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The continuous operation of essential refining equipment, internal mixers, leads to wear on their end faces, resulting in an increased gap between the mixer chamber and the end face. This, in turn, causes material leakage, reducing mixing efficiency and adversely impacting rubber performance. Therefore, investigating metal wear on the mixer's end face during the mixing process is essential. Scholars have introduced dynamic covalent bonds into rubber molecular chains, bestowing self-repairing capabilities upon the materials. This innovation has significant implications for extending rubber lifespan and lowering production costs. It involves adding methacrylic acid (MAA) and excess zinc oxide (ZnO) to construct an ionic crosslinking network, limiting covalent crosslinking of rubber molecules and enabling in-situ polymerization of MAA/ZnO, resulting in self-repairing properties. However, it is crucial to consider corrosive wear induced by MAA's strong acidity on metals. This study combines MAA, ZnO, and multi-walled carbon nanotubes (MWCNTs) through mechanical mixing to create a composite material called zinc methacrylate (ZDMA)/MWCNTs/rubber. The research investigates the in-situ synthesis mechanism of MAA and ZnO and the synergistic mechanism of ZDMA and MWCNTs. The study analyzes the impact of MWCNTs additive amount on the frictional wear of the internal mixer's metal end face. During the mixing process, ZDMA is grafted and polymerized onto rubber's macromolecular chains, forming ionic pairs with strong electrostatic interactions, creating a primarily reversible supramolecular network dominated by ion crosslinking. This ion crosslinking network, along with the three-dimensional mesh structure of MWCNTs, establishes a stable spatial structure within the rubber matrix. The study reveals that increasing the MWCNTs content to 3 phr reduces the aggregation of SiO 2 particles and ZDMA granules within the rubber matrix, resulting in reduced friction coefficients, roughness, and wear rates of the metal. However, exceeding 3 phr of MAA content leads to excessive MWCNT aggregation within the rubber matrix, increasing wear rates, roughness, and friction coefficients due to hindrance of rubber macromolecular chain crosslinking and reduced SiO 2 particle dispersion within the rubber matrix. These findings provide valuable insights into the dynamics of frictional wear in internal mixers. • Continuous mixer use erodes end faces, widens gaps, and hampers rubber performance. • Adding dynamic covalent bonds to rubber enhances self-repair, extending lifespan and cutting production costs. • MAA, ZnO, and MWCNTs create ZDMA/MWCNTs/rubber, studied for frictional wear impact. • Elevated MWCNTs levels (up to 3 phr) lower wear rates, roughness, and friction in rubber. • Excessive MAA (> 3 phr) increases wear, roughness, and friction by blocking crosslinking and reducing dispersion. [ABSTRACT FROM AUTHOR]

During prolonged operation, the end face of the internal mixer, a crucial component in rubber processing, experiences wear, resulting in an increased gap between the mixing chamber and the end face. This gap can lead to material leakage and reduced mixing efficiency, negatively impacting rubber properties. To address this issue, researchers have introduced dynamic covalent bonds into the molecular rubber chains, giving the material self-healing properties. This advancement is essential for extending rubber lifespan and reducing production costs. One common approach involves adding methacrylic acid (MAA) and excess zinc oxide (ZnO) to create ionic crosslinking networks, limiting covalent crosslinking and enabling in-situ polymerization of MAA/ZnO, resulting in self-healing capabilities. However, the strong acidity and corrosive nature of MAA can cause metal wear. In our study, we mechanically blend MAA with ZnO to produce zinc methacrylate (ZDMA)/rubber composites. We investigate the in-situ synthesis mechanism of MAA and ZnO and assess the impact of MAA on the friction and wear of the internal mixer's end face. Our findings reveal that ZDMA ion pairs form an "ion cross-linked network" within the rubber chain, hindering SiO 2 particle dispersion and increasing aggregation within the rubber matrix. This compromises dispersion and leads to abrasive wear from SiO 2 particles, corrosive wear from high-temperature water vapor, and corrosive wear from MAA. Additionally, excessive ZDMA self-polymerization alters SiO 2 particle agglomerates. The strong acidity of MAA and the "ion cross-linked network" within the rubber matrix significantly affect SiO 2 particle dispersion, friction coefficients, metal surface roughness, and metal wear. Our comprehensive analysis, including SEM, dispersion, RPA, metal surface morphology, and CSM friction wear tests, identifies the optimal cross-linking effect with the addition of 15 phr of MAA, resulting in a well-defined "ion cross-linked network" within the rubber matrix, enhancing rubber performance. However, SiO 2 particle dispersion is compromised, leading to increased agglomeration and heightened metal wear. • Prolonged operation of internal mixers causes wear, increasing the gap, impacting rubber quality. • Self-healing rubber with dynamic covalent bonds extends lifespan and reduces costs. • A method involving MAA and ZnO for self-healing, but MAA's acidity causes metal wear. • Blending MAA and ZnO into ZDMA/rubber composites affects dispersion and wear. • An optimal MAA amount enhances rubber performance but compromises SiO 2 dispersion and increases metal wear. [ABSTRACT FROM AUTHOR]

As the essential mixing equipment, long hours of work can cause wear and tear on the end face of the compactor. The wear of the end faces leads to an increase in the gap between the chamber and the end faces, which leads to leakage, reduces the mixing effect, and ultimately affects the rubber properties. Therefore, it is necessary to study the end face metal wear during the mixing process. Thermally cracked carbon black, as recycled material for scrap rubber, can be used as a substitute for other carbon blacks in some fields, vastly reducing the production cost and promoting the reuse of scrap rubber. In this paper, thermally cracked carbon black (CBp) was mixed with multi-walled carbon nanotubes (MWCNTs) and added rubber by mechanical blending to obtain CBp/MWCNTs composites. The synergistic mechanism of CBp and MWCNTs was investigated to analyze the effect of CBp/MWCNTs ratios on the frictional wear of metal on the end face of the compactor. The results showed that MWCNTs cooperated with CBp particles to form a three-dimensional "grape bunch" network structure. On the one hand, the three-dimensional "grape bunch" network structure can adsorb CBp particles to promote the dispersion of CBp particles. On the other hand, the three-dimensional "grape bunch" network structure can also hinder the overflow of aromatic oil and affect oil film formation. At the same time, the three-dimensional "grape bunch" network structure can also form a physical isolation layer between the rubber and the metal. This significantly influences the degree of CBp particle dispersion, friction coefficient, metal surface roughness, and metal wear. It seems that the synergistic effect between MWCNTs and CBp particles is maximized when the content of MWCNTs in CBp/MWCNTs composites is 4 phr, the area of CBp/MWCNTs three-dimensional mesh is maximized, the dispersion of CBp particles is the best, and the wear of CBp/MWCNTs composites on metal is the lowest. • As the essential mixing equipment, long hours of work can cause wear and tear on the end face of the compactor. • The effect of the synergistic effect of CBp and MWCNTs on the friction and wear of end-face metal was analyzed. • The results showed that MWCNTs cooperated with CBp particles to form a three-dimensional "grape bunch" network structure. [ABSTRACT FROM AUTHOR]