North Carolina State University

Gao-Yuan Chen

John A Cuculo

Ferdinand Lundberg

Paul A Tucker

Gang Wu

Jeffrey Denton

Chon-yie Lin

Jiunn-Yow Chen

Ultra-oriented, crystalline synthetic filaments with a combination of high tenacity, high dimensional stability, high modulus, and a high fraction of taut-tie molecular phase are produced by extruding a fiber-forming synthetic polymer melt into a liquid isothermal bath, withdrawing the filaments from the bath and then post-treating them at a very low draw ratio. The bath is preferably maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer to enhance the orientation and promote the formation of stable extended chains. Polymer filaments so produced are characterized in that they have ultra-high birefringence, high tenacity and modulus, a high dimensional stability, and a high fraction of taut-tie molecular phase.

Ultra-oriented crystalline filaments and method of making same

Ultra-oriented, crystalline synthetic filaments with high tenacity are produced by extrusion of a fiber-forming synthetic polymer melt into a liquid isothermal bath maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer, withdrawing the filaments from the bath and then winding up the filaments. Polymer filaments so produced are characterized in that the ratio of the crystalline orientation factor (f.sub.c) to the amorphous orientation factor (f.sub.a) is 1.2 or less, and are further characterized in that the percent crystallinity is less than 40. The filaments also have a fine crystal size. The crystal size is less than 40 .ANG. in the 100 and 105 planes and less than 30 .ANG. in the 010 plane.

Ultra-oriented crystalline filaments

Ultra-oriented, crystalline synthetic filaments with high tenacity are produced by extrusion of a fiber-forming synthetic polymer melt into a liquid isothermal bath maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer, withdrawing the filaments from the bath and then winding up the filaments. Polyethylene terephthalate filaments so produced at 3000-5000 m/min exhibit a crystalline structure and possess birefringence of 0.20-0.22, tenacity of 7-9 g/d, break elongation of 14-30% and boil-off shrinkage of 5-10%.

Melt spinning of ultra-oriented crystalline filaments

Ultra-oriented, crystalline synthetic filaments with high tenacity are produced by extrusion of a fiber-forming synthetic polymer melt into a liquid isothermal bath maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer, withdrawing the filaments from the bath and then winding up the filaments. Polyethylene terephthalate filaments so produced at 3000-5000 m/min exhibit a crystalline structure and possess birefringence of 0.20-0.22, tenacity of 7-9 g/d, break elongation of 14%-30% and boil-off shrinkage of 5%-10%.

Melt spinning of ultra-oriented crystalline polyester filaments

The high speed melt spinning of synthetic polymer fibers is provided with on-line zone heating and cooling by which the strand emerging from the spinneret is initially cooled to an optimum temperature above the glass transition point of the polymer, the maintained near that temperature for a period of time to promote development of desirable fiber properties such as crystallization and crystal orientation, and then finally cooled below the solidification point for take up.

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Midlothian, VA, United States of America

Gao-Yuan Chen