The decreased and disappeared melting peak of Apph suggests that Baph and Apph copolymerized during the preparation, and the melting point of the Baph/Apph blends were dominated by Baph. As seen in Fig. 4, the presence of more SiC particles involves a decrease in the heat polymerization (DH) of the composites. In fact, this energy decreased by 33.6% when the micro-SiC content increased from 0 to 20 wt.%, thus it is clear that the incorporation of the microfillers does not catalyze or enhance the polymerization of the phthalonitrile monomers; this is due to a well-known effect attributed to the ceramics which increases the viscosity of the thermoset materials resulting in an enhancement of the curing temperature[41].