| abstract |
A flexible, ignition resistant, biregional fiber is disclosed, wherein the fiber is preferably derived from a single homogeneous polymeric precursor composition, said biregional fiber comprising an inner core region of a thermoplastic polymeric composition and a surrounding outer sheath region of a thermoset carbonaceous material. The biregional fiber is particularly characterized by having a ratio of the radius of the core region with respect to the total radius of the fiber (r:R) of from about 1:4 to about 1:1.05, an LOI value of greater than 40, a breaking twist angle of from 4 to 13 degrees, and a bending strain value of from greater than 0.01 to less than 50 %. In a further embodiment of the invention, a biregional precursor fiber is disclosed, wherein the biregional precursor fiber is preferably derived from a single homogeneous polymeric composition, and wherein said precursor fiber comprises an inner core region of a thermoplastic polymeric composition and a surrounding outer sheath region of an oxidation stabilized, thermoplastic polymeric composition. The precursor fiber is particularly characterized by having a breaking twist angle of from 17 to 23 degrees. The invention further resides in a method of making the ignition resistant biregional fiber. Preferred end uses for the ignition resistant biregional fibers are disclosed including thermal insulation; flame resistant and fire blocking insulation; blends of the biregional fibers with other natural or polymeric fibers; coated fibers, composites of a polymeric matrix reinforced with the biregional fibers of the invention, electron conductive fibers for battery electrodes, and the like. |