Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session Y16: Complex Soft Materials |
Hide Abstracts |
Sponsoring Units: GSOFT Chair: Troy Shinbrot, Rutgers University Room: 275 |
Friday, March 17, 2017 11:15AM - 11:27AM |
Y16.00001: Toward reduced-order modeling techniques in granular media Ken Kamrin, Hesam Askari, Dan Goldman, Qiong Zhang, Stephen Townsend To model the flow of granular media with high accuracy, a number of subtleties arise and complex constitutive relations are needed to address them. However, making certain rheological simplifications produces a framework that is simple enough to obtain global rule-sets that can be used to aid in design without having to solve any partial differential equations or perform discrete element simulations. This talk will show how reduced-order rule-sets such as the Resistive Force Theory can be obtained from a basic frictional plasticity model, and how plasticity can further be used to produce a family of scaling laws in granular locomotion reminiscent of `wind tunnel' scaling laws in fluid dynamics. These are verified with numerical simulations. [Preview Abstract] |
Friday, March 17, 2017 11:27AM - 11:39AM |
Y16.00002: Abstract Withdrawn
|
Friday, March 17, 2017 11:39AM - 11:51AM |
Y16.00003: Combined effect of moisture and electrostatic charges on powder flow Geoffroy Lumay, Antonella Rescaglio, Julien Schockmel, Nicolas Vandewalle It is well known in industrial applications involving powders and granular materials that the relative air humidity and the presence of electrostatic charges influence drastically the material flowing properties. The relative air humidity induces the formation of capillary bridges and modify the grain surface conductivity. The presence of capillary bridges produces cohesive forces. On the other hand, the apparition of electrostatic charges due to the triboelectric effect at the contacts between the grains and at the contacts between the grains and the container produces electrostatic forces. Therefore, in many cases, the powder cohesiveness is the result of the interplay between capillary and electrostatic forces. Unfortunately, the triboelectric effect is still poorly understood, in particular inside a granular material. Moreover, reproducible electrostatic measurements are difficult to perform. We developed an experimental device to measures the ability of a powder to charge electrostatically during a flow in contact with a selected material. Both electrostatic and flow measurements have been performed in different hygrometric conditions. The correlation between the powder electrostatic properties, the hygrometry and the flowing behavior are analyzed. [Preview Abstract] |
Friday, March 17, 2017 11:51AM - 12:03PM |
Y16.00004: Breaking Propensity: A destructive method seeking structures which determine particle motion. Cordell Donofrio, Eric Weeks It is known that at any given time in a supercooled liquid, particles can be found that have a higher propensity to move. This is found by running simulations with repeated initial positions but with shuffled initial velocities, and observing that some particles are in positions for which they frequently have large displacements. This suggests that local structure may play an important role, and that it may be possible to distinguish ahead of time which particles have a higher propensity for motion. We investigate the magnitude of this effect by simulating the Kob-Andersen binary Lennard-Jones glass former, and measure the propensity signal over a large range of time scales. Additionally, we attempt to 'break' this signal by introducing structural changes, thereby revealing key structural features related to propensity. [Preview Abstract] |
Friday, March 17, 2017 12:03PM - 12:15PM |
Y16.00005: Anomalous Diffusion and Stress Relaxation in Micellar Fluids Radhakrishna Sureshkumar, Subas Dhakal This talk will address two long-standing questions on the dynamics and rheology of micellar fluids. First, it has long been hypothesized that branched micelles are much more efficient in relaxing internal stresses than linear ones via sliding of branches along main chain contours. Second, anomalous surfactant diffusion including superdiffusion has been suggested by experiments. Tracking the motion of branch points as well as individual surfactants poses a great challenge. We use molecular dynamics simulations of cationic surfactant solutions of cetyl-trimethyl-ammonium-chloride in the presence of a hydrotropic salt sodium salicylate to answer the above questions. The mechanisms of branch formation, superdiffusion and the energetics of branch motion will be discussed. ~ [Preview Abstract] |
Friday, March 17, 2017 12:15PM - 12:27PM |
