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As an aromatic polymer in nature, lignin has recently attracted gross attention because of its advantages of high carbon content, low cost and bio-renewability. However, most lignin is directly burnt for power generation to satisfy the energy demand of the pulp mills. As a result, only a handful of isolated lignin is used as a raw material. Thus, increasing value addition on lignin to expand its scope of applications is currently a challenge demanding immediate attention. Many efforts have been made in the valorization of lignin, including the preparation of precursors for carbon fibers. However, its complex structure and diversity significantly restrict the spinnability of lignin. In this review, we provide elaborate knowledge on the preparation of lignin-based carbon fibers ranging from the relationships among chemical structures, formation conditions and properties of fibers, to their potential applications. Specifically, control procedures for different spinning methods of lignin, including melt spinning, solution spinning and electrospinning, together with stabilization and carbonization are deeply discussed to provide an overall understanding towards the formation of lignin-based carbon fibers. We also offer perspectives on the challenges and new directions for future development of lignin-based carbon fibers.

Commercial synthetic fibers of below 10μm in diameter are usually unachievable with conventional melt spinning technology using high molecular weight polymers as the starting materials. The electrospinning process is capable of nanoscale fiber forming but is usually accompanied by the use of 80-90 wt% organic solvents, which greatly reduces the fiber yield and increases process cost as well as causing environmental concerns. We describe herein an approach using the caprolactam monomer as the main starting material for reactive anionic polymerization, propagating the degree of polymerization to achieve suitable melt viscosity for drawing into ultra-fine fibers by the electrostatic field force. The process temperature was well below that of the Nylon 6 melting point. We demonstrate that through this low energy consumption integrated process, essentially all monomers can be transformed into the final Nylon-6 micro/nano fiber assemblies which was unattainable from prior industrial or research processes.

We report the structural transformations of carbon via the melt spinning and subsequent annealing of nickel-carbon alloys. We attained metastable solid solubility of carbon in nickel ribbon by achieving a rapid solidification rate of up to 1.6 × 106 K/s. Excess carbon atoms were found to be dissolved in the nickel lattice causing up to 1.4% strain for an alloy spun at 70 m/s tangential wheel speeds. High temperature heat treatments led to precipitation of carbon from the nickel lattice on the ribbon free surfaces but also led to growth of spherical precipitates within the nickel matrix, an effect consistent with bulk diffusion-driven Ostwald ripening. Carbon was excavated from the ribbons via chemical dissolution of the metal and characterized by electron microscopy and Raman spectroscopy. We found that the microstructure of carbon precipitated from the rapidly quenched ribbon could be tuned by varying the carbon content from 4 to 12 at. % in the precursor and annealing the ribbon at temperatures that ranged from 400 to 1200 °C. Via the step-wise variation of these two parameters, we sequentially transformed amorphous carbon nanospheres with a high BET surface area of 203 m2/g into thick, highly crystalline flakes of graphite that conformed to the shape of the as-spun ribbon.

In the present work, fibers based on heat-resistant amorphous polyimide brand Ultem-1000 were prepared by melt extrusion. Vapor-grown carbon nanofibers (VGCFs) and single-wall carbon nanotubes (SWCNTs) were used to increase the mechanical characteristics of the polymer fibers. The fibers were characterized by scanning electron microscopy (SEM), thermophysical and mechanical tensile analysis. SEM study revealed very good distribution of the carbon nanofillers throughout the polyimide fiber volume. The mechanical testing of the unoriented nanocomposite fibers showed that the introduction of VGCFs or SWCNTs led to an increase in tensile strength and modulus. High-temperature drawing allows obtaining polyimide nanocomposite fibers with significantly increased mechanical properties (»300 MPa for strength and »4.6 GPa for modulus).

Polyethylene glycol (PEG) and glycerol were tested as melt assistants to enhance the melt processability of poly(acrylonitrile-co-1-vinyl imidazole) (co-PAN). The effects of the melt assistants on the molecular mobility of co-PAN were investigated through molecular dynamics (MD) simulations, and the specific volume changes with temperature were analyzed to evaluate the efficiency of the melt assistants theoretically. The MD results demonstrated that both PEG and glycerol increase the specific volume of co-PAN compared to pristine co-PAN. However, the effects of PEG in terms of increasing the specific volume and mobility of co-PAN were superior to those of glycerol. These findings were verified by variations in the shear viscosity of the co-PAN. Spinnability was improved significantly for co-PAN/PEG, and a more uniform co-PAN melt-spun filament could be obtained compared to co-PAN/glycerol. Thus, PEG200 is the best melt assistant for co-PAN, and 15% (w/w) is the optimal content for the melt-spinning of co-PAN.

