Thermal characterization of polymers and polymer blends is as important as polymer synthesis itself. Molecular interactions in polymer blend influence glass transition (T_g) behaviour and the increment of heat capacity at T_g. Hence, it is desirable to know the strength of these intermolecular forces. There has been immense interest in probing the polymer-polymer interaction parameter, c . The modulated temperature DSC (MDSC) is playing very important role in finding out the interaction parameter, c . Characterization of the polymer interfaces becoming an important area in the recent times due to the challenges involved. The polymer interfaces play a major role in developing the successful in situ composites and polymer blends. Hence, the present research on polymer blends focus on polymer interfaces and the development of polymer interfaces. The recent development of micro thermal analysis (m TA) is very useful in characterizing the interfaces. We are presently studying the interface between polypropylene and thermotropic liquid crystalline polymer (TLCP) as a function of compatibilization. The simultaneous TG-DSC and TG-DTA are very useful in understanding the curing and degradation mechanisms, respectively. The evolution of new instrument technique based on the combination of thermal, spectral and optical technique are finding remarkably in characterizing the polymers and polymer blends effectively. The in situ characterization of polymers and polymer blends during processing will be challenging task in future.