Polymers

1. A copolymer of ethylene and an α-olefin said copolymer having

(a) a density in the range 0.900-0.940 g/cm 3 ,

(b) a melt index MI 2 (2.16 kg, 190° C.) in the range 0.01-50 g/10 min,

(c) a molecular weight distribution (Mw/Mn, by conventional GPC) in the range 2.0-4.5,

(d) a comonomer partition factor, C pf >1, and

(e) a melt index MI 2 (2.16 kg, 190° C.) normalised Dow Rheology Index (DRI), [DRI/MI 2 ] in the range 3-20;

wherein the copolymer exhibits specific rheological behavior and processability characteristics that satisfy the following equation in relating the Dow Rheology Index (DRI) and Shear Thinning Index, SHI (2.1/210),

SHI (2.1/210)≦[0.2351×DRI]+C,

with C having a value of 3.4.

2. A copolymer according to claim 1 having a density in the range 0.910 to 0.930 g/cm 3 .

3. A copolymer according to claim 2 having a density in the range 0.915 to 0.925 g/cm 3 .

4. A copolymer according to claim 1 having a melt index MI 2 (2.16 kg, 190° C.) in the range 0.1 to 25 g/10 min.

5. A copolymer according to claim 4 having a melt index MI 2 (2.16 kg, 190° C.) in the range 0.5 to 5 g/10 min.

6. A copolymer according to claim 1 having a molecular weight distribution (Mw/Mn, by conventional GPC) in the range 2.5-4.5.

7. A copolymer according to claim 6 having a molecular weight distribution (Mw/Mn, by conventional GPC) in the range 3.0-4.0.

8. A copolymer according to claim 1 having a [DRI/MI 2 ] in the range 6 to 20.

9. A copolymer according to claim 8 having a [DRI/MI 2 ] in the range 6 to 18.

10. A copolymer according to claim 1 having a comonomer partition factor, C pf in the range 1.1 to 1.50.

11. A copolymer according to claim 10 having a comonomer partition factor, C pf in the range 1.1 to 1.45.

12. A copolymer according to claim 1 having a melt elastic modulus G′(G″=500 Pa) at 190° C. in the range 40 to 150 Pa.

13. A copolymer according to claim 1 having a melt elastic modulus G′(G″=500 Pa) at 190° C. in the range 65 to 150 Pa.

14. A copolymer according to claim 13 having a melt elastic modulus G′(G″=500 Pa) at 190° C. in the range 70 to 105 Pa.

15. A copolymer according to claim 1 having a Dow Rheology Index (DRI)≧6.

16. A copolymer according to claim 15 having a Dow Rheology Index (DRI) in the range 9-25.

17. A copolymer according to claim 15 having a Dow Rheology Index (DRI) in the range 13-25.

18. A copolymer according to claim 15 having a Dow Rheology Index (DRI) in the range 13-20.

19. A copolymer according to claim 1 wherein C has a value of 3.0.

20. A copolymer according to claim 1 wherein C has a value of 2.7.

21. A copolymer according to claim 1 wherein the copolymer is monomodal.

22. A copolymer according to claim 1 wherein the α-olefin has 3 to 10 carbon atoms.

23. A copolymer according to claim 1 wherein the α-olefin is 1-hexene.

24. A process for the preparation of copolymers according to claim 1 comprising copolymerising ethylene and α-olefins in the presence of a catalyst system comprising

(a) a transition metal compound, and

(b) an activated support.

25. A process according to claim 24 wherein the activated support is a fluorinated support.

26. A process according to claim 25 wherein the support comprises silica.

27. A process according to claim 24 wherein the transition metal compound is a metallocene.

28. A process according to claim 24 performed in the gas phase.

29. A process according to claim 24 performed in a single reactor.