Given the superior thermal stability and electromagnetic features, continuous Si–B–(C)–N ceramic fibers have displayed great potential to fulfill the increasing demand for the high-temperature structural and functional materials. Manufacture of such ceramic fibers depends heavily upon the design of processable polymer precursors. Herein, a class of polyborosilazanes (PBSZs) with high spinnability were created through a facile one-pot synthesis. The trade-off between spinnability and ceramic yield of PBSZs was overcome by using heptamethyldisilazane and hexamethyldisilazane as the co-condensing agents to polymerize silicon and boron chloride monomers. The optimal PBSZs can fabricate continuous Si–B–C–N fibers with homogeneous diameter of 7.9 ± 0.5 μm and high ceramic yield of 80 wt%. Experimental characterization and quantum chemical computation revealed the mechanistic pictures of the impact of pendant groups on the polycondensation, melt spinning, and pyrolyzing process. These insights improve our understanding of spinnable pre-ceramic polymers for exploiting high-performance nitride ceramic fibers.

The opaque polyethylene terephthalate (PET) filaments with different mass fractions of TiO2 particles were prepared by low-speed melt spinning and drafting. Basic structures including surface morphology, linear density, orientation degree and crystallinity, and properties including tensile and optical property of the PET/TiO2 filaments were systematically analyzed, especially the visual shielding property. The results showed that TiO2 particles were well-distributed on the filament surface without obvious aggregation, except when the mass fraction of TiO2 exceeded 6%. The addition of TiO2 increased the linear density of the PET filaments. The orientation degree of the filaments was positively correlated with the drafting ratio but hardly influenced by the mass fraction of TiO2. The crystallinity achieved the maximum when the mass fraction of TiO2 was 3% and then decreased gradually. The tenacity of the filaments reduced and the elongation at break enhanced initially and then decreased with the increasing TiO2 content. The opaque effect of the PET filaments improved significantly when the mass fraction of TiO2 was less than 6%, whereas the improvement of the opaque effect slowed down as the mass fraction of TiO2 increased further.

In this study, nanoscale composite SiC-ZrC ceramic fibres, derived from polyzirconocenecarbosilane (PZCS) via melt spinning, electron beam crosslinking, pyrolysis and sintering were investigated in detail. Compared with several commercial products of second-generation SiC fibres, the produced composite fibres exhibit improved thermal stability, mechanical properties and oxidation resistance. SiC grains in the fibre grew from 9.8 nm to 33.9 nm after annealing in an inert atmosphere at 1800 °C for 1 h, as well as decomposition of the SiCxOy phase and the growth of SiC grains affected the mechanical properties of the fibres, and the mechanical properties of the fibres were maintained at 1.1 GPa, accompanied by an increase in the modulus. After the fibres were oxidized at 1100∼1400 °C for 1 h, a dense oxide layer of SiO2-ZrO2 was formed on the surface of the fibres, which slowed down the rate of further fibre oxidation, thus, the fibres exhibited excellent oxidation resistance.

The poor compatibility between a Fe2O3 pigment and a blend of ultrahigh molecular weight polyethylene (UHMWPE)/polyolefin (PO) can result in low spinnability and poor mechanical properties of the resulting fiber. This study modifies the surface of a Fe2O3 pigment with a titanate coupling agent for dope dyeing melt-spun UHMWPE fiber. The effects of the coupling agent dose, reaction temperature and reaction time on the surface properties of the pigments are investigated. In addition, the characteristics of the UHMWPE blend and colored fibers (by dope dyeing with modified and unmodified Fe2O3 pigments) are compared. Notably, 3 wt.% coupling agent in regard to the pigments mass, a coupling agent to toluene mass ratio of 1:5, a reaction time of 30 min, and a reaction temperature of 80 °C achieve the optimal results, which are a 48.4 % lipophilic degree of the modified pigment, a zeta potential of 48.4 mV, and a contact angle of 144.3°. Moreover, SEM images and torque results of the blend melt show that the compatibility between the Fe2O3 pigment and UHMWPE/PO blend is significantly enhanced. With an increasing pigment content, the mechanical properties of the colored fibers decrease, and the K/S values of the colored fibers increase.

We have demonstrated two processes for the synthesis of zinc antimonide powder using rapid melt cooling: melt spinning and cooling in a liquid. The elemental and phase compositions and surface morphology of hot-pressed undoped and 3 wt % In-doped β-Zn4Sb3 samples have been studied by scanning electron microscopy, X-ray diffraction, and optical microscopy, and their Seebeck coefficient, electrical conductivity, and thermal conductivity have been measured in the range 300–700 K. Indium doping has been shown to reduce the lattice thermal conductivity of the material by a factor of 1.5. The 600-K thermoelectric figure of merit of the undoped sample (ZT = 0.8) is half that of the doped sample (ZT = 1.5). We have assessed the effect of thermal cycling in the range 300–700 K on the Seebeck coefficient and electrical conductivity of the samples.

