Browsing by Author "Moniruzzaman, Monir"

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    Emily Bagguley PhD
    (Cranfield University, 2018-09-13 09:13) Gill, Philip; Bagguley, Emily; Kister, Guillaume; Moniruzzaman, Monir
    Solid Composite Propellants for Improved Safety and Mechanical Properties This work looks to optimise and develop novel composite propellant formulations for use in unconventional rocket motor designs, in particular an integrated ramjet rocket motor. The particular design constraints of such a motor require that the booster propellant, required to get the rocket motor up to operational speed, use the same nozzle as the sustainer propellant and as a result must have the same operational requirements such as low pressure (1.5-2 MPa compared to ~10MPa for conventional rocket motors). In simple terms, this work aims to develop an extremely high burn rate propellant which works at extremely low pressures.
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    Mechanophore-linked hydroxyl-terminated polybutadiene for the remote detection and quantification of mechanical stress
    (Elsevier, 2018-10-21) Kister, Guillaume; Moniruzzaman, Monir; Khan, M.; Debnath, S.
    Polymers containing chromophores often exhibit mechanoresponsive behaviour, allowing the remote detection of stress in components such as rocket motors without taking the rockets out of service. Here we describe a polymer comprising a difunctional spiropyran chromophore and methyl methacrylate cross-linked with hydroxyl-terminated polybutadiene (HTPB). This polymer was developed as a sensor for the non-destructive monitoring of mechanical stress by using the force-induced colour changes as a quantitative readout. After about 40 N of load was applied there was a gradual colour changes proportional to the compressive forces on the sample, as revealed by in-situ monitoring using a video camera and UV–Vis spectrometry. The tests highlighted a gradual decrease in the transmitted light intensity at 675 nm with increasing load, due to the opening of the spiropyran rings and their conversion to the coloured merocyanine forms. A reversible change to the initial colour occurred 72 h after the load was removed, but only under artificial fluorescent lighting, confirming that visible light is required for the ring-closing reaction. This new polymer is an ideal candidate for the remote detection of stress-induced damage in inaccessible structures or essential equipment that cannot be withdrawn from service for testing.
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    Prima K I Yahya PhD
    (Cranfield University, 2018-09-13 09:12) Gill, Philip; Yahya, Kharisma; Moniruzzaman, Monir
    Graphene oxide interaction with nitrate esters for novel propellant formulation
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    Self-healing in epoxy thermoset polymer films triggered by UV light
    (2016-07-26) Moniruzzaman, Monir; Christogianni, Paraskevi; Kister, Guillaume
    Self-healing of damaged structures can occur in three processes: capsule-based healing, vascular healing and intrinsic healing of polymers. The latest concept has a tremendous potential to repair damaged polymers and composite structures. Until now self-healing of composite materials has been addressed using capsule based resin with an initiator that polymerises in the damaged region. In this study, self-healing behaviour of cured epoxy thermoset resins modified with an epoxy-functionalised photoresponsive azobenzene molecule has been addressed by UV light without the use of any resin capsules or other component that is not chemically joined with the composites. The study was executed by nanoindentation and atomic force microscopy (AFM). Artificially damaged thermoset films exhibited good self-healing behaviour under UV irradiation only. This effect is attributed to the intrinsic healing mechanism triggered by UV-induced trans→cis isomerization of the azobenzene chromophore which enables the damaged polymeric matrix to recover.
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    Synthesis and characterization of reduced graphene oxide and their application in dye-sensitized solar cells
    (MDPI, 2019-01-15) Ghann, William E.; Kang, Hyeonggon; Uddin, Jamal; Chowdhury, Farzana Aktar; Khondaker, Saiful I.; Kabir, Md Humayun; Moniruzzaman, Monir; Rahman, Mohammed M.
    Reduced graphene oxide has certain unique qualities that make them versatile for a myriad of applications. Unlike graphene oxide, reduced graphene oxide is a conductive material and well suited for use in electrically conductive materials, such as solar cell devices. In this study, we report on the synthesis of graphene oxide as well as the fabrication and characterization of dye-sensitized solar cells with a photoanode which is an amalgam of reduced graphene oxide and titanium dioxide. The synthesized reduced graphene oxide and the corresponding photoanode were fully characterized using Ultraviolet-visible, Fourier transform infrared (FTIR), and Raman Spectrometry. The morphology of the sample was assessed using Atomic Force Microscopy, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy, and Energy Dispersive X-ray Spectroscopy. The photovoltaic characteristics were determined by photocurrent and photo-voltage measurements of the fabricated solar cells. The electrical impedances of both sets of devices were also evaluated. Overall, the solar to electric power efficiency of the device with reduced graphene oxide was observed to be higher (2.02%) than the device without the reduced graphene oxide (1.61%).