Material extrusion additive manufacturing of dual material composite thermoset silicone components

Additive manufacturing (AM) is a disruptive manufacturing process that gives designers freedom to create highly complex shapes through free-form fabrication. The majority of polymers used in extrusion AM are thermoplastics because they are easy to process in affordable machines. While there are a number of moderate modulus thermoplastics in regular use in AM, thermoplastics are known to weaken with increases in temperature or exposure to solvents and many commodity thermoplastics used in AM are brittle. On the other hand, there are few elastomers, and even fewer elastomer reinforcement schemes, that are accessible using standard AM technologies. In this work, we report a novel dual extrusion process that integrates elastomeric silicone with reinforcing thermoplastic. By developing and demonstrating a dual extrusion 3D printer that can process common thermoplastics with commercially available thermosetting silicones, new types of composite elastomers are reported with good mechanical performance. The 0(degrees)/20(degrees)/-20(degrees) grid pattern thermoplastic reinforced samples achieved 2.5 MPa tensile strength in low extension region (0.5 strain), which improves the initial stiffness of the composite component. Desired mechanical responses of composite structures can be realized by tuning the reinforcement volume ratio and infill percentages, and applying various types of reinforcement mesh patterns and thermoplastics.Highlights A dual extrusion process integrates fus filament fabrication and direct ink writing technologies. Thermoplastic reinforced silicone composite with stiff/soft properties. Tunable volume ratio, infill percentage, mesh pattern, and material option.