Spinning technology using melt extrusion and spin-draw processes transforms polymeric materials into highly oriented, crystallized polymeric fibers. Thermoplastic isotactic polypropylene compound with ground CaCO3 (GCC) and precipitate CaCO3 (PCC) with stearic acid surface coating treatment was used in this study. This product was developed in masterbatch form, which contained 70% GCC in resin and 50% PCC in resin. The resulting (masterbatch pellets) polymer can be spun into fibers through a single-screw extruder. Surface and cross-sectional images of fibers were captured by optical microscopy and scanning electronic microscopy for identifying the organic/inorganic interface of fibers. The melt-spun fibers have a distinctive morphology, the particles impact on spinnability, and productivity in the spunbond will alter the mechanical property, thermal property and optical property of fiber-based products. Processing parameters, including spinning speed, throughput rate and take-up roll velocity, were systematically study to understand the structure formation. Meanwhile, different loading concentrations are applied for varied factor comparison of particle size and shape. The Weibull distribution model is applied for determining the tensile property of fibers containing high GCC dosages of 20–40%. Meanwhile, a few more steps of gauge length are utilized for studying the probability of a weak link in polymer materials. Through a systematic discussion of the GCC and PCC comparison study in changing fiber properties, the impact of the particle size on agglomeration formation is emphasized, as well as the breaking mechanism of fibers.

The process of organoyttriumoxanealumoxanes co-condensation with chromium acetylacetonate has been studied, as a result chromium-containing organoyttriumoxanealumoxanes were obtained, which are ceramic-forming oligomers and may have fiber-forming properties. Their physicochemical characteristics have been determined by NMR, IR spectroscopy, SEM, TGA, XRD and elemental analysis. It has been found that when the molar ratio of chromium-containing organoyttriumoxanealumoxanes is Al/Y ≈ 2 and Al/Cr ≈ 180 they have fiber-forming properties. Polymer fibers were produced from chromium-containing organoyttriumoxanealumoxanes by melt spinning. The process of thermochemical transformation of synthesized chromium-containing organoyttriumoxanealumoxanes into the ceramic phase has been studied. It is found out that the pyrolysis of chromium-containing organoyttriumoxanealumoxanes leads to the formation of Y3(CrxAl1−x)5O12, YAlyCr1-yO3 and α-(Al2−xCrxO3). That is, these oligomers can be used to create a new generation of heatresistant, optically-transparent, corrosion—and radiation-resistant multicomponent ceramics based on aluminum, yttrium and chromium oxides.

A solvent-free and easy method to directly functionalize pristine graphene by maleic anhydride (MA) based on Diels-Alder cycloaddition reaction was reported. Functionalized graphene/Polyamide 66 (F...

Masterbatches of polyphenylene sulfide (PPS)/organic montmorillonite (MMT) composites were produced via melt blending. A self-made spinning equipment was then used to produce the PPS/organic MMT composite fibers by melt spinning directly from the masterbatches. X-ray diffractometer and transmission electron microscope were used to examine the dispersibility of organic MMT. The morphology, tensile property, crystallization behavior, and oxidative stability of PPS fibers were investigated. The results indicated that organic MMT could be uniformly distributed in the PPS matrix to form a mixed dispersion of intercalated and exfoliated structure and influence the longitudinal surface morphology of fibers to become rough. The roughness of composite fibers surface was proportional to the content of organic MMT. The organic MMT nanolayers could act as the heterogeneous nucleating agents to improve the crystallization, and the crystallity of composite fibers increased with the increase of organic MMT content. The breaking strength of composite fibers first increased and then decreased by increasing the amount of organic MMT. After the oxidation treatment, the breaking strength of neat PPS fibers and composite fibers declined, but the degree of breaking strength loss for composite fibers is lower than that of neat PPS fibers. The dynamic oxidation induction temperature of composite fibers also showed a significant increase by adding organic MMT. Moreover, the addition of organic MMT could limit the chemical combination of element sulfur and oxygen, retard the generation of sulfoxide groups, and induce the conversion of sulfur atoms from C-S bond to sulfone for improving oxidative stability.

The effect of phosphorus and carbon on crystallization and magnetic properties of iron-based soft magnetic amorphous alloy containing up to 22 at.% B is studied. Ribbons with compositions FeaSi6B22PbCcNb0.85Cu0.65 (a = 68, 66, 64 and 62; b = 2.5, 1.5, 1.25 and 1; c = 0, 3, 2.25 and 7.5) are fabricated by melt spinning. Crystallization of the alloy under heating and its properties are studied by x-ray diffractometry, differential scanning calorimetry, and vibrating sample magnetometry. The composition and the heat treatment of the alloy with the best soft magnetic properties are determined.

In the present study, poly(ethylene terephthalate)-clay nanocomposite multifilament yarns were prepared using two commercial and four nanoclays synthesized from Resadiye Na-montmorillonite (Na-MMT). Two type multifilament yarns, i.e., fully drawn yarn (FDY) and partially oriented yarn (POY), were melt spun. The FDY yarns were prepared using pilot type Buschaert SpinBoy II CC melt spinning machine with a masterbatch feeding ratio of 4–5% in order to meet industrial machine requirements. The POY spinning was made on the Barmag industrial machine, and the POY yarn was subsequently texturized. All multifilament yarns were prepared via the masterbatch approach, similarly used for the preparation of colored dope dyed yarns. The mechanical properties, flame retardancy, thermal stability, and morphology of produced yarns on melt spinning experiments were analyzed and discussed along with the effect of nanoclay properties such as thermal stability, polymer-clay compatibility, and particle size distribution.

