Levich Institute Seminar Announcement, 03/29/2011
Tuesday, 03/29/2011
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Professor Silvina Tomassone
Rutgers University
Department of Chemical and Biochemical Engineering

"Dispersion and Rheology of Silica Nanoparticles in Polyethylene Melt "


ABSTRACT


A novel methodology was developed to elucidate the solid-liquid interactions between solid nanoparticles present within a polymer melt by utilizing a multi-scale model that combines atomistic, meso-scale simulations and Themodynamics theory. The goal of this study was to accurately simulate a real physical polymer melt containing dispersed nanoparticles, while simultaneously observing the effects of nanoparticle solid fraction, polymer chain length, and the relative size of the nanoparticles to the polymer chains. Silica nanoparticles in a polyethylene melt were explored as a case study, where the solid-fluid interaction parameters were determined by iterating the value of the surface tension between the silica and polyethylene at a spherical interface. A transition from dispersed to agglomerated nanoparticle states could be observed while measuring the potential energy of the system and heat capacity within the composite. Furthermore, it was found that a thermodynamically stable dispersion of nanoparticles was established when the radius of gyration of the linear polymer was greater than the radius of the dispersed nanoparticles. In addition, the viscosity of the melt was studied as a function of the polymer chain length, nanoparticle size, and fill fraction of the particles, where it was found that the shear viscosity consistently increased with an increased concentration of particles; a frequently observed experimental effect. The addition of nanoparticles to the melt lead to a more pronounced shear thinning behavior of the target polymer melt, where it was found that when using a constant volume fraction of particles, the use of smaller particles led to an overall increase in melt viscosity. These findings show qualitative agreement with experimental studies reported in the literature.

BRIEF ACADEMIC/EMPLOYMENT HISTORY
  • 2001 -present Assistant Professor Department of Chemical & Biochemical Engineering Rutgers University,Piscataway, NJ
  • 1999 -2001 Post Doctoral Research Associate Levich Institute, City College of New York, New York, NY,
  • Ph. D., Physics ,Northeastern University, Boston, 1998. Faculty Advisor: Prof. A. Widom
CURRENT RESEARCH INTERESTS

  • Surfactant morphology and dynamics
  • Nanoparticles (clean and in suspension)
  • Particle shape monitoring and control in crystallization processes using MD
  • Bio-Nano Robotics
  • Granular Materials