Natural graphite was chemically modified by an acid mixture (H2SO4/HNO3, 4:1) using sonication. The resulting material was then expanded with octadecylamine by the dispersion method. The sample was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG), wide-angle X-ray diffraction (WAXD) and relaxometry—low-field nuclear magnetic resonance (LFNMR). The SEM images revealed the expansion of the graphite layers. The presence of CH absorption was detected in the infrared spectrum of the expanded sample. The WAXD showed an additional diffraction peak at lower 2θangle, indicating that intercalation of octadecylamine was successful. The thermogravimetry curve revealed three degradation steps. Two of them could be attributed to different structures (delaminated and exfoliated). The relaxometry showed that the relaxation time was dependon the frequency and the curve of the graphite/octadecylamine presented two peaks—approximately before 106 Hz and after 107 Hz. The results permitted inferring that organically modified graphite was achieved.
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L. Carreira, L. Mendes, M. Ribeiro and P. Sebastião, "Organically-Expanded Graphite/Octadecylamine: Structural, Thermal and Relaxation Evaluation," Materials Sciences and Applications, Vol. 4 No. 5, 2013, pp. 281-286. doi: 10.4236/msa.2013.45035.
 M. S. S. B. Monteiro, R. P. C. Neto, I. C. S. Santos, E. O. da Silva and M. I. B. Tavares, “Inorganic-Organic Hybrids Based on Poly(ε—Caprolactone) and Silica Oxide and Characterization by Relaxometry Appling Low-Field NMR,” Materials Research, Vol. 15, No. 6, 2012, pp. 825-832. doi:10.1590/S1516-14392012005000121
 P. R. Pinto, L. C. Mendes, M. L. Dias and C. Azuma,“Synthesis of Acryle-Modified Sol-Gel Silica,” Colloid and Polymer Science, Vol. 284, No. 5, 2006, pp. 529-535.
 M. I. B. Tavares, P. S. R. C. da Silva, E. O. da Silva, C. Legramanti, A. A. Passos and R. P. C. Neto, “The Evaluation of Polymeric Composites from Nuclear Magnetic Resonance Relaxometry,” The 6th International Conference on Quantum, Nano and Micro Technologies, ICQNM, Rome, 19-24 August 2012, pp. 52-55.
 L. M. Brito and M. I. Tavares, “ Evaluation of the InfluEnce of Nanoparticles’ Shapes on the Formation of Poly (Lactic Acid) Nanocomposites Obtained Employing the Solution Method,” Journal of Nanoscience and Nanotechnology, Vol. 12, No. 16, 2012, pp. 4508-4513.
 L. C. Mendes, D. F. Silva and A. S. Lino, “Linear LowDensity Poliethylene and α-Zirconium Phosphate Nanocomposites: Evidence from Thermal, Thermo-Mechanical, Morphological and Low-Field Nuclear Magnetic Resonance Techniques,” Journal of Nanoscience and Nanotechnology, Vol. 12, No. 12, 2012, pp. 8867-8873.
 Y. Yang, C. Liu and H. Wu, “Preparation and Properties Of Poly(Vinyl Alcohol)/Exfoliated α Zirconium Phosphate Nanocomposites Films,” Polymer Testing, Vol. 28, No. 4, 2009, pp. 371-377.
 D.-Y. Wang, X.-Q. Liu, J.-S. Wang, Y.-Z. Wang, A. A. Stec and T. R. Hull, “Preparation and Characterization of a Novel Fire Retardant PET/α-Zirconium Phosphate Nanocomposite,” Polymer Degradation and Stability, Vol. 93, No. 5, 2008, pp. 1024-1030.
 L. S. Brandao, L. C. Mendes, M. E. Medeiros, L. Sirelli and M. L. Dias, “Thermal and Mechanical Properties of Poly(Ethylene Terephthalate)/Lamellar Zirconium Phosphate Nanocomposites,” Journal of Aplied Polymer Science, Vol. 102, No. 4, 2006, pp. 3868-3876.
 R. Sengupta, M. Bhattacharya and S. Bandyopadhyay, “A Review on the Mechanical and Electrical Properties of Graphite and Modified Graphite Reinforced Polymer Composites,” Progress in Polymer Science, Vol. 36, No. 5, 2011, pp. 638-670.
