Bulletin of the American Physical Society
2007 Joint Fall Meeting of the Texas Sections of the APS and AAPT; Zone 13 of SPS
Volume 52, Number 16
Thursday–Saturday, October 18–20, 2007; College Station, Texas
Session J2: CM5: Condensed Matter |
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Chair: Chia-Ren Hu, Texas A&M University Room: Rudder Tower 504 |
Saturday, October 20, 2007 10:40AM - 10:52AM |
J2.00001: The Bouncing Jet: A Newtonian Liquid Rebounding off a Free Surface Matthew Thrasher, Sunghwan Jung, Yee Kwong Pang, Chih-Piao Chuu, Harry L. Swinney We find that a liquid jet can bounce off a bath of the same liquid if the bath is moving horizontally with respect to the jet. Previous observations of jets rebounding off a bath (e.g. Kaye effect) have been reported only for non-Newtonian fluids, while we observe bouncing jets in a variety of Newtonian fluids, including mineral oil poured by hand. A thin layer of air separates the bouncing jet from the bath, and the relative motion replenishes the film of air. Jets with one or two bounces are stable for a range of viscosity, jet flow rate and velocity, and bath velocity. The bouncing jet phenomenon can be observed in many household fluids using only minimal equipment, making it accessible as a classroom demonstration and a science project. [Preview Abstract] |
Saturday, October 20, 2007 10:52AM - 11:04AM |
J2.00002: The Study of Water's Interaction With PEG-DM hydrogels through T1 relaxation times Joseph Meier, James Maneval, Erin Jeblonski Polyethylene glycol(PEG), a hydrophilic polymer, is different then poly-propelene glycol(PPG) and polymethylene glycol(PMG) which are hydrophobic. Study of this difference was carried out by empirically determining how water interacts with PEG using a 600 MHz NMR spectrometer to measure T1 relaxation times of water with PEG-dimethacrylate(PEG-DM) hydrogels. The PEG-DM hydrogels were synthesized in a two part reaction involving attaching methacrylic acid to the two ends of the polymer, then cross-linking vinyl groups of the methacylic acid to form a linked matrix of all the PEG-DM molecules. The presentation will cover how the measurements were taken, what can be learned from the T1 relaxation times, and what future studies will entail. [Preview Abstract] |
Saturday, October 20, 2007 11:04AM - 11:16AM |
J2.00003: The Effect of a Nematic Liquid Crystal Environment on the Alignment of the Conductive polymer MEH-PPV as a Function of Polymer Chain Length David Solis, Alexei Tcherniak, Andrew Tangonan, T. Randall Lee, Stephan Link MEH-PPV (poly(2-methoxy, 5 ethyl (2' hexyloxy) para-phenylene vinylene)) is a conductive, highly fluorescent polymer that has important technological applications in photovoltaic devices such as organic solar cells and light emitting diodes. It is known that the polymer conformation can be controlled through the environment in which it is present. By using a nematic liquid crystal solvent, 5CB (4-pentyl-4'-cyanobiphenyl) as a host for the MEH-PPV, we are able to stretch and align the polymer chains along the liquid crystal director to a much greater extent than it is possible in an isotropic solvent. We use single molecule polarization spectroscopy to determine the solute order parameter for the MEH-PPV -- 5CB solute-solvent system. Using MEH-PPV samples with different molecular weights, we are able to investigate the dependence of the solute order parameter on the polymer chain length. We observe a decrease in order parameter for shorter polymer chains with the solute order parameter equaling that of the solvent for a single molecule solute (rhodamine 6G). [Preview Abstract] |
Saturday, October 20, 2007 11:16AM - 11:28AM |
J2.00004: Study of Rubber Composites with Positron Doppler Broadening Spectroscopy: Consideration of Counting Rate Chun Yang, C.A. Quarles We have used positron Doppler Broadening Spectroscopy (DBS) to investigate the uniformity of rubber-carbon black composite samples. The amount of carbon black added to a rubber sample is characterized by phr, the number of grams of carbon black per hundred grams of rubber. Typical concentrations in rubber tires are 50 phr. It has been shown that the S parameter measured by DBS depends on the phr of the sample, so the variation in carbon black concentration can be easily measured to 0.5 phr. In doing the experiments we observed a dependence of the S parameter on small variation in the counting rate or deadtime. By carefully calibrating this deadtime correction we can significantly reduce the experimental run time and thus make faster determination of the uniformity of extended samples. [Preview Abstract] |
Saturday, October 20, 2007 11:28AM - 11:40AM |
J2.00005: Effects of Energetic Ion Particles on Friction of Diamond-Like Carbon Ke Wang, Hong Liang, Jean Michel Martin, Thierry Le Mogne We demonstrate that energetic argon ions introduce phase transformation of a diamond-like-carbon film. Inside an ultrahigh vacuum chamber, energetic Ar ions of 5KeV were generated using an X-ray photon spectroscopy. After ion bombardment, the XPS and friction tests were conducted in situ. The ex situ surface morphological analysis using an atomic force microscope and the multiple-peaks deconvolution of the C 1s XPS peak indicate that the changing ratio of sp2 and sp3 hybridization of carbon dominates the film's friction. We conclude that the friction of the DLC film against itself depends on the carbon phase, not the film's surface roughness. [Preview Abstract] |
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