In vitro degradation behavior of electrospun polyglycolide,polylactide, and poly(lactide‐co‐glycolide)

The electrospinning of polyglycolide (PGA), poly(L ‐lactide) (PLA), and poly(lactide‐co‐glycolide) (PLGA; L ‐lactide/glycolide = 50/50) was performed with chloroform or 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) as a spinning solvent to fabricate their nanofiber matrices. The morphology of the electrospun PGA, PLA, and PLGA nanofibers was investigated with scanning electron microscopy (SEM). The PLGA nanofibers, electrospun with a nonpolar chloroform solvent, had a relatively large average diameter (760 nm), and it had a relatively broad distribution in the range of 200–1800 nm. On the other hand, the PGA and PLA fibers, electrospun with a polar HFIP solvent, had a small average diameter (～300 nm) with a narrow distribution. This difference in the fiber diameters may be associated with the polarity of the solvent. Also, the in vitro degradation of PGA, PLA, and PLGA nanofiber matrices was examined in phosphate buffer solutions (pH 7.4) at 37°C. The degradation rates of the nanofiber matrices were fast, in the order of PGA > PLGA ? PLA. Structural and morphological changes during in vitro degradation were investigated with differential scanning calorimetry and wide‐angle X‐ray diffraction. For the PGA matrix, a significant increase in the crystallinity during the early stage was detected, as well as a gradual decrease during the later period, and this indicated that preferential hydrolytic degradation in the amorphous regions occurred with cleavage‐induced crystallization, followed by further degradation in the crystalline region. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 193–200, 2005     

Effect of nanocrystalline cellulose addition on needleless alternating current electrospinning and properties of nanofibrous polyacrylonitrile meshes

Needleless alternating current (AC)‐electrospinning is capable of achieving high nanofiber generation rates while adding more flexibility to the process development when compared to common direct current (DC)‐electrospinning. However, AC‐electrospinning process may produce very different results than DC‐electrospinning when using the same precursors. This study demonstrated that stable AC‐electrospinning of uniform and mechanically strong polyacrylonitrile (PAN) nanofibrous meshes can be achieved at 30 ± 5 kV rms voltage when 0.75–6.0 wt % of nanocrystalline cellulose‐II with respect to PAN is added to a typical PAN precursor solution. Efficient generation (up to 2 g/h rate or 0.7 g h^?1 cm^?2 mass flux) of nanofibers with 250–500 nm fiber diameters has been observed when using flat fiber‐generating electrodes with diameters up to 25 mm. Depending on the amount of nanocellulose, nanofibrous nanocellulose/PAN meshes revealed large variations in tensile modulus (90–273 MPa) and yield strength (1.0–2.5 MPa), whereas the fiber diameter, air permeability, air resistance, mesh porosity, and water absorption were less affected. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45772.     

基于静电纺丝技术的PLGA载药纳米纤维膜的制备工艺

同轴静电纺丝法制备的聚乳酸-乙醇酸(PLGA)纳米纤维具有良好的生物相容性和生物可降解性, 加之其高孔隙率和高透氧率, 使其能成为优良的药物载体。本文初步摸索了PLGA的同轴静电纺丝的工艺条件, 并通过同轴静电纺丝法制备了PLGA载氟比洛芬酯(FA)的纳米纤维膜, 应用扫描电子显微镜、红外光谱分析观察纤维的表观形貌并确定其微观结构。重点探究了不同溶剂配比的混合溶剂对载药纤维膜药物释放性能影响。研究结果表明在U⁺为+15.00kV, U^-为-2.50kV, 接受距离为15cm, 壳层推进速度为0.4mm/min, 芯层推进速度为0.1mm/min进行静电纺丝时, 所制备的PLGA(壳)/PVP+FA(核)复合载药纤维膜壳核结构良好, 且成功载了约0.5%的FA。当改变壳层混合溶剂(DCM和DMF)和芯层混合溶剂(无水乙醇和DMF)体积比时, 纤维直径会随着DMF的减少而增大。     

Effect of solution properties on nanofibrous structure of electrospun poly(lactic‐co‐glycolic acid)