In this study, polypropylene (PP) and polypropylene/nanoclay composite multifilament yarns with different nanoclay contents were prepared by melt spinning. The knitted fabrics were then made from these yarns and subjected to oxygen plasma treatment for 5 min. The samples were dyed with a disperse dye and an acid dye and the color strength, color coordinates, and fastness properties of the dyed samples were compared. The effect of plasma treatment on the surface chemistry and morphology of the samples was evaluated using Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) analyses, respectively. FTIR analysis confirmed the introduction of oxygen-containing groups on the surface of the plasma-treated samples. AFM images confirmed etching of the fibers, and the surface roughness of the fibers increased significantly after plasma treatment. The incorporation of nanoclay in the multifilament yarns improved the dyeability of the polypropylene/nanoclay composite fibers with disperse and acid dyes. The optimum amount of the nanoclay for obtaining the highest color strength was 2 wt% and 1 wt%, for dyeing with the disperse and acid dye, respectively. Plasma treatment enhanced the dyeability and fastness properties of the fibers. The highest K/S values obtained on plasma-treated PP/nanoclay samples were 1.27 and 10.88 for acid and disperse dyes, respectively. The fastness properties of the samples dyed with the acid dye were generally lower than those of dyed with the disperse dye. The highest washing, dry rubbing, and light fastness properties were obtained on plasma-treated and disperse-dyed PP/nanoclay (2 %) sample, which were 4–5, 3, and 5, respectively.

The hygroscopic and dyeable polyphenylene sulfide (PPS) composite fiber was prepared using a twin-screw extruder and a melt spinning machine. A new dyeing process was proposed and the moisture absorption and dyeing mechanism of the composite fiber was analyzed. The results show that sodium polyacrylate (PAAS) is uniformly dispersed in the PPS matrix and is compatible with PPS at the macromolecular level. The thermal properties of the composite fibers are basically unchanged, and the crystallinity is slightly reduced. With the increase of PAAS content, the normal moisture regain of the composite fiber reached 2.11 % from 0.21 %, and the contact angle decreased from 73.8 ° to 52.3 °. Under the new dyeing technology, the dyeing rate of the composite fiber reached 93 %, and the washing fastness was grade 5. The mechanism of hygroscopicity and dyeing of macromolecular space networks and polyelectrolyte was proposed.

Modification of the rheological and thermal properties of polypropylene (PP) was accomplished through the in-situ generation of PP/poly(trimethylene terephthalate) (PTT) nanocomposites fibrils cont...

The investigation of polypropylene (PP)/clay nanocomposites has received considerable scientific and technological attention during the last decades due to their good mechanical and barrier properties. In the present article, the effects of adding Cloisite15A (C15A) nanoclay in polypropylene (PP) were investigated. PP nanocomposites were prepared by a direct melt mixing method. For better dispersion of C15A, 30 wt% of nanoclay masterbatch was first prepared by melt mixing of PP matrix and acrylic acid grafted PP oligomer (PP- g-AA) in a compounder, before being used to produce nanocomposites with 2 and 5 wt% of C15A. The aim of this work was to used nanoclay filled nanocomposites with suitable properties for cable application like good flame-retardant property; improve dye-ability and resilience of polypropylene. The XRD results indicated an intercalated layer structure for nanocomposites, The SEM examination showed satisfactory dispersion of nanoclay in 2 wt% of C15A and some degree of agglomeration in 5 wt% of C15A. DSC analysis indicated that C15A acts as a nucleating agent and increases crystallinity in the nanocomposite. TGA showed with increasing nanoclay, heat resistance was improved and degradation temperatures increased. Limiting oxygen index (LOI) tests showed increased flame retardancy from 25% for neat polypropylene t0 32.2% for nanocomposites of 5 wt% of C15A. The tensile modulus was improved from 423 MPa for neat polypropylene to 474 MPa for nanocomposites with 5 wt% of C15A. This result indicates that increasing C15A content had a suitable effect on the tensile properties. Melt spinning investigation on low oriented yarn (LOY), draw textured yarn (DTY), and fully drawn yarn (FDY) of 2 wt% C15A nanocomposite showed a reduction of linear density for FDY and an increase of the shrinkage. Furthermore, the obtained results for the improvement of dye-ability and compression resilience showed that PP/C15A is appropriate for textile products.

We studied the microstructure and the thermoelectric properties of the materials based on p-type germanium telluride doped with copper and bismuth and obtained by hot pressing of three type powders prepared by ingot grinding in a planetary mill, their sizes being from hundreds of microns (0.315-mm cell) to hundreds of nanometers (mechanical activation) and by melt spinning. We studied the microstructure, the chips and the composition of the samples by optical and scanning electron microscopy. By the diffractometric and the micro X-ray phase analyses, we revealed the presence of copper oxide and germanium precipitation in the samples. The samples obtained from the powder prepared by the mechanical activation had the largest number of grains with the sizes less than units of microns. We measured the following thermoelectric parameters of the materials: the Seebeck coefficient and the specific electrical and thermal conductivity within the temperature range of 300–800 K. We calculated the coefficient of thermoelectric efficiency ZT; the hot-pressed samples obtained from the powders produced by the melt spinning had the highest value: ZT = 1.5 at 600 K.

