Abstract
13C NMR relaxation measurements were performed on two series of miscible polymer blends: entangled polybutadiene (PB) in perdeuterated oligomeric poly(vinyl ethylene) and entangled poly(vinyl ethylene) (PVE) in perdeuterated oligomeric polybutadiene. A wide range of temperatures (∼ Tg + 50 K to Tg + 200 K) and several compositions (weight fractions of 0, 0.25, 0.5, 0.75, 1) were investigated. The segmental correlation times for the entangled components in both series of blends were extracted and compared to the corresponding terminal dynamics reported by Yang et al. The terminal dynamics have a stronger composition dependence than the segmental dynamics in PB/PVE blends. In contrast, a previous study of polyisoprene/poly(vinyl ethylene) blends revealed that the segmental and terminal dynamics exhibit equivalent dependences on the temperature and composition in that system. The Lodge/McLeish model satisfactorily fits the segmental correlation times in PB/PVE blends, but with the fit parameter φself different than the model prediction. We also found that the segmental dynamics of cis and trans units in the polybutadiene homopolymer have slightly different temperature dependences.
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