Carbon nanotube sheet scrolled fiber composite for enhanced interfacial mechanical properties

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dc.contributor Unnikrishnan, Vinu U.
dc.contributor Barkey, Mark E.
dc.contributor Haque, Anwarul
dc.contributor Allison, Paul Galon
dc.contributor.advisor Roy, Samit Kokkada Ravindranath, Pruthul 2018-06-04T14:58:28Z 2018-06-04T14:58:28Z 2017
dc.identifier.other u0015_0000001_0002909
dc.identifier.other KokkadaRavindranath_alatus_0004D_13341
dc.description Electronic Thesis or Dissertation
dc.description.abstract The high tensile strength of Polymer Matrix Composites (PMC) is derived from the high tensile strength of the embedded carbon fibers. However, their compressive strength is significantly lower than their tensile strength, as they tend to fail through micro-buckling, under compressive loading. Fiber misalignment and the presence of voids created during the manufacturing processes, add to the further reduction in the compressive strength of the composites. Hence, there is more scope for improvement. Since, the matrix is primarily responsible for the shear load transfer and dictating the critical buckling load of the fibers by constraining the fibers from buckling, to improve the interfacial mechanical properties of the composite, it is important to modify the polymer matrix, fibers and/or the interface. In this dissertation, a novel approach to enhance the polymer matrix-fiber interface region has been discussed. This approach involves spiral wrapping carbon nanotube (CNT) sheet around individual carbon fiber or fiber tow, at room temperature at a prescribed wrapping angle (bias angle), and then embed the scrolled fiber in a resin matrix. The polymer infiltrates into the nanopores of the multilayer CNT sheet to form CNT/polymer nanocomposite surrounding fiber, and due to the mechanical interlocking, provides reinforcement to the interface region between fiber and polymer matrix. This method of nano-fabrication has the potential to improve the mechanical properties of the fiber-matrix interphase, without degrading the fiber properties. The effect of introducing Multi-Walled Carbon Nanotubes (MWNT) in the polymer matrix was studied by analyzing the atomistic model of the epoxy (EPON-862) and the embedded MWNTs. A multi-scale method was utilized by using molecular dynamics (MD) simulations on the nanoscale model of the epoxy with and without the MWNTs to calculate compressive strength of the composite and predict the enhancement in the composite material. The influence of the bias/over wrapping angle of the MWNT sheets on the carbon fiber was also studied. The predicted compressive strength from the MD results and the multiscale approach for baseline Epoxy case was shown to be in good relation with the experimental results for Epon-862. On adding MWNTs to the epoxy system, a significant improvement in the compressive strength of the PMC was observed. Further, the effect of bias angle of MWNT wrapped over carbon fiber was compared for 0, 45 and 90. This is further verified by making use of the Halpin-Tsai.
dc.format.extent 115 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Aerospace engineering
dc.subject.other Mechanical engineering
dc.subject.other Mechanics
dc.title Carbon nanotube sheet scrolled fiber composite for enhanced interfacial mechanical properties
dc.type thesis
dc.type text University of Alabama. Dept. of Aerospace Engineering and Mechanics Aerospace Engineering The University of Alabama doctoral Ph.D.

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