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Spinning Process (spinning + process)
Kinds of Spinning Process Selected AbstractsDisturbance Propagation in the Melt Spinning ProcessPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009Anthony McVeigh This work deals with the propagation of a disturbance acting on a fibre in the melt-spinning process, where molten polymer is ejected vertically downwards from an orifice before being drawn onto a wind-up spool. The disturbance may be produced by a sudden horizontal draught of air impinging on a part of the fibre. The flow is modeled as a wave propagating on a moving string under the influence of damping and variable tension. The amplitude of the disturbance is obtained in closed-form along the characteristics which emanate from the boundaries of the localised initial disturbance; the general solution of the damped disturbance is determined numerically. An important aspect of the model is the ability to predict the magnitude of this disturbance close to the orifice, where the extruded polymer is molten and therefore extremely sensitive to disturbances. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanofibers from Laser Spinning: Laser Spinning of Bioactive Glass Nanofibers (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Mater. This cover image is a graphical representation of the laser spinning process described by Félix Quintero et al. on page 3084. Laser spinning involves the use of a high power laser to melt a very small volume from a plate of the precursor material. A high speed supersonic gas jet causes the rapid elongation and cooling of the melt, yielding a glass nanofiber. The authors also describe the use of this technique in producing Bioglass nanofibers. [source] Online temperature measurement and simultaneous diameter estimation of fibers by thermography of the spinline in the melt spinning processADVANCES IN POLYMER TECHNOLOGY, Issue 3 2004M. Golzar Abstract Online measurements of the temperature and the diameter of fibers in the melt spinning process of thermoplastics are discussed. The temperature and the diameter of fibers can be applied in many fields such as fiber formation modelling, cooling rate behavior (Nusselt number), and rheological investigations (apparent extensional viscosity) of polymers. The online measurements along the spinline were carried out with an infrared camera during the melt spinning process. Two different experiments were designed and carried out to find the correction factor, i.e., the emissivity. The results show that the emissivity correction factor depends on the polymer type and the fiber diameter. Usually the diameter of the fibers is measured by an instrument or by direct velocity measurements invoking the continuity equation. In this new approach the diameter is found directly by the evaluation of the measured temperature. Therefore only one apparatus, namely an infrared camera taking snapshots, is required to find the fiber diameter. The key of this method can be seen in the temperature difference between the fiber and the environment. A mathematical procedure was developed to estimate the diameter of the fiber from the distribution curve. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 176,185, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20008 [source] Simulation of dry-spinning process of polyimide fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009Gang Deng Abstract As one type of high-performance fibers, the polyimide fibers can be prepared from the precursor polyamic acid via dry-spinning technology. Unlike the dry-spinning process of cellulose acetate fiber or polyurethane fiber, thermal cyclization reaction of the precursor in spinline with high temperature results in the relative complex in the dry-spinning process. However, the spinning process is considered as a steady state due to a slight degree of the imidization reaction from polyamic acid to polyimide, and therefore a one-dimensional model based on White-Metzer viscoelastic constitutive equation is adopted to simulate the formation of the fibers. The changes of solvent mass fraction, temperature, axial velocity, tensile stress, imidization degree, and glass transition temperature of the filament along the spinline were predicted. The effects of spinning parameters on glass transition temperature and imidization degree were thus discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Melt Spinning of Bacterial Aliphatic Polyester Using Reactive Extrusion for Improvement of CrystallizationMACROMOLECULAR BIOSCIENCE, Issue 6 2007Roland Vogel Abstract This paper reports on an attempt to use reactive extrusion with peroxide as a comfortable pathway for improvement of the crystallization of poly(3-hydroxybutyrate) in a melt spinning process. At first, rheological and thermal properties of the modified melts are determined in order to assess the effect of nucleation. Then spinning tests are carried out. Molecular weights and molecular weight distributions of the spun fibers are determined by chromatographic methods. Average crystallite size is measured by wide angle X-ray scattering. Thermal and textile properties of the spun PHB fibers are also determined. An estimation of the improvement of the crystallization in the spinline and of the inhibition of the secondary crystallization in the fibers from the use of the described way of reactive extrusion is given. [source] Characterization of the polarization in the spun fibersMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009L. Cherbi Abstract The polarization mode dispersion (PMD) is a difficult phenomenon to compensate in the optical fiber. Its reduction can be achieved by the spinning process that provokes the rotation of the birefringence axes of the fiber inciting a coupling of its modes that is controlled at the time of its manufacture. In this work, the Jones Matrix Eigen-Analysis method (JME) is used to characterize the spun fibers to evaluate their PMD and to prove that it is distinctly lower than the standards fibers PMD. Furthermore, the differential group delays (DGD) of spun fibers is determined using the photon counting optical time-domain reflectometry (C-OTDR) method. The obtained results are compared with those found in the JME method. It is noted that the two methods yield practically identical values. The determination of the beat length and the spin period