Y16.00006: Thermal processing routes to structure control in phase separating colloidal gels Tuan Nguyen, Yongxiang Gao, Juntae Kim, Matthew Helgeson Sophisticated thermal quenching and annealing strategies to create bicontinuous or hierarchical morphology have allowed for the creation of molecular materials (metals, ceramics, minerals and polymers) with significantly enhanced properties. Here, we explore new routes by which similar thermal processing strategies can be applied to colloidal gels. Specifically, colloid-polymer mixtures with thermoresponsive bridging attractions are employed to characterize how the thermal path taken through regions of non-equilibrium phase separation and gelation determine the dynamics and arrest of colloidal gelation. Interestingly, we find that the dominant mechanism of gelation (percolation, arrested phase separation or attractive glass formation) is highly sensitive to both the colloid volume fraction as well as the non-equilibrium thermodynamic path to the gelled state. Using recently-developed Fourier correlation microscopy methods, we show that this sensitivity is due to the temperature dependence of competing time scales for diffusion, aggregation and phase separation. Ultimately, we show how the control of these dynamics by thermal processing can be used to tailor the microstructure and rheology of colloidal gels. [Preview Abstract] |
(Author Not Attending)
|
Y16.00007: Melt Structure Evolution of Cu-Zr-Ti Metallic Glasses Rohan Mishra, Anupriya Agrawal, Katharine M. Flores, Kenneth F. Kelton Studying the evolution of melt structure of metallic glasses as we approach their glass transition temperature is essential to understand glass formation. Known for their excellent glass forming ability, Cu-Zr binary metallic glasses are very well studied in the literature. Here, we have focused on Cu-Zr-Ti ternary metallic glasses in order to extend the current understanding of metallic glasses to more complex and eventually more realistic glasses. We have used molecular dynamics simulations to characterize the changes in the structure and dynamics of (Cu$_{\mathrm{50}}$Zr$_{\mathrm{50}})_{\mathrm{1-}}_{x}$Ti$_{x}$ (\textit{0 \textless x \textless } 1) melt with the quenching. We observe that compositions with$ x$ \textless 0.5 form glassy solid and with$ x$ \textgreater 0.6 form crystalline solid for the same quench rates which agrees well with the experimental findings. Here, we have explored the factors that govern if a melt will form a glassy or crystalline solid. We will show that the overall density and dynamics doesn't have significant effect on solidification path the melt will follow. We will focus on the short and medium range order of the melt and their diffusion as a function of composition and temperature to highlight the differences in the melt behavior of the amorphous glasses from their crystalline form. [Preview Abstract] |
Friday, March 17, 2017 12:39PM - 12:51PM |
Y16.00008: Ioffe-Regel localization of longitudinal acoustic excitations and the Arrhenius crossover regime in glass-forming metallic liquids Abhishek Jaiswal, Yang Zhang The Ioffe-Regel (IR) criterion is known to distinguish the boundary between propagating and localized excitations. In previous studies of liquids the localization of transverse excitations within atomic cages at high-temperature has been elucidated using the IR limit. Much less emphasis has been put on the nature of longitudinal excitations and the IR limit. Herein, we map out the wavelength dependent IR crossover temperature of the longitudinal excitations in an excellent Cu-Zr-Al based glass-former. We find that the inflection point of this map occurs at the Arrhenius crossover temperature $T_{A}$ identified from deviations of Arrhenius form in transport properties and the breakdown of Stokes-Einstein relation. The corresponding wavelength of longitudinal excitations at $T_{A}$ equals the limit where all partial pair distribution functions $g(r)$ of the liquid approaches the random structure limit, essentially marking the boundary between the discrete and the continuous liquid. This map allows us to extract a temperature range for the Arrhenius crossover or the landscape-influenced regime in a glass-forming liquid. [Preview Abstract] |
Friday, March 17, 2017 12:51PM - 1:03PM |
