Optimization of Extrusion Three-Dimensional Printing Liquid Silicone Rubber: Managing Thermal History and...

Liquid silicone rubber (LSR) materials are often used in the manufacture of flexible circuit board substrates for wearable devices. However, traditional processing techniques limit the improvement of the molding precision and make it difficult to process complex structures. Three-dimensional (3D) printing is a novel manufacturing method for LSR wearable devices. The influence of the internal temperature field on LSR's curing time was evaluated. The printing performance and mechanical properties were analyzed with three inks (SiO₂/PEG/LSR, PEG/LSR, and LSR) with polyethylene glycol (PEG) and silicon dioxide (SiO₂) modifying LSR. Furthermore, orthogonal experiments were conducted to optimize the material ratios, and the entropy weight method was applied to establish a comprehensive evaluation function that incorporates printable duration, tensile strength, and needle blockage. Under the optimal printing temperature (25 °C), it was clear that the performance of SiO₂/PEG/LSR was the best. The forming accuracy of its line width was 98.5%, the tensile strength was 72.96% higher than pure LSR, and the impact strength remained at ∼6.1 MPa (equivalent to pure LSR). Orthogonal analysis confirmed the LSR dosage as the most significant influence on printability and mechanical properties, and the optimized material ratio was determined as LSR:PEG:SiO₂ = 300:30:1 (by weight). The optimized materials combined with rheological experiments have demonstrated that integrating the thermal history with material modification to improve the printing performance of extrusion-based 3D printing is effective.