K. Song, W. Xu, S. Jambhulkar
Arizona State University,
Keywords: polymer, carbon nanofiber, graphene, 3D printing, spinning, manufacturing
Summary:Manufacturing of advanced materials, especially high-performance composites, requires precise control of material microstructures. Among all parameters to manipulate, the management of nanoparticles in composites, including their locational and orientational order, has been challenging. This talk will cover two case studies from our research group and report the highly efficient manufacturing methods for preferential nanoparticle alignment in polymer matrices. The first case is about one-dimensional thin fibers. During the fabrication procedures, the exfoliation and orientation of graphene layers were achieved via the use of the customized spinning technique. The development of different spinnerets allowed high flexibility to physical dimensions and chemical compositions. The fabrication of co-axial fibers was enabled by the customized spinning line to incorporate graphene layers between polymers. Shear stress generated by the relative movement between polymer layers aligned the graphene layers, at the same time, exfoliated fewer layers from stacked graphite. Different polymers such as polyvinyl alcohol (PVA), thermoplastic polyurethane (TPU), and polyacrylonitrile (PAN) were used to demonstrate the manufacturability of the spinning line. The prepared composites showed enhanced mechanical properties (e.g., stiffness, strength, etc.) and electrical properties that were sensitive to mechanical strains and compressions. The second case was two-dimensional thin films. 3D printing and layer-by-layer (LbL) self-assembly methods were combined to generate layered laminates with thin thickness. 3D printing exhibited its merits in the selective deposition of polymers and the precise control of surface topologies. LbL showed its advantage in forming nano-scale coatings and selective adhesion to deposited substrates. The combination of these two methods displayed the synergy during manufacturing and enabled laminates with polymer/nanoparticle alternatives. The alignment control of carbon nanofibers (CNFs) displayed the high potential in serving as chemiresistive sensors. The application in liquid and gaseous environments showed high sensitivity and selectivity to chemical solvents and volatile organic compounds (VOCs). The two case studies provided an opportunity to understand the nanoparticle alignment mechanisms and the effects on mechanical and functional properties in the composite materials.