Piezoenergetic-Fluoropolymer Project

During my time at Purdue, I was assigned to project proposed by the Army Research Laboratory.  The goal was to create a propellant and energetic material whose sensitivity was increased by means of the piezoelectric effect.


How does it work?

The dipole moment in a crystal are normally equal to zero, and the charges are balanced.

The effects of the balanced charges cancel each other out, leaving no net charge on the crystal faces.

When mechanical stress is applied, the charges are force out of balance.

 

The effect of these dipole moments produce a voltage across the opposite faces.


Background

Different fluoropolymers can exhibit piezoelectric effects when induced into the β phase.  They also work as excellent oxidizers and can be turned into energetic material when mixed with a fuel.  


Method

The goal then is attempt to induce PVDF into the β phase to obtained a voltage potential in an energetic material.

I successfully induced PVDF into the correct phase by two means.  The first was by means of doping.  Addition of titanium dioxide created a structure for the PVDF to reorient itself.

The second method is was by means of electrically poling.  I applied an external voltage difference that aligned the polymer in the right orientation. 

In order to test increased sensitivity in my modified samples,  I compared the voltage outputs of my treated and untreated samples.  I also compared the results of my impact tests.


Results

I performed drop weight tests on the electrically poled samples, and their results were very much unexpected.  The pure samples were siginificantly more sensitive than the poled samples.  This was the exact opposite of what was expected.