Carbon nanotube composites for the micro-world: Design for functionality and manufacturability

Carbon nanotubes (CNTs) are an ideal reinforcement phase for composite applications at the micro-scale. These include specific use in the areas of biomedicine, electromechanical actuators and electrically-conductive polymers. The objective of this paper is to highlight the importance of developing a knowledge base that will enable the design of CNT composites to meet both the micro-scale engineering and manufacturing/machining requirements. To this end, significant results from recent experimental and modeling research on the machining of CNT composites are presented. CNT loading, alignment, dispersion and the interfacial bonding between the CNTs and the matrix have a strong influence on the functionality and machinability of CNT composites. Micro/meso-scale machining studies reveal that an increase in CNT loading improves the machinability of the composite. Visco-elastic/plastic deformation of the polymer-phase plays a significant role while machining the composite with 1.75% CNT loading, whereas for CNT loadings ≥ 5%, the CNT distribution and interface failure effects were found to be important. Microstructure-based CNT composite machining model is presented and model predictions are discussed. This model serves as a design tool to identify critical microstructural parameter combinations of CNT loading, alignment and dispersion that result in favorable machining results. These results were then used to show how the morphology of the machined surface could be harnessed to produce the next generation of micro-fluidic devices with self-mixing capabilities.