Rheological and Mechanical Properties of Co‐Coagulated Nitrile Rubber/Fluoromica Composites

ABSTRACT Rubber formulations containing fluoromica in amounts from 0 to 10 phr were produced via a coagulation process. Data from transmission electron microscopy (TEM) and X‐ray (DRX) diffraction showed that there were both exfoliated and intercalated structures, with more exfoliated structures being present. Rheometric data, such as t90, ts1, and CRI, along with a detailed investigation of curing kinetics, showed that fluoromica slowed down the crosslinking process, which is linked to the large amount of exfoliated structures. Despite fluoromica slowing down the vulcanization process, the effective crosslink densities of the composites were found to be relatively similar. Furthermore, the low Payne effect suggests minimal agglomerate formation, aligning with the observed good exfoliation structures by TEM and DRX. Fluoromica improved the mechanical properties, especially elongation at break, which doubled compared to the unfilled NBRL. This study suggests that the mixed system of exfoliated and intercalated filler combined with a low development of agglomerates enhanced the movement of polymer chains, resulting in a material with increased elongation capacity. Hence, the NBR/fluoromica composites are suitable for producing materials where elongation plays a significant role.