The objective of this work, to study the characteristics of a mixture of the two Lexan polycarbonates, having different (MFI). Experimentations ran by using two different twin extruders, in two stages: The first stage: The polycarbonate grade (30/70%) were melt-blended using (Coperion) a Co- rotating twin-screw extruder (SB). The second stage, the grade was blended in steps of eleven in a Thermo Haake Mini Lab II twin-screw micro compounder (ML). The steps (%PC1 and /%PC2) were (100%/0%), (90%/10%), (80%, 20%)… (0%/100%). Further experimental design dictated a sample without pigment (WOP) consisting of simply PC resin, a sample with PC resin mixed with pigment and additives (WP) to study the characterization of polycarbonate formulation. In both stages, this grade is rheologically characterized at different temperatures using the rotational rheometer. The research aims to identify a comparative characterization study for the viscosity with Thermogravimetric (TGA) and Fourier Transform Infrared Spectroscopy (FTIR) Analysis for the same compositions. TGA was performed under the effect of heating rate, Glass transition temperature (Tg) for PCs blends were measured and related it's affected by the minute variation blends.FTIR technique is particularly useful since it allows identification and localization of compounds to study and identify chemical groups or chemical compounds when the sample absorbs infrared radiation. The focus was extended to the polymer grade to extract the impact of the rheological characteristic, TGA and FTIR to study their correlations in the viscosity data and their bearing effects on properties and design color matching