Electrically conducting compositions
View Patent ↗Disclosed herein is an electrically conducting polymer composition and method of making a composition including an organic polymer; and a first filler including at least one ceramic filler, at least one metallic filler, or a combination including at least one of the foregoing fillers, wherein a trip temperature of the composition does not change by an amount of greater than or equal to ±10° C. when the composition is cycled 100 times between room temperature and the trip temperature. Disclosed herein as well is an electrically conducting polymer composition including a first filler including at least one ceramic filler, at least one metallic filler, or a combination including at least one of the foregoing fillers and a second filler. The compositions of the present invention have a trip temperature that is lower than the HDT temperature of the composition and can have tunable trip temperatures.
1. An electrically conducting polymer composition comprising:
an organic polymer; and
a filler including at least one ceramic filler, at least one metallic filler, or a combination including at least one of the foregoing fillers;
wherein at least a portion of filler has a hardness of greater than or equal to 500 Vickers;
further wherein the composition has a trip temperature less than the heat deflection temperature of the composition at 0.45 MPa and wherein the difference between the trip temperature and the heat deflection temperature is 10° C. or greater.
2. The composition of claim 1 , having a room temperature volume resistivity of less than or equal to 1×10 4 ohm-cm and a positive temperature coefficient of resistance intensity of at least 5.
3. The composition of claim 1 , wherein the difference between the trip temperature of the composition between a 2nd cycle and a 100th cycle is less than or equal to 10° C.
4. The composition of claim 1 , wherein the filler includes a ceramic filler that is electrically conducting and comprises titanium diboride, tin oxide, indium tin oxide, antimony tin oxide, tungsten carbide, titanium nitride, zirconium nitride, titanium carbide, molybdenum silicide, potassium titanate whiskers, vanadium oxide or a combination comprising at least one of the foregoing ceramic fillers.
5. The composition of claim 1 , wherein the filler includes a metallic filler that comprises silver, vanadium, tungsten, nickel, stainless steel, tool steel, neodymium iron boron (NdFeB), samarium cobalt (SmCo), aluminum nickel cobalt (AlNiCo), or a combination comprising at least one of the foregoing metallic filler.
6. The composition of claim 1 , wherein the filler has an average particle size of less than or equal to 1000 microns.
7. The composition of claim 1 , wherein the filler has an average particle size of less than or equal to 250 microns.
8. The composition of claim 1 , wherein the filler is present in an amount of 20 to 95 wt % of the total weight of the electrically conducting polymer composition.
9. The composition of claim 1 , wherein the organic polymer is an amorphous polymer or a semi-crystalline polymer.
10. The composition of claim 1 , wherein a molded article formed from the electrically conducting polymer composition has a Class A surface finish.
11. The composition of claim 1 , wherein the electrically conducting polymer composition has an electrical volume resistivity of less than or equal to 1×10 4 ohm-cm.
12. The composition of claim 1 , wherein the composition has a specific volume change between 0.5-5% at the trip temperature.
13. An article comprising the composition of claim 1 .
14. A method comprising:
blending an organic polymer with a first filler including at least one ceramic filler, at least one metallic filler, or a combination including at least one of the foregoing fillers to form an electrically conducting polymer composition,
wherein at least a portion of the first filler has a hardness of greater than or equal to 500 Vickers; further wherein the electrically conducting polymer composition has a trip temperature less than the heat deflection temperature of the composition at 0.45 MPa and wherein the difference between the trip temperature and the heat deflection temperature is 10° C. or greater; and
molding the electrically conducting polymer composition.
15. The method of claim 14 further comprising the step of: adding a second filler prior to molding in an amount sufficient to generate a continuous conductive network in the composition.
16. The method of claim 15 , wherein the blending step is selected from solution blending, melt blending or a combination including at least one of the foregoing blending steps.
17. The method of claim 14 , further comprising the step of tuning a trip temperature of the electrically conducting polymer composition using an additional processing step.
18. The method of claim 17 , wherein the additional processing step comprises controlling the cooling rate in the part formation step to tune the trip temperature.
19. The method of claim 18 , wherein the cooling process is selected to have a cooling rate of 1° C./min to 1500° C./min.
20. The method of claim 17 , wherein the additional processing step is a heating process to tune the trip temperature.
21. The method of claim 20 , wherein the heating process is selected from the step of annealing the electrically conducting polymer composition.
22. The method of claim 17 , wherein the additional processing step is a molding process selected from injection molding, compression molding, injection-compression molding, thermoforming, or a combination including at least one of the foregoing process.
23. An article comprising a composition made by the method of claim 14 .