Graphene is a carbon isotope composed of carbon atoms and is superior in thermal, electrical and mechanical properties to other nano additives. As carbon-based fiber, graphene can be an ideal assembly unit for fibers and can be macroscopically assembled by wet spinning. Such graphene has attracted much interest as a filler for polymer composite materials by preparing graphene oxide by introducing hydrophilic functional groups for easy dispersion in water. As a composite fiber matrix, alginate, a natural polymer, has high industrial applicability and various studies are being conducted to develop functional new materials.
Graphene oxide and alginate are easily coagulated with divalent metal ions because they have a carboxyl group with a negative charge in the molecule. Wet spinning was carried out using a calcium chloride coagulating solution and graphene oxide/alginate composite fibers were prepared according to the different graphene oxide contents of the dope solution prepared.
The tensile strength of the pure alginate studied was 113 MPa. In this experiment, maximum value of 280 MPa was obtained when graphene oxide was added. Also, as a carbon fiber precursor, reduction was carried out under hydrogen iodide and acetic acid to improve the thermal and electrical properties, and the carbonization proceeded to 800 ℃ by immersing in a nickel which induces graphitization at a low temperature during the carbonization process. As a result, the alginate precursor exhibiting a carbonization yield of 20.3% increased to 36.1% by the addition of graphene oxide. In the TGA measurement, it was confirmed that pyrolysis was induced at low temperature when nickel catalyst was treated with pure alginate fiber. In FT-IR analysis, it was confirmed that many functional groups possessed by pre-carbonized graphene oxide and alginate disappeared, and X-ray diffraction analysis showed that the 2θ = 26.4° peak of the (002) plane shifted to a graphite structure. The intensity (ID/IG) indicating the degree of graphitization in the Raman analysis was 0.85.
Electrical properties were tested for electrical resistance and improved conductivity at 13575.11 S/m for carbonized fibers at 225.15 S/m for reduced fibers. Morphological analysis by SEM showed that the graphene oxide and alginate were well bonded and showed a corrugated layer structure.
Based on the analysis, the characteristics of the graphene oxide/alginate composite fiber as the carbon-based fiber were confirmed, and the analytical value measured after carbonization indicates that the graphite fiber was produced.