Reactive friable polyimide and method of making
Disclosed herein is a friable polyimide powder having a weight average molecular weight, as determined by gel permeation chromatography (GPC) using polystyrene standards, of less than or equal to 24,500 Daltons and a reactive aromatic amine end group concentration greater than or equal to 3 mole percent, wherein 90 weight percent of the powder particles are reducible to less than or equal to 75 micrometers by mechanical grinding. Also disclosed is a method of making the friable polyimide powder, a processed polyimide resulting from the friable polyimide powder and compositions comprising the processed polyimide.
1. A friable polyimide powder having
a weight average molecular weight, as determined by gel permeation chromatography using polystyrene standards, of less than or equal to 24,500 Daltons, and
a reactive aromatic amine end group concentration greater than 3 mole percent,
wherein 90 weight percent of the powder particles are reducible to less than or equal to 75 micrometers by mechanical grinding.
2. The friable polyimide powder of claim 1 , having a weight average molecular weight of 5,000 to 24,500 Daltons.
3. The friable polyimide powder of claim 1 , having a reactive aromatic amine end group concentration of 3.1 to 40 mole percent.
4. The friable polyimide powder of claim 1 , wherein 90 weight percent of the particles are reducible to 1 to 75 micrometers.
5. The friable polyimide powder of claim 1 , wherein 90 weight percent of the particles are reducible to 25 to 75 micrometers by mechanical grinding.
6. The friable polyimide powder of claim 1 , wherein the polyimide is a polyetherimide that comprises units of the formula
wherein
R is a C 2-20 hydrocarbon group,
T is —O— or a group of the formula —O—Z—O— wherein the divalent bonds of the —O— or the —O—Z—O— group are in the 3,3′, 3,4′, 4,3′, or the 4,4′ positions, and
Z is an aromatic C 6-24 monocyclic or polycyclic group optionally substituted with 1 to 6 C 1-8 alkyl groups, 1-8 halogen atoms, or a combination comprising at least one of the foregoing.
7. The friable polyimide powder of claim 6 , wherein R is a divalent group of the formula
wherein
Q 1 is —O—, —S—, —C(O)—, —SO 2 —, —SO—, —C y H 2y — and a halogenated derivative thereof wherein y is an integer from 1 to 5, or —(C 6 H 10 ) z — wherein z is an integer from 1 to 4; and Z is a group derived from a dihydroxy compound of the formula
wherein
R a and R b are each independently a halogen atom or a monovalent C 1-6 alkyl group;
p and q are each independently integers of 0 to 4;
c is 0 to 4; and
X a is a single bond, —O—, —S—, —S(O)—, —SO 2 —, —C(O)—, or a C 1-18 organic bridging group.
8. The friable polyimide powder of claim 7 , wherein each R is independently meta-phenylene, para-phenylene, 4,4′-diphenylene sulfone, a combination comprising at least one of the foregoing, and Z is 4,4′-diphenylene isopropylidene.
9. The friable polyimide powder of claim 6 wherein the polyimide powder is a polyetherimide comprising structural units of the formula
wherein T is a group of the formula —O—Z—O— and derived from bisphenol A and R is m-phenylene.
10. The friable polyimide powder of claim 1 , wherein the polyimide comprises units of the formula
wherein each R is derived from R is a C 2-20 hydrocarbon group and V is an unsubstituted C 6 aromatic hydrocarbon group.
11. The friable polyimide powder of claim 1 , wherein the polyimide comprises units of the formula
wherein V is benzophenone, biphenyl, C 6 aromatic hydrocarbon group, or a combination thereof.
12. A method of making a processed polyimide powder comprising mechanically grinding the friable polyimide powder of claim 1 , sieving the product of grinding with a 75 micrometer sieve, and collecting the particles that pass through the sieve.
13. A processed polyimide powder produced by the method of claim 12 having
a weight average molecular weight, as determined by gel permeation chromatography using polystyrene standards, of less than or equal to 24,500 Daltons, and
a reactive aromatic amine end group concentration greater than 3 mole percent, and
a maximum particle size less than or equal to 75 micrometers.
14. A curable composition comprising the processed polyimide powder of claim 13 and a thermosetting component.
15. The curable composition of claim 14 , wherein the thermosetting component comprises an epoxy component, bismaleimide component, cyanoacrylate component, or a combination thereof.
16. A method of making a friable polyimide powder comprising melt blending
a first polyimide having a weight average molecular weight greater than or equal to 30,000 Daltons with
greater than 3 mole percent of an aromatic diamine under conditions effective to form a friable polyimide powder;
having a weight average molecular weight less than or equal to 24,500 Daltons,
an aromatic amine reactive end group concentration greater than 3 mole percent, and
wherein 90 weight percent of the powder particles are reducible to less than or equal to 75 micrometers by mechanical grinding
wherein the weight average molecular weight is determined by gel permeation chromatography using polystyrene standards, and mole percent is based on the moles of the dianhydride in the first polyimide polymer.
17. The method of claim 16 , wherein the first polyimide has a weight average molecular weight of 30,000 to 80,000 Daltons.
18. The method of any one of claim 16 , wherein the aromatic diamine is added to first polyimide in molten form.
19. The method of claim 16 , wherein the diamine is of the formula H 2 N—R 1 —NH 2 wherein R 1 is a divalent group of the formula
wherein Q 1 is —O—, —S—, —C(O)—, —SO 2 —, —SO—, —C y H 2y — wherein y is an integer from 1 to 5 or a halogenated derivative thereof (which includes perfluoroalkylene groups), or —(C 6 H 10 ) z — wherein z is an integer from 1 to 4.
20. The method of claim 16 , wherein the diamine comprises m-phenylenediamine.