Synergistic regulation of rubber composite properties using wet modified carbon black and dry mixed white carbon black dual filler system

Research background of dual filler system

In tire and rubber product formulations, the selection and mixing method of reinforcing fillers directly affect the dispersion state of fillers, the network structure of fillers, and the interface interaction between fillers and rubber matrix. A study published in the Journal of Applied Polymer Science (DOI: 10.1002/app. 71547) investigated the synergistic effect of a dual filler system consisting of fine-grained wet modified carbon black and dry blended white carbon black in natural rubber, focusing on two different processes: wet mixing and dry mixing. Research has shown that wet mixing and dry mixing are two completely different mixing methods. Wet mixing can reduce the particle size of carbon black aggregates, while the size of white carbon black aggregates mixed through dry mixing is larger; With the help of silane coupling agents, white carbon black can form a chemical cross-linking network with the rubber matrix.

The difference between mixing process and filler dispersion

A specific observation given by the study is that when the amount of white carbon black added is small, compared with dry mixing, the dispersibility and flowability of natural rubber fillers are better and higher under wet mixing process.

. This difference provides a technological basis for the subsequent design of the dual filler ratio. In terms of filler synergy, research suggests that carbon black and white carbon black can exert a synergistic effect in appropriate proportions, thereby improving the performance of rubber composite materials. The objective of this study is to investigate the synergistic mechanism between fine-grained wet modified carbon black and dry mixed white carbon black, as well as the influence of the cross-linked network formed between white carbon black and rubber matrix on material properties.

Comprehensive performance of carbon black 40/white carbon black 20 formula

The study investigated the influence of the ratio of fine-grained carbon black to coarse-grained white carbon black on the filler network structure and filler rubber interface interaction, and determined the optimal ratio that can achieve synergistic improvement of multiple properties.

. The results showed that the carbon black 40/white carbon black 20 sample exhibited the best comprehensive performance. In this formula, a higher amount of carbon black filling helps to form a continuous rigid filler network, promoting efficient stress transmission; An appropriate amount of white carbon black reacts fully with silane coupling agent to form a chemical cross-linking network between the filler and rubber, thereby fully exerting the synergistic reinforcement effect of the biphasic filler system.

Significance for the polymer additive industry

From the perspective of tire and rubber formula design, this study suggests that the synergistic effect of reinforcing fillers not only depends on the ratio of carbon black to white carbon black, but also closely related to the dispersion state brought by the mixing method.

. Wet mixing improves the dispersion and processing flowability of fillers, providing a reference for the process window under high filling formulas; The chemical cross-linking network constructed by silane coupling agent on white carbon black is related to the strength of the filler rubber interface interaction. At the level of rubber additives, the matching of vulcanization system and filler network, as well as the guarantee of long-term performance by anti-aging agents and antioxidants, are still unavoidable links in the comprehensive balance of formulation. This study focuses on the filler system and mixing process, and does not involve specific variables such as anti-aging agents, antioxidants, or vulcanization systems. However, its conclusions about the continuity of filler networks and interfacial cross-linking can provide experimental evidence for the synergistic design of reinforcing fillers and related additives in tire rubber formulations. The research conclusion is based on specific experimental formulas and testing conditions, and the process amplification effect in actual tire formulas still needs to be verified in conjunction with specific systems.

Information source:Coordinated Control of the Properties of Rubber Composites Using a Dual‐Filler System， Organized by Herun Chemical.