Additive manufacturing of silicone composite structures with continuous carbon fiber reinforcement

As a relatively new material deployed in additive manufacturing (AM), silicone and its composites have the potential to realize tunable functionality and heterogeneous, architected properties for a number of applications requiring low modulus, elastic materials. Continuous fiber reinforced composites have been developed for AM to achieve various complex structures that are lightweight with high mechanical properties. AM of silicone-based composites with direct ink writing (DIW) technology has potential application in medical devices, gasket components, flexible soft electronics, and food packaging. However, DIW printed materials have mechanical anisotropy since the extrusion-based printing process creates small changes in geometry during the material deposition process. In addition, silicone elastomers are relatively low modulus in tension and can be reinforced with woven cloth or fibers. In this work, a continuous fiber AM machine is developed to manufacture silicone composite structures with continuous fiber reinforcing the printed silicone. Tensile tests show that the anisotropic property of the perpendicular printed specimens, relative to the tension direction, has been significantly improved by continuous carbon fiber reinforcements. This continuous fiber silicone reinforcement printing technique can be applied to tune fiber volume ratios and orientations for different silicone composite structures to meet the desired strength and stiffness.