<p>Polymer nanocomposites are a constantly evolving material
category due to the ability to engineer the mechanical, thermal, and optical
properties to enhance the efficiency of a variety of systems. While a vast
amount of research has focused on the physical phenomena of nanoparticles and
their contribution to the improvement of such properties, the ability to
implement these materials into existing commercial or newly emerging processing
methods has been studied much less extensively. The primary characteristic that
determines which processing technique is the most viable is the rheology or
viscosity of the material. In this work, we investigate the processing methods
and properties of nanocomposites for thermal interface and radiative cooling
applications. The first polymer nanocomposite examined here is a two-component
PDMS with graphene filler for 3D printing via a direct ink writing approach.
The composite acts as a thermal interface material which can enhance cooling
between a microprocessor and a heat sink by increasing the thermal conductivity
of the gap. Direct ink writing requires
a shear thinning ink with specific viscoelastic properties that allow for the
material to yield through a nozzle as well as retain its shape without a mold
following deposition. No predictive models of viscosity for nanocomposites
exist; therefore, several prominent models from literature are fit with
experimental data to describe the change in viscosity with the addition of
filler for several different PDMS ratios. The result is an understanding of the
relationship between the PDMS component ratio and graphene filler concentration
with respect to viscosity, with the goal of remaining within the acceptable
limits for printing via direct ink writing. The second nanocomposite system
whose processability is determined is paint consisting of acrylic filled with
reflective nanoparticles for radiative cooling paint applications. The paint is
tested with both inkjet and screen-printing procedures with the goal of
producing a thermally invisible ink. Radiative
cooling paint is successfully printed for the first time with solvent
modification. This work evaluates the processability of polymer nanocomposites
through rheological tailoring. </p><br>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/8980421 |
| Date | 13 August 2019 |
| Creators | Jacob M Faulkner (7023458) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/PROCESSING_OF_NANOCOMPOSITES_AND_THEIR_THERMAL_AND_RHEOLOGICAL_CHARACTERIZATION/8980421 |
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