Studies on high-speed melt spinning of noncircular cross- section fibers. I. Structural analysis of as-spun fibers

2001 ◽  
Vol 80 (9) ◽  
pp. 1575-1581 ◽  
Author(s):  
Wataru Takarada ◽  
Hiroshi Ito ◽  
Takeshi Kikutani ◽  
Norimasa Okui
Keyword(s):  
Structural Analysis ◽  
Cross Section ◽  
High Speed ◽  
Melt Spinning ◽  
Noncircular Cross Section ◽  
Spun Fibers

scholarly journals Melt-Spun Fibers from Bio-Based Polyester–Fiber Structure Development in High-Speed Melt Spinning of Poly(ethylene 2,5-furandicarboxylate) (PEF)

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1172
Author(s):  
Wataru Takarada ◽  
Kenichi Sugimoto ◽  
Hajime Nakajima ◽  
Hendrikus A. Visser ◽  
Gert-Jan M. Gruter ◽  
...  
Keyword(s):  
High Speed ◽  
Melt Spinning ◽  
Tensile Modulus ◽  
Structural Development ◽  
Poly Ethylene Terephthalate ◽  
Pet Fibers ◽  
Fossil Resource ◽  
Poly Ethylene ◽  
Induced Crystallization ◽  
Spun Fibers

Poly(ethylene 2,5-furandicarboxylate) (PEF) is regarded as a bio-based alternative or complementary polyester for the widely used fossil resource-based polyester, poly(ethylene terephthalate) (PET). High-speed melt spinning of PEF of low and high molecular weight (L-PEF, H-PEF) was conducted, and the structure and properties of the resultant as-spun fibers were investigated. The occurrence of orientation-induced crystallization was confirmed for the H-PEF at the take-up velocity of 6.0 km/min, the highest speed for producing PET fibers in the industry. Molecular orientation and crystallinity of the as-spun fibers increased with the increase of take-up velocity, where the H-PEF fibers always showed a higher degree of structural development than the L-PEF fibers. The tensile modulus of the high-speed spun H-PEF fibers was relatively low at 5 GPa, whereas a sufficiently high tensile strength of approximately 500 MPa was measured. These values are adequately high for the application in the general semi-engineering fiber field.

Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Liquid Through Channel of Noncircular Cross Section

1994 ◽  
Vol 59 (3) ◽  
pp. 603-615 ◽  
Author(s):  
Václav Dolejš ◽  
Ivan Machač ◽  
Petr Doleček
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Numerical Solution ◽  
Cross Section ◽  
Approximate Calculation ◽  
Newtonian Liquid ◽  
Straight Channel ◽  
Suggested Procedure ◽  
Noncircular Cross Section ◽  
Calculation Results

The paper presents a modification of the equations of Rabinowitsch-Mooney type for an approximate calculation of pressure drop in laminar flow of generalized Newtonian liquid through a straight channel whose cross section forms a simple continuous area. The suitability of the suggested procedure of calculation of pressure drop is demonstrated by the comparison of calculation results with both the published and original results of numerical solution and experiments.

scholarly journals Fiber Formation and Structural Development of HBA/HNA Thermotropic Liquid Crystalline Polymer in High-Speed Melt Spinning

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1134
Author(s):  
Bo Seok Song ◽  
Jun Young Lee ◽  
Sun Hwa Jang ◽  
Wan-Gyu Hahm
Keyword(s):  
Mechanical Properties ◽  
Shear Rate ◽  
High Speed ◽  
Melt Spinning ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Fiber Formation ◽  
Structural Development ◽  
Thermotropic Liquid Crystalline Polymer

