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Phase Morphologies and Viscoelastic Relaxation Behaviors for an LCST‐Type Polymer Blend Composed of Poly(methyl methacrylate) and Poly[( α ‐methyl styrene)‐ co ‐acrylonitrile]
Author(s) -
Zuo Min,
Zheng Qiang
Publication year - 2006
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200600333
Subject(s) - lower critical solution temperature , materials science , viscoelasticity , polymer blend , spinodal , dynamic mechanical analysis , polymer chemistry , poly(methyl methacrylate) , methyl methacrylate , dynamic modulus , phase (matter) , polymer , composite material , thermodynamics , copolymer , chemistry , organic chemistry , physics
Summary: Small amplitude oscillatory shear rheology is employed to investigate the linear viscoelastic behavior of the LCST‐type PMMA/ α ‐MSAN polymer blends as a function of annealing temperature and time. The results reveal that when temperature approaches the separation temperature, the blends exhibit some characteristic of complex thermorheological behavior, such as a shoulder in the dynamic storage modulus G ′ or the linear relaxation modulus G ( t ), the appearance of a loss tangent (tan δ ) peak and the additional relaxation in the relaxation spectrum H ( τ ). All of these can be attributed to the enhanced concentration fluctuations near the phase boundary. The anomalous pretransitional behavior can be quantified to yield the binodal temperature from the inflexion of variation and the spinodal temperature on the basis of the mean field theory. Furthermore, the linear viscoelastic properties of the phase‐separated PMMA/ α ‐MSAN (80/20) blends can be described well by either Palierne's or Bousmina's emulsion model in virtue of the calculated $\alpha /\bar R_v$ value in the whole frequency region.Morphology images of 80/20 PMMA/ α ‐MSAN blends annealed for 4 h at 180 °C observed from phase contrast microscope.