Consolidated polymer film

1. A consolidated polymer film comprising:

a first polymer layer having a first elastic modulus, wherein the first polymer layer comprises a non-melt-processible polymer comprising a polyimide, a poly(amide-imide), a block copolymer of a polyimide or a poly(amide-imide) or a mixture thereof; and

a second polymer layer having a second elastic modulus, wherein the second polymer layer comprises a polyimide, a poly(amide-imide), a block copolymer of a polyimide or a poly(amide-imide) or a mixture thereof, wherein:

a minor surface of the first polymer layer is in contact with a minor surface of the second polymer layer;

the first elastic modulus is different from the second elastic modulus;

the first and second polymer layers are bonded by consolidation; the first and second polymer layers each have a transmittance of greater than 60% in the visible range; and the consolidated polymer film has a b* color of 2 or less for a film thickness of 50 μm or less.

2. The consolidated polymer film of claim 1 , wherein a Mode I interlaminar fracture toughness (G Ic ) between the first and second polymer layers is at least 500 J/m 2 .

3. The consolidated polymer film of claim 1 , wherein the elastic modulus of the first polymer layer is in a range of from 2 to 11 GPa.

4. The consolidated polymer film of claim 1 , wherein a difference between the elastic moduli of the first and second polymer layers is at least 5%.

5. The consolidated polymer film of claim 1 , wherein the first polymer layer, the second polymer layer, or both the first and second polymer layers have a speed of sound of at least 1300 m/s.

6. The consolidated polymer film of claim 1 , wherein the first polymer layer, the second polymer layer, or both the first and second polymer layers further comprise sub-micron fillers.

7. The consolidated polymer film of claim 1 , wherein the polymer of the first polymer layer is cross-linked, the polymer of the second polymer layer is cross-linked, or the polymers of both the first and second polymer layers are cross-linked.

8. The consolidated polymer film of claim 1 , wherein the second polymer layer comprises a non-melt-processible polymer comprising a polyimide, a poly(amide-imide), a block copolymer of a polyimide or a poly(amide-imide) or a mixture thereof.

9. The consolidated polymer film of claim 1 , further comprising a third polymer layer having a third elastic modulus, wherein:

the second polymer layer is positioned between the first and third polymer layers;

a minor surface of the second polymer layer is in contact with a minor surface of the third polymer layer;

the second and third polymer layers are bonded by consolidation; and

(i) the second elastic modulus is smaller than the first elastic modulus and the third elastic modulus is greater than the second elastic modulus, or (ii) the second elastic modulus is greater than the first elastic modulus and the third elastic modulus is greater than the second elastic modulus, or (iii) the second elastic modulus is greater than the first elastic modulus and third elastic modulus smaller than the second elastic modulus.

10. The consolidated polymer film of claim 9 , wherein the third polymer layer comprises a polyimide, a poly(amide-imide), a block copolymer of a polyimide or a poly(amide-imide), a polycarbonate, a polyethylene naphthalate, a polystyrene, a poly(methyl methacrylate) a polyethylene terephthalate, a polyethylene terephthalate glycol, a poly cyclohexylenedimethylene terephthalate glycol, a polyether imide, a polysulfone, a polyether sulfone, a polyarylsulfone, a polyaryletherketone, a cyclic olefin copolymer, or a mixture thereof.

11. The consolidated polymer film of claim 9 , wherein the third polymer layer comprises a non-melt-processible polymer comprising a polyimide, a poly(amide-imide), a block copolymer of a polyimide or a poly(amide-imide) or a mixture thereof.

12. The consolidated polymer film of claim 9 , further comprising a fourth polymer layer having a fourth elastic modulus, wherein a major surface of the fourth polymer layer is in contact with major surfaces of the first, second and third polymer layers, and the fourth polymer layer is bonded to at least one of the first, second and third polymer layers by consolidation.

13. The consolidated polymer film of claim 9 , wherein the fourth polymer layer comprises a non-melt-processible polymer comprising a polyimide, a poly(amide-imide), a block copolymer of a polyimide or a poly(amide-imide) or a mixture thereof.

14. A consolidated polymer film comprising:

a first polymer layer having a first yield strength, wherein the first polymer layer comprises a non-melt-processible polymer comprising a polyimide, a poly(amide-imide), a block copolymer of a polyimide or a poly(amide-imide) or a mixture thereof; and

a second polymer layer having a second yield strength, wherein the second polymer layer comprises a polyimide, a poly(amide-imide), a block copolymer of a polyimide or a poly(amide-imide) or a mixture thereof, wherein:

a minor surface of the first polymer layer is in contact with a minor surface of the second polymer layer;

the first yield strength is different from the second yield strength;

the first and second polymer layers are bonded by consolidation; the first and second polymer layers each have a transmittance of greater than 60% in the visible range; and the consolidated polymer film has a b* color of 2 or less for a film thickness of 50 μm or less.

15. The consolidated polymer film of claim 14 , wherein a difference between the yield strength of the first and second polymer layers is at least 5%.