High-speed melt spinning of thermotropic liquid crystalline polymer (TLCP) resin composed of 4-hydroxybenzoic acid (HBA) and 2-hydroxy-6-napthoic acid (HNA) monomers in a molar ratio of 73/27 was conducted to investigate the characteristic structure development of the fibers under industrial spinning conditions, and the obtained as-spun TLCP fibers were analyzed in detail. The tensile strength and modulus of the fibers increased with shear rate in nozzle hole, draft in spin-line and spinning temperature and exhibited the high values of approximately 1.1 and 63 GPa, respectively, comparable to those of industrial as-spun TLCP fibers, at a shear rate of 70,000 s−1 and a draft of 25. X-ray diffraction demonstrated that the mechanical properties of the fibers increased with the crystalline orientation factor (fc) and the fractions of highly oriented crystalline and non-crystalline anisotropic phases. The results of structure analysis indicated that a characteristic skin–core structure developed at high drafts (i.e., spinning velocity) and low spinning temperatures, which contributed to weakening the mechanical properties of the TLCP fibers. It is supposed that this heterogeneous structure in the cross-section of the fibers was induced by differences in the cooling rates of the skin and core of the fiber in the spin-line.

Calculation of hydraulic resistivity coefficients for turbulent fluid flow in channels of noncircular cross section

1967 ◽  
Vol 23 (4) ◽  
pp. 1042-1047 ◽  
Author(s):  
M. Kh. Ibragimov ◽  
I. A. Isupov ◽  
L. L. Kobzar' ◽  
V. I. Subbotin
Keyword(s):  
Fluid Flow ◽  
Cross Section ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Noncircular Cross Section

High-Speed Melt Spinning of Sheath-Core Bicomponent Polyester Fibers: High and Low Molecular Weight Poly(ethylene Terephthalate) Systems

1997 ◽  
Vol 67 (9) ◽  
pp. 684-694 ◽  
Author(s):  
J. Radhakrishnan ◽  
Takeshi Kikutani ◽  
Norimasa Okui
Keyword(s):  
Molecular Weight ◽  
High Speed ◽  
Melt Spinning ◽  
Ethylene Terephthalate ◽  
Maxwell Model ◽  
Low Molecular Weight ◽  
Structural Development ◽  
Solidification Temperature ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene

Sheath-core bicomponent spinning of high molecular weight poly (ethylene terephthalate) (hmpet, IV = 1.02 dl/g) and low molecular weight pet (lmpet, IV = 0.65 dl/g) is done at a take-up velocity range of 1 to 7 km/min. The structures of the individual components in the as-spun bicomponent fibers are characterized. Orientation and orientation-induced crystallization of the hmpet component are enhanced, while those of the lmpet component are suppressed in comparison to corresponding single component spinning. Numerical simulation with the Newtonian model shows that elongational stress in the hmpet component is enhanced and that of the lmpet decreases during high-speed bicomponent spinning. The difference in elongational viscosity is the main factor influencing the mutual interaction between hmpet and lmpet, which in turn affect spinline dynamics, solidification temperature, and structural development in high-speed bicomponent spinning. Simulation with an upper-convected Maxwell model shows that considerable stress relaxation can occur in the lmpet component if the hmpet component solidifies before lmpet. A mechanism for structural development is also proposed, based on the simulation results and structural characterization data.

Analysis of the Variable Cross-Section Duct and Straightening Device Geometry Effects on the Hydrogen Combustion Process

2021 ◽  
pp. 62-71
Author(s):  
O.V. Guskov ◽  
V.S. Zakharov ◽  
Minko
Keyword(s):  
Combustion Chamber ◽  
Cross Section ◽  
High Speed ◽  
Power Plants ◽  
Combustion Process ◽  
Variable Cross Section ◽  
Hydrogen Combustion ◽  
Variable Cross ◽  
Calculation Methods ◽  
Transition Channel

The development and research of high-speed aircrafts and their individual parts is an urgent scientific task. In the scientific literature there is information about the integral characteristics of aircrafts of this type, but there is no detailed consideration of such an important part as the transition channel between the air intake and the combustion chamber. The article considers several flow path configurations. The numerical simulation results of hydrogen combustion in the channels of variable cross section using a detailed kinetic mechanism are presented. Based on the analysis of the data obtained, the models of the transition channel and the combustion chamber showing the best characteristics were selected. The impulse and the fuel combustion efficiency are used as criteria for comparing the flow paths. The difference in the application of two calculation methods is described. The presented results and calculation methods can be used at the stage of computational research of the working processes in advanced power plants.

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