Thermodynamics Behavior for Polymer Blends

The aim of the present work was to study the thermodynamic behavior of polymer blend via determination of miscibility . Miscibility (or immiscibility) tests are performed in three techniques: viscometry method, DSC analyzer and FTIR to test polymer blend in solid state. Two polymer blends were prepared . the first one was Poly methyl methacrylate (PMMA) and Poly vinyl acetate (PVAc) , and the second was Poly vinyl chloride (PVC) and Polystyrene (PS).Calculations of Flory -Huggins interaction parameter for two systems was performed and the results pointed to miscible blend for PMMA/PVAc blends and immiscible blend for PVC/PS blends. So there is a good agreement between the experimental results and calculations of interaction parameter based on Flory - Huggins theory .Differential scanning colarimetry (DSC) analyzer gave thermogram curves revealing one glass transition temperature for PMMA/PVAc blends except at (20/80) composition , this indicates that the system is miscible except at (20/80) composition . But , PVC/PS blends showed two glass transition temperature so the system is immiscible.FTIR analysis for PMMA/PVAc blends depicted a weak interaction between the two polymers