NTI Research
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/3658
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Browsing NTI Research by Author "Alan G. MacDiarmid NanoTech Institute"
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Item High Temperature Structural Transformations of Few Layer Graphene Nanoribbons Obtained By Unzipping Carbon Nanotubes(2013-11-11) Castillo-Martínez, Elizabeth; Carretero-González, Javier; Sovich, Justin; Lima, Márcio. D.; Alan G. MacDiarmid NanoTech InstituteMultilayer and few layer graphene nanoribbons produced by oxidative unzipping of carbon multiwalled carbon nanotubes (MWNT 10 > N > 5) and N ≤ 4 carbon few walled nanotubes (FWNT) were annealed at temperatures up to 1400 °C and the resulting carbon nanostructures were studied. Transmission electron microscopy imaging of the graphene nanoribbons annealed in bulk shows higher structural stability in larger width multilayer graphene nanoribbons than in narrow few layer nanoribbons. Fringes of dark and bright contrast along the edges of MLG indicate edge closure within the layers of the stacked graphene nanoribbons. On the other hand, narrow FLG nanoribbons fuse within each other or collapse when annealed leading to three different nanostructures: large area MLG plates several microns wide, graphitic onions of approximately 100 nm in diameter and nanocrystalline/amorphous composite particles.Item Preparation and Characterization of Nanocomposites of Poly-P-Phenylene Benzobisthiazole with Graphene Nanosheets(2014-01-16) Choudhury, Arup; Alan G. MacDiarmid NanoTech InstitutePoly-p-phenylene benzobisthiazole (PBT)/graphene nanocomposite films were fabricated using a simple method with methanesulfonic acid (MSA) as the processing solvent. In this approach, graphene nanosheets were exfoliated in the MSA solution of PBT using ultrasonication and mechanical stirring, and then processed into thin films. The structure and composition of as-prepared graphene oxide (GO) and reduced graphene oxides (rGO) were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The electrical conductivity of pristine PBT was enhanced by 10 orders of magnitude upon incorporation of 5 wt% rGO nanosheets. The enhanced conductivity of the nanocomposites was interpreted by the percolation model. The thermo-oxidative stability of PBT was improved with the incorporation of both GO and rGOs, while rGOs showed more pronounced effect. On addition of only 5 wt% GO, the tensile strength and Young's modulus of PBT increased by ~4-fold and ~7-fold, respectively, whereas relatively inferior tensile properties were observed for the PBT/rGO nanocomposites. The enhanced mechanical properties could be attributed to the molecular-level dispersion of the exfoliated GO nanosheets in PBT matrix, as evidenced by the results from morphological studies. A modified Halpin-Tsai model has been used to evaluate the reinforcement or orientation effects of GO/rGO on the Young's modulus of the nanocomposites.