University od Manchester, UK
Dr Cristina Vallés is a lecturer in Polymer Nanocomposites at the Department of Materials (University of Manchester, UK). She obtained a PhD from the University of Zaragoza (Spain) on the production of carbon nanotubes, during which she also explored the potential of these nanomaterials for multifunctional polymer nanocomposites. After that, as a postdoctoral researcher at The University of Bordeaux (France), she developed a new method for the chemical production of graphene through the exfoliation of graphite intercalation compounds. In 2011, she joined the University of Manchester with the main motivation of exploring the potential of graphene for emerging technological applications. She acquired deep knowledge on the structure, properties and processing of graphene, taking the exceptional properties of graphene from the nanoscale to macroscopic mechanically reinforced and electrically conductive composite materials. Further, she has studied the potential of graphene for ultra-flexible supercapacitors printed on textiles for wearable electronics. Her research activity in the field of Functional Nanomaterials has been published in over 50 high-ranking, peer-reviewed international journals. She has presented her research work in more than 50 International Scientific Conferences and has several patents accepted out of her work. In her research career to date she has formed and actively maintain multiple collaborations in an international and interdisciplinary context, including both academia and industry. Some of the main current foci of her group’s research include the fabrication of multifunctional polymer nanocomposites for applications in the aerospace sector and graphene/polymer fibres for wearable electronics. Dr Vallés is also working on the development of sustainable materials that can replace products currently used in industry, e.g. she is currently leading a research project on sustainable replacements for coal tar pitch binders.
Due to their high specific strength and stiffness, low density, multifunctionality, ease integration into consolidated components and enormous design versatility, carbon fibre reinforced plastics (CFRPs) are increasingly used in many industrial sectors. In particular, driven by new targets for lower CO2 emissions and the need for light-weight structures, the global demand for these composites is expected to continue to grow. This rapid growth in the adoption of CFRPs is, however, leading to major environmental challenges in waste management, which includes off-cuts generated during composite manufacturing and end-of-life CFRP products. Thus, novel out-of-autoclave (OoA) strategies for repairing CFRPs that will enable facile maintenance of components and, thus, will reduce unnecessary scrappage, while avoiding the use of an autoclave and the huge energy consumption typically associated to it are currently in high demand.
This paper will show our recent research on the development of OoA in-situ strategies to repair CFRPs through Joule heat curing of carbon nanomaterials based electrically conductive epoxy nanocomposite mixtures used as adhesives [1, 2]. How the nature, dimensionality and loading of the carbon nanoparticles (graphene, CNTs and their combinations) embedded into the adhesive as the conductive component affect the heating rate and distribution of the Joule heat generated within the adhesive during the repair process is investigated as key to optimize the thermoset curing, hence, the OoA repair process. The mechanical properties of the CFRPs repaired by Joule heat (including lap shear strengths and fatigue resistance) are compared with those found for the CFRPs repaired in an oven, and the failure mechanism of the joints is also discussed to gain insight on new directions to improve this OoA repair method, which will lead to important energy savings relative to the conventional in the oven repair.
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