Support medium development for 3D printing natural rubber latex via direct ink writing in the support bath technique

The direct manufacturing of rubber products from natural rubber latex through 3D printing, particularly extrusion in air, faces challenges in creating intricate shapes. Research suggests that utilizing 3D printing with extrusion in a support medium, known as direct ink writing (DIW), is effective for crafting complex-shaped rubber products. However, few studies have explored 3D printing natural rubber as a support medium. This study focuses on formulating a support medium for the DIW printing of natural rubber by incorporating triethanolamine (TEA) and alcohol in varying proportions. Key characteristics, such as viscosity, were assessed for each formulation, along with essential printing parameters, such as speed and flow rate. A suitable support liquid consisting of TEA (2.5 g), alcohol (160 g), Carbopol (1.5 g), and water (200 g) was determined for DIW printing natural rubber. The optimal settings were determined to be a nozzle size of 0.85 mm, a speed of 30 mm/s, and a flow rate of 30 mm³/s. Comparative results from the forming process indicate that 3D-printed rubber specimens exhibit poorer mechanical properties than traditionally molded specimens, owing to material uniformity. The vulcanized rubber system with the EV pattern exhibited superior mechanical characteristics. The developed support medium for DIW printing shows potential for use in intricate natural rubber products; however, further exploration of additional parameters is crucial for advancing complex-shaped natural rubber manufacturing using 3D printers.