Heat activated gels for cable filling applications

1. A heat activated gel for cable filling comprising:

a) a semi-crystalline, selectively hydrogenated block copolymer having the general formula C-A 1 -B 1 , wherein C is a semi-crystalline, hydrogenated polymer block of butadiene having a vinyl content before hydrogenation of 15 mol % or less and a molecular weight less than the molecular weight of the A 1 block, A 1 is a mono-alkenyl arene polymer block, and B 1 is a non-crystalline, hydrogenated polymer block of a conjugated diene;

b) a selectively hydrogenated diblock copolymer having the general formula A 2 -B 2 , wherein A 2 is a mono-alkenyl arene polymer block, and B 2 is a hydrogenated polymer block of a conjugated diene; and

c) a low polarity fluid,

wherein the semi-crystalline, selectively hydrogenated block copolymer and the selectively hydrogenated diblock copolymer are dissolved in the low polarity fluid.

2. The heat activated gel of claim 1 wherein the mass ratio of the semi-crystalline, selectively hydrogenated block copolymer to the selectively hydrogenated diblock copolymer ranges from 75:25 to 25:75.

3. The heat activated gel of claim 1 wherein the total mass of the semi-crystalline, selectively hydrogenated block copolymer and the selectively hydrogenated diblock copolymer is from about 1 to about 20 wt. %.

4. The heat activated gel of claim 1 wherein the mono-alkenyl arene polymer block A 1 and the mono-alkenyl arene polymer block A 2 are formed by polymerization of styrene.

5. The heat activated gel of claim 1 , wherein the conjugated diene in the B 2 block is butadiene, isoprene, or mixtures thereof.

6. The heat activated gel of claim 1 , wherein prior to hydrogenation, the B 1 block, the B 2 block, or the B 1 and B 2 blocks are polybutadiene blocks having a vinyl content greater than 25 mol %.

7. The heat activated gel of claim 1 wherein the low polarity fluid is selected from the group consisting of mineral oil, low toxicity synthetic oils, gas-to-liquid synthetic oils, and mixtures thereof.

8. The heat activated gel of claim 1 , wherein the C block has a vinyl content of 10 mol % or less.

9. The heat activated gel of claim 1 , comprising from about 4 to about 10 wt. % of a combination of the semi-crystalline, selectively hydrogenated block copolymer and the selectively hydrogenated diblock copolymer, and about 90 to about 96 wt. % of the low polarity fluid.

10. A process for forming a heat activated gel comprising

forming a mixture comprising a semi-crystalline, selectively hydrogenated block copolymer having the general formula C-A 1 -B 1 wherein C is a semi-crystalline, hydrogenated polymer block of butadiene having a vinyl content before hydrogenation of 15 mol % or less and a molecular weight less than the molecular weight of the A 1 block, A 1 is a mono-alkenyl arene polymer block, and B 1 is a non-crystalline, hydrogenated polymer block of a conjugated diene;

a selectively hydrogenated diblock copolymer having the general formula A 2 -B 2 , wherein A2 is a mono-alkenyl arene polymer block, and B2 is a hydrogenated polymer block of a conjugated diene; and a low polarity fluid; and

optionally heating the mixture.

11. A cable comprising the heat activated gel of claim 1 .

12. A process for forming the cable of claim 11 , comprising filling the cable with the heat activated gel of claim 1 at a temperature of less than about 130° C.

13. A process for severing the cable of claim 11 comprising heating a zone of the cable to a temperature of at least 130° C. for a time sufficient to activate the gel and then severing the cable in the heated zone.

14. The heat activated gel of claim 1 , wherein the heat activated gel has a 6 s −1 /200 s −1 ratio of a low shear viscosity to a high shear viscosity of at least 6.7 after being heated to a temperature of at least 130° C.

15. The heat activated gel of claim 1 , wherein the heat activated gel after being heated to a temperature of at least 130° C., and upon standing at a temperature from about 80° C. to about 100° C. for 24 hours, the heat activated gel exhibits no separation of the low polarity fluid.

16. The heat activated gel of claim 1 , the heat activated gel has a 6 s −1 /200 s −1 ratio of a low shear viscosity to a high shear viscosity of at least about 6.7 prior to any heat activation.

17. The heat activated gel of claim 1 , wherein prior to heat activation, the gel has a 200 s −1 high shear viscosity that is about 20%-50% of a 200 s −1 high shear viscosity exhibited by a reference sample having only components b) and c).

18. A heat activated gel for cable filling comprising:

a) a semi-crystalline, selectively hydrogenated block copolymer having the general formula C-A 1 -B 1 , wherein:

C is a semi-crystalline, hydrogenated polymer block of butadiene having a vinyl content before hydrogenation of less than 15 mol %, a melting point of at least 74° C., and a molecular weight less than the molecular weight of the A 1 block;

A 1 is a mono-alkenyl arene polymer block having a molecular weight of at least 9,000 g/mol; and

B 1 is a non-crystalline, hydrogenated polymer block of a conjugated diene having a molecular weight from about 80,000-160,000 g/mol;

b) a selectively hydrogenated diblock copolymer having the general formula A 2 -B 2 , wherein A2 is a mono-alkenyl arene polymer block, and B2 is a hydrogenated polymer block of a conjugated diene; and

c) a low polarity fluid.

19. The heat activated gel of claim 18 , wherein

the C block has a molecular weight of about 13,000-15,000 g/mol, and a vinyl content prior to hydrogenation of about 8 mol %; the A 1 block has a molecular weight of about 80,000-90,000 g/mol; and the B1 block has a molecular weight of about 109,000-142,000 g/mol; and

the A 2 block has a molecular weight of about 36,000 g/mol, and

the B 2 block has a molecular weight of about 96,000 g/mol.

20. The heat activated gel of claim 18 , wherein components a) and b) are present in a 1:1 weight ratio.