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Design of experiments was adopted to evaluate the effect of selected test parameters on the viscoelastic behaviors of polyester tire cords through dynamic mechanical analysis systematically. Design of experiments results showed that temperature, static load, and dynamic amplitude had significant effects on the responses of complex modulus (E*) and Tan δ. Furthermore, temperature had significant interactions with static load and dynamic amplitude factors on the responses. None of the test parameters had any significant effect on the response of glass transition temperature (Tg). Below Tg, thermoplastic tire cords exhibited a high and constant dynamic modulus, whereas, beyond this point, the modulus decreased dramatically. The thermosetting tire cords exhibited a constant performance due to an ordered and tight molecular chain arrangement. The magnitude of Tan δ reached its peak value at Tg due to the increase in internal friction as a result of increasing temperature. The dynamic modulus increased and Tan δ decreased with the increasing static load as a result of restricting the mobility of chain segments. The reverse was true when the dynamic amplitude increased, most probably because of higher chain segment mobility and early stage of polymer chain slippage. Activation energy (Ea), derived from Arrhenius equation, can be used to predict its long-term performance. Tg shifted to a higher temperature as the frequency increased. In addition, by increasing the twist level of the polyester tire cord, the dynamic modulus decreased and Tan δ increased. Tg was evaluated as the upper limit working temperature, Tan δ was related to energy dissipation, and E* determined the overall performance of the tire cord. By displacing Tg to a higher temperature, reducing the magnitude of Tan δ and increasing the dynamic modulus are of great importance to a tire cord's performance. [ABSTRACT FROM AUTHOR]

Polyacrylonitrile-based pre-oxidized fibers with improved thermal stability, flame retardant, and mechanical properties were made from the pristine polyacrylonitrile fibers through chemical pretreatment followed by pre-oxidation in air. The morphological structure of the polyacrylonitrile-based pre-oxidized fibers was investigated by Fourier transfer infrared spectra, X-ray diffraction, scanning electron microscopy, and X-ray energy dispersive spectrometer. The changes of characteristic functional groups and chemical compositions confirmed the successful modification of the polyacrylonitrile fibers during pre-treatment. The grooves and cracks on the surface of polyacrylonitrile-based pre-oxidized fibers were remarkably decreased in comparison with that of pristine polyacrylonitrile fibers. The evolution of crystalline structure of the polyacrylonitrile fibers proved the occurrence of cyclization reactions during pre-oxidation. Meanwhile, thermal stability, flame retardant, and mechanical properties of polyacrylonitrile-based pre-oxidized fibers were also investigated by thermogravimetric analyzer, oxygen index meter, micro combustion calorimeter, and single fiber tensile tester, respectively. The results demonstrated that the polyacrylonitrile-based pre-oxidized fibers initially pre-treated by hydroxylamine hydrochloride, followed by monoethanolamine, had a high limiting oxygen index of 40.1 and breaking strength of 2.03 cN/dtex. The peak of heat release rate and total heat release of polyacrylonitrile-based pre-oxidized fibers decreased significantly while its charred residues increased, contributing to the improved flame retardant property. [ABSTRACT FROM AUTHOR]

Many efforts have been made to study new reinforced materials to meet the increasing demands of various products. Hybrid cords have attracted a great deal of attention due to low cost and incomparable properties. Nylon and polyester are currently two of the most prevalent materials used as tire cords, while how to incorporate both of their desirable properties into one cord has been a meaningful scientific research. In this study, a new advanced polyester tire cord was developed by adopting the design of experiment. Its stress-strain curve demonstrated a high modulus typical for the standard polyester thus improving tire dimensional stability and handling performance and high breaking elongation up to 21.7% that was a favorable characteristic of nylon cord creating a hybrid effect. H-adhesion experiment showed that this advanced cord had comparable adhesion to rubber as the standard polyester tire cord and could be used for production of tires. [ABSTRACT FROM AUTHOR]

In this paper, a hierarchical cylinders method is proposed to resolve penetration of yarns. The performance of the hierarchical cylinders method is accelerated by applying a spatial subdivision algorithm. The spatial subdivision algorithm refines the detected regions according to the properties of weft knitted fabric, which greatly reduce the calculation of collision detection. Based on the cuboid particle system, penalty contact forces act on the yarns with problematic penetration. Experimental results demonstrate that the proposed algorithm and method are efficient for weft knitted fabric simulation. [ABSTRACT FROM AUTHOR]

