Authors:

Conor Costello

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About Paper:

Flexoelectricity is defined as the coupling between strain gradient and electrical polarization in a dielectric material. It has become a topic of increasing interest since the turn of the century as its potential application in nanoscale sensors, actuators, energy harvesters, and more is researched. This project investigated the flexoelectric properties of several polymers and their associated energetic material composites including poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) and aluminum (Al)/P(VDF-TrFE), poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) and Al/P(VDF-HFP), hydroxyl-terminated polybutadiene (HTPB), ammonium perchlorate (AP)/HTPB, Al/AP/HTPB, polytetrafluoroethylene (PTFE), and polydimethylsiloxane (PDMS). The roughly thumb-sized samples were tested using the cantilever beam method, which involves clamping one end and oscillating of the free end of the sample to generate a strain gradient. The resulting current from the electrode-covered sample is measured. The micron-scale-thickness P(VDF-TrFE) samples showed higher flexoelectric performance after the addition of aluminum powders, although no statistically significant difference between the neat and aluminized samples was found. All other polymeric and energetic materials were of millimeter-scale thickness and tested with the same experimental setup. The study on the flexoelectric properties of HTPB and its propellant compositions (AP/HTPB and Al/AP/HTPB) concluded that adding Al and AP to HTPB to create a solid propellant sample vastly decreased the flexoelectric performance, with similar, yet less extreme, trends present for the other aluminized (energetic) materials. This study has furthered the understanding of flexoelectric performance in energetic materials, yet more research must be conducted to bridge the gap between experimental results and applications in nano- scale devices.

Source:

Purdue University / 2023

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Co-authors:

Conor Costello