Solution gel spinning

In 4.3 we have already seen that polymers, in the rubber or fluid condition, crystallize much more rapidly when their chains are oriented. Therefore a stretched rubber, if stereospecific in its molecular structure, is able to crystallize at a temperature considerably above its equilibrium thermodynamic melting point. Also a thermoplast such as polyethylene, when in the molten state or in solution, can crystallize spontaneously when the chains are being orientated in elongational flow. The latter case is utilized when polyethylene is spun from a diluted solution (gel spinning process), resulting in fibres of super-high strength and stiffness ( Dyneema fibres). 

Schematic diagram of solution (gel) spinning of UHMWPE (Ward, 1987). 

Pemiings, 1976). However, these and related attempts held less interest for industrial apphcations after discovery of the simple and straightforward solution (gel) spinning technique by Smith and Lemstra in 1980. 

A modern wet spinning technology, known as solution gel spinning, is now used for ultrahigh molecular weight PE (UHMWPE) (500,000-5000,000), to obtain extended-chain PE fibers. 

P.J. Lemstra, C.W.M. Bastiaansen, S. Rastogi, Basic aspects of solution (Gel)-spinning and ultra-drawing of ultra-high molecular weight polyethylene. Structure Formation in Polymeric Fibers Salem, D. R., Ed. Hanser Munich, 2000, pp. 186-223. 

Lemstra, P.J., Bastiaansen, C.W.M., and Rastogi, S., Basic Aspects of Solution(Gel)-Spinning and Ultra-Drawing of Ultra-High Molecular Weight Polyethylene , in Structure Formation in Polymeric Fibers, Editor Salem, D.R., Hanser Gardner Publications Inc, 2000. 

Solubility of polymers in tetramethyl ammonium hydroxide aqueous solution was measured by dipping the wafer on which the polymer solution was spin-coated, for 1 min. at 25°C. The prebake was carried out at 90°C for 5min. Sensitivity of resists was measured after the exposure with CA 800(Cobilt) or KrF excimer laser(0.9mJ/cm2/1 pulse). The polymer structure was determined by iH-NMR, 13C-NMR(FX90Q apparatus,JEOL) and 2 Si-NMR. The molecular weight distribution was determined with a Toyo Soda Model 801 gel permeation chromatograph at 40°C. The four columns were connected in series, each packed with G-2000H8x3 and G-400H8(Toyo Soda polystylene gel), respectively. 

De Gennes scaling concepts for polymer solutions and melts and the concept of reptation movement of polymer chains in melts Pennings discovery of chain extension and shish-kebab formation in stirred solutions of very high MW polyethylene this eventually led to the ultra-high modulus gel-spinning process of polyethylene... 

The next major development was the "gel-spinning" by Smith and Lemstra (1979), where a "gel fibre" is first produced by spinning a dilute solution of very high molecular weight polyethylene into cold water after drying this "gel fibre" is drawn in a hot oven at... 

Fig. 3. Tensile strength at break, a, after hot-drawing against take-up speed during gel-spinning of UHMWPE at different concentrations of aluminium stearate (wt.- %) in the spinning solution (Die e = 14.5 cm, a = 6" and D = 1.8 mm). With permission of the publishers Chapman Hall Ltd, (C)...

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