Research Goals
Theoretical Background


Below is a week by week report on the weeks happenings...

bulletThe First Week

The first few days were hectic and filled with anxiety. Getting acclimated to a new environment and trying to figure out what project to pick were definitely taxing on the brain, especially following a month of relaxation, since school ended at the end of April. For two days we listened to mentors present their research and projects. Finally though, on Wednesday we were able to decide, we had three choices, pick #1 being our favorite. Later that day at an ice cream social at Dr. Larry Weaver’s House, Larry and Kristan told us who got what project. Fortunately, I got my top pick, which was a project with Dr. Chris Sorensen, on Aerosol gelation, click on the Research goals and Theoretical Background links to learn more about it. The next day, a Thursday, I began my journey into Aerosol gels. Mrs. Sarah Elizabeth Gilbertson a graduate student in physics in search of her masters was already working on the project. She is the resident expert on aerosol gels, besides Dr. Sorensen, and she began to teach me on the subject and I worked with her on her project to learn more. She had been working on gelling an aerosol with liquid phase precursors, but to date she had not accomplished such a feat. Thus ended the first week, a hectic week filled with much reading on aerosol gels.

bulletThe Second Week
bulletWe began this week with a bang...a styrene and oxygen explosion in the 100mL cylindrical chamber. Unfortunately, we only attained a thin layer of soot plastered to the walls of the small chamber. We later performed another explosion with similar results. This led to the idea that we were not getting enough volume fraction from the styrene vapor. At this point we went to take a TEM (Transmission electron Micrograph) of our soot. The TEM showed us little aggregation, and another interesting feature. There were noticeably large black monomers, about 300 nm in diameter, amongst the smaller monomers, about 5-10 nm in diameter. This led to the idea that the large black monomers were pyrolized Styrene droplets that did not fully combust, hence the low yield of aggregation. Only a shell of some thickness was being combusted. Back to the drawing board.
bulletThe Third Week
bulletDuring this week we performed a light scattering experiment on our 100 mL bomb chamber, in order to determine the volume fraction. We have two quartz glasses on the chamber. We fill the chamber up with the vapor produced by the nebulizer, then measure the peak intensity through the chamber from the laser, and do the same having no vapor in the chamber. By how much the peak intensities attenuated we can determine the volume fraction. The volume fraction was measured to be ~10-4, so we're at the right order of volume fraction. thus, the styrene must not be combusting fully. This week also featured the arrival of the 30 year old 20 liter apparatus a.k.a. "the detention droid". Its age shows. It will take a lot of work to get this new bomb chamber operational, I need to set up the system in which the dust disperses, the ignition system, find a way to seal the chamber up, in order to adjust the pressure inside of it, and some other problems.
bulletThe Fourth Week
bulletThis week featured a large "boom". Since we were not getting full combustion of styrene we decided to add a background gas. This background gas happened to be acetylene. The oxygen and acetylene combustion is our bread and butter for creating carbon aerosol gel. The thought process here is...since the styrene isn't combusting fully, then if we add some more energy (acetylene) to the system, perhaps the combustion of the acetylene will add enough humph to the system so that the styrene combusts fully. When we performed the first combustion, there was a deafening boom from our chamber as it broke the 1/4" quartz glass on the sides of the bomb chamber. Fortunately, we combusted the chamber in a strong fume hood and we were out of the room at the time of the ignition. Whew. Following that exhilarating event, we needed to redesign the chambers sides to ensure such an explosion does not occur again. Two this aluminum discs should do the trick and they did. 
bulletThe Fifth Week
bulletWith our chamber redesigned, we were able to create a gel using acetylene, styrene, and oxygen. The week was cut short due to being kicked out, because of asbestos roaming from the ceilings and into the air, a remnant of the tornado damage. Fortunately, the air quality tests were negative. We were actually way below the maximum daily exposure limit, a few orders of magnitude. But nonetheless, we were pleased to know that we were able to make gel from a mixture of styrene, oxygen, and acetylene. It was estimated that the gel yield was increased by about 10%. This was noticed qualitatively too, as the bomb chamber was noticeably fuller.
bulletThe Sixth Week