A two-step process for preparing polyimide nanofiber was used in this work, and the nanofibers of precursor polyamic acid (PAA) were prepared by electrospinning. The polyimide nanofibers were obtained through thermal imidization at different thermal imidization temperatures. The influences of different imidization temperatures on morphology, chemical structure, thermal stability, and mechanical properties of the polyimide nanofibers were investigated by Fourier Transform Infrared Spectroscope (FT-IR), Scanning Electronic Microscopy (SEM), thermal gravimetric analysis (TGA) and Electromechanical Universal Testing Machine. The experimental results show that the imidization of PAA nanofibers was not complete under 290° but complete under 350°. With the rise of imidization temperature from 290° to 350°, the polyimide nanofibers became thinner, and the thermal stability of polyimide nanofibers was also improved. The breaking strength and elongation at break of the nanofiber membranes increased at higher imidization temperature. [ABSTRACT FROM AUTHOR]

Ployacrylonitrile (PAN) nanofibers were formed by electrospinning. Amidoxime polyacryonitrile (AOPAN) nanofibrous membranes were formed by reaction between PAN nanofibrous membranes and hydroxylamine hydrochloride, and Fe(III)-AOPAN metal chelated nanofibrous membranes were prepared for immobilizing catalases. The enzymatic membrane reactor (EMR) with immobilized catalases was assembled, and the fluxes of membrane and conversion ratio of EMR were studied. The immobilized catalases showed better resistance to pH and temperature change than that of the free form, and the storage stabilities of immobilized catalases were higher than that of the free catalases. The flux of the membrane and the conversion ratio of EMR were calculated, and the reusability of the EMR was studied. The results of experiments show that the immobilized catalases had a high affinity with the nanofibers, and the EMR has excellent performance. [ABSTRACT FROM AUTHOR]

Two polymer solutions of polyacrylonitrile, polyvinyl pyrrolidone, and Ni(CH3COOH)2 in dimethylformamide were electrospun into ternary composite nanofibers, followed by stabilization and carbonization processes to obtain porous carbon/nickel composite nanofibers with diameters of 100-200 nm. The study revealed that carbon/nickel composite nanofibers were successfully prepared, which allowed nickel particles with diameters of 20-70 nm to be uniformly distributed in the carbon nanofibers. It was also observed that the fibrous structures with particles embedded formed and the fibers broke into shorter fibers after sintering. X-ray diffraction indicated that embedded particles crystallized with the face centered cubic structure. The Brunauer-Emmett-Teller analysis revealed that carbon/nickel composite nanofibers with meso-pores possessed larger specific surface area than that of carbon nanofibers. The specific capacitance of the composite nanofiber electrode was as high as 103.8 F/g and showed stable cyclicity (73.8%). [ABSTRACT FROM AUTHOR]

This study aimed at the development and characterization/evaluation of polyethylene glycol (PEG) encapsulated in supporting polymer matrices (e.g., electrospun nanofibres) as innovative form-stable phase change materials (PCMs) for storage and retrieval of thermal energy. Ultrafine phase change fibres consisting of PEG (acting as phase change materials) and polyamide 6 (PA6, acting as supporting materials) were successfully fabricated by electrospinning technique. The effects of PEG amount and two different molecular weights (Mn) of PEG on structural morphology and thermal energy storage/retrieval property of PEG/PA6 ultrafine phase change fibres were systematically studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The SEM images showed that neat PA6 nanofibres were smooth with cylindrical shape, but the tubercles and/or beads in fibres were observed for PEG/PA6 ultrafine phase change fibres with increasing PEG amount and higher molecular weight of PEG. The average fibre diameters ranged from about 80 to 150 nm and increased with increasing the PEG amount and molecular weight of PEG, which resulted from the increased viscosity and decreased conductivity of composite spin dopes. The DSC results indicated that the enthalpies of melting and crystallization of PEG/PA6 ultrafine phase change fibres increased with increasing PEG amount, and were lower than those of neat PEG powders. [ABSTRACT FROM AUTHOR]

