Phase equilibrium in blends of crystalline poly(ethylene oxide) amorphous poly(methyl acrylate) or poly(methyl methacrylate)

Phase separation in blends of crystalline poly(ethylene oxide) (PEO) and am orphous poly(methyl methacrylate) (PMMA) or poly(methyl acrylate) (PIMA) ha s been examined using DTA, small-angle light scattering, and polarized micr oscopy. The structure of the polymer blends was analysed by the wide-angle X-ray diffraction technique. It is found that phase separation takes place in both systems above the melting point (T-m) of the crystalline component. PEO/PMMA blends have an upper critical solution temperature above the glas s transition temperature and T-m of the system. Components of PEO/PMMA blen ds are compatible in two regions: when the PMA concentration is 0.0-0.5 wei ght fraction or exceeds 0.8 weight fraction. PEO and Ph LA are immiscible i n the melt at intermediate concentrations. It is shown that compatibility o f components in the melt of crystalline and amorphous polymers is not a uni versal property of polymer blends. (C) 2000 Society of Chemical Industry.