The new biobased polymer blends were synthesized from polyurethanes (PUs) which are derived from glycerol modified linseed oil and diphenyl methane-4, 4̕-diisocyante (DPMDI) and cardanol based dyes with aminophenols. The thermal stability of the polymer blends was investigated by thermogavimetric analysis (TGA), the rate of thermal degradation was determined by derivative thermogravimetry (DTG) and the exothermic and endothermic behavior of thermal degradation was ascertained by differential thermal analysis (DTA). The expected mechanism of the reaction and structure of the polymer blends prepared were investigated by FTIR study. The kinetic parameters such as activation energy and order of reaction of thermal degradation of polymer blends were calculated by Freeman- Anderson’s method. Also the significant effect of NCO/OH molar ratio of polyurethanes and the nature of aminophenols on the thermal stability of polymer blends were investigated.