Casting solvent effect on crystallization behavior and morphology of poly(ethylene oxide)/poly(methyl methacrylate)

Abstract

Poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends were prepared by casting from either chloroform or benzene solvents. After casting from solvents, all samples used in this study were preheated to 100°C and held for 10 min. Then, the solvent effect on the crystallization behavior and thermodynamic properties were studied by differential scanning calorimeter (DSC). Also, the morphology of spherulite of casting film was studied by polarized optical microscope. From the DSC and polarizing optical microscopy (POM) results, it was found that PEO/PMMA was miscible in the molten state no matter which casting solvent was used. However, the crystallization of PEO in the chloroform-cast blend was more easily suppressed than it was in the benzene-cast blend. Relatively, the chloroform-cast blend showed the greater melting-point depressing of PEO crystals. Also, the spherulite of chloroform-cast film showed a coarser birefringence. It was supposed that the chloroform-cast blend had more homogeneous morphology. It is fair to say that polymer blends, cast from solvent, are not necessarily in equilibrium. However, the benzene-cast blends still were not in equilibrium even after preheating at 100°C for 10 min. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1627–1636, 2000