Long chain branched propylene-alpha-olefin copolymers

1. A substantially isotactic propylene interpolymer having an average of 0.001 long chain branches per 1000 total carbons and comprising (A) at least 60 weight percent (wt %) units derived from propylene, and (B) between 1 and 40 wt % units derived from ethylene, the propylene interpolymer characterized by (1) a g′ ratio of less than 1 measured at interpolymer number average molecular weight (Mn)and (2) a relative compositional drift of less than 50%.

2. The isotactic propylene interpolymer of claim 1 which is further characterized by propylene chain segments having a chain isotacticity triad index of at least 70 mole percent.

3. The isotactic propylene interpolymer of claim 1 in which the g′ ratio is less than 0.96.

4. The isotactic propylene interpolymer of claim 1 in which the relative compositional drift of less than 40%.

5. The isotactic propylene interpolymer of claim 1 in which the propylene chain segments have a chain isotacticity triad index of at least 80 mole percent.

6. The isotactic propylene interpolymer of claim 1 comprising between 1 and 20 wt % units derived from ethylene.

7. The isotactic propylene interpolymer of claim 1 further characterized by at least one of the following properties:

(a) A weight average molecular weight (Mw) of at least 50,000 grams per mole (g/mol);

(b) A unimodal molecular weight distribution, and an Mw/Mn of less than 4;

(c) A critical shear rate at the onset of surface melt fracture (OSMF) of at least 4,000 sec −1 ; and

(d) A nominal weight percent crystallinity of from greater than 2 to 40 wt %.

8. The isotactic propylene interpolymer of claim 7 further comprising at least two of properties (a)-(d).

9. The isotactic propylene interpolymer of claim 7 having a Mw/Mn of less than 3.5.

10. An article comprising the propylene interpolymer of claim 1 .

11. A film, fiber, sheet, tube, molded profile, coating, dispersion, emulsion or foam comprising the propylene interpolymer of claim 1 .

12. A substantially isotactic propylene interpolymer having an average of 0.001 long chain branches per 1000 total carbons and comprising (A) at least 90 weight percent (wt %) units derived from propylene, and (B) between 1 and 10 wt % units derived from ethylene, the propylene interpolymer characterized by a log 10 intrinsic viscosity of less than 0.5 at a log 10 weight average molecular weight of 5.8, a g′ ratio of less than 1 measured at interpolymer number average molecular weight (Mn) and a relative compositional drift of less than 50%.

13. A substantially isotactic propylene interpolymer having an average of 0.001 long chain branches per 1000 total carbons and comprising (A) at least 90 weight percent (wt %) units derived from propylene, and (B) between 1 and 10 wt % units derived from ethylene, the propylene interpolymer characterized by a log 10 intrinsic viscosity of less than 0.35 at a log 10 weight average molecular weight of 5.5, a g′ ratio of less than 1 measured at interpolymer number average molecular weight (Mn) and a relative compositional drift of less than 50%.

14. The article of claim 10 wherein the article is a multilayer film prepared by cast, blown, calendered or extrusion coating processes.

15. The article of claim 14 wherein the article is at least one of a greenhouse film, heat-seal film, shrink film, lamination film, biaxially-oriented film, extrusion coated film, liner, over-wrap film and agricultural film.

16. The article of claim 10 wherein the article is a multi-component fiber.

17. The fiber of claim 16 wherein the fiber is a core/sheath fiber in which the substantially isotactic propylene interpolymer comprises an outer surface layer.

18. The fiber of claim 17 wherein the fiber is a staple fiber, tow fiber, twisted fiber or monofilament.

19. A crosslinked, substantially isotactic propylene interpolymer of claim 1 .

20. A blend comprising the substantially isotactic propylene interpolymer of claim 1 and at least one other polymer.