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

Poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends were pre pared by casting from either chloroform or benzene solvents. After casting from solvents, all samples used in this study were preheated to 100 degrees C and held for 10 min. Then, the solvent effect on the crystallization beh avior and thermodynamic properties were studied by differential scanning ca lorimeter (DSC). Also, the morphology of spherulite of casting film was stu died by polarized optical microscope. From the DSC and polarizing optical m icroscopy (POM) results, it was found that PEO/PMMA was miscible in the mol ten state no matter which casting solvent was used. However, the crystalliz ation of PEO in the chloroform-cast blend was more easily suppressed than i t was in the benzene-cast blend. Relatively, the chloroform-cast blend show ed the greater melting-point depressing of PEO crystals. Also, the spheruli te 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 equi librium. However, the benzene-cast blends still were not in equilibrium eve n after preheating at 100 degrees C for 10 min. (C) 2000 John Wiley & Sons, Inc.