The cross sectional composition of films of poly (oxyethylene) and poly (vinyl acetate) blends was observed by using a polarizing microscope. Graded structures across the thickness of the films were created by establishing temperature gradients from the top to the bottom surfaces the films during annealing. The results were confirmed by FTIR spectra. It was shown that the structure of the gradient, step or sea-island, was controled by the molding temperature and times. The driving force for the appearance of gradation was considered to be convection across the temperature gradient and the density and surface tension differences between the blended polymers in the molding process.
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