Thermal analysis of solution cast mixtures of PCL and phenoxy has been carried out with various programmed temperature profiles．Results from experiments conducted in a quasi-equi-librium state show that PCL crystallizes in the mixtures upon cooling．Furthermore，depres-sions were observed in melting and crystallization temperatures．The melting point depres-sion pheonomenon is found tO be explicable in terms of thermodynamic mixing of a crystalli-ne polymer with an amorphous polymer．To this end，an analytical expression appropriate to the crystalline-amorphous polymer pair derived from Scott’s equation for thermodynamic mi-xing of two polymers was used．From this expression the interaction parameter for this poly-met pair is calculated to be—0.155 at 320 K，indicating that the system is well compatible．The crystallization temperature which depends strongly on both the composition and the cooling rate is attributed to the migrate of the PCL segments．Any factor which retards the migration will depress the crystallization temperature

Double crystallization peaks were also observed in the process of cooling．