Abstract
Hyperbranched polyethers with different structures and molecular weights (MW) were synthesized using the A2+B3 approach by varying monomer ratio, A2 structure, and reaction time. Effects of backbone structure and MW on melt rheological behaviors were investigated by both small amplitude oscillatory shear and steady shear measurements. Master curves were constructed using the time-temperature superposition principle and compared. In the reduced frequency range covered, lgG″~lg(ω·aT) always show a slope of 1.0, suggesting a terminal zone behavior; in contrast, unexpected step changes or plateaus are observed on lgG′ master curves. Effects of backbone structure and MW on master curves were discussed. The Cox-Merz rule was tested at different temperatures and was found to be applicable when flow instability was absent.
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