Browsing by Author "Lekawa-Raus, Agnieszka"

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    Carbon nanotube films spun from a gas phase reactor for manufacturing carbon nanotube film/carbon fibre epoxy hybrid composites for electrical applications
    (Elsevier, 2019-09-06) Chen, Jinhu; Lekawa-Raus, Agnieszka; Trevarthen, James; Gizewski, Tomasz; Lukawski, Damian; Hazra, Kalyan; Rahatekar, Sameer S.; Koziol, Krzysztof K. K.
    Working towards improvement of the electrical performance of carbon fibre (CF) reinforced polymer composites used in aircrafts, we have developed new routes of production of hybrid carbon nanotube (CNT)/CF epoxy composites. It was shown that the use of CNT films produced via one-step chemical vapour deposition (CVD) based method and in-process control of films morphology combined with standard vacuum bagging based manufacture of the composites results in very good electrical performance of the final material, delivering high potential for lightning strike related applications including electromagnetic interference (EMI) shielding and static dissipation for the composite components used in aerospace and transport sector. Simultaneously, the process is much simpler, inexpensive and easy to upscale than previously proposed methods.
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    Extreme magneto-transport of bulk carbon nanotubes in sorted electronic concentrations and aligned high performance fiber
    (Nature Publishing Group, 2017-09-22) Bulmer, John S.; Lekawa-Raus, Agnieszka; Rickel, Dwight G.; Balakirev, Fedor F.; Koziol, Krzysztof K. K.
    We explored high-field (60T) magneto-resistance (MR) with two carbon nanotube (CNT) material classes: (1) unaligned single-wall CNTs (SWCNT) films with controlled metallic SWCNT concentrations and doping degree and (2) CNT fiber with aligned, long-length microstructure. All unaligned SWCNT films showed localized hopping transport where high-field MR saturation definitively supports spin polarization instead of a more prevalent wave function shrinking mechanism. Nitric acid exposure induced an insulator to metal transition and reduced the positive MR component. Aligned CNT fiber, already on the metal side of the insulator to metal transition, had positive MR without saturation and was assigned to classical MR involving electronic mobility. Subtracting high-field fits from the aligned fiber's MR yielded an unconfounded negative MR, which was assigned to weak localization. It is concluded that fluctuation induced tunnelling, an extrinsic transport model accounting for most of the aligned fiber's room temperature resistance, appears to lack MR field dependence.