The properties of polymer blends greatly depend on the morphologies formed during processing, and the thermodynamic non-equilibrium nature of most polymer blends makes it important to maintain the morphology stability to ensure the performance stability of structural materials. Herein, the phase coarsening of co-continuous, immiscible polyamide 6 (PA6)-acrylonitrile-butadiene-styrene (ABS) blends in the melt state was studied and the effect of introduction of nano-silica particles on the stability of the phase morphology was examined. It was found that the PA6-ABS (50/50 w) blend maintained the co-continuous morphology but coarsened severely upon annealing at 230 °C. The coarsening process could be divided into two stages: a fast coarsening process at the initial stage of annealing and a second coarsening process with a relatively slow coarsening rate later. The reduction of the coarsening rate can be explained from the reduction of the global curvature of the interface. With the introduction of nano-silica, the composites also showed two stages of coarsening. However, the coarsening rate was significantly decreased and the phase morphology was stabilized. Rheological measurements indicated that a particle network structure was formed when the concentration of nano-silica particles was beyond 2 wt%. The particle network inhibited the movement of molecular chains and thus suppressed the coarsening process.

The isothermal and nonisothermal crystallization behaviors of PVDF/MWCNT composites containing pristine and hydroxide groups (-OH) functionalized MWCNT (MWCNT-g-OH) were investigated using Avrami, Ozawa, and Mo equations. It was found that Avrami and Mo equations were suitable for describing the crystallization kinetics while the Ozawa equation failed. The crystallization kinetics was greatly influenced by the MWCNT loading and the interfacial interactions between MWCNT and PVDF matrix. MWCNTg-OH was more effective in increasing the crystallization rate due to the stronger interfacial interactions. Strong interfacial interactions ensure good contact between the PVDF and MWCNT-g-OH, which was beneficial for the heterogeneous nucleating process.