Ethylene homopolymers with a reverse short chain branch distribution
Disclosed herein are ethylene homopolymers generally characterized by a density of less than 0.94 g/cm 3 and an inverse short chain branch distribution. These homopolymers can be further characterized by a ratio of Mw/Mn from 2 to 100, a number of short chain branches from 2 to 20 short chain branches per 1000 total carbon atoms, and wherein at least 50% of the short chain branches are methyl branches.
1. An ethylene homopolymer having:
a density of less than or equal to about 0.925 g/cm 3 ;
a number of short chain branches (SCB's) in a range from about 3 to about 15 SCB's per 1000 total carbon atoms; and
a number of SCB's per 1000 total carbon atoms of the homopolymer at Mw that is greater than at Mn;
wherein at least about 50% of the SCB's are methyl branches.
2. The homopolymer of claim 1 , wherein the homopolymer is further characterized by a number of SCB's per 1000 total carbon atoms at Mz that is greater than at Mn.
3. The homopolymer of claim 1 , wherein:
the density is in a range from about 0.905 to about 0.922 g/cm 3 ;
the number of SCB's per 1000 total carbon atoms is in a range from about 4 to about 12; and
at least about 70% of the SCB's are methyl branches.
4. An article of manufacture comprising the homopolymer of claim 3 .
5. The homopolymer of claim 1 , wherein the homopolymer is further characterized by:
a ratio of Mw/Mn in a range from about 5 to about 20; and
a ratio of Mz/Mw in a range from about 2.5 to about 7.
6. The homopolymer of claim 1 , wherein the homopolymer is further characterized by:
a Mw in a range from about 80,000 to about 500,000 g/mol;
a Mn in a range from about 10,000 to about 60,000 g/mol; and
a Mz in a range from about 500,000 to about 2,000,000 g/mol.
7. The homopolymer of claim 1 , wherein the homopolymer is further characterized by:
a number of long chain branches (LCB's) per 1000 total carbon atoms in a range from about 0.1 to about 8;
a peak melting point in a temperature range from about 120 to about 132° C.; and
a percent crystallinity in a range from about 35 to about 70%.
8. An article of manufacture comprising the homopolymer of claim 7 .
9. An ethylene homopolymer having:
a density in a range from about 0.90 to about 0.925 g/cm 3 ;
a number of long chain branches (LCB's) per 1000 total carbon atoms in a range from about 0.3 to about 2;
a number of SCB's per 1000 total carbon atoms of the homopolymer at Mw that is greater than at Mn; and
a ratio of Mw/Mn in a range from about 2 to about 100;
wherein at least about 50% of the SCB's are methyl branches.
10. An article of manufacture comprising the homopolymer of claim 9 .
11. The homopolymer of claim 9 , wherein the homopolymer is further characterized by a number of SCB's per 1000 total carbon atoms at Mz that is greater than at Mn.
12. The homopolymer of claim 9 , wherein:
the density is in a range from about 0.905 to about 0.922 g/cm 3 ;
the ratio of Mw/Mn is in a range from about 6 to about 16; and
at least about 75% of the SCB's are methyl branches.
13. An article of manufacture comprising the homopolymer of claim 12 .
14. The homopolymer of claim 9 , wherein the ratio of Mw/Mn is in a range from about 4 to about 30.
15. The homopolymer of claim 9 , wherein the homopolymer is further characterized by:
a Mw in a range from about 150,000 to about 800,000 g/mol;
a Mn in a range from about 15,000 to about 45,000 g/mol; and
a Mz in a range from about 500,000 to about 2,000,000 g/mol.
16. The homopolymer of claim 9 , wherein the homopolymer is further characterized by:
a number of short chain branches (SCB's) per 1000 total carbon atoms in a range from about 4 to about 9;
a peak melting point in a temperature range from about 120 to about 130° C.; and
a percent crystallinity in a range from about 45 to about 60%.
17. An article of manufacture comprising the homopolymer of claim 16 .
18. A polymerization process comprising:
contacting a catalyst composition with ethylene and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an ethylene polymer, wherein:
the catalyst composition comprises a nickel diimine complex, a metallocene compound, and an activator; and
the ethylene polymer is characterized by:
a density of less than or equal to about 0.925 g/cm 3 ;
a number of short chain branches (SCB's) in a range from about 3 to about 15 SCB's per 1000 total carbon atoms; and
a number of SCB's per 1000 total carbon atoms of the polymer at Mw that is greater than at Mn; and
wherein at least about 50% of the SCB's are methyl branches.
19. The process of claim 18 , wherein:
the ethylene polymer comprises an ethylene homopolymer;
the catalyst composition further comprises a co-catalyst; and
the polymerization reactor system comprises a slurry reactor, a gas-phase reactor, a solution reactor, or a combination thereof.
20. The process of claim 19 , wherein the ethylene homopolymer is further characterized by:
a ratio of Mw/Mn in a range from about 5 to about 30.