The focus of this paper is on the viscoelastic properties of concentra
ted polymer solutions and polymer melts. Dynamic mechanical measuremen
ts were performed on various polystyrene/ethylbenzene solutions with p
olymer concentrations ranging from 40% up to 100% and temperatures fro
m T-g + 30 degrees C up to 70 degrees C (230 degrees C for polymer mel
ts). The basis polymers are two commerical grade polystyrenes (BASF) w
ith M(w) = 247 kg/mol and 374 kg/mol, respectively. To avoid solvent l
oss due to evaporating during the measurements, a special sealing tech
nique was used. A phenomenological model which describes quantitativel
y the relaxation spectrum of concentrated polymer solutions from the f
low regime up to the glass transition regime is developed. The relaxat
ion data of the respective polymer melt and the glass transition tempe
rature of the solution are the only input parameters needed. The tempe
rature dependence is described by a universal, concentration invariant
WLF-equation. The relaxation spectra are divided into two parts accou
nting for the entanglement and the segmental relaxation modes, respect
ively. The relaxation strength related to the flow and entanglement re
gime scale with c(2.3), whereas the segmental relaxation strength does
not alter with concentration. All relaxation times change with concen
tration proportional to c(3.5). Flow curves can be calculated from the
se relaxation spectra and thus, our results are useful for engineering
applications.