Conductive thermosets by extrusion
View Patent ↗Methods of preparing conductive thermoset precursors containing carbon nanotubes is provided. Also provided is a method of preparing conductive thermosets containing carbon nanotubes. The carbon nanotubes may in individual form or in the form of aggregates having a macromorpology resembling the shape of a cotton candy, bird nest, combed yarn or open net. Preferred multiwalled carbon nanotubes have diameters no greater than 1 micron and preferred single walled carbon nanotubes have diameters less than 5 nm. Carbon nanotubes may be adequately dispersed in a thermoset precursor by using a extrusion process generally reserved for thermoplastics. The thermoset precursor may be a precursor for epoxy, phenolic, polyimide, urethane, polyester, vinyl ester or silicone. A preferred thermoset precursor is a bisphenol A derivative.
1. A conductive thermoset precursor consisting essentially of:
a thermoset precursor having a viscosity greater than 15 poise, said thermoset precursor selected from the group consisting of epoxy precursor, phenolic precursor, polyimide precursor, urethane precursor, polyester precursor, vinyl ester precursor or silicone precursor, and
carbon nanotubes having diameters less than 1 micron,
wherein said carbon nanotubes are present at a concentration of 1 to 15% by weight.
2. The conductive thermo set precursor of claim 1 , wherein the weight per epoxide in said thermoset precursor is in the range of 600 to 4000 gram precursor/gram equivalent epoxide.
3. The conductive thermoset precursor of claim 1 , wherein the viscosity of said thermoset precursor is in the range of 20 to 600 poise.
4. The conductive thermoset precursor of claim 1 , wherein the melting point of said thermoset precursor is between 30 and 350° C.
5. The conductive thermoset precursor of claim 1 , wherein said carbon nanotubes include single walled carbon nanotubes having diameters less than 5 nanometers.
6. The conductive thermoset precursor of claim 1 , wherein said carbon nanotubes are in the form of aggregates of carbon nanotubes, said aggregates having a macromorphology resembling birds nest, cotton candy, combed yam or open net.
7. The conductive thermoset precursor of claim 1 , wherein said carbon nanotubes were dispersed in said thermoset precursor by extrusion.
8. The conductive thermoset precursor of claim 1 , wherein said carbon nanotubes were dispersed in said thermoset precursor by the use of a co-rotating or counter rotating twin screw extruder.
9. The conductive thermoset precursor of claim 1 , further comprising a diluting agent.
10. The conductive thermoset precursor of claim 9 , wherein the diluting agent is another thermoset precursor which does not react with said thermoset precursor to cure into a final thermoset product.
11. The conductive thermoset precursor of claim 1 , wherein said conductive thermoset precursor is not a solid at room temperature.