Dynamic Vulcanization and Structure‐Property Relationship of High‐Performance Fluoroelastomer/Polyamide‐12 Thermoplastic Elastomeric Blends

ABSTRACT

High‐performance thermoplastic vulcanizates (TPVs) from fluorinated elastomers are constrained by intrinsic immiscibility, inadequate interfacial adhesion, and restricted melt‐processability. In this study, these challenges are addressed by designing novel fluoroelastomer (FKM)/polyamide‐12 (PA12) (60/40 w/w) TPVs via dynamic vulcanization using a diamine curing agent. This study thoroughly investigates the relationship between dynamic vulcanization, microstructural development, and the resulting mechanical, dynamic mechanical, and oil swelling resistance properties. Torque‐time curves show that elastic resistance grows as the curative loading increases from 0.5 to 2 php, suggesting the gradual formation of rubbery networks within the FKM domains and enhanced melt cohesion of the TPVs. Frequency‐sweep test revealed   shear‐thinning behavior at low frequency, aligning with an elastically linked rubber phase dispersed in a continuous PA12 matrix. Controlled dynamic vulcanization substantially improved phase morphology, reducing FKM domain size from ∼3.6 µm in the uncured (neat blend) to ∼2.0 µm at 2.0 php. Interestingly, upon dynamic vulcanization, the glass transition temperature ( T _g ) values of FKM and PA12 shifted toward each other, indicating improved interdomain interactions between the phases. The microstructural changes and interdomain interactions significantly improved the mechanical properties, showing a twofold increase in tensile strength and a sixfold rise in elongation at break compared to the uncured specimen (neat blend) at the highest curative level (2 php). The developed TPVs showed outstanding oil swelling resistance, with only 0.5–2.5% volume swell in ASTM oil #3 at 150°C over 72 h, among the lowest reported for this type of TPVs and enhanced thermal stability, both increasing with vulcanization level.