May 12 - May 18

Week 7 
Returning to the Nanoparticles lab on Tuesday, larger ratios of liquid crystal to polymer were tested. Each test mixture was approximately 0.50 g, with the ratio of liquid crystal varied from 55 to 70%. Four different mixtures were again measured using the same procedure. The substrates containing 55%, 60%, and 65% liquid crystal were placed in the vacuum press, which served to both uniformly distribute the polymer dispersed liquid crystal and harden the film. The mixture containing 70% liquid crystal was placed between glass and the PDLC distributed evenly under a balloon press. Spacers were also added to each PDLC mixture in order to regulate the droplet size of the liquid crystal. The table below shows the measurements and experimental ratios for each of the four tests. 

Polymer	Mass Added	Experimental Ratio
0.45	0.2399 g	0.4272
0.40	0.2065 g	0.4066
0.35	0.1762 g	0.3524
0.30	0.1504 g	0.2926
Liquid Crystal	Mass Added	Experimental Ratio
0.55	0.2864 g	0.5728
0.60	0.2967 g	0.5934
0.65	0.3238 g	0.6476
0.70	0.3537 g	0.7074

The results of this experiment showed that greater ratios of liquid crystal have greater transparency changes under an applied voltage. As a result, the prototype will use a mixture containing approximately 70% liquid crystal to maximize the shift in opacity. Each of the experimental substrates below were tested with an applied voltage of around 28 volts. This changed the orientation of the liquid crystal and the polarization allowing light to pass through.   In the image below, the four test plates are shown with varying ratios of liquid crystal. The tests with PDLC film between conductive substrates contain multiple air bubbles, while the glass showed uniform opacity.