Structure and properties of low-isotacticity polypropylene elastomeric fibers prepared by sheath-core bicomponent spinning: effect of localization of high-isotacticity component near the fiber surface

2015 ◽  
Vol 35 (3) ◽  
pp. 277-285 ◽  
Author(s):  
Youhei Kohri ◽  
Tomoaki Takebe ◽  
Yutaka Minami ◽  
Toshitaka Kanai ◽  
Wataru Takarada ◽  
...  
Keyword(s):  
Melt Spinning ◽  
Elastic Recovery ◽  
Fiber Surface ◽  
Core Composition ◽  
Contraction Ratio ◽  
Spinning Process ◽  
Core Components ◽  
Section Structure ◽  
Layer Composition ◽  
Spun Fibers

Abstract Sheath-core type bicomponent melt-spun fibers were produced by extruding the melts of low-isotacticity polypropylene (LPP) as the core component and the blend of LPP and high-isotacticity PP (IPP) as the sheath component. IPP content in the sheath was changed from 8 wt% to 40 wt% while sheath/core composition was varied from 50/50 to 10/90. Accordingly overall IPP content was kept constant at 4 wt%. Even though the overall IPP content was intact, bicomponent fibers with lower contraction ratio after spinning, higher elastic recovery and slightly higher modulus and strength were obtained by increasing the IPP content in the sheath and decreasing the sheath layer composition, i.e., localizing the IPP to the region near the surface in the fiber cross-section. Structure analysis of the as-spun fibers suggested the suppression of crystallization of LPP in the sheath by blending IPP. By contrast, enhancement of molecular orientation and crystallization of the sheath component were found to occur by localizing the IPP to the region near the fiber surface. It was speculated that this behavior was caused by the kinematic mutual interaction of the sheath and core components in the melt spinning process.

On the Cooling of Fibers

1983 ◽  
Vol 105 (4) ◽  
pp. 830-834 ◽  
Author(s):  
A. Moutsoglou
Keyword(s):  
Melt Spinning ◽  
Fiber Diameter ◽  
Fiber Surface ◽  
Subsequent Increase ◽  
Boundary Layer Equations ◽  
Axial Temperature ◽  
Spinning Process ◽  
Radiative Losses ◽  
Filament Surface ◽  
Local Speed

The effects of the stretching of filaments on the cooling of fibers during the melt-spinning process are studied numerically. The filament is modeled as a continuous, cylindrical cone that moves steadily through an otherwise quiescent environment, with its diameter attenuating exponentially. Radiative cooling from the fiber surface is also accounted for in the analysis. The buoyancy-affected laminar and turbulent boundary layer equations are solved by a finite difference scheme, to determine the axial temperature variation of the filament. It is found that the reduction of the fiber diameter and the subsequent increase in the local speed of the filament enhances greatly the cooling from the filament surface, whereas the increase of the cooling due to radiative losses is not significant for all the flow cases considered.

Effect of Crucible Parameters on Planar Flow Melt Spinning Process

2015 ◽  
Vol 68 (6) ◽  
pp. 1125-1129 ◽  
Author(s):  
M. Swaroopa ◽  
L. Venu Gopal ◽  
T. Kishen Kumar Reddy ◽  
B. Majumdar
Keyword(s):  
Melt Spinning ◽  
Planar Flow ◽  
Spinning Process

PLA/Carbon Nanotubes Multifilament Yarns for Relative Humidity Textile Sensor

2011 ◽  
Vol 6 (3) ◽  
pp. 155892501100600 ◽  
Author(s):  
Eric Devaux ◽  
Carole Aubry ◽  
Christine Campagne ◽  
Maryline Rochery
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Relative Humidity ◽  
Melt Spinning ◽  
Flexible Sensor ◽  
Spinning Process ◽  
Textile Sensor ◽  
Multifilament Yarns

Polylactide (PLA) was mixed with 4 wt.% of carbon nanotubes (CNTs) to produce electrical conductive multifilament yarns by melt spinning process for humidity detection. Thanks to a variation of electrical conductivity, this flexible sensor could detect the moisture presence. The introduction of plasticizer was necessary to ensure higher fluidity and drawability of the blend during the spinning process. The plasticizer modifies the crystallinity and the mechanical properties of the yarns. The effectiveness of this sensor (PLA/4 wt.% CNTs fibres) sensitive to humidity, is optimal when the spinning conditions are adapted. In this way, the temperature and the rate of the drawing roll were reduced. The influence of these parameters on the crystallinity, the mechanical properties and the sensitivity of the yarns were studied. Once the appropriate spinning conditions found, one humidity sensitive yarn was processed and the repeatability and efficient reversibility of its sensitivity were highlighted.

Study on the equivalent luminance of luminous fibers in photopic vision and scotopic vision

2017 ◽  
Vol 88 (10) ◽  
pp. 1157-1163 ◽  
Author(s):  
Yanhong Yan ◽  
Chengxia Liu ◽  
Xiaojun Ding
Keyword(s):  
Experimental Data ◽  
Rare Earth ◽  
Melt Spinning ◽  
Emission Spectra ◽  
Scotopic Vision ◽  
Photopic Vision ◽  
Earth Material ◽  
Long Afterglow ◽  
Polyamide Fiber ◽  
Spinning Process

Colored luminous fibers were prepared by a melt spinning process, adding colored pigments and long afterglow rare earth material into polyamide fiber. The colored luminous fibers had a variety of colors in photopic vision, and emitted colored light in mesopic vision and scotopic vision. Based on the experimental data of the emission spectra and the test luminance of the luminous fibers, the effect of the emissive colors of the luminous fibers on the equivalent luminance at different vision states was analyzed. The results showed that the effect of the emissive colors of white, red, yellow, and green luminous fibers on the equivalent luminance was not obvious in photopic and scotopic vision, but that of blue luminous fiber was obvious in photopic vision but not in scotopic vision.

Microstructure Analysis of Melt-Spun Al3Ti Intermetallics by XRD and EXAFS

1996 ◽  
Vol 460 ◽  
Author(s):  
Jinmin Chen ◽  
W. E. Frazier ◽  
E. V. Barrera
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Melt Spinning ◽  
Composition Range ◽  
Processing Parameters ◽  
Wheel Speed ◽  
Annealing Temperatures ◽  
Melt Spun ◽  
Temperature Heat ◽  
Spinning Process

ABSTRACTIn an effort to expand the composition range over which Al3Ti is stable, various amounts of niobium were substituted for titanium and processed by melt-spinning. Several samples were annealed both at 600°C and 1000°C for 24 hours. The effects of processing parameters such as wheel speed, the amount of niobium, and annealing temperatures on the structure were investigated by XRD and EXAFS. XRD showed that for all the samples the only structure present was DO22-The DO22 structure was stable even after the high temperature heat treatments. By means of EXAFS, niobium atoms were observed to occupy titanium sites in the DO22 structure. Furthermore, in the unannealed samples, increasing wheel speed of the melt spinning process or the niobium concentration tended to distort the crystal structure. It was observed that Ti EXAFS had different results from the Nb EXAFS beyond their occupying similar sites, which suggested there may exist some composition zones, i.e. rich Nb zone or rich Ti zones, although the structures present were still DO22. The samples were found to experience different distortions as a function of annealing temperatures.

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