Study On Rheology Of Partially Miscible Polymer Blend

Mixing different polymers can lead to a wide range of phase behavior that directly influences the associated physical properties and ultimate applications. For a partially miscible polymer pair, phase behavior is determined by composition and temperature. For a mixture of certain composition, thermally induce phase separation can proceed by two different mechanisms: nucleation and growth (NG), or spinodal decomposition (SD), which result in different types of morphologies: droplet-matrix or co-continuous morphology, respectively. And the associated properties are often very complex. One of these properties, the viscoelasticity is of great interest for both scientific and practical industrial reasons, since the characteristic rheological responses might give not only helpful information on the internal structure of such materials, but also useful instruction for polymer processing. Thus the direct correlation between rheological functions and phase behavior, morphology is of significance. In addition, the blend system approaches the phase boundary; there is strong interaction between the rheology and thermodynamics. It is well known the phase behavior can be markedly changed by processing flow, in turn, once the phase behavior changes, the viscoelastic properties of polymer blend show inevitably some characteristic responses. Therefore, the prediction of phase behavior of polymer blend subjected to flow is also very important.In the thesis, the linear viscoelastic behavior of partially miscible blend of poly(styrene-co-maleic anhydride) (SMA) and poly(methyl methacrylate) (PMMA) in homogenous and phase-separated regions measured by small amplitude oscillatory shear (SAOS), and the phase behavior of the blend without flow and with flow determined by small angle light scattering (SALS), SAOS and modeled based on polymer reference interaction site model (PRISM) and polymer conformation tensor rheological model (PCTRM) are reported. The main aim is to manifest the relationship between rheological responses of the phase-separated blend and the internal structure, and to establish a model for describing and predicting the phase behavior of partially miscible blend subjected to shear flow.