Using sodium thiosulfate and hydrochloric acid as the raw materials and a silica aqueous dispersion as the carrier, sulfur is generated in situ by a chemical precipitation method, and an in situ sulfur‐silica/natural rubber (in situ S‐Silica/NR) composite is prepared. The in situ sulfur is characterized, and its effects on the natural rubber composites' cross‐linking density, vulcanization characteristics, mechanical properties, aging properties, dynamic mechanical properties, and Payne effect are studied. The experimental results show that the particle size of in situ sulfur is small, with a maximum of 5 μm, and the cross‐linking ability is stronger than commercial sulfur. Due to the strong surface adsorption force of silica, the interfacial bonding strength is enhanced, and the dispersion of the two components in the rubber matrix is improved. Compared with commercial sulfur‐silica/natural rubber (S‐Silica/NR) composites, the tensile strength is 20.3% higher, the elongation at break is 28.5% higher, and it better retains its aging properties and has a lower rolling resistance. This study provides a theoretical basis for the development of functional rubber vulcanizing agents and the preparation of high‐performance rubber composites.

The drying process of natural rubber latex significantly affects the structure of the raw rubber network and vulcanizate crosslinking network, resulting in various anti-aging performances. In the present study, a microwave generator was used as an efficient source of clean energy; potassium oleate was introduced as a foaming agent to increase the porosity and water loss channel of the latex system. Aiming at dehydrating and drying natural rubber latex efficiently, an aging resistant rubber composite was prepared. Meanwhile, the mechanism of the foaming agent-assisted microwave drying process on the raw rubber network and the cross-linking network was studied. The experimental results show that the prepared rubber using by this process has higher plastic retention and fluidity. Moreover, it contains more non-rubber components (e.g. protein and acetone extract) and better network structure of raw rubber and vulcanized rubber. It is found that applying this process increases the tensile product by 13.5% and the retention rate of the tensile product after aging by 15.3 times. This process is important for the development of the rubber industry in the direction of green environmental protection, energy conservation, and high efficiency.

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This paper prepared potassium oleate/silica/natural rubber composites by atomization spray drying technology. This study compared the effects of the environmental protection accelerator potassium oleate and amine accelerator 1,3-diphenylguanidine on the Payne effect, silane reaction index, vulcanization performance, mechanical properties, static and dynamic mechanical properties, and aging properties of silica/natural rubber. The results show that potassium oleate can promote the silane reaction and increase the silane reaction's efficiency. When potassium oleate formed the silica coating, the carboxyl group of potassium oleate and the hydroxyl group of silica were bonded to form a covalent bond, which reduced the polarity of silica and promoted the dispersion effect of silica in the rubber matrix and enhanced the compatibility with rubber. Compared with the original formulation, after adding 3 phr of potassium oleate, the fracture elongation of vulcanized rubber was increased by 17.2%, tensile product increased by 57.3% and rolling resistance decreased by 54.6%. After adding 3 phr of 1,3-diphenylguanidine, the fracture elongation of vulcanized rubber was increased by 1.1%, tensile product increased by 51.1% and rolling resistance decreased by 48.6%. In contrast, the anti-aging performance of the rubber composites with potassium oleate was better than that of 1,3-diphenylguanidine. This study opens up a new way to apply a new green rubber accelerator and prepare high-performance rubber composites.