Browsing by Author "Hawkins, S"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Effect of gamma-irradiation on the mechanical properties of carbon nanotube yarns
    (Elsevier, 2011-11-01) Miao, M; Hawkins, S; Cai, JY; Gengenbach, TR; Knott, RB; Huynh, CP
    Gamma-irradiation of carbon nanotube yarns in air has significantly improved the tensile strength and modulus of the yarns, presumably because of an increased interaction between the individual nanotubes. The improvement has been much greater for tightly structured yarns than for loosely structured yarns. Sonic pulse tests have also shown increased sound velocity and dynamic modulus in the carbon nanotube yarns as a result of gamma-irradiation treatment. X-ray photoelectron spectroscopic analyses on progenitor carbon nanotube forests show that gamma-irradiation treatment in air has dramatically increased the concentration of oxygen, for example as carboxyl groups, in the carbon nanotube assemblies in proportion to radiation dose, indicating that carbon nanotubes were oxidized under the ionizing effect of the gamma-irradiation. Such oxygen species are thought to contribute to the interaction between carbon nanotubes and thus to the improvement of carbon nanotube yarn mechanical properties. Crown Copyright (C) 2011 Published by Elsevier Ltd.
  • No Thumbnail Available
    Item
    Enhanced mechanical performance of CNT/polymer composite yarns by γ-irradiation
    (Springer Nature, 2014-02-22) Cai, JY; Min, J; Miao, MH; Church, JS; McDonnell, J; Knott, RB; Hawkins, S; Huynh, C
    Multiwall carbon nanotube (CNT) spun yarns were subjected to γ-irradiation in an oxygen rich environment, followed by the application of epoxy to form CNT/epoxy composite yarns with a high CNT fraction. The method for fabrication of the CNT/polymer composite yarns was presented, and the effect of γ-irradiation on the mechanical performance of the pure CNT spun yarns and their epoxy composite yarns were studied. The γ-irradiated CNT yarns were also characterized by X-ray Photoelectron Spectroscopy and Raman spectroscopy. The results of this study have demonstrated that the γ-irradiation is an effective micro-engineering tool to improve mechanical properties of the CNT spun yarn and its epoxy composite yarn. © 2020 Springer Nature Switzerland AG
  • No Thumbnail Available
    Item
    Single step preparation of meso-porous and reduced graphene oxide by gamma-ray irradiation in gaseous phase
    (Elsevier B.V., 2014-04-01) Dumée, LF; Feng, CF; He, L; Yi, ZF; She, FS; Peng, Z; Gao, WM; Banos, C; Davies, JB; Huynh, C; Hawkins, S; Duke, MC; Gray, S; Hodgson, PD; Kong, LX
    A facile and highly efficient route to produce simultaneously porous and reduced graphene oxide by gamma ray irradiation in hydrogen is here demonstrated. Narrowly distributed nano-scale pores (average size of ∼3 nm and surface density >44,900 pore μm−2) were generated across 10 μm thick graphene oxide bucky-papers at a total irradiation dose of 500 kGy. The graphene oxide sheet reduction was confirmed to occur homogeneously across the structures by Fourier transform infrared spectroscopy and Raman analysis. This one-step, catalyst-free, high penetration and through-put technique, offers great promises potential for the mass production of reduced graphene oxide from cheap graphene oxide. © 2014 Elsevier B.V.