The crystallization and rheological behaviors of in situ microfibrillar isotactic polypropylene/polyamide 66 composites with a selective β‐nucleating agent distribution

In situ microfibrillar composites (MFCs) with isotactic polypropylene (iPP) as matrix and β‐nucleating agents filled polyamide 66 (β‐PA66) as dispersed microfibrils were fabricated through multistage stretching extrusion technology. The simultaneous effects of β‐nucleating agents, shear‐flow and microfibrils on the crystallization and rheological behaviors of iPP were explored. Crystallization analysis demonstrated that the counteraction of shear flow and β‐nucleating agents resulted in the absence of β‐crystal in the as‐extruded MFCs. When the MFCs were annealed at 210°C for 10 min, the flow field was erased accompanied with the migration of β‐nucleating agents from PA66 phase to surface, which in turn inducing the formation of β crystal in the recrystallized samples. Shear rheological investigations suggested that the β‐NAs at interface mechanically integrated the PA66 and iPP phase thus improving the interfacial adhesion. These findings provided a potential way to solve the interfacial problems of MFCs.