 Y. L. Hsin, K. C. Hwang and C. T. Yeh, “Poly(Vinylpyrrolidone)-Modified Graphite Carbon Nanofibers as Promising Supports for PtRu Catalysts in Direct Methanol Fuel Cells,” Journal of american Chemical Society, Vol. 19, No. 32, 2007, pp. 9999-10010. doi:10.1021/ja072367a
 D. K. Resende, C. B. Dornelas, M. I. B. Tavares, A. S. Gomes, L. A. Moreira, L. M. Cabral and L. A. Simeoni, “Preparacao de Argila Modificada com Cloreto de Cetilpiridíneo e Avaliacao da Interacao desta com o PVC,” Polímeros, Vol. 30, No. 3, 2011, pp. 1379-1382.
 Z. González, A. Sanchez, C. Blanco, M. Granda, R. Menédez and R. Santamaría, “Enhanced Performance of a Bi-Modified Graphite Feltas the Positive Electrode of a Vanadium Redox Flow Battery,” Electrochemistry Communications, Vol. 13, No. 12, 2011, pp. 1379-1382.
 M. Mallesha, R. Manjunatha, C. Nethravathi, G. S. Suresh, M. Rajamathi, J. S. Melo, T. V. Venkatesha, “Functinalizatized-Graphene Modified Graphite Electrode for the Selective Determination of Dopamine in Presence of Uric Acid and Ascorbic Acid,” Bioelectrochemistry, Vol. 81, No. 2, 2011, pp. 104-108.
 E. Zacco, M. I. Pividori, X. Llopis, M. Del Valle and S. A. Alegret, “Renewable Protein A Modified Graphite-Epoxy Composite for Electrode Mical Immunosensing,” Journal of Immunological Methods, Vol. 286, No. 1-2, 2004, pp. 35-46. doi:10.1016/j.jim.2003.11.014
 A. Malas and C. K. Das, “Development of Modified Expanded Graphite-Filled Solution Polymerized StyreneButadiene Rubber Vulcanizates in the Presence and Absence of Carbon Black,” Polymer Engineering and Science, Vol. 53, No. 2, 2013, pp. 1-9.
 E. R. de sousa, E. P. Marques, E. N. Fernandes, J. Zhang and A. L. B. Marques, “Graphite Electrodes Modified by 8-Hydroxyquinolines and Its Application for the Determination of Copper in Trace Levels,” Journal of the Brazilian Chemical Society, Vol. 17, No. 1, 2006, pp. 177-183.
 M.-H. Chen, T.-Y. Lin and T.-C. Chou, “Trichloroethylene Sensor by Using Electrodeposited Pb-Modified Graphite Strip Electrode,” Journal of the Electrochemical Society, Vol. 149, No. 3, 2002, pp. 487-492.
 Y.-X. Pan, Z.-Z. Yu, Y.-C. Ou and G.-H. Hu, “A New Process of Fabricating Electrically Conducting Nylon 6/Graphite Nanocomposites via Intercalation Polymerization,” Journal of Polymer Science Part B: Polymer Physics, Vol. 38, No. 12, 2000, pp. 1626-1633.
 F. M. Uhl and C. A. Wilkie, “Polystyrene/graphite Nanocomposites: Effect on Thermal Stability,” Polymer Degradation and Stability, Vol. 76, No. 1, 2002, pp. 111-122.
 V. Panwar, B. Kang, J.-O. Park, S. Park and R. M. Mehra, “Study of Dielectric Properties of Styrene Acrylonitrile Graphite Sheets Composites in Low and High Frequency Region,” European Polymer Journal, Vol. 45, 2009, pp. 1777-1784. doi:10.1016/j.eurpolymj.2009.02.020
 D. M. Sousa, G. D. Marques, J. M. Cascais and P. J. Sebastiao, “Desktop Fast-Field Cycling Nuclear Magnetic Resonance Relaxometer,” Solid State Nuclear Magnetic renance, Vol. 38, No. 1, 2010, pp. 36-43.
 M. S. M. Preto, M. I. B. Tavares, P. J. Sebastiao and R. B. V. Azeredo, “Determination of Herbal Authenticity by Low-Field NMR,” Food Chemistry, Vol. 136, No. 3-4, 2013, pp. 1272-1276.