X-ray amorphous ribbons of aluminum-based alloys doped with transition (Ni, Fe) and rare earth (La) metals in various ratios were obtained by melt spinning. The mechanical characteristics and fracture surfaces of the ribbons under conditions of uniaxial tension with speeds from 0.01 to 10 mm/min were studied. It was shown that, with an increase in the rate in all investigated alloys, the strength limit increases and low plasticity remains. Inhomogeneous deformation is realized by the initiation and spread of shear bands. The mixed fracture surface indicates a brittle-viscous fracture with a high ratio of the viscous component. A significant influence of the scale factor on the strength characteristics of the ribbons was confirmed. The tensile strength of the ribbons increases with rising iron content and decreasing nickel content when the influence of the scale factor is excluded. It is experimentally shown on ribbons with a low-melting tin coating that local heating in shear bands reaches the melting point of tin of 231.9°C.

Melt spinning of special chips of poly(butylene terephthalate)-block-(tetramethylene oxide) was studied. The obtained fiber possesses rubber-like elasticity at room temperature. The basic properties of this elastomer fiber are fineness 1.7 dtex, tensile strength 3.35 cN/dtex, breaking extension 68%, and elastic recovery >95% at 15% elongation. A new type of elastomer staple fiber of this block-copolymer is successfully fabricated by a traditional production line for melt spinning.

Development of novel antibacterial fibers with mass production is urgently required in the technical textiles industry. In this paper, a series of segmented-pie composite microfibers based on polyamide 6 (PA6) and different amounts of copper–carbon nanoparticles (CuCNPs) were fabricated by utilizing a melt-spinning apparatus with twin-screw extruders. The encapsulation of CuCNPs and the formation of segmented-pie structure of as-prepared PA6/CuCNP microfibers were confirmed. The CuCNPs or their agglomeration with an average diameter of approximately 200 nm exhibited a uniform distribution in PA6/CuCNP segmented-pie microfibers. Compared with the pure PA6 microfibers, the PA6/CuCNP segmented-pie microfibers showed obviously enhanced crystallinity, thermal stability as well as UV resistance. As the CuCNP content increased to 1.0 wt%, the tensile strength and initial modulus increased to 3.79 cN/dtex and 22.4 cN/dtex, respectively. Importantly, the PA6/CuCNP segmented-pie microfibers presented excellent antimicrobial activities to both Escherichia coli and Staphylococcus aureus (antimicrobial efficiency around 99%) and great antifungal activity to Candida albicans (antimicrobial efficiency around 82%). Taken together, our present study demonstrated that the PA6/CuCNP segmented-pie microfibers show great prospects in the fabrication of technical textiles for healthcare applications.

Melt spinning is the most extensively used method of fabricating polymeric fibers in the textile industry. This series of studies aimed to construct an automatic abnormality diagnosis system for polypropylene (PP) as-spun fiber produced by the melt spinning process. Part I of this study aimed to construct the processing parameter optimization for the PP as-spun fiber produced by the melt spinning machine. The product quality resulting from the processing parameters of the melt spinning process included six control factors: extruder temperature, gear pump temperature, die-head temperature, rotational speed of extruder, rotational speed of gear pump, and take-up speed. The quality characteristics included fiber fineness, breaking strength, breaking elongation, and modulus of resilience. The quality data were derived from the experiments, the design of which were based on the orthogonal array of the Taguchi method in order to calculate the signal-to-noise ratio, analysis of variance, and confidence interval. Principal component analysis was then applied to eliminate the multi-correlation of the output responses and transform the correlated responses into principal components, to obtain multi-quality optimum processing parameters. These optimum parameters, including the extruder temperature (180°C), gear pump temperature (220°C), die-head temperature (240°C), the rotational speed of the extruder (7.5 rpm), the rotational speed of the gear pump (15 rpm), and take-up speed (700 rpm) would later be used to build a prediction of an abnormality diagnosis system for identification of fault processing parameters in a melt spinning machine in Part II of this study.

A reversible confinement of ionic liquid (IL) among the amide segments has been carried out for the preparation of high-modulus and high-strength aliphatic semicrystalline nylon 6 fibers. In this research work, the suppression or the weakening of the hydrogen bonds during the conventional low-speed melt spinning process is followed by a hot-drawing stage and a subsequent IL extraction of the IL out of the 2% wt IL-confined fibers and an immediate thermal stabilization process for the improvement of the properties of the pristine nylon 6 fibers. The resulted crystal structural developments of the IL-confined fibers are attributed to ultimate molecular orientations, which have contributed to the developments of the overall fiber properties. Here, the influences of the IL on the γ and the α crystal phases, the γ-α transition, the morphological properties, and the tensile properties are investigated. The FTIR reported, experimentally, additional peaks at 1237 cm–1 for the γ crystal phase and at 1417 and 1476 cm–1 for the α crystal phase, in conformity with the theoretical computations. The XRD demonstrated that the conventional low-speed melt spinning can successfully be used to prepare as-spun IL-confined fibers having highly improved properties. The so prepared as-spun IL-confined fibers are found to have a γ phase structure that has a small crystal size and high crystal perfections. Fortunately, the γ-to-α crystal phase transition for the IL-confined nylon 6 fibers can be acquired during the hot-drawing stage (stress-induced phase transformation). Furthermore, the IL extraction process followed by a thermal stabilization process, interestingly, has led to significant increases in both of the tensile strengths and the tensile moduli of the reverted nylon 6 fibers. The values that are found are 8.46 cN/dtex for the tensile strength and 39.09 cN/dtex for the tensile modulus. The structure–property relationships between the IL-confined and the reverted nylon 6 fibers have also been discussed.

