Fully compounded elastomers are important for a range of applications including tires, seals, footwear, and soft robotics. 3D printing of fully compounded rubber is still relatively unexplored area. This work describes the 3D printing of a fully compounded thermoset elastomer based on sulfur cured nitrile butadiene rubber (NBR) with a carbon black filler. Current printing processes are not suitable for typical compounded elastomers due to their low modulus and high viscosity. Thus, entirely new printing methodologies are needed to print these materials. This research investigated the creation of new printing approaches for thermoset elastomers and the effect of material behavior on the printing process. Critical cure behavior (scorch time), high viscosity, and post-print shrinkage were three key challenges in the process to print the NBR compound. The effect of scorch time of thermoset elastomers on the printing process is described by comparing Rubber Process Analyzer (RPA) data. It was found that the scorch time and the viscosity were key parameters in the printing process. Post-print and after cure shrinkage of NBR compounds is a challenge for dimensional accuracy. Shrinkage, tensile modulus, elongation at break, and hardness of the printed materials were characterized. Properties of compression-molded control samples and printed samples were compared. The results showed the 3D printed elastomer samples had good properties with high elongation to break.

3D printing of fully compounded thermoset elastomers

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.