yarns were investigated. The influences of twist setting temperatures and periods of time on morphology and mechanical properties were discussed. The results showed that the alignment degree of nanofibers along the filament axis could reach 70.9 %. The twist angle increased with increasing twists and the number of filaments. With increasing twists, the breaking stress and strain increased initially and then decreased; the maximum breaking stress and strain were 34.7 MPa and 26.1 %, respectively; the initial modulus decreased with increasing twists and plies, the maximum modulus was 391.3 MPa. Both the breaking stress and strain increased with the increase of twist setting temperatures and times. The optimal setting temperature and time were 90 °C and 30 min, respectively, the maximum breaking stress and strain were 32.8 MPa and 20.8 %, meanwhile, the crystallinity improved from 34.5 % to 39.9 %. This study demonstrates the possibility of continuously and stably manufacturing PAN nanofiber yarns.

Polyacrylonitrile nanofiber yarns and fabrics produced using a novel electrospinning method combined with traditional textile techniques

Highly aligned polyacrylonitrile (PAN) nanofiber yarns were prepared continuously by a modified electrospinning method. The effects of the different spinning parameters, including applied voltage, solution flow rate, distance between two needles, distance between the neutral metal disc (NMD) and neutral hollow metal rod (NHMR) and rotation speed of the NMD, on yarn formation and physical characteristics of the nanofibers and the yarns were analytically investigated. The distance between two needles, distance between the NMD and NHMR and rotation speed of the NMD were found to be three main parameters affecting nanofiber alignment of the resultant yarns. The results also showed that the applied voltage and rotation speed of the NMD had a very slight effect on diameters of nanofibers. The diameters of both nanofibers and yarns increased to a threshold value and started to reduce thereafter with the distance between two needles increasing. The diameters of both nanofibers and yarns presented the increasing trend at the higher flow rate. Meanwhile, the yarn diameters decreased with increasing the distance between the NMD and NHMR and the rotation speed of the NMD. Moreover, the effect of nanofiber alignment on the mechanical property of the resultant PAN nanofiber yarns was also investigated in this paper. It was found that the increase in the fiber alignment brought about the improvement in the yarn tensile strength. Eventually, the obtained continuous PAN nanofiber yarns were employed to manufacture fabrics by traditional textile techniques, including braiding, weaving and knitting, which showed the potential application in the textile industry.

A Fast Response Ammonia Sensor Based on Coaxial PPy-PAN Nanofiber Yarn.

Highly orientated polypyrrole (PPy)–coated polyacrylonitrile (PAN) (PPy–PAN) nanofiber yarn was prepared with an electrospinning technique and in-situ chemical polymerization. The morphology and chemical structure of PPy–PAN nanofiber yarn was characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and fourier transform infrared spectroscopy (FTIR), which indicated that the PPy as the shell layer was homogeneously and uniformly polymerized on the surface of PAN nanofiber. The effects of different concentration of doping acid on the responses of PPy–PAN nanofiber yarn sensor were investigated. The electrical responses of the gas sensor based on the PPy–PAN nanofiber yarn to ammonia were investigated at room temperature. The nanoyarn sensor composed of uniaxially aligned PPy–PAN nanofibers with a one-dimensional structure exhibited a transient response, and the response time was less than 1 s. The excellent sensing properties mentioned above give rise to good potential application prospects in the field of ammonia sensor.

Continuous polyacrylonitrile nanofiber yarns: preparation and dry-drawing treatment for carbon nanofiber production

Drawing of electrospun polyacrylonitrile nanofiber yarns in dry conditions can significantly improve tensile strength as well as fiber and yarn quality.

Fabrication of continuous nanofiber yarn using novel multi‐nozzle bubble electrospinning

A novel multi‐nozzle bubble electrospinning apparatus, including spinning unit, metering pump, constant flow pump, metal funnel and yarn winder, was designed for the preparation of continuous twisted polyacrylonitrile nanofiber yarns, and the principle of nanofiber yarn spinning was studied. An innovative spinning unit consisting of nozzle and air chamber was used to improve the production of nanofibers. Double conjugate electrospinning was developed using two pairs of oppositely charged spinning units to neutralize the charges. The effects of applied voltage, air flow rate, overall solution flow rate and funnel rotary speed on the fiber diameter, production rate and mechanical properties of the nanofiber yarns were analyzed. Nanofibers could be aggregated stably and bundled continuously, then twisted into nanofiber yarns uniformly at an applied voltage of 34 kV, air flow rate of 1200 mL min−1 and overall solution flow rate of 32 mL h−1. With an increase in the funnel rotary speed, the twist angle of the nanofiber yarns gradually increased when the take‐up speed was constant. The yarn tensile strength and elongation at break showed an increasing trend with increasing twist angle. Nanofiber yarns obtained using this novel method could be produced at a rate from 2.189 to 3.227 g h−1 with yarn diameters ranging from 200 to 386 µm. Nanofiber yarns with a twist angle of 49.7° showed a tensile strength of 0.592 cN dtex−1 and an elongation at break of 65.7%. © 2013 Society of Chemical Industry