Y16.00009: Topological phases in (Na$_{2}$O)$_{x}$(P$_{2}$O$_{5})_{100-x}$ glasses. Chandi Mohanty, Ralph Chbeir, Andrew Czaja, Ping Chen, Punit Boolchand We have synthesized titled glasses in the 0 \textless x \textless 0.50 range of soda paying special attention to their dryness. Pure P$_{2}$O$_{5}$ glass was synthesized by flash evaporation of bulk powder in a quartz tube as it was pumped in several attempts, and the variation of T$_{g}$ and enthalpy of relaxation ($\Delta $H$_{nr})$ measured for each attempt. These data show that as the glass got drier, T$_{g}$ increased to 431\textdegree C and $\Delta $H$_{nr}$ became miniscule. At higher soda content (x \textgreater 20{\%}), T$_{g}$(x) increased steadily, but with appearance of a local maximum near x $=$ 37.5{\%}. On the other hand $\Delta $H$_{nr}$ term, revealed a Trapezoidal-like minimum in the 32.5 {\%} \textless x \textless 42.5{\%} range, suggestive of a reversibility window or the isostatically rigid Intermediate Phase, with glasses at x \textgreater 42.5{\%} in the flexible phase while those in the 20{\%} \textless x \textless 32.5{\%} range in the stressed rigid phase. We have also obtained Raman scattering, IR reflectance and fragility index measurements on the present glasses, and these will discussed with recent$^{1}$ results in the field. \begin{enumerate} \item D.L. Sidebottom J. Chem. Phys. \textbf{140}, 154501(2014). \end{enumerate} [Preview Abstract] |
Friday, March 17, 2017 1:03PM - 1:15PM |
Y16.00010: Slow homogenization of binary As-S melts and vibrational evidence of As Quasi-Tetrahedral Units in glasses. Soumendu Chakravarty, Shreeram Dash, Ralph Chbeir, Ping Chen, Punit Boolchand FT-Raman profiling experiments on binary As-S melts are undertaken to establish the kinetics of homogenization of 1gram batch sizes using As$_{\mathrm{2}}$S$_{\mathrm{3}}$ and dry S as starting materials. These data reveal that melts take typically 3 weeks of reaction at 700\textdegree C to homogenize. Such slow kinetics of melt homogenization were noted earlier in Ge -- S binary and reflect the super-strong$^{\mathrm{1}}$ character (fragility index m \textless 20) of melts in the Intermediate Phase$^{\mathrm{1}}$ composition range. An important consequence of these homogenization experiments is that the Raman active 537 cm$^{\mathrm{-1}}$ mode predicted$^{\mathrm{2}}$ for the stretch vibration of S$=$As of Quasi Tetrahedral S$=$As(S$_{\mathrm{1/2}})_{\mathrm{3}}$ units is now observed in homogeneous glasses. Compositional trends of the mode scattering strengths, fragility index and the non -- reversing enthalpy of relaxation at T$_{\mathrm{g}}$ in these homogeneous glasses will be presented. \item S. Chakravarty, and P. Boolchand, J. Phys. Chem. B 118, 2249(2014). \item P. Chen et al. Phys. Rev. B 78, 224208 (2008). [Preview Abstract] |
Friday, March 17, 2017 1:15PM - 1:27PM |
Y16.00011: Intermediate Phase Spectroscopy of (Na$_{\mathrm{2}}$O)$_{\mathrm{x}}$[(B$_{\mathrm{2}}$O$_{\mathrm{3}})_{\mathrm{y}}$(GeO$_{\mathrm{2}})_{\mathrm{1-y}}$]$_{\mathrm{1-x}}$ glasses Aaron Welton, Ralph Chbeir, Andrew Czaja, Punit Boolchand The titled ternary is of interest because the two end members, viz., y$=$ 0, i.e., Sodium Germanate $^{\mathrm{1}}$, and y $=$ 1, Sodium Borate $^{\mathrm{2}}$ have been studied earlier and show the isostatically rigid Intermediate Phase (IP) to occur in the x $=$ 0.14 to x $=$ 0.19 range and in the x $=$ 0.20 to x $=$ 0.40 range of soda respectively. In the present work we now report on bulk glasses at y $=$ 0.75 synthesized over a wide range x $=$ 0 to x $=$ 0.30 of soda. Our motivation is to understanding the evolution of the IP in the pseudo-ternary glasses as the base glass connectivity is altered. Preliminary MDSC experiments show T$_{\mathrm{g}}$(x) to increase with x and to reveal a broad maximum at 510 C centered near x $=$ 0.25. Furthermore, an IP is found in the x $=$ 0.20 to x $=$ 0.33 range of soda where a reversibility window is observed. The window is centered near the T$_{\mathrm{g}}^{\mathrm{max}}$ content at x$=$ 0.25. IR reflectance show modes of BO$_{\mathrm{4}}$ and BO$_{\mathrm{3}}$ units but also those of bonded water. Raman scattering largely shows modes observed earlier in Sodium borate glasses$^{\mathrm{2}}$. 1 V. Rompicharla et al. J PCM 20, 202101 (2008) 2K. Vignarooban et al. EPL 108, 56001(2014). [Preview Abstract] |
Friday, March 17, 2017 1:27PM - 1:39PM |
Y16.00012: Topological Phases in Alkaline-Earth Borates Ralph Chbeir, Chad Holbrook, Andrew Czaja, Punit Boolchand Raman scattering has proved to be a powerful method to probe local-, intermediate --( rings) and extended-range (structural groupings) structure in Li- and Na-Borates$^{\mathrm{1}}$ and Ba-Borates$^{\mathrm{2}}$. Along with AC calorimetric (MDSC) data on non -reversing enthalpy of relaxation, we could identify the Stressed-rigid, Intermediate and Flexible phases in these Borate glasses. These efforts are directed towards better understanding the connection between these phases and glass structure. Here we report preliminary Raman scattering and MDSC results on Sr-Borates over a wide composition range 0 \textless x \textless 45{\%}, taking special care to synthesize dry and homogeneous melts by induction melting starting materials. Trends in glass transition temperatures T$_{\mathrm{g}}$(x) show a broad maximum (T$_{\mathrm{g}}^{\mathrm{max}} \quad =$ 650\textdegree C) centered near 33 mole{\%} of SrO, and a reversibility window with a width extending from 27.5{\%} to 37.5{\%} and centered about the T$_{\mathrm{g}}^{\mathrm{max}}$ composition. Results on Topological phases in the Sr- and Ba-borates will be compared. \item Vignaroban EPL \item C. Holbrook Ph.D. Thesis (2015). [Preview Abstract] |