of spun fibers are carried out using the polarization-sensitive optical frequency-domain reflectometer (POFDR). © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 341,347, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24045 [source] In vitro hydrolytic degradation of centrifugally spun polyhydroxybutyrate,pectin composite fibresPOLYMER INTERNATIONAL, Issue 12 2009L John R Foster Abstract BACKGROUND: Centrifugal spinning is a novel fibre-forming process that readily permits the incorporation of additives while avoiding the thermal damage often associated with conventional melt spinning. Centrifugal spinning of a viscous solution of poly(3-hydroxybutyrate) (PHB) mixed with pectin was used to fabricate a range of fibres containing different concentrations of this biologically active agent. The influence of this blending on fibre morphology and in vitro degradation in an accelerated hydrolytic model at 70 °C and pH of 10.6 is reported. RESULTS: Blending influenced the physiochemical properties of the fibres, and this significantly affected the degradation profile of both the fibre and its PHB constituent. A greater influence on degradation was exerted by the type of pectin and its degree of esterification than by variations in its loading. CONCLUSION: Centrifugal spinning permits the fabrication of composite fibrous matrices from PHB and pectin. Incorporation of the polysaccharide into the fibres can be used to manipulate degradation behaviour and demonstrates a model for doping of matrices with active biological constituents. The unique features of the centrifugal spinning process, as illustrated by the structure of the fibres and the degradation profiles, suggest possible applications of centrifugally spun biopolymers as wound scaffolding devices and in tissue engineering. Copyright © 2009 Society of Chemical Industry [source] Fiber-forming blend polypropylene-polyvinyl alcoholPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2001Anton Marcin Abstract The preparation of a fiber-forming blend consisting of polypropylene and polyvinyl alcohol mixed with glycerol and with polypropylene grafted with maleic anhydride were studied. The physical and mechanical properties of blend fibers were also studied. The rheological measurements for semiquantitative evaluation of technological compatibility of the components and for processing the polymeric material in extruding and spinning process were carried out. The experimental results revealed the technological compatibility of the polypropylene-polyvinyl alcohol blend in the presence of glycerol and polypropylene grafted with maleic anhydride. The colloidal structure of interface layer is assumed to be in a three- or four-component system. The mixture of polyvinyl alcohol with glycerol allows for the preparation of well spun fiber-forming polypropylene blends. Polypropylene-polyvinyl alcohol blend fibers consisting of up to 20% polyvinyl alcohol with sufficient mechanical properties, higher porosity and significantly higher sorption of water than polypropylene fibers alone were prepared. Copyright © 2001 John Wiley & Sons, Ltd. [source] Comparison of multivariate methods for robust parameter design in sheet metal spinningAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 3 2004Corinna Auer Abstract Sheet metal spinning is a very complex forming process with a large number of quality characteristics. Within the scope of a joint project of the Department of Statistics and the Chair of Forming Technology the impact of process parameters (design factors) on important quality characteristics has been investigated both theoretically and experimentally. In the past, every response has been treated individually and uncontrollable disturbances (noise factors) have been neglected. Now this approach has been extended to robust multiresponse parameter design. For this, a review of common multivariate approaches for robust parameter design has been carried out, which also leads to the proposal of some new variants. In addition to the theoretical comparison, the methods were applied to data gained in the sheet metal spinning process. The obtained results were evaluated in terms of applicability, limitations and quality accuracy. Practical experiments confirmed the high degree of efficiency that the finally proposed method based on desirabilities promises. Copyright © 2004 John Wiley & Sons, Ltd. [source] Conformational transition and liquid crystalline state of regenerated silk fibroin in waterBIOPOLYMERS, Issue 6 2008Xin-Gui Li Abstract The conformational transition of molecular chains of regenerated silk fibroin (SF) aqueous solution is systematically investigated by circular dichroism, Raman, IR, and UV,vis spectroscopies. It is found that an initial random coil conformation of the SF can be readily changed into an ordered ,-sheet structure by optimizing the solution conditions, such as the SF concentration, pH, temperature, or metal-ion content. Circular dichroic spectra quantitatively confirm a steadily decreased content of the random coil conformation but a significantly increased ,-sheet content after an ultrasonic or extruding treatment. Furthermore, the extrusion is more powerful to achieve high ,-sheet content than the ultrasonic. It is interesting that the polarized optical micrographs of the SF aqueous solution extruded by injection illustrate the formation and existence of liquid crystalline state. A study of extrusion in vitro could be used as a model system to understand the natural silk spinning process in silkworm. © 2007 Wiley Periodicals, Inc. Biopolymers 89: 497,505, 2008. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Effect of the age of a spin pack on the dyeing properties of poly(ethylene terephthalate) fibresCOLORATION TECHNOLOGY, Issue 2 2005Sule Altun The spin pack is an essential component of melt spinning processes. However, the age of the spin pack can affect the physical properties of polymers. The dyeing properties of poly(ethylene terephthalate) fibres over time in relation to spin pack age were investigated in the present study. With an increase in the age of the spin pack, an increase in colour strength and a decrease in fibre crystallinity were observed. The crystallinity decrease of the fibres through spin pack age was explained by the increase in polymer melt temperature due to increase in spin pack pressure. [source] | ||||||||||||||||