Electrospinning of poly(lactic‐co‐glycolic acid) (PLGA) in chloroform or 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) was investigated, focusing on its solution parameters, to develop nonwoven biodegradable nanofibrous structures for tissue engineering. PLGA nanofibers were obtained by electrospinning of 15 wt % PLGA solution and the resulting average fiber diameters were varied with the range of 270–760 nm, depending on solution property. When small amounts of benzyl triethylammonium chloride (BTEAC) was added to the PLGA/chloroform solution, the average diameter was decreased from 760 to 450 nm and the fibers were densely amounted in a straight shape. In addition, the average fiber diameter (270 nm) of nanofibers electrospun from polar HFIP solvent was much smaller than that (760 nm) of nanofibers electrospun from nonpolar chloroform solvent. Therefore, it could be concluded that conductivity or dielectric constant of the PLGA solution was a major parameter affecting the morphology and diameter of the electrospun PLGA fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1214–1221, 2006     

Flurbiprofen axetil loaded coaxial electrospun poly(vinyl pyrrolidone)–nanopoly(lactic‐co‐glycolic acid) core–shell composite nanofibers: Preparation,characterization, and anti‐adhesion activity

Flurbiprofen axetil (FA)‐loaded coaxial electrospun poly(vinyl pyrrolidone) (PVP)–nanopoly(lactic‐co‐glycolic acid) core–shell composite nanofibers were successfully fabricated by a facile coaxial electrospinning, and an electrospun drug‐loaded system was formed for anti‐adhesion applications. The FA, which is a kind of lipid microsphere nonsteroidal anti‐inflammatory drug, was shown to be successfully adsorbed in the PVP, and the formed poly(lactic‐co‐glycolic acid) (PLGA)/PVP/FA composite nanofibers exhibited a uniform and smooth morphology. The cell viability assay and cell morphology observation revealed that the formed PLGA/PVP/FA composite nanofibers were cytocompatible. Importantly, the loaded FA within the PLGA/PVP coaxial nanofibers showed a sustained‐release profile and anti‐adhesion activity to inhibit the growth of the IEC‐6 and NIH3T3 model cells. With the significantly reduced burst‐release profile, good cytocompatibility, and anti‐adhesion activity, the developed PLGA/PVP/FA composite nanofibers were proposed to be a promising material in the fields of tissue engineering and pharmaceutical science. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41982.     

Effect of air blowing on the morphology and nanofiber properties of blowing‐assisted electrospun polycarbonates

Polycarbonate (PC) nanofibers are prepared using the air blowing‐assisted electrospinning process. The effects of air blowing pressure and PC solution concentration on the physical properties of fibers and the filtration performance of the nanofiber web are investigated. The air blowing‐assisted electrospinning process produces fewer beads and smaller nanofiber diameters compared with those obtained without air blowing. Uniform PC nanofibers with an average fiber diameter of about 0.170 μm are obtained using an applied voltage of 40 kV, an air blowing pressure of 0.3 MPa, a PC solution concentration of 16%, and a tip‐to‐collection‐screen distance (TCD) of 25 cm. The filtration efficiency improvement of the air blowing‐assisted electrospun web can be attributed to the narrow distribution of fiber diameter and small mean flow pore size of the electrospun web. Performance results show that the air blowing‐assisted electrospinning process can be applied to produce PC nanofiber mats with high‐quality filtration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Process Optimization and Empirical Modeling for Electrospun Poly(D,L‐lactide) Fibers using Response Surface Methodology

Summary: Ultrafine fibers were spun from poly(D ,L ‐lactide) (PDLA) solution using a homemade electrospinning set‐up. Fibers with diameter ranging from 350 to 1 900 nm were obtained. Morphologies of fibers and distribution of fiber diameters were investigated varying concentration and applied voltage by scanning electron microscopy (SEM). Average fiber diameter and distribution were determined from about 100 measurements of the random fibers with an image analyzer (SemAfore 5.0, JEOL). A more systematic understanding of process parameters of the electrospinning was obtained and a quantitative relationship between electrospinning parameters and average fiber diameter was established by response surface methodology (RSM). It was concluded that the concentration of polymer solution played an important role in the diameter of fibers and standard deviation of fiber diameter. Lower concentration tended to facilitate the formation of bead‐on‐string structures. Fiber diameter tended to increase with polymer concentration and decrease with applied voltage. Fibers with lower variation in diameter can be obtained at lower concentration regardless of applied voltage. Fibers with uniform diameter and lower variation in diameter can be obtained at higher concentration and higher applied voltage. Process conditions for electrospinning of PDLA could be chosen according to the model in this study.

Contour plots of average fiber diameter as a function of concentration and applied voltage.     

