Nanomaterial processing for multifunctional patterned composites for in situ sensing applications
Date
2014
Authors
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Publisher
University of Delaware
Abstract
The increasing performance demands on composite materials have stimulated the development of new approaches and manufacturing techniques to integrate various system functionalities within the composite structure. Opportunity exists to produce smart, self-sensing composites, by altering the microstructure of the composite where sensors can be patterned for assessing damage locality and severity. Introduction of nanomaterials into continuous fiber-reinforced composites either at the fiber/matrix interface or within the polymer matrix enables further tailoring of mechanical and electrical properties. Carbon nanotubes have been studied extensively for modifying the mechanical and physical properties of fiber composites. Recently graphene has generated scientific and technical interest due to potential lower raw material costs and ease of processing. This work studies graphene nano-platelet processing parameters to determine the suitability of graphene nanocomposites for in situ sensing applications. Processing parameters for optimizing the piezoresistive response of graphene nano-platelet composites for in situ sensing applications are determined and applied in for the development of a patterning media suitable for deposition onto glass fibers. A new approach to selectively modify the electrical properties of composite fibers is employed to selectively deposit carbon nanotube and graphene nano-platelet enhanced patterning media through an adapted screen printing process. These nano-modified depositions create hierarchical patterns of piezoresistive sensors as fully integrated components and form a distributed sensor network at the fiber/matrix interface. New analysis tools for resistance based sensing techniques are applied to nanocomposites and patterned unidirectional hybrid nanocomposites to assess damage onset and accumulation. The sensitivity of the electrical response for the graphene nano-platelet is compared with the electrical response of the carbon nanotube networks. Real-time monitoring of the electrical resistance change is then utilized to shed light on the nature and progression of damage in the composite.