APPARATUS AND METHOD FOR HEATING AT PYROLYTIC TEMPERATURES USING MICROWAVE RADIATION
Heating and processing a polymeric material is achieved using a microwave absorbing structure that defines a processing chamber to receive the polymeric material (e.g., one or more precursors to form a polymer). A microwave radiation source directs microwave radiation to the microwave absorbing structure, which absorbs the radiation and can process the material.
1 . An apparatus for heating a material, the apparatus comprising:
a microwave absorbing structure defining a processing chamber to receive the material, the microwave absorbing structure comprising a sample holder made of ceramic or carbon and at least partially surrounded by a microwave radiation absorbing material;
a microwave radiation source that generates microwave radiation in the direction of the microwave absorbing structure to thermally activate polymer processing of the material; and
an inert gas source in fluid communication with the microwave radiation source to surround the microwave absorbing structure in an inert gas atmosphere.
2 . The apparatus of claim 1 , wherein the microwave radiation absorbing material is made of nickel oxide, silicon carbide, yttria-stabilized zirconia, iron oxide, melamine, or carbon.
3 . The apparatus of claim 1 , wherein the sample holder and the microwave radiation absorbing material are embedded within a thermally insulating porous ceramic.
4 . The apparatus of claim 3 , wherein the thermally insulating porous ceramic is alumina.
5 . The apparatus of claim 1 , wherein the microwave radiation source is a conventional microwave oven.
6 . The apparatus of claim 1 , further comprising a microwave waveguide to direct the microwave radiation to the microwave absorbing structure.
7 . The apparatus of claim 1 , wherein the material to be heated comprises one or more carbon precursors.
8 . A method of processing a polymeric material, the method comprising:
positioning the polymeric material within a microwave absorbing structure, the microwave absorbing structure comprising a sample holder made of ceramic or carbon and at least partially surrounded by a microwave radiation absorbing material;
directing microwave radiation from a microwave radiation source to the microwave absorbing structure to process the polymeric material; and
providing an inert gas atmosphere to the microwave absorbing structure using an inert gas source in fluid communication with the microwave radiation source.
9 . The method of claim 8 , wherein the microwave radiation absorbing material is made of nickel oxide, silicon carbide, yttria-stabilized zirconia, iron oxide, melamine, carbon, or mixtures thereof.
10 . The method of claim 8 , wherein the sample holder and the microwave radiation absorbing material are embedded within a thermally insulating enclosure.
11 . The method of claim 10 , wherein the thermally insulating enclosure comprises a porous ceramic.
12 . The method of claim 10 , wherein the thermally insulating enclosure comprises alumina.
13 . The method of claim 8 , wherein the microwave radiation source is a conventional microwave oven.
14 . The method of claim 8 , further comprising directing the microwave radiation to the microwave absorbing structure using a microwave waveguide.
15 . The method of claim 8 , wherein the polymeric material comprises an aerogel.
16 . The method of claim 15 , wherein the aerogel comprises a polyamic acid aerogel, polybenzoxazine aerogel, phenolic resin aerogel, isocyanate derived aerogel, hydrocarbon aerogel, biopolymer aerogel, or inorganic aerogel.
17 . The method of claim 8 , wherein processing the polymeric material comprises carbonizing the polymeric material.
18 . The method of claim 8 , wherein the polymeric material is partially carbonized prior to applying microwave radiation.
19 . The method of claim 18 , wherein the partially carbonized polymeric material is obtained by applying heat to the polymeric material in a conventional oven for a predetermined of time.
20 . The method of claim 18 , wherein microwave radiation from the microwave radiation source is applied for a period of time between 5 minutes and 15 minutes.