Air permeability of electrospun polyacrylonitrile nanoweb

Ultrafine fibers were spun from polyacrylonitrile (PAN) solution in N,N‐dimethylformamide using a homemade electrospinning setup. Fibers with diameter ranging from 80 to 340 nm were obtained. Fiber size and fiber size distribution were investigated for various concentration, applied voltage, and tip‐to‐collector distance using image analysis. The diameters of the electrospun fibers increase when increasing the solution concentration and decrease slightly when increasing the voltage and needle tip‐to‐collector distance. Porosity and air permeability are vital properties in applications of electrospun nanofibrous structures. In this study, effects of process parameters on the porosity and air permeability of electrospun nanoweb were investigated as well. Results of statistical analysis showed that solution concentration and applied voltage have significant influences on pore diameters. It was concluded that nanofiber diameter played an important role on the diameter of pores formed by the intersections of nanofibers. A more realistic understanding of porosity was obtained and a quantitative relationship between nanoweb parameters and its air permeability was established by regression analysis. Two separate models were constructed for predicting air permeability in relation to process parameters. Optimization of electrospinning process for producing nanoweb with desirable air permeability is well achieved by these models. The models presented in this study are of high importance for their ability to predict the air permeability of PAN nanoweb both by process or structure parameters. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

静电纺丝法纺制聚乳酸纳米纤维无纺毡

采用静电纺丝法制备了生物降解聚乳酸(PLLA)纳米纤维无纺毡。分析了纺丝液浓度、电压、接收距离、挤出速度等因素对纤维形态的影响。结果表明:纺丝液的浓度和挤出速度对纤维直径的影响较为明显,溶液挤出速度增大,所得纤维微孔含量及尺寸也增大;适当的电压和接收距离有利于收集无液滴纤维;随着纤维直径的减小,无纺毡的孔径呈减小趋势。在PLLA质量分数为5．7％、挤出速度0．8 mL／h、接受距离 15．5 cm、电压8 kV的静电纺丝条件下,可制备纤维直径为200-400 nm的PLLA纳米纤维无纺毡。     

Electrospinning of poly(hydroxybutyrate‐co‐hydroxyvalerate) fibrous tissue engineering scaffolds in two different electric fields

Poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) was electrospun into ultrafine fibrous nonwoven mats. Different from the conventional electrospinning process, which involves a positively charged conductive needle and a grounded fiber collector (i.e., positive voltage (PV) electrospinning), pseudo‐negative voltage (NV) electrospinning, which adopted a setup such that the needle was grounded and the fiber collector was positively charged, was investigated for making ultrafine PHBV fibers. For pseudo‐NV electrospinning, the effects of various electrospinning parameters on fiber morphology and diameter were assessed systematically. The average diameters of PHBV fibers electrospun via pseudo‐NVs were compared with those of PHBV fibers electrospun via PVs. With either PV electrospinning or pseudo‐NV electrospinning, the average diameters of electrospun fibers ranged between 500 nm and 4 μm, and they could be controlled by varying the electrospinning parameters. The scientific significance and technological implication of fiber formation by PV electrospinning and pseudo‐NV electrospinning in the field of tissue engineering were discussed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Effect of experimental parameters on needleless electrospinning from a conical wire coil

In this study, a conical wire coil was used as spinneret to launch a novel needleless electrospinning. Multiple polymer jets were observed on the surface of the coil in the electrospinning process. Productivity of the nanofibers can be enhanced to >2.5 g/h by using this novel nozzle. The fiber productivity and diameter together with diameter distribution were dependent on the concentration of the polymer solution, applied voltage, and collecting distance. This novel concept of using wire coil as the electrospinning nozzle depicts a model of large‐scale needleless electrospinning system for nanofiber production. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

An investigation into the influence of electrospinning parameters on the diameter and alignment of poly(hydroxybutyrate‐co‐hydroxyvalerate) fibers

Electrospinning is an effective technology for the fabrication of ultrafine fibers, which can be the basic component of a tissue engineering scaffold. In tissue engineering, because cells seeded on fibrous scaffolds with varying fiber diameters and morphologies exhibit different responses, it is critical to control these characteristics of electrospun fibers. The diameter and morphology of electrospun fibers can be influenced by many processing parameters (e.g., electrospinning voltage, needle inner diameter, solution feeding rate, rotational speed of the fiber‐collecting cylinder, and working distance) and solution properties (polymer solution concentration and conductivity). In this study, a factorial design approach was used to systematically investigate the degree of influence of each of these parameters on fiber diameter, degree of fiber alignment, and their possible synergetic effects, using a natural biodegradable polymer, poly(hydroxybutyrate‐co‐hydroxyvalerate), for the electrospinning experiments. It was found that the solution concentration invoked the highest main effect on fiber diameter, whereas both rotational speed of the fiber‐collecting cylinder and addition of a conductivity‐enhancing salt could significantly affect the degree of fiber alignment. By carefully controlling the electrospinning parameters and solution properties, fibrous scaffolds of desired characteristics could be made to meet the requirements of different tissue engineering applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of the processing parameters on needleless electrospinning from double ring slits spinneret using response surface methodology

