Browsing School of Physics by Author "KHAN, UMAR"
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Boron nitride nanosheets as barrier enhancing fillers in melt processed composites
COLEMAN, JONATHAN; KHAN, UMAR; BARWICH, SEBASTIAN (2015)In this work we have used melt-processing to mix liquid-exfoliated boron–nitride nanosheets with PET to produce composites for gas barrier applications. Sonication of h-BN powder, followed by centrifugation-based size-selection, ... -
Development of stiff, strong, yet tough composites by the addition of solvent exfoliated graphene to polyurethane
COLEMAN, JONATHAN; KHAN, UMAR; O'NEILL, ARLENE; MAY, PETER (2010)We have prepared graphene dispersions, stabilised by polyurethane in tetrahydrofuran and dimethylformamide. These dispersions can be drop-cast to produce free-standing composite films. The graphene mass fraction is determined ... -
Enhancing the mechanical properties of BN nanosheet-polymer composites by uniaxial drawing
KHAN, UMAR; MAY, PETER; COLEMAN, JONATHAN (2014)We have used liquid exfoliation of hexagonal Boron-Nitride (BN) to prepare composites of BN nanosheets of three different sizes in polyvinylchloride matrices. These composites show low levels of reinforcement, consistent ... -
Flexible, transparent dielectric capacitors with nanostructured electrodes
KHAN, UMAR (2012)We have prepared flexible, transparent, dielectric capacitors by spraycasting very thin networks of single walled nanotubes (SWNTs) or silver nanowires (AgNWs) onto either side of free-standing polymer films. Impedance ... -
High strength composite fibres from polyester filled with nanotubes and graphene
KHAN, UMAR; O'NEILL, ARLENE; COLEMAN, JONATHAN (2012)We have prepared composite fibres based on the polyester, polyethylene terephthalate (PET), filled with both single walled nanotubes and graphene by a combination of solution and melt processing. On addition of ?2 wt% ... -
Improved adhesive strength and toughness of polyvinyl acetate glue on addition of small quantities of graphene
COLEMAN, JONATHAN; KHAN, UMAR; MAY, PETER (2013)We have prepared composites of polyvinyl acetate (PVAc) reinforced with solution exfoliated graphene. We observe a 50% increase in stiffness and a 100% increase in tensile strength on addition of 0.1vol% graphene compared ... -
Improving the mechanical properties of graphene oxide based materials by covalent attachment of polymer chains
KHAN, UMAR; O'NEILL, ARLENE; MCGOVERN, IGNATIUS; COLEMAN, JONATHAN (2013)We report on the modification of graphene oxide (GO) with polyvinylalcohol (PVA) leading to the mechanical improvement of GO based materials. First, GO was covalently functionalised with PVA by esterification of carboxylic ... -
Large-Scale Exfoliation of Inorganic Layered Compounds in Aqueous Surfactant Solutions
COLEMAN, JONATHAN; WANG, JING; KHAN, UMAR; NICOLOSI, VALERIA; DUESBERG, GEORG (2011)Thumbnail image of graphical abstract A method to exfoliate MoS2 in large quantities in surfactant-water solutions is described. The layered material tends to be exfoliated as dispersions of thin, relatively defect-free ... -
Polymer reinforcement using liquid-exfoliated boron nitride nanosheets
O'NEILL, ARLENE; COLEMAN, JONATHAN; KHAN, UMAR; MAY, PETER (2013)We have exfoliated hexagonal boron nitride by ultrasonication in solutions of polyvinylalcohol in water. The resultant nanosheets are sterically stabilised by adsorbed polymer chains. Centrifugation-based size-selection ... -
Preparation of high concentration dispersions of exfoliated MoS 2 with increased flake size
COLEMAN, JONATHAN NESBIT; O'NEILL, ARLENE; KHAN, UMAR (2012)Solvent exfoliation of inorganic layered compounds is likely to be important for a range of applications. However, this method generally gives dispersions of small nanosheets at low concentrations. Here we describe methods, ... -
The preparation of hybrid films of carbon nanotubes and nanographite/graphene with excellent mechanical and electrical properties
COLEMAN, JONATHAN; KHAN, UMAR; O'CONNOR, IAN EDWARD; GOUNKO, IOURI (2010)We have prepared mixed dispersions of single walled nanotubes and nano-graphite / graphene in the solvent N-methyl pyrrolidone. This allows the deposition of hybrid films by vacuum filtration. Scanning electron microscopy ... -
Reinforcement in melt-processed polymer-graphene composites at extremely low graphene loading level
KHAN, UMAR; COLEMAN, JONATHAN (2014)We have prepared polymer nanocomposites reinforced with exfoliated graphene layers solely via melt blending. For this study polyethylene terephthalate (PET) was chosen as the polymer matrix due to its myriad of current and ... -
Reinforcement of metal with liquid-exfoliated inorganic nano-platelets
COLEMAN, JONATHAN NESBIT; MAY, PETER; KHAN, UMAR (2013)We have prepared metal matrix composites (MMCs) of a pewter alloy filled with liquid-exfoliated Molybdenum Telluride (MoTe2) nano-platelets. The combination of MoTe2 and pewter was chosen due to their near-identical ... -
Scalable production of large quantities of defect-free few-layer graphene by shear exfoliation in liquids
KHAN, UMAR; COLEMAN, JONATHAN; NICOLOSI, VALERIA; BOLAND, CONOR (2014)In order to progress from the lab to commercial applications it will be necessary to develop industrially scalable methods to produce large quantities of defect-free graphene. Here we show that high-shear mixing of graphite ... -
Sensitive, high-strain, high-rate bodily motion sensors based on graphene-rubber composites
KHAN, UMAR; COLEMAN, JONATHAN (2014)Monitoring of human bodily motion requires wearable sensors which can detect position, velocity and acceleration. They should be cheap, lightweight, mechanically compliant and display reasonable sensitivity at high strains ... -
Size selection of dispersed, exfoliated graphene flakes by controlled centrifugation
COLEMAN, JONATHAN; O'NEILL, ARLENE; MAY, PETER; KHAN, UMAR (2012)Liquid exfoliation of graphene generally results in flakes with lateral size of one micron or less on average, too small for many applications. In this paper we describe a method to separate an existing dispersion with ... -
Study of the mechanical, electrical and morphological properties of PU/ MWCNT composites obtained by two different processing routes
KHAN, UMAR; COLEMAN, JONATHAN NESBIT (Elsevier, 2012)A comparative study of the influence of processing route on polyurethanes (PU)/ Multiwalled carbon nanotube (MWCNT) composites mechanical and electrical properties and also morphology was undergone employing two differentiated ... -
Thermoelectric behavior of organic thin film nanocomposites
COLEMAN, JONATHAN; KHAN, UMAR (2013)Organic thin film nanocomposites, prepared by liquid-phase exfoliation, were investigated for their superior electrical properties and thermoelectric behavior. Single-walled carbon nanotubes (SWNT) were stabilized by ...