Draw speed

After these improvements the system was able to measure at drawing speeds up to 500 m/min on one channel. At higher velocities vibrations spoiled the measurements. The water remaining on the tube after the measuring chamber was removed using a pressured air system. 

The final test of the prototype was performed during actual drawing operation. In Figure 6 an example is shown with all four channels recorded during tube drawing. To see the influence of tube velocity the drawing speed was increased every 30 sec, going from zero to 350 tn/sec. 

Figure 6. Measurements from the four wall thickness channels at different drawing speeds.

The four channel scanning system showed stable measurements up to 250 m/min drawing speed. At 300-350 m/min some measurements were unstable on two channels. At drawing velocities over 350 m/min measurements were unstable on all four channels. The four traces are better identified in colors on the computer screen than in this grey tone figure. 

Dittmann at al. later developed a very simple method for preparing such stationary phases [41 ]. They packed a capillary with 3-pm ODS beads and then drew a heated wire along the capillary to achieve sintering of the beads. Since changes in the drawing speed directly affected both EOF and retention, they inferred that the heat treatment led to detachment of a part of the C18 ligands from the silica beads. 

This feature will be increasingly Important as battery manufacturers continue to increase the cell capacity with thinner separators. The pore structure is usually influenced by polymer composition, and stretching conditions, such as drawing temperature, drawing speed, and draw ratio. In the wet process, the separators produced by the process of drawing after extraction (as claimed by Asahi Chemical and Mitsui Chemical) are found to have much larger pore size (0.24—0.34 fixxi) and wider pore size distribution than those produced by the process of extraction (0.1—0.13 after drawing (as claimed by Tonen). ... 

One of the earliest conventional methods for the assessment of spinnability was the "pulling rod" test drawing a thread from the melt by means of a glass rod. Of course this very simple and convenient method is qualitative, since the drawing speed and the heat transfer are not controlled. Yet the thread length gives an immediate impression of the spinnability. 

Fig. 24a shows results for R, = 5 and 7. It can be seen that for low imposed draw speeds R = Rn, i e. the polymer remains in contact with the dife wall throughout. When the imposed draw speed is increased the polymer leaves the die wall and R increases quite dramatically. In contrast to hydrostatic extrusion higher deformation ratios are obtained at higher production speeds, in this case reaching 50 cm/min. It... 

Hot-melt thermoplastic primary coatings for optical fibers have also been employed to a limited extent (26,27). They may be formulated with reasonably low glass transition temperatures, but particle contamination is a difficult quality control problem with these materials. UV-curable coating formulations have largely supplanted hot melt coatings owing to the increased draw speed which they offer. 

Tube No OD (ym) Wall thickness (ym) Machine draw ratio True draw ratio Draw speed (m/min) Corona Voltage (kV)... 

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