Needleless electrospinning technology was an effective processing method which can fabricate large scale nanofibers. We first developed a novel double rings slit spinneret to overcome the shortcomings of current needleless electrospinning spinnerets. The solution of the flow rate was controlled accurately by peristaltic control pump. Response surface methodology was adopted to investigate the influence of the processing parameters on the morphology and diameter of nanofibers. The main spinning processing parameters comprised solution concentration, applied voltage, collection distance and solution flow rate. The analysis of variance was used to evaluate response surface reduced quadratic model for nanofiber diameter. The linear and quadratic coefficients were obtained. The morphology of nanofibers was observed by scanning electron microscopy. Effects of different processing parameters on the nanofiber mean diameter have been discussed. Predicated values have a good agreement with actual values for nanofiber diameter. Actual nanofiber diameter ranges from129.15 to 404.70 nm with different process parameters. Mechanical properties of nanofiber membrane have been investigated. High quality and high throughout nanofiber could be continuously produced. This novel needleless electrospinning spinneret has a great potential for large scale nanofibers production to promote electrospinning technology development. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46407.     

The effects of processing parameters on the morphology of PLA/PEG melt electrospun fibers

Electrospinning of a polymer melt is an ideal technique to produce highly porous nanofibrous or microfibrous scaffolds appropriate for biomedical applications. In recent decades, melt electrospinning has been known as an eco‐friendly procedure as it eliminates the cytotoxic effects of the solvents used in solution electrospinning. In this work, the effects of spinning conditions such as temperature, applied voltage, nozzle to collector distance and collector type as well as polyethylene glycol (PEG) concentration on the diameter of melt electrospun polylactic acid (PLA)/PEG fibers were studied. The thermal stability of PLA/PEG blends was monitored through TGA and rheometry. Morphological investigations were carried out via optical and scanning electron microscopy. Based on the results, blends were almost stable over the temperature range of melt electrospinning (170 ? 230 °C) and a short spinning time of 5 min. To obtain non‐woven meshes with uniform fiber morphologies, experimental parameters were optimized using ANOVA. While increasing the temperature, applied voltage and PEG content resulted in thinner fibers, PEG concentration was the most influential factor on the fiber diameter. In addition, a nozzle to collector distance of 10 cm was found to be the most suitable for preparing uniform non‐woven PLA/PEG meshes. At higher PEG concentrations, alterations in the collector distance did not affect the uniformity of fibers, although at lower distances vigorous bending instabilities due to polarity augmentation and viscosity reduction resulted in curly fibrous meshes. Finally, the finest and submicron scale fibers were obtained through melt electrospinning of PLA/PEG (70/30) blend collected on a metallic frame. © 2017 Society of Chemical Industry     

Effects of some electrospinning parameters on morphology of natural silk‐based nanofibers

Natural silk, from Bombyx mori solutions were electrospun into nanofibers, with diameters ranged from 60 to 7000 nm. The effects of electrospinning temperature, solution concentration and electric field on the formation nanofibers were studied. Optical and scanning electron microscope were used to study the morphology and diameter of electrospun nanofibers. It was observed that the nanofibers became flattened with ribbon‐like shape with increasing the electrospinning temperature. The nanofiber diameter increases with the increase in the concentration of silk solution at all electrospinning temperature. With increasing the voltage of electric field at 50°C, morphology of the nanofibers changes from ribbon‐like structure to circular cross section. Referring to the literature the probable mechanism responsible for the change of morphology is pointed out. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of processing conditions on polymorphic behavior,crystallinity, and morphology of electrospun poly(VInylidene fluoride) nanofibers

The polymorphism and crystallinity of poly(vinylidene fluoride) (PVDF) membranes, made from electrospinning of the PVDF in pure N,N‐dimethylformamide (DMF) and DMF/acetone mixture solutions are studied. Influence of the processing and solution parameters such as flow rate, applied voltage, solvent system, and mixture ratio, on nanofiber morphology, total crystallinity, and crystal phase content of the nanofibers are investigated using scanning electron microscopy, wide‐angle X‐ray scattering, differential scanning calorimetric, and Fourier transform infrared spectroscopy. The results show that solutions of 20% w/w PVDF in two solvent systems of DMF and DMF/acetone (with volume ratios of 3/1 and 1/1) are electrospinnable; however, using DMF/acetone volume ratio of 1/3 led to blockage of the needle and spinning process was stopped. Very high fraction of β‐phase (～79%–85%) was obtained for investigated nanofiber, while degree of crystallinity increased to 59% which is quite high due to the strong influence of electrospinning on ordering the microstructure. Interestingly, ultrafine fibers with the diameter of 12 and 15 nm were obtained in this work. Uniform and bead free nanofiber was formed when a certain amount of acetone was added in to the electrospinning solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42304.     