Friday, March 17, 2017 1:39PM - 1:51PM |
Y16.00013: Correlation study of real delay time and imaginary delay time in 1-dimensional weak disorder optical media Peeyush Sahay, Huda M. Almabadi, Prabhakar Pradhan Real delay time ($\tau_{r})$ provides a measure of the time spent by photons inside an optical system. The measurement of $\tau_{r}$ is conducted in terms of energy ($E)$ derivative of the Wigner phase delay ($\varphi )$, as $\tau_{r} =d\phi /dE\propto d\phi /cdk$; $k$ and $c$ represents wavenumber and the speed of light, respectively. The characterization of $\tau_{r}$ requires interferometric system to measure $\varphi $ of the light waves scattering from the medium $[R=\sqrt r \exp (-i\phi )$]. We investigated the possibility of extracting the $\tau_{r}$ information from the intensity measurement of the backscattered waves. The study was performed on a 1D model of weak disordered optical system and short sample length by numerically evaluating the backscattered light intensity. An imaginary delay time ($\tau_{i})$, defined as $\tau_{i} =d\theta /cdk$, where $\theta $ represents an `\textit{imaginary phase}', was obtained upon expressing the backscattered intensity as $RR^{\ast }=\vert R\vert^{2}=r=\exp (-\theta )$. The result shows a strong correlation between $r$ and $\varphi $; with \quad $\tau _{r}$ and $\tau_{i}$ exhibiting similar statistical distribution but with a shift. The magnitude and variation of the mean and std values of $\tau_{r}$, and the std values of $\tau_{i}$ with sample lengths are nearly the same, which indicates about one parameter theory of delay time. This work potentially paves way for extracting phase information from the intensity distribution without using interferometric systems. [Preview Abstract] |
Friday, March 17, 2017 1:51PM - 2:03PM |
Y16.00014: Collective versus single-particle dynamical fluctuations in a glass-forming liquid Rajib Pandit, Elijah Flenner, Horacio E. Castillo We propose a decomposition of the four-point dynamic structure factor $S_4(k,t)$ of a glass-forming liquid into two contributions: a single-particle contribution $S_4^{sp}(k,t)$ and a collective contribution $S_4^{coll}(k,t)$. We apply this decomposition to the case of a binary hard-sphere mixture in three dimensions. For packing fractions near the glass transition, we find that at times of the order of the alpha relaxation time $\tau_{\alpha}$, the collective contribution can be up to two orders of magnitude larger than the single-particle one. By contrast, at times two orders of magnitude longer than $\tau_{\alpha}$, the single particle contribution becomes dominant. The collective part can be cleanly extracted at all times, and we use it to study the dynamic correlation length and the collective part of the dynamic susceptibility for timescales up to $100 \tau_{\alpha}$. [Preview Abstract] |
Friday, March 17, 2017 2:03PM - 2:15PM |
Y16.00015: Fragility Index variation in (Li$_{2}$O)x(B$_{2}$O$_{3})$100-x melts Charles Skipper, Ralph Chbeir, Chandi Mohanty, Punit Boolchand We have measured the fragility index (m) of titled melts as a function of Li$_{2}$O content in the 0\textless x\textless 35{\%} range using Modulated DSC. In this approach, one measures the real and imaginary part of the complex specific heat as a function of modulation frequency ($\nu )$, and deduces an activation energy by plotting the log of the enthalpy relaxation time as a function of inverse Temperature obtained at various $\nu $. For pure B$_{2}$O$_{3}$ glass with a T$_{g} \quad =$ 308\textdegree C, we obtain m $=$ 28 (1). With increasing x, m is found to monotonically increase to 38(1) as x increased to 15{\%}, but then to plateau at a value of m $=$ 42(2) in the range 18{\%}\textless x\textless 25{\%}. These values in m are significantly lower than those reported earlier$^{1}$. In particular, the range of x where we observe a plateau in m, authors of ref. 1 observed a linear increase in the 41\textless m\textless 62 range. T$_{g}$ of our glasses are found to be significantly greater than those of ref. 1, suggesting that the lower value of m in our glasses could be a manifestation of the reduced concentration of bonded water. The range of x across which a plateau is observed also happens to coincide where the isostatically rigid Intermediate Phase reported recently$^{2}$. $^{1}$ G.D.Chryssikos et al. JNCS \textbf{196}, 244 (1996). $^{2}$ K. Vignarooban et al. EPL \textbf{108}, 56001 (2014). [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700