Home
Scope
Location
Speakers
Program
Abstracts
Author index
Organizing Committee
Scientific Committee
Venue & Accomodation
Registration
News
Contact
|
 |
ORAL PRESENTATION
Session: 7 Applications to complex materials: glasses, micelles, colloids, blends, interfaces
(scheduled: Thursday, 11:10 )
Atomistic molecular dynamics simulation of the temperature and pressure dependences of local and terminal relaxations in cis-1,4-polybutadiene
G. Tsolou, V.G. Mavrantzas
1 Department of Chemical Engineering, University of Patras, GR 26504, Greece
2 Institute of Chemical Engineering and High-Temperature Chemical Processes (FORTH-ICE/HT), Patras GR 26504, Greece
We have explored features of local and terminal relaxation in cis-1,4-polybutadiene (cis-1,4-PB) over a wide range of temperature and pressure conditions by conducting atomistic molecular dynamics simulations (MD) with a united atom model on a 32-chain C128 cis-1,4-PB system [1]. Segmental relaxation was analyzed in terms of the dipole moment time autocorrelation function (DACF) of the simulated polymer. By Fourier transforming the DACF, the dielectric spectrum was computed and the validity of the time-temperature and time-pressure superposition principles were checked to decide for the appearance or not of additional relaxation mechanisms at low enough temperatures or high enough pressures. The relative contribution of thermal energy and volume to segmental relaxation was also calculated and evaluated in terms of the ratio QV/QP [2]. In contrast to experimental studies in other polymers [3], our results support that, in the temperature and pressure range studied, segmental and chain relaxations are influenced similarly by pressure and temperature variations. Further information about the dynamics of the intermediate chain segments has been extracted through the calculation of the dynamic structure factor. Current efforts focus on the determination of characteristic relaxation times in cis-1,4-PB and their variation with density or temperature and pressure, separately. © IWNET 2006
[1] G. Tsolou, V.A. Harmandaris, V.G. Mavrantzas, Macromol. Theory Simul. 15, 381 (2006).
[2] G. Tsolou, V.A. Harmandaris, V.G. Mavrantzas, J.Chem.Phys. 124, 084906 (2006).
[3] G. Floudas, T. Reisinger, J. Chem.Phys. 111, 5201 (1999).
|
|
 |
and Kleanthi for IWNET 2006