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1. (WO2013048690) RHEOLOGICAL METHODS TO DETERMINE THE PREDISPOSITION OF A POLYMER TO FORM NETWORK OR GEL
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CLAIMS

is claimed is:

A method to determine the predisposition of a polymer to form network or gel in a composition, comprising the steps of:

(a) obtaining a composition of a polymer in a diluent,

(b) measuring the shear stress of the composition as a function of shear rate or measuring the shear rate of the composition as a function of shear stress,

(c) determining the yield stress using the Herschel-Bulkley equation:

T = T0 + k(r)n

where, τ = Shear Stress

τ0 = Yield Stress

k = consistenc y

γ = shear rate

and n = power law exponent

, and

(d) comparing the yield stress, thereby determining the predisposition of the polymer to form a network or gel.

The method according to claim 1 , wherein the diluent comprises a lubricating oil and the polymer is an alpha-olefm copolymer.

3. The method according to claim 2, wherein the lubricating oil contains a Group I, II, III, IV or V base oil.

4. A method to determine the predisposition of a polymer to form network or gel in a composition, comprising the steps of:

(a) obtaining a composition of a polymer in a diluent, and

(b) determining at least one of (i) the storage modulus G' and loss modulus G" of the composition by subjecting the composition to sinusoidal (oscillating) stress or strain of certain amplitude and frequency, (ii) the phase lag (angle) of the response strain or stress δ, or (iii) the tangent (tan) δ, and

(c) assessing at least one of the G', G", δ, or tan(5) determined, thereby determining the predisposition of the polymer to form a network or gel.

5. The method according to claim 4, wherein the diluent comprises a lubricating oil and the polymer is an alpha-olefm copolymer.

6. The method according to claim 4, wherein the lubricating oil contains a Group I, II, III, IV or V base oil.

7. The method according to claim 1, wherein the polymer is an ethylene copolymer having an ethylene content of at least about 50 wt. %, by weight of the ethylene copolymer.

8. The method according to claim 1, wherein the polymer is a polymer composition that comprises at least 30 wt.%, based on the weight of the polymer composition, of a first copolymer of ethylene and an alpha-olefm comonomer, and 70 wt.% or less, based on the weight of the polymer composition, of a second copolymer of ethylene and an alpha-olefm comonomer, wherein the first copolymer has a lower ethylene content than the second copolymer.

9. The method of claim 1, further comprising selecting the polymer for use in a lubricating oil composition, and forming a lubricating oil composition comprising the polymer.

10. The method of claim 4, further comprising selecting the polymer for use in a lubricating oil composition, and forming a lubricating oil composition comprising the polymer.

11. A lubricating oil composition comprising a polymer selected according to the method of claim 9.

12. A lubricating oil composition comprising a polymer selected according to the method of claim 10.

13. The method of claim 1, wherein the comparing in step (d) comprises correlating the yield stress to a predetermined standard.

14. A method to determine the predisposition of a test polymer to form gel in a

composition, comprising the steps of:

(a) forming a sample composition comprising a sample polymer and a diluent,

(b) determining the yield stress of the sample composition,

(c) determining the gellation level of the sample composition,

(d) obtaining a correlation between yield stress with the gellation level of the sample composition to obtain a standard,

(d) obtaining a test polymer,

(e) determining the yield stress of the test polymer,

(f) applying the correlation obtained in step (d) to determine the

predisposition of the polymer to form a network or gel.

15. The method of claim 14, further comprising the step of (g) selecting the polymer for use in a lubricating oil composition, and forming a lubricating oil composition comprising the polymer.

16. The method according to claim 7, wherein the ethylene copolymer is an

ethylene/propylene copolymer.