The phase morphology development in blends of DGEBA/POM/DDS was studied at cure temperatures below the melting temperature of POM, namely 150, 145, and 140 degrees C. The phase separation behavior of the blends varying from 5 up to 30 wt % POM was examined with OM, SALLS, and SEM. Different demixing mechanisms were observed depending on the blend composition. Curing at 150 degrees C induced RIPS followed by crystallization inside the POM-rich matrix phase. When cured at 145 degrees C, all blends showed spherulitic crystallization starting before the RIPS. This resulted in a gradient of phase-separated structures. It has been shown that increasing the nucleation density could suppress the interspherulitic demixing. This has been realized by changing the thermal history of the thermoplastic in the blends or by lowering the cure temperature to 140 degrees C. Moreover, the intraspherulitically segregated epoxy resin continued to cure and generated a "spherulite-like" morphology. Next, the spherulite growth rate of POM at 150 and 145 degrees C was determined for blends cured for 4 h at 180 degrees C, for blends cured at 150 and 145 degrees C, and finally for blends without hardener. Curing the epoxy resin favors the crystallization rate of POM in the blends. Depending on the cure temperature and blend composition, different spherulite growth rates were observed. The fastest growth rate was observed for the blends cured at 180 degrees C and the slowest growth rate for the blends without hardener.