Aramid pulp modified with imidazolium ionic liquids as a potential replacement for carbon black in fluorinated rubber composites

Carbon black (CB) is the most used reinforcement for the manufacturing of rubber compounds. However, its harmful impact is well known, thus, alternative materials are developed day by day to replace CB. In this paper, aramid pulp (AP), a fibrillated configuration of aramid fibers, was used aiming to manufacture fluoroelastomer copolimer (FKM) composites with similar properties to those fabricated with CB. AP was incorporated at 5 per hundred of rubber (phr) and its physical/mechanical/thermal properties were compared with a commercial formulation (prepared with 30 phr of CB). The FKM/AP compounds presented similar mechanical properties to those of FKM/CB. Moreover, due to the entanglement mechanism for the FKM/AP, higher reinforcement effectiveness (ratio between the glassy and elastomeric modulus) is presented for these composites, compared with those FKM/CB. Ionic liquids (IL) promoted AP defibrillation, which also improved the entanglement of the reinforcement with the polymeric matrix. These features imparted higher dynamic mechanical thermal response and thermal resistance of the composites with AP and IL-treated AP, compared with those reinforced with CB.