Rate dependent mechanical performance of ethylene-methacrylic acid (EMAA) copolymers and POSS-enhanced EMAA nanocomposites

POLY 201

Stephanie Deschanel, sdeschan@mit.edu1, Mary C. Boyce, mcboyce@mit.edu1, and Robert E. Cohen2. (1) Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, (2) Department of Chemical Engineering, Massachusetts Institute of Technology, MA
Polymeric materials possess highly rate sensitive material response which offers different mechanical deformation and failure behavior in different temperature and frequency regimes. In this study, the deformation of Ethylene Methacrylic Acid copolymers are evaluated under compression at strain rates ranging from 10-4 to 104/s. The time-dependent mechanical behavior is evidenced by rate-dependent elastic moduli and rate-dependent large deformation stress-strain behavior. The nature of the rate sensitivity has been observed to change as one moves between different temperature and frequency regimes, where various primary and secondary molecular mobility mechanisms are accessed. Methacryl-POSS was also incorporated through melt blending to characterize the effects of nanoscale structural alterations on the macroscopic rate-dependent mechanical behavior of these new nanocomposites. A large enhancement of rubbery modulus was found with addition of small weight fractions of POSS whereas the enhancement of glass modulus was comparatively modest.

Segmented Block Copolymers
8:30 AM-12:20 PM, Tuesday, March 27, 2007 McCormick Place South -- Room S504A, Level 5, Oral

Division of Polymer Chemistry

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007