TiO2 fibers were successfully prepared by combining electrospinning and calcination processes without using the conventional sol-gel method. Polymethyl methacrylate (PMMA) and tetrabutyl titanate (TBT) were used as TiO2 precursor blended with chloroform to form a homogeneous solution for preparing PMMA/TBT composite fibers. The electrospun fibers were calcinated at 500 °C for 4 h in air atmosphere to obtain TiO2 fibers. XRD, SEM TEM and Brunauer-Emmett-Teller (BET) were used to study structures and morphology of the PMMA/TBT and TiO2 fibers. The photocatalytic property of TiO2 fibers was evaluated by photocatalytic degradation of methyl orange (MeO) under UV irradiation. The results demonstrate that mesoporous TiO2 fibers with larger specific surface area possessing pure anatase phase were successfully prepared and the average diameter of PMMA/TBT fibers decreased from 1.5 µm to 1.0 µm after calcination. The TiO2 fibers show high photocatalytic reactivity in photodegradation of MeO solutions. [ABSTRACT FROM AUTHOR]

In this study, Poly (L-lactic acid)/Captopril composite nanofiber membranes were electrospun for drug delivery. Different mass fractions of Poly (L-lactic acid), different ratios of Captopril and the influences of PEG4000 added in the spinning solution are discussed. The morphology, chemical components, the surface areas and pore sizes, wettability of the composite nanofiber membranes were investigated. The results showed that the diameters of the composite nanofibers increased with the increase of Poly (L-lactic acid) mass fractions, the diameters decreased with the increase of Captopril content as well as the addition of the surfactant. Fourier Transform Infrared (FT-IR) showed the chemical components of Captopril remained unchanged when it was electrospun into the composite nanofibers. The surface areas pore width and pore volume of the composite nanofibers became a little larger than those of poly (L-lactic acid) nanofibers, and the wettability of the composite nanofiber membranes was better than those of poly (L-lactic acid) nanofiber membranes. Wettability was improved by an increase of the drug load amount. [ABSTRACT FROM AUTHOR]

Porous carbon/cobalt (C/Co) composite nanofibers with diameters of 200-300 nm were prepared by electrospinning and subsequent carbonization processes. Two polymer solutions of polyacrylonitrile (PAN), polyvinyl pyrrolidone (PVP), and Co (CH3COOH)2 (Co (OAc)2) were used as C/Co composite nanofiber precursors. The study revealed that C/Co composite nanofibers were successfully prepared and cobalt particles with diameters of 20-30 nm were uniformly scattered in the carbon nanofibers. It was also observed that clear fibrous morphology with grainlike particles and good structural integrity were still maintained after calcination. The TGA analysis indicated the improved thermal stability properties of the composite nanofibers. The Brunauer-Emmett-Teller (BET) analysis indicated that C/Co composites nanofibers with meso-pores possessed larger specific surface area than that of carbon nanofibers. [ABSTRACT FROM AUTHOR]

Laurie acid (LA)/polyethylene terephthalate (PET) ultrafine composite fibres as form-stable phase change materials (PCM) were prepared successfully via electrospinning. The morphology, thermal energy storage properties, thermal stability and flammability properties of electrospun LA/PET composite fibres were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC), respectively. It was found by SEM investigation that the average fibre diameter generally increased with increasing content of LA in the LA/PET composite fibres. The morphology of electrospun composite fibres changed from a cylindrical shape with a smooth surface (without LA) to a rough and non-uniform structure (with LA). The DSC measurements indicated that there was little change of the phase transition temperatures of the composite fibres, but there was a decrease of the heat enthalpies compared with the pure lauric acid. The TGA results showed that both the onset thermal degradation temperature and charred residue at 700 °C of composite fibres were lower than those of the pure PET fibres, due to the thermal instability of LA. The MCC tests showed that there were two peaks of heat release rate, which corresponded respectively to combustion of LA and PET in the electrospun composite fibres. It could be also found that the first peak increased and the second peak decreased with increasing LA content in composite fibres. [ABSTRACT FROM AUTHOR]

In the current work, 3-D glass fibre woven fabric-reinforced composites were fabricated by impregnating epoxy resin in a hand lay-up procedure for the hollow integrated core sandwich structure. Four types of 3-D structures were investigated in terms of the impact properties as a function of the z-direction fibre length (5, 6 and 7 mm) and covered skins (covered with aluminium) in core structures. Impact properties including peak load, time to peak load, and absorbed energy were evaluated. It was found that the 3-D hollow integrated core sandwich composites covered with aluminium skin considerably enhanced the impact resistance. Photographs of the impact damage taken after impact tests were analyzed and discussed in terms of a hollowing on the front face sheet against the load applied, and whitening spread in the impact point on the back face sheet of the composites was also studied. [ABSTRACT FROM AUTHOR]

