Nonisothermal crystallization kinetics of poly(ethylene terephthalate) and poly(methyl methacrylate) blends

The nonisothermal crystallization kinetics of poly(ethylene terephthalate) (PET) and poly(methyl methacrylate) (PMMA) blends were studied. Four compositions of the blends [PET 25/PMMA 75, PET 50/PMMA 50, PET 75/PMMA 25, and PET 90/PMMA 10 (w/w)] were melt-blended for I h in a batch reactor at 275 degrees C. Crystallization peaks of virgin PET and the four blends were obtained at cooling rates of 1 degrees C, 2.5 degrees C, 5 degrees C, 10 degrees C, 20 degrees C, and 30 degrees C/min, using a differential scanning calorimeter (DSC). A modified Avrami equation was used to analyze the nonisothermal data obtained. The Avrami parameters n, which denotes the nature of the crystal growth, and Z(t), which represents the rate of crystallization, were evaluated for the four blends. The crystallization half-life (t1/2) and maximum crystallization (t(max)) times also were evaluated. The four blends and virgin polymers were characterized using a thermogravimetric analyzer (TGA), a wide-angle X-ray diffraction unit (WAXD), and a scanning electron microscope (SEM). (c) 2006 Wiley Periodicals, Inc.