The development of an excellent, bioabsorbable hemostatic material for deep wound remains a challenge. In this work, a biodegradable cotton-like biomimetic fibrous mat of poly (l-lactic acid) (PLLA) was made by melt spinning. Subsequently, SD composite was prepared by cross-linking sodium alginate (SA) with dopamine (DA). It was immobilized on the fibre surface, which inspired by mussel byssus. Finally, Fe3+ was loaded onto the 0.5SD/PLLA composite by chelation with the carboxyl of alginate and phenolic hydroxy of dopamine. The haemostasis experiment found that the hemostatic time 47 s in vitro. However, the bleeding volume was 0.097 g and hemostatic time was 23 s when 20Fe3+-0.5SD/PLLA was applied in the haemostasis of the rat liver. As a result of its robust hydrophilicity and bouffant cotton-like structure, it could absorb a large water from blood, which could concentrate the component of blood and reduce the clotting time. Furthermore, the addition of Fe3+ in the 0.5SD/PLLA had a significant effect on improve hemostatic property. It also displayed excellent antibacterial property for Escherichia coli and Staphylococcus aureus. Notably, it possesses superior hemocompatibility, cytocompatibility and histocompatibility. Hence, 20Fe3+-0.5SD/PLLA has high potential application in haemostasis for clinical settings due to its outstanding properties., Graphical abstract Image 1, Highlights • Biodegradable cotton-like PLLA fibrous mat with bouffant structure as hemostasis skeleton was reported. • Fe3+-0.5SD/PLLA composite was prepared through SD immobilized on the fiber surface and Fe3+ coordination with carboxyl of SA. • Fe3+-0.5SD/PLLA displayed excellent haemostatic performance in vitro and vivo with the synergistic effect between SD and Fe3+. • Fe3+-0.5SD/PLLA possessed excellent antibacterial activity, hemocompatibility, cytocompatibility and histocompatibility.

A polymer based bag filter with high temperature resistance plays a key role in dust and acid gas treatment in the power industry. Currently, the polymers used for preparing filters with improved heat resistance include those with a high content of aromatic units. But the aromatic structure inevitably leads to a high melting point, which is disadvantageous for melt spinning. Here, we report a polyamide 66 and polyamide 6T copolymer (PA66-co-PA6T) fiber with both high thermal stability and good spinnability. The retention rates of heat resistance of fibers after heat treatment at 185 °C and 200 °C were higher than 97.8% and 88.4%, respectively. This high thermal stability is ascribed to the high thermal degradation activation energy (E), which was confirmed by DSC, TG, and XRD characterization studies and fitting of kinetic data. PA66-co-PA6T with good melt spinnability, high heat resistance strength and low cost is expected to be applied in high-temperature resistance filtration equipment such as bag filters, expanding the application range of PA66 materials.

The development of reprocessable and healable room temperature photoactuators from a main-chain azobenzene (azo) liquid crystalline poly(ester-urea) (PEU) is described for the first time. The azo PEU was prepared via Michael addition polymerization of an ester and urea unit-containing azo monomer with both acrylate and methacrylate end-groups and 1,2-ethanedithiol. It showed high thermal stability, low glass transition temperature, a broad range of a smectic liquid crystalline phase, reversible photoresponsivity, and dynamic hydrogen bonding interactions among urea groups. Its well-oriented fibers and films were prepared via the melt spinning method and special melt pressing approach, respectively, whose azo mesogenic alignment was along the fiber axes and homeotropic to the film surfaces, respectively. The fibers showed highly reversible UV light-induced bending (toward the light source) and visible light-induced unbending, whereas the films exhibited rapid and reversible bending (away from the light source) under UV irradiation alone together with the spontaneous quick unbending upon turning off the UV light (both at room temperature). The reasons for the special photomobile behaviors of the azo PEU films and the decisive role of the urea unit-induced physical crosslinking in their photomobility were disclosed. The successful fabrication of a remotely controlled electric circuit by using a photodeformable azo PEU film (with attached filter paper slips soaked with aqueous NaCl solution) as a photoswitch as well as the high reprocessability and healability of the azo PEU actuators was also demonstrated. Such a multifunctional main-chain azo PEU with good film-forming ability, room temperature photomobility, high reprocessability and healability holds much promise in various photoactuating applications.

