Fibres 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). 

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... 

R. Kirschbaum, J. L. J. van Dingenen, Advances in gel spinning technology and Dyneema fibre applications . Integration of polymer science and technology, 3 Rolduc Conf. Elsevier Amsterdam (1988). 

Recently elastic polyolefin fibres have also been introduced (generic name lastol), they are cross-linked and stable at temperatures up to 220 °C and above.- High-tenacity polyethylene fibres, with ultra high molecular weight (UHMW-PE, Dyneema) have been available for some time they are produced by a gel-spinning process at high dilution. 

UHMWPE is a type of polyolefin that is commercially produced in the fibre form as Dyneema by DSM and as Spectra by Honeywell. It is produced by gel spinning. 

Jacobs, M.J.N. and Mencke, JJ. (1995) New technologies in gel spinning the world s strongest fibre. Internationales Techtextil Symp., Frankfurt, Paper 2.13. 

Considering fibres based on poly(hydroxybutyrate) or higher PHAs, no successful process was reported for preparation of PHB fibres by conventional fibre processing technology, i.e. melt or gel spinning with subsequent hot drawing. Therefore, more sophisticated procedures have to be developed to achieve reasonable draw ratios, resulting in production of anisotropic material with important improvement of properties. 

Wang, J., Miao, M., Wang, Z., Humphries, W., Gu, Q., 2013b. A method of mobilizing and aligning carbon nanotubes and its use in gel spinning of composite fibres. Carbon 57, 217-226. 

As described earlier, the main prerequisite for the creation of high performance self-reinforced polymer composites is a thermoplastic polymer fibre with the necessary mechanical properties to make the creation of the final composites attractive. Ultrahigh molecular weight polyethylene (UHMWPE) fibres with veiy high mechanical properties, produced by gel spinning, became commercially... 

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