EFFECT OF PHASE SEPARATION ON DYNAMIC VISCOELASTICITY OF POLY(METHYL METHACRYLATE)/POLY(α-METHYLSTYRENE-CO-ACRYLONITRILE)BLENDS

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Blends of Poly(methyl methacrylate)(PMMA)and poly(α-methylstyrene-co-acrylonitrile)(αMSAN)exhibit an LCST behavior and are miscible at lower temperatures than the cloud points.The temperature dispersion of dynamic viscoelasticity of the blend system was measured in the single-phase and phase-separated states.It was found that some thermal histories during sample preparation bring the structural equilibrium to PMMA and αMSAN.Such a thermal condition was used for all the measurements to attain the experimental reproducibility.Temperature dispersion curves of dynamic viscoelastic functions, E', E" and tan δ, for the blends in single-phase and phase-separated cases located between those of PMMA and αMSAN in order of the component ratio.The shapes of the curves of phase-separated blends, however, become quite different from those of single-phase ones at temperatures above 80℃.The curves of E' and tan δ of blend samples in phase-separation show the broad relaxation and locate close to those of the rich component.Correspondingly, the peaks of the E" curves of phase-separated samples become broader than those for single-phase.Only the PMMA/αMSAN(40/60) blend in a phase-separated state shows two peaks on the E" curve when it was annealed at 200℃.These two peaks become more apparent with the annealing time suggesting the phase separation proceeds.
社団法人日本材料学会の論文
1995-09-15