The anion exchange membrane (AEM) in fuel cells requires new, stable, and improved electrocatalysts for large scale commercial production of hydrogen fuel for efficient energy conversion. Fe40Ni20Co20P15C5, a novel metallic glass ribbon, was prepared by arc melting and melt spinning method. The metallic glass was evaluated as an efficient electrocatalyst in water-splitting reactions, namely hydrogen evolution reaction under acidic and alkaline conditions. In addition, oxygen evolution reaction in alkaline medium was also evaluated. In 0.5 M H2SO4, the metallic glass ribbons, after electrochemical dealloying, needed an overpotential of 128 mV for hydrogen evolution reaction, while in 1 M KOH they needed an overpotential of 236 mV for hydrogen evolution. For the oxygen evolution reaction, the overpotential was 278 mV. The electrochemical dealloying procedure significantly reduced the overpotential, and the overpotential remained constant over 20 hours of test conditions under acidic and alkaline conditions. The improved electrocatalytic activity was explained based on the metastable nature of metallic glass and the synergistic effect of metal hydroxo species and phosphates. Based on the excellent properties and free-standing nature of these metallic glass ribbons in electrolyte medium, we propose the current metallic glass for commercial, industrial electrocatalytic applications.

To further explore the application feasibility of Zr2Co alloy in tritium-related fields, hydrogenation/dehydrogenation properties of this material of crystalline or amorphous structure, prepared by arc melting or melt spinning, were studied by pressure-composition temperature measurement, X-ray diffraction, differential scanning calorimeter, thermal desorption spectroscopy. It was found that the two kinds of Zr2Co alloys can absorb hydrogen in a close full concentration of ~9 mmol/g, and may have similar equilibrium hydrogen pressure in the order of 10−6 Pa at room temperature. In their hydrogenated samples various hydrides were observed to form, including ZrH2, Zr2CoH5, ZrCoH3 and an amorphous one with gradually decreasing general thermostability. The amorphous alloy exhibited easier hydrogen induced disproportionation caused by highly stable ZrH2 and much slower hydrogen absorption kinetics. This disproportionation behavior of the crystalline alloy was found to be entirely suppressed by changing heating process. The results firmly indicate that crystalline Zr2Co alloy could be more favorable for tritium treatment due to very low equilibrium pressure and the feasibility of eliminating the disproportionation.

Polyhydroxyalkanoates (PHAs), also known as bacterial polyesters, are considered novel polymers for fabricating biomedical products, such as sutures and hernia meshes, because of their biocompatibility and slow biodegradability. Poly-4-hydroxybutyrate (P4HB) is a commonly used PHA that was explored in this study as an absorbable biomaterial for several medical applications, including controlled drug delivery. Currently, P4HB is melt spun and drawn into filaments at high processing temperatures (~200°C), precluding the incorporation of thermally sensitive drugs within the polymer during melt spinning. Post-spinning drug incorporation can potentially cause nonuniform drug absorption that leads to an uneven release profile. This raises the need for a low temperature spinning process for these polymers. Until now, there has been no defined procedure to produce P4HB fibers through a low temperature solution spinning process. This study focuses on determining suitable wet spinning conditions to form continuous P4HB fibers. After several preliminary tests, it was found that a chloroform-based spin dope with 10-15% polymer concentration facilitated the extrusion of continuous stretchable fibers into a coagulation bath containing reagent alcohol. Subsequently, several P4HB fibers were spun with various spin dope concentrations, coagulation bath temperatures, and spin draw ratios to assess their effect on fiber structure and properties.

We prepared Fe80Si8B6Nb5Cu amorphous-nanocrystalline strips with different phosphorus addition by the melt spinning method, and their nanocrystalline magnetic powder core was obtained after a series of processing. Then, the microstructure, micromorphology, thermal behavior, and magnetic properties were studied. The results show that the atomic radius difference (σ) affected the glass formation ability; thus, first, the grain size and coercivity decreased and then increased. The (Fe80Si8B6Nb5Cu)99P nanocrystalline core has the better comprehensive magnetic properties than those of Fe80Si8B6Nb5Cu; its μe (75.93) is 5% higher, and Pcm (370 W/kg) is 14% lower than those of Fe80Si8B6Nb5Cu (i.e., 72.98 and 431.2 W/kg, respectively).

Rare earth permanent magnets are essential components in many fields of technology due to their excellent magnetic properties. There are some techniques used in the manufacture of permanent rare earth magnets: the powder metallurgy to obtain anisotropic HD sintered permanent magnets and the melt spinning and HDDR processes to obtain isotropic and anisotropic bonded permanent magnets. In this work, the influence of the melt spinning parameters on the microstructural and magnetic properties of the Pr14FebalCo16B6 alloy was studied. The alloy was melted and rapidly cooled at 9.9 x 105°C/s. The parameters used in the process were: wheel speed of 15 m/s and 20 m/s and ejection pressure of 25.3 kPa and 50.7 kPa. Ribbons and/or flakes of 30 μm thickness and width until 5 mm were obtained. Results show that the melt spinning alloys are nanocrystalline and that the parameters of the process influence the microstructure and their magnetic properties. Mean crystallite size up to 38.5 nm and intrinsic coercivity (iHc) up to 254 kA/m were obtained.

Various types of conjugate fibers comprised of polylactide (PLA) and polyethylene terephthalate (PET), with their blend in the sheath, PET as the core, were produced by high-speed melt-spinning. Du...

