Observation of boson peaks by inelastic neutron scattering in polyolefins
- Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6197 (United States)
- Corporate Research Laboratories, Exxon Research and Engineering Company, Annandale, New Jersey 08801 (United States)
- Intense Pulsed Neutron Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Inelastic neutron scattering was used to probe the nature of the boson peak in atactic polypropylene (aPP), head-to-head polypropylene (hhPP), polyisobutylene (PIB) and a 1/1 mass ratio hhPP/PIB blend. Atactic polypropylene is among the most {open_quotes}fragile{close_quotes} of glass formers and was found to have a shoulder rather than the distinctive peak exhibited by the other three polymers. This difference is already apparent at 15 K where relaxations are not expected to occur. The results suggest that the fragility of hhPP is intermediate between aPP and PIB. Within this group of polymers which have similar chemical structures the position of the boson peak appears to correlate with the glass transition temperature and the cohesive energy density. The possibility of a correlation with chain stiffness as expressed by the characteristic ratio is also discussed. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 351851
- Journal Information:
- Journal of Chemical Physics, Vol. 111, Issue 4; Other Information: PBD: Jul 1999
- Country of Publication:
- United States
- Language:
- English
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