Polyvinyl acetate (PVAc) and PVAc/titanium dioxide (TiO2) nanofiber mats were prepared by electrospinning process. In this study, three types of solution were used. The first was PVAc dissolved in only acetone, the second was prepared by adding TiO2 sol into PVAc-acetone solution in sol-gel method, the third was prepared by adding ethanol into PVAc-acetone solution. The effect of solution properties such as viscosity, surface tension, and electrical conductivity on the formation and morphology of electrospun fibers was investigated. Pure PVAc had a beads-on-string structure, but the beads almost disappeared when the TiO2 was added. Electrospun fibers had average diameters of 529, 596, 333, 303nm for PVA/TiO2 volume ratios of 100 : 0, 100 : 10, 100 : 20, and 100 : 30, respectively. Since the added TiO2 precursor dispersed in ethanol solvent was in the ratio of 1 : 30, it was necessary to prepare the solution with same ratio of ethanol for contrast (ethanol is a nonsolvent of PVAc). As the concentration of ethanol increased, the average diameter of nanofibers decreased and change in the bead shape from spindle-like to spherical was observed on the whole. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) functional films were deposited on the surface of polyester nonwoven fabrics at room temperature by direct current (DC) reactive magnetron sputtering. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were employed to study the topographies and chemical compositions of the functional fabric surfaces, respectively. Scanning electron microscopy (SEM) was used to investigate the interracial microstructures and adhesion between the substrate and TiO2 coating. The AFM observations indicated that there was a significant difference in the surface morphology of the polyester fibres before and after TiO2 sputter coating. XPS spectra reflected the chemical features of the deposited TiO2 nanostructures. The SEM images showed that TiO2 thin films deposited on the substrate under confirmed processing conditions had unique, fine surfaces and good adhesion to the substrate. It was found that the deposition of TiO2 on the polyester nonwoven fabrics significantly improved their ultraviolet (UV) absorption and antistatic properties. [ABSTRACT FROM AUTHOR]

Functional silver-polypropylene nanocomposite fibers are prepared using melt-compounding and sputter coating techniques. The functional nanostructures formed on the fiber surfaces are characterized by Atomic force microscopy. The Environmental Scanning Electron Microscopy equipped with an energy dispersive X-ray analysis system is employed to examine the chemical compositions of the nanocomposite fibers. It is found that incorporating the silver nanoparticles by melt-compounding caused severe aggregation of the nanoparticles at the polypropylene fiber surface. By contrast, the coverage of the sputter coated fiber surfaces is much more consistent. The anti-bacterial properties of the nanocomposite fibers are also investigated and compared. The antibacterial tests revealed the better performance of silver sputter coated fibers. [ABSTRACT FROM AUTHOR]

This work reports the preparation of the polyamide 6 (PA6)/organically modified montmorillonite (O-MMT) composite nanofibres by a facile compounding and electrospinning. The O-MMT was firstly dispersed in N,N-dimethyl formamide and then compounded with PA6 which was dissolved in formic acid. The composite solution was electrospun to form PA6/O-MMT composite nanofibres. The structures and morphology of the composite nanofibres were characterised by scanning electron microscopy (SEM), x-ray photoelectron spectra (XPS), atomic force microscopy (AFM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the O-MMT layers were well exfoliated within the composite nanofibres and were oriented along the fibre direction. The homogeneous and cylindrical composite nanofibres showed decreased fibre diameters owing to the enhanced conductivity of the polymer solution. The results characterised by thermogravimetric analyses (TGAs) showed that the loading of O-MMT improved the thermal stability of the composite nanofibres. [ABSTRACT FROM AUTHOR]

Fibrous textiles have been increasingly used in a variety of industries. In these applications, the surface properties of textile materials play a very important role. The surface properties of textile materials can be modified by various techniques. Copper (Cu) nanocomposite textiles are prepared by magnetron sputter coating. The nanocomposite textiles with different thickness of coatings are investigated by atomic force microscope (AFM), energy-dispersive X-ray analysis, and opto-electrical tests. The AFM observations reveal the growth of the Cu nanostructures formed on the fiber surface as the sputtering time increases. The surface conductivity of the textiles coated with Cu nanostructures shows a significant increase compared to the uncoated ones. The increased coating thickness leads to better electrical conductivity. The coated textiles also show considerable improvement in UV and visible light shielding, examined by UV/Vis spectrometer. [ABSTRACT FROM AUTHOR]