An In‐Depth Investigation Into Crosslink Density Evolution of Thermo‐Oxidative Aged Carbon Black‐Filled Rubber: Experimental and Theoretical Analysis

ABSTRACT Carbon black (CB)‐filled rubbers are extensively employed as damping elements across multiple fields, yet their mechanical performance degrades unavoidably under concurrent thermal and mechanical loading in service. To this end, accelerated artificial thermo‐oxidative aging experiments, equilibrium swelling measurements and dynamic mechanical analysis (DMA) tests of CB‐filled rubber under various aging temperatures were carried out to better understand the mechanical property degradation mechanism. It was observed that thermo‐oxidative aging temperature and time had a great effect on the Payne effect of CB‐filled rubber. Maier‐Göritz (MG) model was used to describe the Payne effect of CB‐filled rubber, and the network density evolution was discussed by use of MG model parameters. Meanwhile, qualitative analysis of crosslink density was conducted on the basis of network density evolution results, which were verified by equilibrium swelling tests in order to accurately reveal the mechanism of the Payne effect of CB‐filled rubber. It was noticed that both qualitative analysis results and equilibrium swelling tests ones exhibited the same evolution trend with an increase of aging temperature and time. In this work, the crosslink density evolution was comprehensively investigated from experimental and theoretical analysis, which can provide guidance value to better understand the degradation mechanism of CB‐filled rubber.