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Zhang X.-C.,University of Bristol | Scarpa F.,University of Bristol | McHale R.,Thomas Swan and Co. | Peng H.-X.,Zhejiang University
Polymer (United Kingdom) | Year: 2016

This work describes the effects of tailoring the morphology of the re-agglomeration network and interfacial bonding by embedding poly(methyl methacrylate) decorated single wall nanotubes (SWNTs) into an epoxy resin. We report the time history of the re-agglomerations in the resin, and the rheological properties of the uncured suspensions to assess the effectiveness of the carbon nanotubes crosslinking on the curing process. A dispersion index was used to quantitatively evaluate the level of re-agglomeration. Both the pristine SWNTs and the polymer decorated SWNTs showed the effectiveness of re-agglomeration in improving rheological storage and loss modulus up to 770% and 50% respectively comparing with samples containing uniformly dispersed filler structure, suggested a novel filler arrangement for optimum composites damping performance. Dynamic mechanical analyser tests of the cured composites show that the re-agglomeration provides an increase of the energy dissipation capability when an appropriate interfacial bonding is in place. These results suggest that the morphology of re-agglomerates offers an effective interesting nano-reinforcement architecture for composites targeted at energy absorption and vibration damping. © 2016 Elsevier Ltd. All rights reserved.

Brocchi E.A.,Pontifical Catholic University of Rio de Janeiro | Moura F.J.,Pontifical Catholic University of Rio de Janeiro | Solorzono I.G.,Pontifical Catholic University of Rio de Janeiro | Motta M.S.,Thomas Swan and Co.
Advanced Materials Research | Year: 2010

It is well recognized the importance of nano-structured materials in the present technological stage. Due to their unique properties these materials can be used in a large number of applications. One example is the growing interest in nanocomposites, in which a very fine dispersion of a ceramic phase in a metal matrix will significantly improve the material properties. In view of that, extensive studies have been carried out on a variety of materials such as alloys and different types of composites. Recently, the authors have developed a novel chemical method for insitu formations of Cu-Al2O3 and Ni-Al2O3 nanoscale composites by decomposition of their mixed nitrate solutions, to co-form the nano oxides, followed by preferential reduction of CuO or NiO by hydrogen at very low temperature. Studies carried out by the authors on the kinetics of reduction of such fine oxides indicated that under low partial pressure of hydrogen (0.25 atm) in argon, the oxides of Ni and Cu can be reduced completely, in a low temperature range of 523 to 623 K. The composites containing nanosized metal-metal oxide particles have been found to be quite homogeneous in nature. In view of this, Cu-Ni and Ni-Co alloys was also produced by mixing the respective aqueous nitrate solutions, followed by decompositions of their nitrates to their mixed oxides and subsequent low temperature hydrogen reduction. In that context, the purpose of the present work is to address the fundamental aspects of the synthesis procedure, emphasizing the basic thermodynamics background of the two steps involved. Also, the work aims to illustrate the outcome, by presenting experimental conditions and providing relevant characterization of the obtained nano-materials, by means of electronic microscopy and X-Ray Diffraction. Examples are given in terms of the obtained nano-composites and alloys. © (2010) Trans Tech Publication.

Varrla E.,Trinity College Dublin | Paton K.R.,Trinity College Dublin | Paton K.R.,Thomas Swan and Co. | Backes C.,Trinity College Dublin | And 4 more authors.
Nanoscale | Year: 2014

To facilitate progression from the lab to commercial applications, it will be necessary to develop simple, scalable methods to produce high quality graphene. Here we demonstrate the production of large quantities of defect-free graphene using a kitchen blender and household detergent. We have characterised the scaling of both graphene concentration and production rate with the mixing parameters: mixing time, initial graphite concentration, rotor speed and liquid volume. We find the production rate to be invariant with mixing time and to increase strongly with mixing volume, results which are important for scale-up. Even in this simple system, concentrations of up to 1 mg ml-1 and graphene masses of >500 mg can be achieved after a few hours mixing. The maximum production rate was ∼0.15 g h-1, much higher than for standard sonication-based exfoliation methods. We demonstrate that graphene production occurs because the mean turbulent shear rate in the blender exceeds the critical shear rate for exfoliation. © 2014 the Partner Organisations 2014.

Anastasaki A.,University of Warwick | Nikolaou V.,University of Warwick | Zhang Q.,University of Warwick | Burns J.,University of Warwick | And 11 more authors.
Journal of the American Chemical Society | Year: 2014

Photoinduced living radical polymerization of acrylates, in the absence of conventional photoinitiators or dye sensitizers, has been realized in "daylight'"and is enhanced upon irradiation with UV radiation (λmax ≈ 360 nm). In the presence of low concentrations of copper(II) bromide and an aliphatic tertiary amine ligand (Me6-Tren; Tren = tris(2-aminoethyl)amine), near-quantitative monomer conversion (>95%) is obtained within 80 min, yielding poly(acrylates) with dispersities as low as 1.05 and excellent end group fidelity (>99%). The versatility of the technique is demonstrated by polymerization of methyl acrylate to a range of chain lengths (DPn = 25-800) and a number of (meth)acrylate monomers, including macromonomer poly(ethylene glycol) methyl ether acrylate (PEGA 480), tert-butyl acrylate, and methyl methacrylate, as well as styrene. Moreover, hydroxyl- and vic-diol-functional initiators are compatible with the polymerization conditions, forming α,ω-heterofunctional poly(acrylates) with unparalleled efficiency and control. The control retained during polymerization is confirmed by MALDI-ToF-MS and exemplified by in situ chain extension upon sequential monomer addition, furnishing higher molecular weight polymers with an observed reduction in dispersity (Crossed D sign = 1.03). Similarly, efficient one-pot diblock copolymerization by sequential addition of ethylene glycol methyl ether acrylate and PEGA480 to a poly(methyl acrylate) macroinitiator without prior workup or purification is also reported. Minimal polymerization in the absence of light confers temporal control and alludes to potential application at one of the frontiers of materials chemistry whereby precise spatiotemporal "on/off" control and resolution is desirable. © 2013 American Chemical Society.

Istrate O.M.,Trinity College Dublin | Paton K.R.,Trinity College Dublin | Paton K.R.,Thomas Swan and Co. | Khan U.,Trinity College Dublin | And 3 more authors.
Carbon | Year: 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 potential applications. PET and PET/graphene nanocomposites were melt compounded on an internal mixer and the resulting materials were compression molded into films. Transmission electron microscopy and scanning electron microscopy revealed that the graphene flakes were randomly orientated and well dispersed inside the polymer matrix. The PET/graphene nanocomposites were found to be characterized by superior mechanical properties as opposed to the neat PET. Thus, at a nanofiller load as low as 0.07 wt%, the novel materials presented an increase in the elastic modulus higher than 10% and an enhancement in the tensile strength of more than 40% compared to pristine PET. The improvements in the tensile strength were directly correlated to changes in elongation at break and indirectly correlated to the fracture initiation area. The enhancements observed in the mechanical properties of polymer/graphene nanocomposites achieved at low exfoliated graphene loadings and manufactured exclusively via melt mixing may open the door to industrial manufacturing of economical novel materials with superior stiffness, strength and ductility. © 2014 Elsevier Ltd. All rights reserved.

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