This article investigates melt spinning of polypropylene (PP) with high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) blend fibers at different compositions, as well as the effects of HDPE and LLDPE on the bonding ability of blend fibers in thermal bonding process at different temperatures have been studied. HDPE and LLDPE were added to PP at 3, 5, 7, and 10 wt% to measure the upper threshold of such blends. While HDPE was added up to 7 wt%, PP/LLDPE blend fibers were only spun up to 3 wt% of LLDPE. Differential scanning calorimetry (DSC) revealed that increasing both HDPE and LLDPE contents lead to higher crystallinity values due to polyethylenes nucleating effect on PP. By adding HDPE and LLDPE, the tensile strength of blend fibers before and after bonding was decreased drastically compared to pure PP fibers. On the other hand, the addition of HDPE to PP and increasing bonding temperature enhanced bonding strength.

We have worked out conditions for the preparation of microcrystalline n-type lead telluride-based materials doped with lead iodide and investigated their microstructure and thermoelectric properties. The materials were prepared by hot-pressing powders produced by grinding an ingot to a particle size on the order of hundreds of microns in a planetary mill and to a particle size under hundreds of nanometers (mechanical activation) and by melt spinning. Fracture surfaces of the hot-pressed samples were examined on an optical and a scanning electron microscope. All of the samples had a nonuniform microstructure, with both small and larger grains present. In the samples prepared from the powders produced by mechanical activation, nanograins were detected. We have measured the Seebeck coefficient, electrical conductivity, and thermal conductivity of the samples at room temperature and in the range 300–800 K and evaluated their lattice thermal conductivity and thermoelectric figure of merit, ZT. Their lattice thermal conductivity was shown to decrease with decreasing grain size. The highest thermoelectric figure of merit, (ZT)max = 1.32 at 630 K, was offered by the materials produced from the mechanically activated powder.

We have assessed the informativeness of X-ray diffraction patterns in the form of a halo, characteristic of metallic alloys prepared by liquid quenching (melt spinning) (using an Fe78P20Si2 alloy as an example) and oxide films grown on unheated substrates by ion beam sputtering of targets with an appropriate composition (LiNbO3 and Ca10(PO4)6(OH)2). Simulation results for X-ray diffraction patterns of expected crystalline phases with allowance for the size effect in diffraction demonstrate that a model halo agrees well with the halos observed in X-ray diffraction patterns of the samples under study. Observed correlations lead us to conclude that, inherent in rather large crystals, coherence of elastically scattered waves is lost in the structures considered here because of the random mutual orientation of crystalline nuclei of the corresponding phases with ultimately small dimensions. For this reason, translational symmetry, limited by the ultimately small dimensions of mutually misoriented crystallites, is the most transparent characteristic of the nature of such (quasi-amorphous) structures for systems with strong interatomic bonding.

Melt spinning has proven effective in maintaining chemical homogeneity and introducing multiscale microstructures that can reduce the lattice thermal conductivity and consequently enhance the thermoelectric performance of consolidated bulk materials. In this work, p-type Bi0.52Sb1.48Te3 bulk alloys are fabricated by melt spinning (MS) followed by subsequent plasma activated sintering (PAS). The influence of different MS atmospheres (air, Ar, N2, and He) on the morphologies of MS ribbons and the thermoelectric properties of MS-PAS bulk materials has been investigated systematically. Because of the relatively high thermal conductivity, a He atmosphere expedites the heat dissipation in the MS process and results in severe sublimation of tellurium and thus inferior thermoelectric performance. In contrast, an Ar atmosphere can essentially prevent heat loss of the fusant and suppress the sublimation of tellurium. Consequently, the corresponding Bi0.52Sb1.48Te3 sample (MS in Ar atmosphere) presents the highest peak ZT and average ZT values of 1.09 (at 340 K) and 0.81 (in 300-500 K), respectively. The average ZT of the sample prepared using an Ar atmosphere is almost three times the one prepared using a He atmosphere. This reflects the importance of using the appropriate atmosphere during the melt-spinning process. This result, which indicates that melt spinning in an Ar atmosphere is preferable to avoid heat loss, can also be extended to other materials.

Poly(ethylene terephthalate)/clay nanocomposite multifilament yarn was manufactured by conventional masterbatch approach. Poly(butylene terephthalate) was used as a carrier polymer in masterbatch steps. The masterbatches were diluted into pilot melt spinning machine and subsequently drawn with 2.65 ratios to prepare fully oriented yarn. The degree of dispersion in nanocomposite fibers was analyzed by X-ray diffractometry and scanning electron microscopy. Even though the addition of nanoclay reduced mechanical properties of nanocomposite fibers, dimensional stability could be improved at certain clay contents. The flammability properties were sufficiently improved, and no significant changes were observed with increasing clay content. The main novelty of this paper is the development of a proper approach for the selection of optimum carrier polymer for nanoclay in masterbatch preparation, as well as proper nanoclay for desired polymers. The acid-base approach is used in evaluating the surface free energy of commercial nanoclay and calculation the total interaction energies between polymer and clay surfaces. Such an approach gives adequate information about polymer-clay compatibility and provides a useful tool in the selection of optimum carrier polymer, as well as proper nanoclay for the desired polymer during masterbatch preparations.