Enhanced fatigue resistance of plasma modified pyrolysis carbon black filled natural rubber composites

Owning to the requirement of cost reduction and environmental protection, the application of pyrolysis carbon black (CBp) in dynamic rubber products becomes a hot topic in recent years. However, the fatigue resistance of CBp filled rubber composite is poor. Therefore, the evolution of micro- mesoscopic structure in modified CBp filled natural rubber (NR) composites during the tensile fatigue process is investigated to find the influencing factor for enhancing the fatigue resistance in this study. Results indicate that the particle/aggregate size distribution turns to be narrower after the aggregate size filtering treatment while a decreased particle/aggregate size and an improved polarity can be observed after argon plasma treatment. As a result, the average fatigue life of NR composites filled with CBp treated by air classifier, plasma modification and their combination are increased by 21%, 57% and 107%, respectively. It is found that the filler dispersion and the filler-polymer interaction deteriorate during the fatigue process. This evolution is inhibited by filler modification. Besides, the fatigue lives of filled rubber show a correspondence to their total and physical cross-linking densities as well as the bound rubber contents. The filler-polymer interaction can be proposed as an important factor in extending the fatigue life of rubber composites. These findings provide not only a promotion on the application value of CBp in fatigue resistance of rubber composite by different modification methods, but also an innovative perspective for exploring the fatigue resistance of rubber material from the aspects of filler-rubber interaction, and a scientific guidance for the development of long-life dynamic rubber products.