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- Nanotechnology research practices and future trendsPublication . Khan, Imran
- Time resolved strain dependent morphological study of electrically conducting nanocompositesPublication . Khan, Imran; Mitchell, Geoffrey; Mateus, Artur; Kamma-Lorger, Christina S.An efficient and reliable method is introduced to understand the network behaviour of nano-fillers in a polymeric matrix under uniaxial strain coupled with small angle x-ray scattering measurements. The nanoparticles (carbon nanotubes) are conductive and the particles form a percolating network that becomes apparent source of electrical conduction and consequently the samples behave as a bulk conductor. Polyurethane based nanocomposites containing 2% w/w multiwall carbon nanotubes are studied. The electrical conductivity of the nanocomposite was (3.28×10-5s/m).The sample was able to be extended to an extension ratio of 1.7 before fracture. A slight variation in the electrical conductivity is observed under uniaxial strain which we attribute to the disturbance of conductive pathways. Further, this work is coupled with in- situ time resolved small angle x-ray scattering measurements using a synchrotron beam line to enable its measurements to be made during the deformation cycle. We use a multiscale structure to model the small angle x-ray data. The results of the analysis are interpreted as the presence of aggregates which would also go some way towards understanding why there is no alignment of the carbon nanotubes.
- Multiscale Structure Evolution in Electrically Conductive Nanocomposites Studied by SAXSPublication . Khan, Imran; Mohan, Saeed D.; Belbut, Miguel; Kamma-Lorger, Christina S.; Mateus, Artur; Mitchell, Geoffrey R.The successful introduction of nanostructured materials is hampered by the lack of a quantitative and qualitative understanding of the structure–property relationship within the nanocomposites. Variation in the electrical conductivity of nanocomposite materials depends on the structure evolution of the nanoscale fillers within the polymer phase. This article pertains to the small angle x-ray scattering study of electrically conductive nanocomposites to understand the structure-property relationship. The nanocomposites in this study are comprised of thermoset polyurethane as the matrix material with carbon nanotubes as the filler material. A percolation threshold of 0.5% wt/wt was observed along with substantial changes in the electrical conductivity of the nanocomposites. The small angle x-ray scattering data exhibits mass and surface fractal regimes indicating multiple structure evolution in the nanocomposites. Moreover, the data is interpreted using the crossovers of the scaling laws and sizes are measured to characterize the microstructure with a possible explanation for structural development.
- Part Specific Applications of Additive ManufacturingPublication . Khan, Imran; Mateus, Artur; Lorger, Christina S. Kamma.; Mitchell, Geoffrey R.Additive manufacturing is one of the most important technological advances which has been implemented and recognised as a modern manufacturing technology with many advantages over conventional approaches. Fused deposition modelling is an additive manufacturing technology commonly used for modelling, prototyping, and production applications. In this work sample holding grips are designed and printed using fused deposition modelling. These are used in time-resolved experiments which require a dedicated system to study one to one structure-property relationships in electrically conductive nanocomposites under uniaxial strain. The grips serve not only to hold the sample during stretching but also have electrodes to measure the electric current and the voltage drop across the sample under uniaxial strain, as they are insulated from the rest of the tensiometer assembly. In such kind of experimental work, the success of the experiment strongly depends upon the grips as the fracture or slip of the sample during the experiment can ruin the data and lead to a loss of confidence on measurement. The use of additive manufacturing was a particular advantage in the optimization of the design of the grips.