Multifunctional Composites through Inkjet-printed Architectures.

摘要

This project report builds upon the previously reported results obtained from the pioneering project funded by EOARD (FA8655- 11-1-3072), in which, for the first time, an inkjet printer was successfully used to prepare self-ameliorating composite systems for aircraft structures [1-3]. A range of polymer systems were printed onto carbon fibre composite pre-preg using the same consistent hexagonal pattern. After curing, the composite systems were optimised and tested to determine their fracture toughness and shear properties. Self-repair ability of 30-40% has been obtained from 0.02% microscopically accurate addition of jetted polymer agent between the composite plies, prior to the cure process. Inkjet printing is a flexible method to print patterns that can be designed before printing, and this technique can be used to selectively toughen composite areas where higher damage resistance is required, such as holes, joints and other stress concentration areas. In this work, PMMA micro- droplets were printed onto prepreg before curing, and remained arrested between composite plies without direct contact with the neighboring micro-droplets after curing, which preserved the structural integrity of the novel composite system. As the thickness of deposits on substrate by inkjet printing is sub-micron, the introduced thickness to the composite is negligible, which is an advantage over conventional toughening methods. Since the interface between the plies is likely to be the main source of micro-cracks, discrete thermoplastic microdroplet deposition imparts multifunctional properties whilst enhancing its structural integrity in service.