| 摘要 |
The invention comprises an elastomeric crystalline polypropylene fibre having gamma orientation and a heat stable orientation angle of 10 to 30 degrees, which angle is defined as the azimuthal extent of the intensity of the (040) X-ray diffraction arc at 2 #q=16,7 degrees. Preferably the fibre has a gamma intensity of at least 1,0, an orientation angle of 10 to 21 degrees and a tensile recovery on the second and succeeding cycles from a 25% elongation of at least 90%. In an example (1) crystalline polypropylene of melt index 0,7 is extruded as a melt at 289 DEG C. through a spinneret containing 34 orifices of 0,015 inch in diameter arranged in a rectangle 1 inch by 3/16 inch in a staggered disposition. The yarn is advanced at 45 yards per minute and is quenched by means of an apparatus disposed perpendicularly to the face of the spinneret. This quenching apparatus comprises a 3/4 inch outside diameter tube containing a plurality of 1/16 inch diameter holes adapted to direct air against the walls of the cylindrical chamber in which it is mounted, except the wall facing the threadline. The as-spun yarn has a total denier of 1,409, an orientation angle of 22 degrees and a gamma intensity ratio of 1,5. |
