ISOTACTIC PROPYLENE COPOLYMER FIBERS, THEIR PREPARATION AND USE

摘要

Fibers comprising a propylene homopolymer or a copolymer of propylene and at least one of ethylene and one or more unsaturated comonomers exhibit desirable properties. The homopolymers are characterized as having <13>C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity. The copolymers are characterized as (A) comprising at least about 60 weight percent (wt%) of units derived from propylene, and (B) having at least one of the following properties: (i) <13>C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity, (ii) a 13-value greater than about 1.4 when the comonomer content of the copolymer is at least about 3 wt%, (iii) a skewness index, Six, greater than about -1.20, (iv) a DSC curve with a Tme that remains essentially the same and a Tmax that decreases as the amount of comonomer in the copolymer is increased, and (v) an X-ray diffraction pattern that reports more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta (Z-N) catalyst.