Using chloroprene rubber waste in rubber blends: optimizing performance by adding fillers

In the present study, chloroprene rubber waste (CRW) was used in an attempt to extend its use and create a value-added material based on natural rubber (NR) and CRW blends. Conventional fillers including carbon black (CB), silica (SS) and calcium carbonate (CC) were used individually to optimize the performance of the rubber blends. The properties evaluated were the curing characteristics, physical and dynamic properties and thermal stability. From the results obtained, it is clear that the type and amount of filler play a crucial role in promoting the performance of the blend. A faster curing rate was observed for the blends containing CB and CC, while SS-filled NR/CRW blends showed the opposite trend. SS-filled NR/CRW blends exhibited tremendously improved tensile properties compared with CB- and CC-filled blends. This is because two types of competing interactions/reactions take place: the dipole–dipole interaction between SS and CRW and the silane coupling reactions. The tensile properties are also in good agreement with the observed dynamic properties. A higher storage modulus and a lower damping factor were found in the blends containing CB and SS, indicating more restricted molecular mobility caused by rubber–filler interactions.