bulletFrustrations over setting up the solid fuel experiment reached an all time high. I had ordered a part from a company the previous week and when it arrived, I realized that they sent me the wrong part. Besides that, the process of making the solid phase experiment had been coming along relatively smoothly. On the liquid phase side, we decided to move onto using titanium tetrachloride with oxygen and acetylene. These precursors would yield some titanium dioxide carbon aerosol gel combination. The technical advantages of titanium dioxide gels is enormous. They would be photo catalytic and because of which, can clean up nitrogen oxides and dangerous organic compounds. Also, it would perform hydrolysis, so perhaps as a potential hydrogen fuel cell.
bulletThe Seventh Week
bulletSuccess!!! the end of this week my hard work paid off and the solid phase experiment was finally ready to be performed, after much . I started the tests with just flour in order to work out the kinks in the system i.e. leaks, pressures, ignition system. Prior to this grandiose moment, Elizabeth and I had also created a very low yield of some titanium dioxide and carbon gel. The gel was grayish as compared to the carbon black and it also had a firmer quality to it. So we went to get a TEM (transmission electron micrograph) of the product.
bulletThe Eighth Week
bulletThe results from our TEM of the titanium dioxide carbon gel came in. We were getting beautiful fractal aggregates, but interspersed throughout the aggregates were large black balls. We came to realize that the black balls were burnt titanium drop cores that never fully combusted, just like the styrene droplets. This was unfortunate, because it meant with our current experimental set-up was insufficient. One major problem was that we could not get the droplet size of our fuel vapor any smaller than ~3 micron in diameter. This was due to the fact that we created our vapor from a nebulizer (it breaks up the surface tension of the liquid by shaking at a certain frequency, thus creating a vapor) that operated at a frequency of 2.5 megahertz. That was the smallest droplet size we could attain. Furthermore, we had to stick to liquid fuels that had a viscosity at or below the viscosity of water. Resulting in a limited amount of liquids that could be used, mostly hydrocarbons or some very dangerous liquids, and that wouldn't result in any new novel aerosol gels, just carbon. So, the move to solid phase precursors was apparent to see if some new aerosol gel could be possible, or perhaps there would be a similar problem with solid phase, where there was not full combustion. Speaking of the solid phase experiment, it was going smoothly. I managed to get everything working and I had done an aluminum combustion. I had to move to electric matches as an ignition source, because the spark gap was not powerful enough to ignite the aluminum powder. Unfortunately, I hardly got any alumina, this fact led me to believe that perhaps the powder was just not very reactive and that something was wrong with the dispersion system, since I only got caked on aluminum and not any aerosol soot.
bulletThe Ninth Week
bulletI determined that the nozzles the dust was coming out of in the bomb chamber were depositing most of the dust directly onto the surface of the sphere and not in an aerosol form, so the combustion was happening when most of the dust was lying in a pile. So I went to the machine shop and fixed this by plugging up the holes facing the sphere. Then the most painful thing happened (not physically). An air leak coming from the solenoid valves that controlled the dispersion system. With the high pressures I was using, I was always kind of scared something bad would happen, since I rarely work with high pressure ~300 PSI. Long story short, as I went to tighten the bolt where the leak was coming from, the darn thing broke. This piece was special to this device so I went on a quest for it. Unfortunately, I had to let a machinist make it, and due to his schedule, it would not be done until after I was gone. : ( Also, to add to the misfortune, I determined that the aluminum powder being used was just not very flammable. By throwing some in a Bunsen burner, there should be some large white flash, but there was not much of any different in the flame. We took some apparently finer powder the physics demonstration lab had and threw that in the burner, resulting in a magnificent white flash. Hmmm.
bulletThe Tenth Week
bulletThis week consisted only of three days and I was determined to work around my problem by jimmy rigging something, in order to get some solid phase results. First, I was going to borrow some of the aluminum powder from the demo lab, and secondly find another way to disperse the dust. Amazingly, I was able to create a way of doing this by running some copper tubing into the chamber and hooking a metal funnel to the end of it. The dust would be loaded into the funnel, then a blast of oxygen would disperse the dust in the chamber. Unfortunately, I still needed a way to independently fill the sphere with oxygen, in order to make the atmosphere in the sphere 100% oxygen. Even though I wasn't able to finish this, I was able to set up the experiment and show how to use it and show what work still needs to be done to execute the solid phase experiment to Eli, who would take over the experiment after I left. My final presentation is tomorrow, then I go back home, I had a great time.



Home | Research Goals | Theoretical Background | Progress | Contact | Feedback

This site was last updated 08/05/08