Sheet structure incorporating graphitic material, and method of manufacture
This specification presents sheets including graphitic materials, including sandwich structures, thermoformed or wet-formed single layer or multilayer structures of graphitic materials, and methods of forming a layer of graphitic material. In accordance with one aspect, the specification presents a multi-layer structure comprising a core layer having a core density between 0.01 and 1 g/cm 3 ; and a skin layer covering the core layer, the skin layer having at least 10% by weight of a graphitic material, the graphitic material having one or more of graphene oxide, reduced graphene oxide, graphene, graphite oxide, reduced graphite oxide and graphite, the skin layer having a skin density of between 0.5 and 2 g/cm 3 , a thickness ratio of the skin layer to the core layer being of between 1:1000 and 1:1.
1 . A multi-layer structure comprising:
a core layer having a core thickness between 30 microns and 5 cm and a core density between 0.01 and 0.05 g/cm 3 ; and
at least two skin layers superposed over one another, each one of the skin layers having an in-plane graphene orientation, the at least two skin layers covering the core layer, each of the skin layers having a skin thickness between 3 microns and 500 microns and at least 10% by weight of a graphitic material, the graphitic material having one or more of graphene oxide, reduced graphene oxide, graphene, graphite oxide, and reduced graphite oxide, each of the skin layers having a skin density of between 0.5 and 2 g/cm 3 , a thickness ratio of the at least two skin layers to the core layer being of between 1:1000 and 1:5.
2 . The multi-layer structure of claim 1 , wherein the at least two skin layers have between 20% and 90% of one or more of graphene oxide, graphene, graphite oxide, and reduced graphite oxide.
3 . The multi-layer structure of claim 1 , wherein the skin thickness is below 20 μm, and the graphitic material is one or more of graphene oxide, graphite oxide and reduced graphite oxide.
4 . The multi-layer structure of claim 1 , wherein the at least two skin layers have between 10% and 100% by weight of the graphitic material.
5 . The multi-layer structure of claim 1 , wherein the thickness ratio is of between 1:100 and 1:5.
6 . The multi-layer structure of claim 1 , wherein the core layer is made of one of wood, wood based material, foam material and porous polymer.
7 . The multi-layer structure of claim 1 , wherein the graphitic material is one of graphene oxide and reduced graphene oxide.
8 . The multi-layer structure of claim 1 , further comprising an adhesive layer between the at least two skin layers and the core layer.
9 . The multi-layer structure of claim 1 , wherein the multi-layer structure is a sandwich structure having the at least two skin layers and a third skin layer sandwiching the core layer, the skin layers having a skin density higher than the core density.
10 . The multi-layer structure of claim 9 , wherein the core is a graphitic based material foam.
11 . The multi-layer structure of claim 1 , wherein the graphitic material is graphene oxide.
12 . The multi-layer structure of claim 1 , wherein the at least two skin layers include a cross-linker.
13 . The multi-layer structure of claim 12 , wherein the cross-linker is present in a concentration of between 0.01% to 30% by weight per gram of graphitic material.
14 . The multi-layer structure of claim 12 , wherein the cross-linker is one or more of boric acid (BA), borax (BX), calcium salt, glyoxal, glutaraldehyde (GA), dicarboxylic acids and diamines.
15 . The multi-layer structure of claim 1 , wherein the at least two skin layers include a polymer.
16 . The multi-layer structure of claim 15 , wherein the polymer is present in a concentration of 25% to 50% weight of the at least two skin layers.
17 . The multi-layer structure of claim 15 , wherein the polymer is present in a proportion of between 1:99 and 4:1 of the graphitic material by weight.
18 . The multi-layer structure of claim 17 , wherein the proportion is between 1:19 and 4:1.
19 . The multi-layer structure of claim 18 , wherein the proportion is between 1:19 and 3:1.
20 . The multi-layer structure of claim 19 , wherein the proportion is between 1:9 and 3:7.
21 . The multi-layer structure of claim 19 , wherein the proportion is of between 1:19 and 1:1.
22 . The multi-layer structure of claim 21 , wherein the polymer is a cellulose ether.
23 . The multi-layer structure of claim 22 , wherein the cellulose ether is one or more of carboxymethylcellulose (CMC), hydroxypropymethylcellulose (HPMC), Methylcellulose (MC), Hydroxypropylcellulose (HPC), Hydroxyethylcellulose (HEC).
24 . The multi-layer structure of claim 18 , wherein the proportion is between 1:9 and 4:1.
25 . The multi-layer structure of claim 24 , wherein the proportion is between 3:7 and 7:3.
26 . The multi-layer structure of claim 25 , wherein the polymer is polyethylene glycol (PEG).
27 . The multi-layer structure of claim 17 , wherein the polymer is one or more of polyethylene glycol (PEG), cellulose ether, Polyvinyl-alcohol (PVA), Polyvinylpyrrolidone (PVP) and polyethylenimine (PEI).
28 . The multi-layer structure of claim 1 , wherein the multi-layer structure forms an acoustic transducer diaphragm in an electronic device.
29 . The multi-layer structure of claim 28 , wherein the acoustic transducer diaphragm has a non-planar shape including a bend forming a closed shape on the surface of the multi-layer structure.
30 . The multi-layer structure of claim 29 , wherein the bend has a truncated cone shape.
31 . The multi-layer structure of claim 1 wherein the graphitic material has one or more of graphene oxide, graphene, graphite oxide, and reduced graphite oxide.
32 . A multi-layer structure comprising:
a core layer having a core density between 0.01 and 1 g/cm 3 ; and
a skin layer covering the core layer, the skin layer having at least 10% by weight of a graphitic material, the graphitic material having one or more of graphene oxide, reduced graphene oxide, graphene, graphite oxide, reduced graphite oxide and graphite, the skin layer having a skin density of between 0.5 and 2 g/cm 3 , a thickness ratio of the skin layer to the core layer being of between 1:1000 and 1:1;
comprising at least two skin layers superposed over one another, each one of the skin layers having an in-plane graphene orientation, the in-plane orientation being different for the two skin layers.
33 . The multi-layer structure of claim 32 , wherein the in-plane orientation of each one of the skin layers rotate from one skin layer to the other in a manner to complete one or more rotations between 0 and 180 degrees, the multi-layer structure presenting uniform mechanical properties in all orientations.
34 . A multi-layer structure comprising:
a core layer having a core density between 0.01 and 1 g/cm 3 and being a graphitic based material foam; and
a skin layer covering the core layer, the skin layer having at least 10 % by weight of a graphitic material, the graphitic material having one or more of graphene oxide, reduced graphene oxide, graphene, graphite oxide, reduced graphite oxide and graphite, the skin layer having a skin density of between 0.5 and 2 g/cm 3 , a thickness ratio of the skin layer to the core layer being of between 1:1000 and 1:1.
35 . A multi-layer structure comprising:
a core layer having a core thickness between 30 microns and 5 cm and a core density between 0.01 and 1 g/cm 3 ; and
at least two skin layers superposed over one another, each one of the skin layers having an in- plane graphene orientation, the at least two skin layers covering the core layer, each of the skin layers having a skin thickness between 3 microns and 500 microns and at least 10 % by weight of a graphitic material, the graphitic material having one or more of graphene oxide, reduced graphene oxide, graphene, graphite oxide, and reduced graphite oxide, each of the skin layers having a skin density of between 0.5 and 2 g/cm 3 , a thickness ratio of the at least two skin layers to the core layer being of between 1:1000 and 1:1
wherein the multi-layer structure has an average density of from 0.1186 g/cm 3 to 0.3475 g/cm 3 .