Polyisobutylene: A most unusual polymer |
| |
| Authors: | K Kunal M Paluch C M Roland J E Puskas Y Chen A P Sokolov |
| |
| Institution: | 1. Department of Polymer Science, The University of Akron, Akron, Ohio 44325‐3909;2. Institute of Physics, Silesian University, ulica Uniwersytecka 4, 40‐007 Poland;3. Naval Research Laboratory, Chemical Division, Code 6120, Washington, District of Columbia 20375‐5342 |
| |
| Abstract: | The influence of molecular weight, M, on the fragility and fast dynamics in polyisobutylene (PIB) was studied using dielectric and mechanical relaxation spectroscopies, calorimetry, and Raman spectroscopy. The measurements indicate a decrease in fragility with increasing M for shorter chains, in the range of M where Tg is M‐dependent. Such behavior is not observed for other polymers and is at odds with traditional theoretical models that predict an increase in fragility with chain length. These results confirm the unusual character of PIB, as evident in various properties including extremely low gas permeability, a low fragility, and a segmental relaxation spectrum much broader than expected for a low‐fragility material. The reason for this anomalous behavior remains unclear, but might be related to the symmetric structure of the PIB repeat unit, together with comparable flexibility of both structural components, the backbone and side groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1390–1399, 2008 |
| |
| Keywords: | dielectric relaxation fragility glass transition light scattering mechanical spectroscopy polyisobutylene Raman spectroscopy structure‐property relationship |
|
|
