共查询到20条相似文献,搜索用时 15 毫秒
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E.A. Theisen M.J. Davis S.J. Weinstein P.H. Steen 《Chemical engineering science》2010,65(10):3249-3259
Planar-flow melt spinning (PFMS) is a single-stage rapid manufacturing technique for producing thin metal sheets or ribbons. Commercial acceptance of PFMS requires ribbons to be cast with uniform thickness to tolerance. The process feeds molten metal through a nozzle onto a moving wheel where a puddle is formed and from which a continuous ribbon is ‘spun’. This study focuses on the time dependent behavior of the process. The dynamics of the process are modeled using unsteady mass balances, combined with a Bernoulli model of flow. Variations over a number of time scales are observed. The time scale over which the process can be treated as ‘quasi-steady’ is identified. Measuring the evolution of the puddle length and ribbon thickness within a cast indicates that the solidification rate also varies with time and a maximum in solidification rate is inferred. 相似文献
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Experimental and simulation studies of optimization of the melt spinning process were carried out for nylon 6 fibers. The experiment and process simulation demonstrated that one criterion that can be applied in scaling up an optimized melt spinning process is to achieve the similar real time history of temperature and deformation rate in the spinway. Some aspects of the experiments and process simulation are discussed, together with the results of real time history analysis for a case of nylon 6 spinning. 相似文献
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The purpose of this study is to develop a steady-state thermal model for melt spinning of polyester fiber by incorporating the radial heat conduction inside the fiber and the combined effect of radiation and convection at the boundary. The governing equations are obtained from the energy, mass, and momentum balances coupling with the rheological properties of the fibers. The effects of drag, surface tension, gravity, and inertia force are also taken into consideration in the analysis. The velocity profile, temperature profile, and the variation of cross-sectional area of the filament along the axial direction are solved by employing a finite-difference scheme. 相似文献
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基于熔融纺丝动力学模型及理论,建立了涤纶全拉伸丝(FDY)熔融纺丝模型。在已知工艺参数条件下,模拟了丝条温度、速度、取向和结晶在纺程上的变化。结果表明:在纺程200,700,800,1 300,1 500 cm处,模拟值与实测值误差均小于10%,该模型可用于实际生产的模拟;根据模型,获得了热辊温度及速度对涤纶FDY的取向及结晶的定量关系;随着GR1速度降低和GR1温度提高,纤维的取向度和结晶度升高;随着GR2速度增加和GR2温度提高,纤维的取向度越大,结晶度越高。 相似文献
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Takeshi Kikutani Kazuhito Nakao Wataru Takarada Hiroshi Ito 《Polymer Engineering and Science》1999,39(12):2349-2357
On-line measurement of birefringence was performed in the high-speed melt spinning process of poly(ethylene terephthalate) using an apparatus that incorporates a rotating polarizer for the measurement of the optical retardation of running filament. Particular attention was paid to the detailed measurements in the vicinity of neck-like deformation. Through the measurement at the take-up velocity of 5 km/min, development of birefringence under the strain rate up to about 1 ms?1 was investigated. To analyze the relation between applied stress and birefringence, tension and temperature profiles of the spin-line were calculated based on the experimentally obtained diameter profiles. Even though the strain rate is extremely high, a linear relationship between birefringence and a parameter calculated by dividing stress by temperature was confirmed to hold up to birefringence and stress/temperature values of about 0.017 and 10 kPa/K, respectively. 相似文献
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A high molecular weight polyethylene terephthalate was spun into fibers in the speed range from 3,000–7,000 mpm. The effect of modifying threadline dynamics through a combination of enhanced and/or retarding air quenches on the resulting spinning performance, fiber structure, and mechanical properties was examined. Particular combinations of these threadline temperature profile modifications were shown to result in significant improvements in spinning performance and as-spun fiber structure. Extensive characterization of select fiber samples revealed higher orientation and crystallinity, larger crystal dimensions, and greater mechanical properties. These results also demonstrated the ability to provide continued improvement in fiber properties at very high take-up speeds where typically a decline is observed. It is concluded that the threadline temperature profile can be altered in such a way as to significantly enhance the resulting spinning performance and fiber structure over a wide range of take-up speeds. 相似文献
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Susumu Kase 《应用聚合物科学杂志》1974,18(11):3279-3304
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《合成纤维工业》2015,(6):43-48
将超高相对分子质量聚乙烯(UHMWPE)与共混组分聚烯烃(PB)按一定质量比计量,并加入质量分数为0.3%的抗氧剂1010,在双螺杆挤出机上共混造粒,研究了PB的用量对UHMWPE/PB共混物熔点和流变性能的影响;采用实验室熔融纺丝装置对UHMWPE/PB共混物进行纺丝,拉伸得到UHMWPE/PB共混纤维,研究了共混纤维的形貌、结晶性能和力学性能。结果表明:在共混温度为230~290℃时,UHMWPE/PB共混物可实现宏观上均匀共混;共混物具有介于两共混组分熔点之间的单一熔点,共混物熔点随UHMWPE含量的提高而提高;共混物熔体属假塑性流体,270~320℃条件下,随UHMWPE含量的增加,UHMWPE/PB共混物结构黏度指数逐渐增加,黏流活化能逐渐减小,共混物的熔体黏度对温度不敏感;当UHMWPE/PB质量比为1∶1,纺丝温度为310℃时,共混物具有良好的可纺性,经过19倍的后拉伸,所获得的UHMWPE/PB共混纤维直径为45μm,断裂强度可达16.4 c N/dtex,初始模量约190.0 c N/dtex。 相似文献