Novel colloidal nanofiber electrolytes from PVA‐organoclay/poly(MA‐alt‐MVE), and their NaOH and Ag‐carrying polymer complexes

Novel multifunctional polymer nanofiber electrolytes with covalence crosslinked structures from various solution blends of reactive intercalated poly(vinyl alcohol)/octadecylamine montmorillonite (as a matrix polymer), poly(maleic anhydride‐alt‐methyl vinyl ether) (as a partner polymer) and their NaOH‐absorbing and Ag‐carrying polymer complexes were fabricated via electrospinning. Chemical, physical, morphological, and electrical properties of nanofiber structures were investigated by FTIR, XRD, SEM, and electrical analysis methods. Ag precursors in fiber composites significantly improved phase separation processing, fiber morphologies, diameter distributions, and electrical properties of the fibers. In situ generation of Ag nanoparticles and their distribution on nanofiber surfaces during fiber formation occurred via complex formation between silver cations and electronegative functional groups from both matrix and partner polymers as stabilizing/reducing agents. Electrical resistance and conductivity strongly depended on matrix/partner polymer ratios and absorption time of NaOH solution on nanofibers. Addition of NaOH changed the electrical properties of fiber structures from almost dielectric state to excellent conductivity form. The fabricated unique nanofiber electrolytes are promising candidates for applications in power and fuel cell nanotechnology, electrochemical, and bioengineering processes as reactive semiconductive platforms. POLYM. ENG. SCI., 56:204–213, 2016. © 2015 Society of Plastics Engineers     

Melt electrospinning from poly(L‐lactide) rods coated with poly(ethylene‐co‐vinyl alcohol)

Rodlike poly(L ‐lactide) (PLLA) samples coated with poly(ethylene‐co‐vinyl alcohol) (EVOH) were made. Fibers were produced from these rodlike samples by using a melt electrospinning system equipped with a laser irradiating device, and the effects of EVOH content and the processing parameters of the melt electrospinning on fiber diameters were investigated. We also studied the fiber formation mechanism from the rods during the laser melt electrospinning process. The following conclusions were reached: (i) coating of EVOH on PLLA rods has a remarkable effect on decreasing fiber diameter from 3 μm to around 1 μm; (ii) increases in the electric field strength and temperature of spinning space decrease the average diameter of fibers produced from pure PLLA rods, and longer collector distance leads to lager PLLA fiber diameter; and (iii) the migration of PLLA component from the core to the surface of electrospun fibers takes place during the fiber formation process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication of PLA/PEG/MWCNT electrospun nanofibrous scaffolds for anticancer drug delivery

In the present study, polylactic acid (PLA)/polyethylene glycol (PEG)/multiwalled carbon nanotube (MWCNT) electrospun nanofibrous scaffolds were prepared via electrospinning process and their applications for the anticancer drug delivery system were investigated. A response surface methodology based on Box–Behnken design (BBD) was used to evaluate the effect of key parameters of electrospinning process including solution concentration, feeding rate, tip–collector distance (TCD) and applied voltage on the morphology of PLA/PEG/MWCNT nanofibrous scaffolds. In optimum conditions (concentration of 8.15%, feeding rate of 0.2 mL/h, voltage of 18.50 kV and TCD of 13.0 cm), the minimum experimental fiber diameter was found to be 225 nm which was in good agreement with the predicted value by the BBD analysis (228 nm). In vitro drug release study of doxorubicin (DOX)‐loaded nanofibrous scaffolds, higher drug content induced an extended release of drug. Also, drug release rate was not dependent on drug/polymer ratio in different electrospun nanofibrous formulations. The equation of M_t = c₀ + kt^0.5was used to describe the kinetic data of DOX release from electrospun nanofibers. The cell viability of DOX‐loaded nanofibrous scaffolds was evaluated using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide, a tetrazole assay on lung cancer A549 cell lines. We propose that DOX‐incorporated PLA/PEG/MWCNT nanofibrous scaffold could be used as a superior candidate for antitumor drug delivery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41286.     

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