Induced anisotropy in polymer nanocomposites by fused filament fabrication

Additive manufacturing (AM) was first introduced through fused filament fabrication (FFF), also known as the patented Fused Deposition Modeling (FDM). This AM method is used to process various thermoplastics for applications in fields such as military, medicinal, and even house-hold consuming.

To increase the versatility of printed polymers, thermoplastic-matrix nanocomposites are often used to gain specific properties as mechanical strength, conductivity, or protection from the elements. However, the AM of micro- and nanocomposites is far from trivial. Addition of nanomaterials in concentrations required to achieve the desired properties significantly affects properties as stiffness, heat transfer, melt viscosity, and other characteristics. These altered properties in turn affect the FFF printing procedure. Furthermore, the printing process itself affects the dispersion and orientation of the nanoparticles within the final material. These effects should be accounted for in the printing design to optimize the properties of the final product.

This talk will present a few concepts and applications of incorporating the anisotropic nature of the FFF process itself. Harnessing the flexibility of printing parameters such as temperature, printing orientation and patterning, the baseline characteristics of the pre-printed filament characteristics could be altered to derive properties such as mechanical anisotropy and electrical conductivity. We show that FFF process improves the dispersion of nanoparticles, induces orientation in 1D and 2D nanoparticles, and thus increase both homogeneity and intrinsic anisotropy in the printed nanocomposite. We also demonstrate altered post print conductivity in conductive nanocomposites, induced by printing orientation, resolution and patterning – including induced electrical anisotropy in an isotropic pre-printed material. These results demonstrate the versatility of AM, and FFF specifically, in tailoring and fine-tuning the properties of polymer nanocomposites. This powerful tool, if understood, can be used for bio-mimicry, light-weight and corrosion resistance integrated electrical devices, and other smart-materials applications.