Reinforcing behavior of reclaimed rubber filled natural rubber composites

With the growing volume of waste rubber products, the pressures on the environment and resources become increasingly serious. The reclamation of waste rubber products is one of the practical methods to meet this challenge. Therefore, the application of reclaimed rubber (RR) attracts researchers' attention. In this work, different contents of natural rubber (NR) matrix are replaced by RR and the reinforcing behavior of the RR phase is discussed. The results show that the crosslinking density, Payne effect and 100% modulus increase with increase in RR content in the NR/RR blends when the RR content is not more than 60 phr, and then drop when the RR content gets to 80 phr. It is inferred that both the NR and the RR constitute co-continuous phases when the RR content is 60 phr, and the RR phase is the only continuous phase when its content reaches 80 phr, which can be confirmed by SEM observation. Besides, the curing rate is enhanced with increase of the RR content. It is also found that structures with high crosslinking density appear when the RR is incorporated into the NR matrix. Finally, it is proposed that carbon black in the RR, a structure with high crosslinking density and a continuous rubber matrix are important factors influencing the reinforcement behaviour in RR filled rubber composites. (c) 2023 Society of Chemical Industry.