Multiple conjugate electrospinning method for the preparation of continuous polyacrylonitrile nanofiber yarn

AbstractContinuous polyacrylonitrile nanofiber yarns were fabricated by the homemade multiple conjugate electrospinning apparatus, and the principle of yarn spinning was studied. The effects of the applied voltage, flow rate, spinning distance, and funnel rotary speed on the diameter and mechanical properties of nanofiber yarn were analyzed. The diameter of the nanofibers decreased with increasing applied voltage and the flow rate ratio of the positive and negative needles (FP/FN), whereas the diameter of nanofibers increased with increasing overall flow rate and needle distance between the positive and negative. Subsequently, the diameter of the yarns increased first and then decreased with increasing applied voltage, FP/FN, and needle distance. However, the diameters of the yarns increased dramatically and then remained stable with increasing overall flow rate. The nanofibers were stably aggregated and continuously bundled and then uniformly twisted into nanofiber yarns at an applied voltage of 20 kV, an overall flow rate of 6.4 mL/h, a needle distance of 18.5 cm, and an FP/FN value of 5:3. With increasing funnel rotary speed, the diameters of the nanofibers and yarns decreased, whereas the twist angle of the nanofiber yarns gradually enlarged. Meanwhile, an increase in the twist angle brought about an improvement in the yarn mechanical properties. Nanofiber yarns that prepared showed diameters between 70 and 216 μm. Nanofiber yarns with a twist angle of 65° showed a tensile strength of 50.71 MPa and an elongation of 43.56% at break, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40137.

Uniaxially aligned polyacrylonitrile nanofiber yarns prepared by a novel modified electrospinning method

A modified electrospinning setup was used to manufacture uniaxially aligned nanofiber yarns. Compared with the traditional electrospinning setup, two oppositely placed metal needles were employed and applied with positive and negative voltages respectively. Meanwhile, a neutral metal disc and hollow metal rod were placed oppositely in the middle of the two needles. Nanofibers ejected from two needles were oriented in the gap between the metal disc and the tapered sharp end of hollow metal rod. A nanofiber bundle was obtained and twisted by rotating the metal disc and fastening the hollow metal rod. After passing through the hollow metal rod, a yarn was continuously wound by a rotating take-up roll. The morphologies of polyacrylonitrile (PAN) nanofiber yarns were characterized. It was found that well-aligned nanofiber yarns with the diameters varying from 52μm to 105μm were fabricated successfully by turning PAN concentrations. In addition, the mechanical behavior test showed that the yarns possessed proper mechanical properties, which could be used for potential applications such as composites and tissue engineering.

Electrospun Polyacrylonitrile nanofiber yarn prepared by funnel-shape collector

The homemade electrospinning set-up was used to prepare Polyacrylonitrile nanofiber yarn. Compared with the traditional electrospinning set-up, the special difference in this method was that the funnel-shape collector with high-speed airflow inside was employed. The yarn forming process was investigated and the effect of spinneret-to-collector distance and LiCl (lithium chloride) additives on the yarn forming process was discussed. The results showed that the nanofiber yarn was fabricated successfully by using our electrospun set-up. The spinneret-to-collector distance 3cm was most appropriate for fabricating electrospun nanofiber yarn. When 0.6wt.% LiCl was added in polymer solution, fiber convergence was observed obviously and the fiber arranged along the yarn longitudinal direction.

Manufacturing of twisted continuous PAN nanofiber yarn by electrospinning process

The development of a modified method to produce heat treated twisted nanofibrous yarns using two oppositely metallic spinnerets system is presented. This method allows the production of more uniform, stronger twisted poly acrylonitrile (PAN) yarns. The novelty of this system permits for in-situ heat treating of the nanofiber yarns. The average diameter of twisted nanofiber yarns is 340.65 µm with 5.8 CV%. The values of the initial modulus and stress of heat treated yarns increase from 1.90 GPa and 61.30 MPa in untreated one to 4.51 GPa and 116.56 MPa, respectively. In order to quantify the alignment of the nanofibers Fourier power spectrum (FPS) and image analysis were used. So the treated yarn shows more degree of nanofiber alignments than the untreated one.

Manipulation of the electric field of electrospinning system to produce polyacrylonitrile nanofiber yarn

Electrospinning is a process that produces nanofiber through the action of an external electric field imposed on a polymer solution or melt. This paper introduces a new system capable of producing continuous uniaxially aligned PAN nanofiber yarn by manipulating the electric field. The manipulation was carried out by employing a negative charged bar in the electric field of conventional electrospinning system, leading to the formation of an electrostatic multipolar field. As a result, the main stream was redirected towards a rotating take up unit, collecting the twisted yarn consisting of uniaxially aligned nanofibers. The yarns were then treated in boiling water under tension and their mechanical properties were compared with those of the untreated ones.