Mechanical and Viscoelastic Responses of Glassy Polymers and Their Nanocomposites

The mechanical behavior of polymeric glasses is important in daily application as well as for advanced materials insertion into industries as diverse as aerospace to micro/nano-electronics. In our labs we are addressing fundamentals of such performance through two routes. First, we are examining the fingerprinting of non-linear viscoelastic behavior of polymer glasses using mechanical spectral hole burning (MSHB) measurements that probe dynamic heterogeneity in glassy materials. Here we have shown that the strong β-relaxation in poly(methyl methacrylate) (PMMA) is responsible for the hole burning response of the polymer. Ongoing work is examining polycarbonate, which has a very weak β-relaxation and seems to show weaker hole burning behavior. In addition, we are beginning work to examine how to use nanoparticulates and rigid rod small molecules to antiplasticize polymers in a way that leads to increased glass transition temperatures.

Some Publications

1. S.C.H. Mangalara and G.B. McKenna*, “Mechanical hole-burning spectroscopy of PMMA deep in the glassy state,” J. Chem. Phys., 152, 074508 (2020).

2. Z. Qian and G.B. McKenna*,”Mechanical spectral hole burning of an entangled polymer solution in the stress-controlled domain,” Phys. Rev. E., 98, 012501 (2018).

3. Nabila Shamim and Gregory B. McKenna*, “Mechanical spectral hole burning in polymer solutions: Comparison with large amplitude oscillatory shear fingerprinting,” Journal of Rheology, 58, 43-62 (2014).

4. Q. Qin, H. Doen and G.B. McKenna*, “Mechanical Spectral Hole Burning in Polymer Solutions,” J. Polymer Science. Part B. Polymer Physics, 47, 2047-2062 (2009).

5. Q. Qin, X. Shi and G.B. McKenna*, “Mechanical Holeburning Spectroscopy in an SIS Tri-Block Copolymer,” J. Polymer Science. Part B.: Polymer Physics, 46, 3277-3284 (2007).

Funding

  • National Science Foundation. Division of Civil, Mechanical and Manufacturing Innovation Mechanics of Materials and Structures (MOMS).
  • National Science Foundation. Division of Materials Research (DMR, Polymers Program).
  • American Chemical Society Petroleum Research Fund.
  • John R. Bradford Endowment at Texas Tech University.
  • Paul Whitfield Horn Professorship at Texas Tech University.