In order to use sepiolite nanofibers as cis-polybutadiene rubber fillers, the hydrophilic character of sepiolite nanofibers should be modified by grafting organic group and controlling surface free energy for improving compatibility of sepiolite nanofibers in rubber matrix. The relationship between the performance of the cis-polybutadiene rubber filled with sepiolite and the coupling modification was investigated, and the influence of coupling agent -(2,3-epoxypropoxy)propyltrimethoxysilane dosage on mechanical properties of cis-polybutadiene rubber materials was also studied. The results showed that the mechanical properties could be improved obviously after reinforcement by modified sepiolite nanofibers. The optimum dosage of coupling agent -(2,3-epoxypropoxy)propyltrimethoxysilane was 7%, and the tensile strength and tearing strength increased by 108.3% and 74.1%, respectively. On this basis, the reinforcement mechanism of the composite rubber materials was also discussed. 1. Introduction Nowadays, cis-polybutadiene rubber materials play a critical role in many fields. Owing to the characteristics of cold tolerance, wear resistance, excellent elastic, age resistance, and so forth, cis-polybutadiene rubber materials have become a kind of useful product in the fields of rubber shoes, rubberized fabric, automotive sponge, and so forth [1–3]. However, cis-polybutadiene rubber materials belong to organic materials, which have disadvantages of low compressive strength, high cost, and poor dimensional stability, especially not being able to form crystals at room temperature unless it is sufficiently stretched (stress-induced crystallization), and thus the stress-induced crystallization of cis-polybutadiene rubber materials is obviously lower than that of natural rubber [4–6]. Therefore, cis-polybutadiene rubber fillers have been developed in the recent years. The prime fillers in rubber industry such as carbon black production always make reinforced rubber deep color, which limits its applications in medical, sports, and domestic products. Moreover, the above fillers will consume large amounts of energy such as petroleum and natural gas and emit lots of heat and waste gas composed by the prime greenhouse gas of carbon dioxide and gaseous pollutants of sulfur dioxide and nitrogen oxide. This process would not only exacerbate tensions in the energy supply, but also pollute the environment [7–10]. Comparing with the former, the application of natural mineral materials as cis-polybutadiene rubber fillers will solve the serious environmental pollution problem.
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