Dynamic viscoelasticity of poly (methylmethacrylate)/poly(a-methylstyrene-co-acrylonitrile) blends near the phase-separation temperature
Zheng Qiang; Araki Osamu; Takigawa Toshikazu; Takahashi Masaoki; Masuda Toshiro
Abstract:Mixtures of Poly (methyl methacrylate) (PMMA) and poly (a -methylstyrene-co-acrilonitrile) (a MSAN) exhibit a LCST type of phase behavior. Dynamic rheological properties of PMMA/a MSAN blends of various compositions were measured at temperatures below, near, and above the phase-separation temperature. The time-temperature superposition was tried to obtain the master curves of G' and G'' at 160 degree. The time-temperature superposition principle failed above a certain temperature due to a phase separation. The 'breakdown' temperature is close to the cloud temperature Tc of the blend samples. Comparison of log G' vs. log G'' relation between the two components and the blends was made. The results show that the slopes of log G' vs. log G'' plots in the terminal region are dependent on the composition of the blends. The rheological measurements have been found to be useful for characterizing the phase-separation of PMMA/a MSAN blends. Key Words:polymer blends, dynamic viscoelasticity, time-temperature superposition, phase-separation