Additive manufacturing of synthetic rubber ink with high solid content reinforced by networked silica

Abstract

Silica is a reinforcing filler commonly used in the production of environmentally friendly tires, as tires reinforced with silica have lower rolling resistance, which translates into reduced energy consumption and improved fuel economy. However, achieving the optimal dispersion of silica within the rubber matrix is crucial for maximizing its reinforcing effects. In this study, a three- dimensionally networked silica (NS) was introduced in various amounts to rubber inks to improve their tensile strength and increase miscibility to enable their use in additive manufacturing. The results show that synthetic rubber ink with a high content of styrene–butadiene rubber (90%) and reinforced by NS possesses adequate viscosity for use in the direct ink write (DIW) process. NS was confirmed to have an impact on the rheological properties and printability of the rubber ink as well as to improve the tensile strength of the printed parts. Different formulations were tested to study and facilitate the vulcanization process and identify the optimal curing conditions as well as the print parameters to use in DIW printing. The successful printing and vulcanization of various printed structures demonstrates the potential for using the developed printable ink in additive manufacturing. This study opens up new possibilities for creating rubber products (such as tire treads) with adequate flexibility and high tensile strength.