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Ran Tao

Dr. Ran Tao is a Research Associate working in the Security Technologies Group of the Materials Measurement Laboratory (MML) at the National Institute of Standards and Technology.  Her research experience includes structural and dynamics characterization of polymeric materials, nanocomposites, fiber-reinforced hierarchical composites, small molecular glass forming liquids, colloids, foams, etc.  She specializes in using advanced rheological techniques and thermal analysis methods to address different materials science challenges.

Selected non-NIST publications:

  1. R. Tao, E. Gurung, M.M. Cetin, M.F. Mayer, E.L. Quitevis, S.L. Simon, Fragility of ionic liquids measured by Flash differential scanning calorimetry, Thermochim. Acta 2017, 654, 121-129.
  2. R. Tao, S.L. Simon, Rheology of Imidazolium-Based Ionic Liquids with Aromatic Functionality, J. Phys. Chem. B 2015, 119, 35, 11953-11959.
  3. R. Tao, S.L. Simon, Bulk and shear rheology of silica/polystyrene nanocomposite: Reinforcement and dynamics, J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 621–632.
  4. R. Tao, S.L. Simon, Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite, J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1131–1138
Current Research Interests
  • Hard-sphere suspensions in biaxial shear flow
  • Flow-induced anisotropy in complex fluids
  • Rate-dependent properties of impact mitigating materials using ultrasound imaging
  • Interphase properties of hierarchical polymer-based composites
 Current Projects
  • End effect correction for orthogonal small strain oscillatory shear in a rotational shear rheometer
  • Visualization of agglomerates breakdown in shear thickening fluids by large amplitude oscillatory shear
  • Structure-property relationships in next-generation ballistic witness materials

Previous NIST Projects
Rheological Characterization of Ballistic Witness Materials using Rubber Process Analyzer (RPA)


An oil-based modeling clay, Roma Plastilina No. 1 (RP1), was chosen by both the National Institute of Justice (NIJ) and the Department of Defense (DoD) as the standard backing material for body armor testing since the 1970s.  Body armor is tested for both penetration and deformation effects (the backface signature) by placing the armor against a backing material, also known as a ballistic witness material (BWM).  Therefore, the backing material plays a critical role in the standard testing procedure.  Unfortunately, over the decades since RP1 was adopted as the standard, changes have been made to the RP1 formulation by the clay manufacturer.  Newer versions of RP1 are stiffer at room temperature than the original RP1.  Ballistics practitioners and researchers must now thermally treat the material prior to use in order to meet specifications developed in the 1970s.  Therefore, the ballistic testing community has begun to look for an alternative ballistic witness material to replace RP1.


The research at NIST focuses on rheological characterizations of the RP1 modeling clay and future methods for other potential ballistic witness materials.  The goal is to understand rheological properties of clay-like materials, which are dependent on shear history, time, and temperature, in an effort to extract suitable material parameters that govern the material performance in actual usage conditions. This research is anticipated to provide clay manufacturers with fundamental information about the rheological characteristics, or flow properties, and to inform modeling efforts so that better clay deformation models can be developed, and furthermore, to provide information to guide the establishment of standards related to clay specifications, as well as conditioning and handling protocols.



Created June 4, 2019, Updated September 9, 2019