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Taehwan Oh 《Polymer Engineering and Science》2006,46(5):609-616
Dimensional change and profile development in the melt spinning process of polyethylene terephthalate hollow fibers were studied through the numerical simulations and experimental results. The simulation predicts the final dimensions and profiles development of the hollow fibers at various positions from the die. Experimental results show that the melt extruded from the spinneret coalesces initially to form a hollow inner core and the cross‐sectional shape holds for over the whole spinline with only variation in the hollow portion. Analysis of the effect of spinning parameters on hollow portion shows that the spinning temperature, mass throughput rate, and take‐up speed are the most critical variables in controlling the hollow portion followed by quench air velocity. The quench air temperature has relatively less effect than the other variables. As the mass throughput rate and quench air velocity increase and the take‐up speed and spinning temperature decrease, the hollow portion increases. To investigate the effect of die geometry, die having a different ratio of inner to outer diameter was used. The effect of change of process variables decreases as the die gap becomes narrow. POLYM. ENG. SCI. 46:609–616, 2006. © 2006 Society of Plastics Engineers 相似文献
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This study has been carried out to investigate the processing parameters affecting polyetheretherketone's (PEEK) spinnability in a melt spinning process. PEEK has excellent mechanical and thermal properties and fibers made from it could be used in extreme environments. Different PEEK grades were characterized thermally and rheologically to see which one is the most suitable for fiber spinning. The spinning tests made with the most suitable grade (Victrex 151G) show that increased processing temperature, increased capillary diameter or shorter spinning path length improves spinnability. The best fibers made in optimal processing conditions (400°C temperature, 30/1 mm capillary, and 5 cm spinning path) were 18 μm in average diameter. Because of the limitations of the system used, variations in fiber thickness were noticeable and worsened the spinning stability. Scanning electron microscope photos confirmed these variations, and they were also visible in an optical microscope. The selected low‐viscosity PEEK grade provided good spinnability but gave filaments with only mediocre mechanical properties, the tensile strength being around 280 MPa. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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The crystallization behavior of poly(ethylene) terephthalate (PET) melt spun into fiber monofilaments was examined using a laboratory set-up. The wind-up speeds ranged from free fall under gravity to 1500 m/min. The major additional variables that were manipulated included the mass flow rate and the filament temperature profile. The structure of the as-spun fibers was probed using tensile tests, differential scanning calorimetry, optical birefringence, and x-ray diffraction. It was found that while the filaments that had been spun nonisothermally were essentially amorphous, those that had been made under isothermal conditions at temperatures ranging from 180°C to 240°C were oriented and crystalline. In addition, the rate of oriented crystallization was much greater than that under quiescent conditions at the same temperature. This is perhaps the first published study which shows that highly crystalline (up to 40% crystallinity) PET fibers can be obtained at low spinning speeds merely by altering the fiber temperature profile while the material is still above the polymer glass transition temperature. 相似文献
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W. K. Martin 《应用聚合物科学杂志》1988,35(4):953-963
In the nylon 6 melt spinning process at speeds of 900 and 1200 m/min the quenching is done in a stepwise manner. The effect on physical data of the drawn yarn is investigated and correlation between quench height, water takeup, and boiloff shrinkage discussed. Length changes across the takeup machine are also measured as function of quench height and seem to correlate with physical data. The speed of length changes for both finished and unfinished yarn as a function of quench height suggests a molecular oscillation along the spinning line rather than a continuous orientation of the molecular structures. A secondary disorientation zone is defined. 相似文献
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The dynamics of melt spinning was examined in the case of a Lethersich liquid taking also into account a phenomenologic way as well the transition zone between shear and elongational flow. The shape of the fluid jet was measured under many spinning conditions; the filament temperature and the fluid viscosity were then calculated. The experimental viscosity temperature relationship was compared with the W. L. F. equation, and the comparison makes it clear that the Newtonian model is not adequate whereas all the experimental evidence is in qualitative accordiance with the proposed model. 相似文献