Viscoelasticity of Polymer Blends
Solutions of Mixture of Polystyrene and Poly (vinyl methylether) in Dibutyl Phthalate
1988 Volume 16 Issue 4 Pages 171-175
Details
1988 Volume 16 Issue 4 Pages 171-175
Linear viscoelaticity was investigated for solutions of the mixture of polystyrene (PS) and poly (vinyl methylether) (PVME) in dibutyl phthalate. Concentrations of PS and PVME were 0.076 g cm-3 and 0.774 g cm-3, respectively. Molecular weight of PVME was 6.0×104; molecular weights of PS samples were 4.39×104, 1.90×105, 9.5×105 and 1.26×106. The solution formed a single phase at low temperatures and became turbid at about 80°C. The storage modulus, G′, and the loss modulus, G″, were measured at several temperatures ranging from 4 to 60°C. The results could be reduced to a reference temperature, 30°C, through the frequency-temperature superposition principle.
When PS molecular weight was 4.39×104 or 1.90×105, the viscoelastic properties of blend solution were similar to those of narrow-distribution polymer. The plateau modulus was independent of the PS molecular weight. The maximum relaxation time increased as the molecular weight of PS increased. When PS molecular weight was 9.5×105 or 1.26×106, a second plateau region appeared at lower frequencies. The modulus of the second plateau region was lower than that of the first one and coincided with the plateau modulus of the 0.076 g cm-3 solution of PS in an ordinary solvent, and its maximum relaxation time increased as the molecular weight of PS increased. The first plateau region may be originated by PVME-PVME and PVME-PS entanglments and the second plateau by PS-PS entanglements.
