cured under nitrogen at 400 u00b0 c for 10 min the temperature of the oven was ramped at 4 u00b0 c min the cured film was black in color table 1 presents the viscosity of the mixture before film casting as well as the optical density gloss dielectric constant dissipation factor and initial tear resistance of the cured film a cross section of the cured film fig1 was analyzed by transmission electron microscopy tem which revealed a uniform distribution of carbon domains derived from the pan as well as syloid u00ae c803 particles in the polyimide phase the carbon domains were observed to be less than 2 microns in diameter 10 wt loading of cellulose acetate in pan cellulosic polymer polyimide precursor blend with matting agent in this example 65 g of the paa pan and syloid u00ae c803 mixture prepared in comparative example a was mixed with 5 3 g of a 10 wt solution of cellulose acetate cac dissolved in dmac to prepare a pan cellulose acetate polyimide precursor blend containing syloid u00ae c803 matting agent the methods and procedures of comparative example a were followed to prepare and cure a film from the blend the cured film was black in color table 1 presents the viscosity of the blend before film casting as well as the optical density gloss dielectric constant dissipation factor and initial tear resistance of the cured film a cross section of.