Narrow MWD, compositionally optimized ethylene interpolymer composition, process for making the same and article made therefrom
A polymer composition comprises at least two polymer components, the first component having an ATREF peak temperature, T peak1 , and a viscosity average molecular weight, M v1 , and the second component having an ATREF peak temperature, T peak2 , and a viscosity average molecular weight, M v2 , wherein the temperature differential between T peak2 and T peak1 decreases with increased composition density and M v1 /M v2 is less than or equal to 1.2. the composition is further characterized as having a M w /M n of less than or equal to 3.3, an I 10 /I 2 >6.6, and a composition density less than 0.945 gram/cubic centimeter.
1. A polymer composition comprising at least two ethylene polymer components, the first polymer component is a homogeneously branched linear ethylene polymer, wherein the composition is characterized as having:
a) a M w /M n of less than or equal to 3.3, as determined by gel permeation chromatography (GPC),
b) an I 10 /I 2 in the range of from greater than 6.6 to about 8.2, as determined in accordance ASTM D-1238, Condition 190° C./2.16 kg and Condition 190° C./10 kg,
c) a composition density less than 0.945 gram/cubic centimeter, as determined according to ASTM-792,
d) the first polymer component having a first viscosity average molecular weight, M v1 , and the second polymer component having a second viscosity average molecular, M v2 , wherein M v1 /M v2 is less than or equal to 1, as determined using ATREF-DV, and
e) a first ATREF peak temperature, T peak1 , and a second ATREF peak temperature, T peak2 , corresponding to the at least two components and as determined using analytical temperature rising elution fraction (ATREF), wherein the temperature differential between T peak2 and T peak1 , ΔT, decreases with increased composition density such that ΔT is less than 23° C. at composition densities of greater than or equal to 0.926 g/cm 3 and is greater than 43° C. at composition densities less than or equal to 0.92 g/cm 3 .
2. The composition of claim 1 wherein the I 10 /I 2 ratio is greater than or equal to 7.1, as determined in accordance with ASTM D-1238, Condition 190° C./10 kg.
3. The composition of claim 1 further characterized as having a density differential between the two components less than or equal to 0.028 g/cm 3 , as measured in accordance with ASTM D-792.
4. The composition of claim 1 wherein the M v1 /M v2 is in the range of from about 0.8 to about 1, as determined using an ATREF-DV technique.
5. The composition of claim 1 wherein at least one of the first polymer component or second polymer component is prepared using a homogeneous catalyst system.
6. The composition of claim 1 , wherein the second polymer components is a heterogeneously branched ethylene polymer.
7. The composition of claim 1 wherein both the first and second polymer components are homogeneously branched ethylene polymers.
8. The composition of claim 7 wherein at least one of the homogeneously branched ethylene polymers is a substantially linear ethylene polymer.
9. The composition of claim 1 , wherein the first component is present in the composition in an amount of at least 40 wt. %.
10. The composition of claim 1 , wherein the first component is present in the composition in an amount of at least 60-75 wt. %.
11. The composition of claim 1 , wherein the first component is present in the composition in an amount of at least 65-70 wt. %.