TY  - JOUR
AU  - Schwahn, Dietmar
AU  - Pipich, Vitaliy
AU  - Richter, Dieter
TI  - Composition and long-range Density Fluctuations in PEO/PMMA Polymer Blends - a Result of asymmetric Component Mobility
JO  - Macromolecules
VL  - 45
IS  - 4
SN  - 1520-5835
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2013-00648
SP  - 2035-2049
PY  - 2012
AB  - Fluctuations of density and composition were observed in the disordered regime of a symmetric poly(ethylene oxide) (PEO) and a poly(methyl methacrylate) (PMMA) polymer blend. This blend is of particular interest as the glass transition (TG) of both polymers happens at very different temperatures thereby inducing a dynamic asymmetry in the molecular dynamics. Small-angle neutron scattering and oscillatory shear rheology were the principle experimental tools. Composition fluctuations determined the Flory–Huggins parameter as well as glass and gelation temperature (TA). The density fluctuations are of long-range and show a mass fractal dimension whose strength enlarges below the glass transition. A fairly constant TA about 40 K above TG separates two regions of distinctively different fluctuation behavior. A comparison of viscoelastic plateau modulus and high frequency modulus determined from rheology and SANS show that the relaxation modes in the regime between TG and TA are determined by the freezing segmental modes of PMMA.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000300757000034
DO  - DOI:10.1021/ma2019123
UR  - https://juser.fz-juelich.de/record/129128
ER  -